Chemistry

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Phytochemical investigation and biological activities of genus Corydalis
(Institute of Sciece & Technology, 2024-12) Maharjan, Binita; Dr. Ram Lal (Swagat) Shrestha
The Himalayan region in Nepal is home to high-altitude flora known for their rich bioactive compounds. These compounds hold significant medicinal value and have been traditionally used to treat a variety of diseases. Among these, species of the Corydalis genus are recognized for their abundance of isoquinoline alkaloids, known for their diverse bioactivities. The three species, Corydalis chaerophylla, collected from Phulchowki, Lalitpur and C. govaniana, and C. casimiriana, collected from Langtang, Rasuwa, Nepal were extracted sequentially with hexane, methanol, and chloroform. The extracts of C. chaerophylla were subjected to liquid chromatography diode array detection multiple stage mass spectrometry (LC-DAD-MSn) analysis, resulting in the identification of fifteen alkaloids. Antimicrobial testing of extracts revealed significant inhibition with methanol and chloroform extracts, supported by high phenolic content (113 mg GAE/g in chloroform) and antioxidant activity (IC50 = 261.5 μg/mL in the DPPH assay). The methanol extract exhibited strong α-amylase inhibitory activity (IC50 = 51.52 μg/mL), highlighting its potential as an antidiabetic agent, but was less toxic in brine shrimp lethality analysis (LC50 = 196 μg/mL) compared to the chloroform extract. However, in vivo acute oral toxicity studies showed toxic effects for methanol (LD50 = 1000.36 mg/kg BW) and chloroform (LD50 = 515 mg/kg BW) extracts, requiring careful dose optimization for therapeutic applications. Chromatographic separation of chloroform extracts of different Corydalis species led to the isolation of thirteen pure alkaloids, including four new compounds from whose structures were elucidated by 1D and 2D NMR spectroscopy and mass spectrometry. The energy and force minimized molecular structures of these four compounds were obtained from quantum mechanical calculations using Becke, 3-parameter, Lee–Yang–Parr (B3LYP) functional and 6-31G* basis set at the density functional theory (DFT) level. The new identified compounds were named as Chaeronepaline-A (1), Chaeronepaline-B (2), Chaeronepaline-C (3), and Chaeronepaline-D (4), respectively, owing to the C. chaerophylla species from Nepal. Additionally, known alkaloids such as bicuculline (5), corydalmine (6), 8-hydroxydihydrosanguinarine (7), dihydrosanguinarine (8), and scoulerine (9) were isolated from C. chaerophylla, while govaniadine (10), was isolated and characterized from C. govaniana and stylopine (11), adlumine (12), and adlumidine (13) were identified from C. casimiriana. In a first set of experiment, berberine, californidine, and govaniadine demonstrated low-density lipoprotein receptor (LDLR) induction in human hepatocyte model similar to 2.5 μM simvastatin. Californidine and berberine decreased proprotein convertase subtilisin/kexin type 9 (PCSK9) expression, contrasting with simvastatin, which increased PCSK9. Govaniadine showed a statin-like effect by increasing both LDLR and PCSK9 levels. Further testing in the hepatocyte model showed that berberine, californidine, and govaniadine reduced total cholesterol levels, suggesting a promising hypocholesterolemic effect. Also, in the second set, the newly isolated alkaloids (1-4) were also evaluated in Huh7 cells to examine their impact on LDLR and PCSK9 expression and cholesterol biosynthesis for potential hypocholesterolemic activity. Results indicated that compounds 2 and 3 increased LDLR expression and inhibited cholesterol synthesis, with compound 2 additionally reducing PCSK9 secretion in Huh7 cells. Thus, this study identified and characterized bioactive alkaloids from Corydalis species, with compound 2 (chaeronepaline-B) demonstrating significant hypocholesterolemic potential by modulating LDLR, PCSK9, and cholesterol biosynthesis pathways. These findings highlight the therapeutic promise of Corydalis alkaloids, warranting further in vivo validation. नेपालको हिमाली क्षेत्रका उच्च भू-भागमा पाइने वनस्पतिहरू जैविक सक्रिय यौगिकहरूले भरिपूर्ण छन् । यी यौगिकहरूले महत्वपूर्ण औषधीय मूल्य राख्दछन् र परम्परागत रूपमा विभिन्न रोगहरूको उपचारका लागि प्रयोग हुँदै आएका छन् । Corydalis प्रजातिले जैविक सक्रियता देखाउनुका साथै यसमा आइसोक्विनोलिन एल्कालोइडहरू प्रचुर मात्रामा पाईन्छन् । नेपालबाट सङ्कलित Corydalis chaerophylla, C. govaniana र C. casimiriana को नमूनाहरूमा हेक्जेन, मिथानोल, र क्लोरोफर्म जस्ता घोलकको प्रयोग गरी सङ्कलित गरियो । C. chaerophylla का हेक्जेन, मिथानोल, र क्लोरोफर्मका एक्सट्राक्टहरूलाई LC-DAD-MSn विश्लेषण द्वारा १५ विभिन्न प्रकारका एल्कालोइडहरू पहिचान गरियो । मिथानोल र क्लोरोफर्म एक्सट्राक्टहरूले चार प्रकारका जीवाणु र एक ढुसी विरुद्ध महत्वपूर्ण गतिविधि देखाए, जसमा क्लोरोफर्म एक्सट्राक्टले उच्च फिनोलिक सामग्री (११३ mg GAE/g) र DPPH Assay मा उत्कृष्ट एन्टिअक्सिडेन्ट क्षमता (IC50 २६१.५ μg/mL) देखायो। मिथानोल एक्सट्राक्टले अल्फा–एमाइलेज अवरोध (IC50 ५१.५२ μg/mL) र कम विषाक्तता (LC50 १९६ μg/mL) देखायो, तर इन भिभो टक्सिसिटी परीक्षणले मिथानोल र क्लोरोफर्मका LD50 क्रमशः १०००.३६ र ५१५ mg/kg BW रहेको देखायो। तीनवटै बिरुवाहरूका क्लोरोफर्म एक्सट्राक्टहरूलाई क्रोमाटोग्राफिक विधिबाट १३ विभिन्न शुद्ध एल्कालोइडहरू अलग गरियो, जसमा Corydalis chaerophylla बाट चार नयाँ एल्कालोइडहरू पत्ता लगाइयो । यी नयाँ यौगिकहरूको संरचना 1D र 2D स्पेक्ट्रोस्कोपी र मास स्पेक्ट्रोमेट्री प्रयोग गरी व्याख्या गरियो । यी चार यौगिकहरूको ऊर्जा र बल न्यूनतम आणविक संरचनाहरू B3LYP कार्यात्मक र 6-31G* आधार DFT स्तरमा सेट प्रयोग गरेर क्वान्टम मेकानिकल गणनाहरूबाट प्राप्त गरियो । तिनीहरूलाई क्रमशः Chaeronepaline-A (१), Chaeronepaline-B (२), Chaeronepaline-C (३), Chaeronepaline-D (४) नाम दिइयो । यस्तै, C. chaerophylla बाट bicuculline (५), corydalmine (६), 8-hydroxydihydrosanguinarine (७), dihydrosanguinarine (८), scoulerine (९) जस्ता ज्ञात यौगिकहरू अलग गरिएको थियो, भने C. govaniana बाट govaniadine (१०) अलग गरी पहिचान गरिएको थियो र stylopine (११), adlumine (१२), तथा adlumidine (१३) लाई C. casimiriana बाट पहिचान गरिएको थियो । Berberine, californidine र govaniadine ले LDLR वृद्धि गर्ने गुण देखायो, जुन Simvastatine को तुलनामा लगभग समान थियो । Californidine र berberine ले PCSK9 को प्रभाव कम गरे, जबकि govaniadine ले स्टाटिन–जस्तै प्रभाव देखायो । नयाँ एल्कालोइडहरू (१–४) लाई Huh7 कोषहरूमा LDLR र PCSK9 को एक्सप्रेशन र कोलेस्ट्रोल बायोसिन्थेसिसमा तिनीहरूको प्रभाव मूल्याङ्कन गर्न परीक्षण गरियो । परिणामले यौगिक २ र ३ ले LDLR वृद्धि गरेको र कोलेस्ट्रोल संश्लेषण रोक्ने प्रतिक्रिया देखियो । यौगिक २ ले PCSK9 को स्राव पनि घटायो, जसले यसलाई सम्भावित हाइपोक्लोलेस्टेरोलिमिक एजेन्टको रूपमा संकेत गर्‍यो । यी निष्कर्षहरूले Corydalis एल्कलॉइडहरूको चिकित्सीय सम्भावनालाई प्रकाश पार्छ, जसले थप in vivo अनुसन्धानको आवश्यकता देखाउँछ।
Kinetics for Oxidation of Penicillanic Acid Derivatives by Per-Iodatocuperate (III) Complexes In The Presence Of Cobalt (III) Catalyst in Alkaline Medium
(Institute of Science & Technology, 2024-06) Sahu, Yuv Raj; Prof. Dr. ajaya Bhattarai
Ampicillin, amoxicillin, dicloxacillin carbenicillin, and oxacillin are penicillanic acid derivatives (PADs) or β-lactam antibiotics. After consumption of these PADs or antibiotics for a selected purpose, non-degraded forms of these species are accumulated in the environment from waste-water, hospitals, and sewage or land-fill sites. The oxidation process is a kind of degrading method of these antibiotics from environmental aqueous medium. The kinetics and mechanism of oxidation of Penicillanic acid derivatives by diperiodatocuprate [DPC (III)] and Co (III) Chloride catalyst in the aqueous alkaline medium were studied UV/Visible spectrophotometrically at 298 K and ionic strength of 0.10 mol dm-3. After checking their melting points and re-crystallization of these penicillanic acids, from Sigma Aldrich trade, solutions were prepared and stored after confirmation of concentration iodometrically. The reagent DPC (III) was synthesized by Jaiswal and Yadava method. The formation of DPC (III) reagent was confirmed by the appearance of a peak by UV/Visible spectrophotometer and showed maximum absorbance peak at 415 nm. The reaction between DPC (III) and ampicillin in aqueous alkaline medium showed (AMP: DPC-III) 1:4 stoichiometry. The reaction between DPC (III) and amoxicillin showed (AMX: DPC-III) 1:2 stoichiometry. Similarly, one mole of dicloxacillin consumes 4 moles of DPC (III) and one mole of carbenicillin consumed 4 moles of DPC (III) in aqueous alkaline medium while stoichiometry of oxacillin and DPC (III) was declared to be 1:4. The reaction products, in each re-dox reaction, were identified by spot test, CHNS, FT-IR, and LC-MS spectral studies. The reactions were of pseudo-first-order with respect to DPC (III) concentration and fractional order with respect to AMP / AMX / DCLX / CRBC/OXC as well as alkali concentration. The addition of periodate showed a retarding effect on the rate of oxidation and was of negative fractional order. Monoperiodatocuprate (MPC-III) was found to be the main active species in the alkaline medium in the form of [Cu (H2IO6)(H2O)2] or [Cu (H3IO6)(H2O)2]+. Absorbance collected from UV/Visible spectrophotometer was converted into uncatalyzed (kU) , catalyzed (kc), and thence total rate constant (kT), and these data were used to verify the Beer- Lambert’s law, and many more plots like order plots, verification plots, etc. Catalytic constant (KC) was also calculated. Stoichiometry of different reactions for the complex formation was determined from Job’s method. Depending on stoichiometry and other evidence like FT-IR, LC-MS, and CHNS, a probable reaction mechanism was also proposed for each redox reaction. Different equilibrium constants (K1, K2, and K3) were calculated. Slopes and intercepts obtained from these verification plots were utilized to calculate variable activation as well as thermodynamic parameters and thence computed. एम्पिसिलिन, एमोक्सिसिलिन, डिक्लोक्सासिलिन, कार्बेनिसिलिन र ओक्सासिलिन पेनिसिलिक एसिड डेरिभेटिभ्स (PADs) वा बिटा-ल्याक्टम एन्टिबायोटिक हुन्। यी PADs वा एन्टिबायोटिकहरू चयन गरिएको उद्देश्यका लागि उपभोग गरेपछि, यी प्रजातिहरूको गैर-अपघटित रूपहरू फोहोर-पानी, अस्पतालहरू, र ढल वा ल्यान्ड-फिल साइटहरूबाट वातावरणमा जम्मा हुन्छन्। ओक्सीकरण प्रक्रिया यी एन्टिबायोटिकहरूको एक प्रकारको क्षरण वा खण्डीकरण विधि हो। जलीय क्षारीय माध्यममा diperiodatocuprate [DPC (III)] र Co (III) क्लोराइड उत्प्रेरक द्वारा पेनिसिलिक एसिड डेरिभेटिभहरूको अक्सीकरणको गतिविज्ञान र संयन्त्रलाई 298 K र 0.10 d mol को आयनिक शक्तिमा UV/दृश्यमान स्पेक्ट्रोफोटोमेट्रिक रूपमा अध्ययन गरियो। सिग्मा एल्ड्रिच ट्रेडका यी पेनिसिलिक एसिडहरूको पग्लने बिन्दुहरू र पुन: क्रिस्टलाइजेसन जाँच गरेपछि, आयोडोमेट्रिक विधिबाट Concentration पुष्टि भएपछि स्तरयुक्त घोलहरु तयार गरी भण्डार गरिएको थियो। अभिकर्मक अथवा अक्सिडेन्ट DPC (III) जैसवाल र यादव विधिबाट संश्लेषित गरिएको थियो। DPC (III) अभिकर्मक को गठन UV/दृश्य स्पेक्ट्रोफोटोमिटरबाट शिखर को उपस्थितिले पुष्टि गरिएको थियो र 415 nm मा अधिकतम अवशोषण शिखर देखायो। जलीय क्षारीय माध्यममा DPC (III) र एम्पिसिलिन बीचको प्रतिक्रिया (AMP: DPC-III) 1:4 stoichiometry देखायो। त्यस्तै, DPC (III) र amoxicillin बीचको प्रतिक्रिया (AMX: DPC-III) 1:2 stoichiometry देखायो। त्यसैगरी, DPC (III) र कार्बेनिसिलिनको बीचको प्रतिक्रिया (CRBC: DPC-III) 1:4 stoichiometry, DPC (III) र डाइक्लोक्सासिलिनको बीचको प्रतिक्रिया (DCLX: DPC-III) 1:4 stoichiometry र DPC (III) र oxacillin बीचको प्रतिक्रिया (OXC: DPC-III) 1:4 stoichiometry देखायो। प्रत्येक अक्सीकरण -रिडक्सन—अक्सीडेसन_ प्रतिक्रियाका उत्पादनहरू स्पट टेस्ट, CHNS, FT-IR, र LC-MS स्पेक्ट्रल अध्ययनहरूका सहयोगले पहिचान गरिएको थियो। प्रतिक्रियाहरू DPC (III) र AMP / AMX / DCLX / CRBC/ OXC साथै क्षार एकाग्रताको सन्दर्भमा आंशिक क्रमको सम्बन्धमा छद्म-पहिलो-क्रमका थिए। Periodate को थपले अक्सीकरण दरमा रिटार्डिङ प्रभाव देखायो र नकारात्मक अंशात्मक क्रमको पाइयो। मोनोपेरियोडाटोक्युप्रेट (MPC-III) क्षारीय माध्यममा [Cu (H2IO6)(H2O)2] वा [Cu (H3IO6)(H2O)2]+ को रूपमा मुख्य सक्रिय रहेको पाइयो। UV/Visible spectrophotometer बाट सङ्कलन गरिएको absorbance लाई uncatalyzed (kU) दर स्थिर, उत्प्रेरित (kc) दर स्थिराँक र त्यसपछि कुल दर स्थिराँक (kT), उत्प्रेरक स्थिराँक (KC) र स्लो स्टेप दर (k) स्थिराँकमा रूपान्तरण गरिएको थियो । यी डाटाहरू बियर-लाम्बर्टको नियम प्रमाणित गर्न प्रयोग गरियो र अर्डर रेखाचित्र, प्रमाणीकरण रेखाचित्रहरू आदि बनाइयो। कम्पलेक्स संरचनाको लागि विभिन्न अक्सीकरण प्रतिक्रियाहरूको स्टोइचियोमेट्री चाहि Job's विधिबाट निर्धारण गरिएको थियो। stoichiometry र FT-IR, LC-MS र CHNS जस्ता अन्य प्रमाणहरूमा निर्भर गर्दै, प्रत्येक अक्सीकरण प्रतिक्रियाको लागि एक सम्भावित प्रतिक्रिया संयन्त्र पनि प्रस्ताव गरिएको थियो। विभिन्न सन्तुलन स्थिरांक (K1, K2, र K3) गणना गरियो। यी रेखाचित्रहरूबाट प्राप्त Slopes र Intercepts का सहयोगले Activational स्थिराँक चर सक्रियता र थर्मोडायनामिक प्यारामिटरहरू गणना गरियो।
Isolation and Characterization of Antibiotics from Actinomycetes Collected in Nepal
(Institute of Science & Technology, 2024-07) Thapa, Bijaya Bahadur; Prof.Dr. Nirajan Parajuli, Dr.Khaga Raj Sharma
Actinomycetes are a distinct class of Gram-positive bacteria with a filamentous mycelium-like that of fungi. They produce many potential antitumor, anticancer, and antimicrobials; a key source of biologically active compounds to combat infectious diseases and others. Moreover, multi-drug resistant (MDR) pathogens cause serious problems in both humans and animals. This issue demands a need for stronger antimicrobial agents. This research has examined the secondary metabolites produced by soil-based actinomycetes collected in various parts of Nepal. Actinomycetes were isolated from soils by using the International Streptomyces Project 4 (ISP4) medium. Most of the aerial mycelia of bacterial isolates had a greyish-white color whereas some of them appeared bluish-white. The prominent colonies of isolated bacteria were cultured in a Tryptic Soy Broth (TSB) medium. The Gram-positive nature of the isolated bacteria was confirmed by Gram staining. Ethyl acetate extracts of the isolates were prepared after shake flask fermentation in the TSB medium. The antimicrobial activity of the isolates was carried out against Staphylococcus aureus American Type Culture Collection (ATCC) 43300, Shigella sonnei ATCC 25931, Salmonella typhi ATCC 14028, Klebsiella pneumoniae ATCC 700603 and Escherichia coli ATCC 25922 bacteria, and observed through primary and secondary microbiological screening. Primary screening of the isolates was performed by the perpendicular-streaking method. Most of the isolates showed strong antimicrobial activity against the tested pathogens. A total of 11 bacterial isolates exhibited significant zones of inhibition against both Gram-positive and Gram-negative pathogens. Isolates BT1, BT2, BT3, AB1, PT7, and PC1 showed greater antimicrobial efficacy against tested pathogens based on their minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values. Isolates BT5, BT13, BT33, BT36, and BT39 exhibited remarkable antimicrobial efficacy against tested pathogens. Among the isolates, isolate PC1 showed the highest zone of inhibition (32 mm. against E. coli, 30 mm. against S. typhi, 30 mm. against S. sonnei, and 30 mm. against K. pneumoniae) in all tested pathogens except in S. aureus. The genomic deoxyribonucleic acid (DNA) of the isolated bacteria was extracted using the standard protocol of molecular biology. The amplified polymerase chain reaction (PCR) product was then subjected to 16S Ribosomal ribonucleic acid (rRNA) sequencing. As such this study identified five Streptomyces species (Streptomyces sp.BT1, Streptomyces sp. BT2, Streptomyces sp. BT3, Streptomyces sp. BT5 and Streptomyces sp. PC1). The metabolic profiles of the ethyl acetate extracts were investigated using liquid chromatography-high resolution tandem mass spectrometry (LC-HRMS/MS). Fifty-eight compounds were annotated from the raw data files of tandem mass using MestReNova (Mnova) software. Then, the annotated compounds were further validated through SIRIUS software. Out of the annotated compounds from LC-HRMS/MS, four of them were detected for the first time in Streptomyces species, namely Cyclo(Ile-Ser) from isolate BT2, 2-n-hexyl-5-n-propylresorcinol from isolate BT1, 3-((6-methylpyrazin-2-yl)methyl)-1H-indole from isolate PC1, and Cyclo(D-Leu-L-Trp) from isolate BT2. Total 7 antibiotics were annotated which were myxopyronin B, blasticidin H, flavofungin, xenocoumacin 2, okilactomycin A, butyrolactol A and SF2415-B2. Accordingly, this research identified that Nepal's varied ecology offers ideal circumstances for the existence of several Streptomyces species from the soil habitat which can produce specialized secondary metabolites including antibiotics. This study set up a platform in Nepal, which inspired for isolation of rare actinomycetes, which could produce new therapeutics including antibiotics.
COVID-19 Global Pandemic: Analysis of Secondary Metabolites from Natural Products to Aid the Engineering of Drugs
(Institute of Science and Technology, 2024-08) Shrestha, Asmita; Dr. Salyan Bhattarai, Dr. Khaga Raj Sharma
SARS-CoV-2 (Severe acute respiratory syndrome coronavirus 2), the pathogenic agent of Coronavirus (CoV) disease-19 (COVID-19), has wreaked havoc around the world since the end of 2019, underscoring the need for effective COVID-19 treatment. Even though COVID-19 is no longer a pandemic, research should still be done to find effective treatments for these potentially lethal CoVs because new and deadly CoVs can appear at any time and represent a threat of spreading new CoV pandemics. The frequent unfolding of new mutants of the virus may impose serious concerns again regarding the efficacy of therapeutic agents, therefore any advancement toward the development of potent antiviral medications is always critical. Since secondary metabolites have been used to cure several ailments, they could be useful in managing COVID-19. Quantitative understanding and characterization of dynamic molecular processes are key issues in modern biology and need sophisticated computational experimental methodologies to get molecular-level information on ligand-binding configurations, interactions, and dynamic conformational landscapes. To better understand the basis of the activity of secondary metabolites with biological activity, this research incorporated the pharmacokinetics study, molecular docking, molecular dynamics simulations, binding free energy (BFE) calculation, and density functional theory (DFT) analyses utilizing different computational tools followed by spike protein assays. The study began with the selection of a diverse library of 191 metabolites relying on their antiviral properties known for their potential bioactivities. These metabolites were screened against key viral proteins: S1-RBD of spike (S) protein and RNA-dependent-RNA-polymerase (RdRp); involved in the viral entry, replication, and infection processes of SARS-CoV-2. Based on in silico investigation, cordifolioside A was identified to be the most potent of the 26 secondary metabolites selected from Tinospora Species. It showed proper binding free energy of -25.09 kcal/mol, significant GOLD fitness score (58.27), reactivity, suitable pharmacokinetic profile along with considerable stability with target S1-RBD of SARS-CoV-2. Furthermore, the in vitro experiment using Tinospora cordifolia crude extract, which was conducted because it contains an appropriate quantity of cordifolioside A, revealed that it inhibits the binding of human angiotensin converting enzyme 2 (hACE2) with S1-RBD of SARS-CoV-2 by 50 % at a concentration of approximately 1.25 mg/mL. Of the 36 flavonoids, cyanidin was determined to be the more potent due to its adequate pharmacokinetic profile, binding free energy (-25.09 kcal/mol) with proper interactions, GOLD fitness score of 51.91, appropriate stability of its complex with S1-RBD, and sufficient reactivity. Additionally, as cyanidin is present in red grapes (Vitis vinifera), in vitro investigation is carried out on it and the findings indicate that it significantly interferes by 50 % at a concentration of approximately 1.25 mg/mL to the interaction of hACE2 with S1-RBD of SARS-CoV-2. Neferine, an alkaloid, was found to be an inhibitor of RdRp and S1-RBD of SARS-CoV-2 among screened 79 selected compounds. Neferine exhibited the appropriate stability and reactivity when complexed with RdRp, exhibiting an S-score of -5.083 and a binding energy of -9.1 kcal/mol. Neferine also demonstrated notable interactions with key amino acid residues in S1-RBD of the SARS-CoV-2 Omicron variant, with a binding energy of -7.6 kcal/mol and in vitro assay of neferine shows its acceptable binding with S1-RBD accompanied by IC50 of 99.60 ± 0.328 μg/mL. Among the 50 terpenes, cryptotanshinone was discovered to be a strong inhibitor of the S1-RBD Omicron variant, exhibiting stability, proper pharmacokinetic profile, and good binding affinity (-7.6 kcal/mol) with target protein. With an IC50 of 25.5 ± 0.463 µg/mL, cryptotanshinone was able to inhibit the binding of hACE 2 with S1-RBD of the SARS-CoV-2 Omicron variant, validating the results of the in silico analysis. In conclusion, this thesis offers a comprehensive computational study for the identification of secondary metabolites with potential inhibitory effects against SARS-CoV-2. The results present a significant contribution to the search for effective and safe treatments for COVID-19. Further preclinical investigation is necessary to validate and optimize these promising metabolites as potential COVID-19 therapeutics. कोभिड–१९ -COVID–19_ रोगको सङक्रमण सार्स–कोभ–२ -SARS–CoV–2_ नामक भाइरसको कारणले हुन्छ । जसले विश्वमा सन् २०१९ को अन्त्यबाट जटिल स्वास्थ्य समस्या सिर्जना गरेको थियो । पछिल्लो समय कोभिड–१९ को जोखिम विश्वमा कम भएता पनि यसको पुर्ण निवारण वा निर्मुल भएको अवस्था छैन । विभिन्न कारणले गर्दा सार्स–कोभ–२ मा म्युटेशन (एमिनो एसिडमा बदलाब हुने रसायनिक क्रिया) भई यसको नयाँ स्वरूपहरु -Variants_ संसारमा देखा परिरहेका छन् । भाइरसको नयाँ स्वरूपले यसबाट हुने सङक्रमणको जोखिम कायम नै राखेको छ । त्यसैले यस विषयमा थप वैज्ञानिक अनुसन्धानको आवश्यकता रहेको देखिन्छ । सार्स–कोभ–२ मा हुने यस्तो म्युटेसनले चिकित्साशास्त्रका क्षेत्रमा थप चिन्ता र चासो थपेको छ । त्यसैले भरपर्दो एन्टिभाइरल औषधी वा खोपको विकास तर्फ अझै प्रगती गर्नु पर्ने देखिएको छ । वनस्पतीबाट भाइरस नियन्त्रणको लागि औषधीजन्य गुण भएका यौगिक पत्ता लगाउनु यस अनुसन्धानको प्रमुख उदेश्य हो किनकी वैज्ञानिकहरूले गरेका यस अगाडीका शोधले पनि त्यस्तो संभावना प्रष्टाएको छ । त्यस्ता यौगिकले सार्स–कोभ–२ को प्रोटिनमा के कस्तो रसायनिक गुण देखाउछ, सोको गहन खोजमा यो अध्ययन केन्द्रित गरिएको छ । जसको लागि यस अनुसन्धानमा फार्माकोकाइनेटिक्स अध्ययन -Pharmacokinetics study_, मलिक्युलर डकिङ् -Molecular docking_, मलिक्युलर सिमुलेशन -Molecular Dynamics Simulation_, र डेन्सिटी फङसन सिद्धान्त -DFT_ मा आधारित विश्लेषण विभिन्न कम्प्यूटेशनल सफ्टवेयरको माध्यमबाट गरिएको छ । यस अनुसन्धानमा वनस्पतीबाट निकालिएका १९१ वटा यौगिकमा सार्स–कोभ–२ को स्पाइक प्रोटिन -Spike Protein_ र आरएनए–डिपेन्डेन्ट–आरएनए–पोलिमरेज -RdRp_ मा कम्प्यूटेशनल अध्ययन गरिएको छ । मलिक्युलर सिमुलेशन नामक कम्प्युटेशन अनुसन्धानले यसको थप पुष्टी पनि गरेको छ । यस्तो सैध्दान्तिक अनुसन्धानलाई थप वैज्ञानिक आधारहरू प्रदान गर्न प्रयोगशालामा आधारित प्रोटिन एस्से -Protein assay_पनि गरिएको छ । इन सिलिको -In silico_ अनुसन्धानको आधारमा, टिनोस्पोरा प्रजातिहरूबाट -Tinospora species_चयन गरिएका २६ secondary मेटाबोलाइटहरूमध्ये कर्डिफोलियोसाइड ए लाई -cordifolioside A_ सबैभन्दा शक्तिशाली मानिएको छ । यसले (-@%=)( kcal/mol) को उचित binding free energy, महत्त्वपूर्ण गोल्ड -GOLD_ फिटनेस स्कोर, प्रतिक्रियाशीलता, उपयुक्त फार्माकोकाइनेटिक प्रोफाइल -pharmacokinetic profile_ र SARS–CoV–2 को लक्ष्य S1–RBD सँग पर्याप्त स्थिरता देखाएको छ । यस बाहेक, Tinospora cordifolia कच्चा एक्स्ट्र्याक्ट प्रयोग गरी इन भिट्रो (in vitro) सञ्चालन गरिएको थियो किनभने यसमा कर्डिफोलियोसाइड ए को उपयुक्त मात्रा हुन्छ, यसले SARS–CoV–2 को S1–RBD सँग मानव एन्जियाटेन्सिन रूपान्तरण गर्ने इन्जाइम 2 (ACE2) लाई लगभग !.@% mg/mL को एकाग्रतामा ५० % ले बाइन्ड गर्न रोक्छ । ३६ फ्लेभोनोइडहरू मध्ये, cyanidin, यसको पर्याप्त फार्माकोकाइनेटिक प्रोफाइल, उचित अन्तरक्रियाको साथ binding free energy (-@%=)( kcal/mol) , ५१.९१ को गोल्ड फिटनेस स्कोर, S1–RBD संग यसको कम्प्लेक्सको उपयुक्त स्थिरता, र पर्याप्त प्रतिक्रियाशीलता। थप रूपमा, रातो अंगूर -Vitis vinifera_ मा साइनिडिन (cyanidin) पाइने भएकोले, यसले SARS–CoV–2 को S1–RBD सँग मानव एन्जियोटेन्सिन रूपान्तरण गर्ने इन्जाइम 2 (ACE2) लाई लगभग !.@% mg/mL को एकाग्रतामा ५० % ले बाइन्ड गर्न रोक्छ। स्क्रिन गरी चयन गरिएका ७९ एल्कालोइडहरूमध्ये नेफेरिन -neferine_ SARS–CoV–2 को RdRp र S1–RBD को अवरोधक भएको पाइयो । RdRp संग bind हुँदा neferine ले उपयुक्त स्थिरता र प्रतिक्रियाशीलता प्रदर्शन गर्यो, –५.०८३ को S–स्कोर र –(=! kcal/mol को binding energy प्रदर्शन गर्दै नेफेरिनले SARS–CoV–2 Omicron भेरियन्टको S1–RBD मा मुख्य एमिनो एसिड अवशेषहरूसँग (amino acid residues) –&=^ kcal/mol को binding energy को साथ उल्लेखनीय अन्तरक्रिया पनि प्रदर्शन ग¥यो र नेफेरिनको इन भिट्रो परीक्षणले S1-RBD सँग ९९.६० + ०.३२८ μg/mL को IC50 सँग स्वीकार्य बाइन्डिङ देखाउँछ । ५० ट्रपिनहरू -terpenes_ मध्ये, क्रिप्टोटानशिनोन -cryptotanshinone_ S1–RBD ओमिक्रोन भेरियन्टको बलियो अवरोधकको रूपमा पत्ता लगाइएको छ, जसले स्थिरता, उचित फार्माकोकाइनेटिक प्रोफाइल, र लक्ष्य प्रोटीनको साथ राम्रो बन्धन सम्बन्ध (–७.६ kcal/mol_ प्रदर्शन गर्दछ । इन सिलिको विश्लेषणको नतिजालाई प्रमाणित गर्दै २५.५ + ०.४६३ µg/mL को IC50 सँग, क्रिप्टोटान्सिनोनले SARS–CoV–2 Omicron भेरियन्टको S1–RBD सँग hACE 2 को बाइन्डिङ्लाई रोक्न सक्षम छ । यस अनुसन्धानले कोभिड–१९ को औषधी विकास गर्न प्रभावकारी र सुरक्षित उपचारहरूको खोजीमा महत्वपूर्ण योगदान प्रस्तुत गरेको छ ।
Synergetic effect of the addition of Nono-Silica in Red Clay-Based Geopolymer product
(2024) Gurung, Sunil; Arvind Pathak
Available in fulltext
GREEN SYNTHESIS OF SILVER/ZINC OXIDE NANOCOMPOSITES USING LEAF EXTRACT OF DESMOSTACHYA BIPINNATA (KUSH) AND STUDY OF ITS PHOTOCATALYTIC ACTIVITIES
(Amrit Campus, 2024-10-28) Anita Bhattarai; Ramesh
Removing organic pollutants including textile waste solution and dyes has become an essential requirement for maintaining a secure and healthy environment. Therefore, the present study deals with the synthesis of ZnO and Ag/ZnO nanocomposites using the leaf extract of Desmostachya bipinnata. The leaf extract of Desmostachya bipinnata contained a different bio-active compound that serves the dual purpose of acting as stabilizing and reducing agents. Out of various methods, green synthesis has been extensively employed for its simplicity, low-cost, and eco-friendly nature. The characterization of the as-synthesized ZnO and Ag/ZnO nanocomposties were subjected to ultra violet visible (UV-vis) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD). XRD pattern revealed the crystalline nature of nanoparticles. The crystallite size of Ag/ZnO was found to be 12-14 nm, according to Debye Scherer formula. The synthesized NPs and NCs were used for the catalytic photodegradation of Methylene blue (MB). The MB was degraded at room temperature under exposure to UV light. The degradation efficiency of ZnO, and 25 % Ag/ZnO were found to be 79 % and 85 %, respectively. Therefore, it was found that Ag/ZnO nanocomposites have potential to degrade MB as organic dye, and can be used for wastewater treatment.
Study on effect of sodium stearate surfactant in mixed solvent media
(2024) Yadav, Brahma Deo; : Prof. Dr. Ajaya Bhattarai
The specific conductivity of sodium stearate(SS) surfactant in double distilled water, different percentage of methanol are studied by conductometric method at three temperatures (298.15, 308. 15, 318.15) K. The Critical Micelle Concentration (CMC) of sodium Stearate is determined at all temperatures. CMC is increased with an increase in temperature of the solution. the CMC of SS in distilled water at (298.15, 308. 15, 318.15) K. is 0.0008M, 0.0010M, 0.0020M was obtained . The specific conductance is decreased with increase in percentage of methanol in the solution. The corrosion rate of surfactant is observed. FESEM image, EDX graph shows the purity of the sample. The percentage of elements present in sodium stearate surfactant is explained by EDX data. The percentage of C, O, Na, sodium stearate surfactant is observed 77, 14.2, 2.5 percent by weight.
Iresine herbstii stem alkaloids as green inhibitor for mild steel corrosion in M H2SO4 solution
(2024) Pant, Naresh Prashad; Dr. Deval prasad Bhattarai
The study examined the methanol extract obtained from Irsine herbstii stem as a green inhibitor for mild steel corrosion in a 1M H2S04 environment. Characterization of the extract was carried out using Fourier Transform Infrared Spectroscopy and potentiostat. Additionally, inhibition efficiency was determined through both weight loss and electrochemical measurement methods, with results indicating a maximum inhibition efficiency of 87.28%. Thermodynamic parameters further confirmed the feasibility and spontaneity of the adsorption process. Overall, the findings underscored the potential effectiveness of the inhibitor derived from Irsine herbstii alkoloid extract in mitigating mild steel corrosion in acidic environments.
Estimation of Copper in Copper Ores Collected from Jangkot Rolpa, Nepal
(2024-06) Rajaure, Anil; Dr. Deval Prasad Bhattarai
Nepal is a country rich in natural resources. There is evidence of the presence of mines of different types of elements, but scientific research in this field is found to be less. Zinc, iron, copper, etc. are the major sources of mines here which have been extracted since time immemorial. But these days, significant research and extraction of such minerals have not been found to occur. In this context, it seems desirable to study and research the mines available in Nepal. In this study, five samples of copper ores were collected from Jangkot Rolpa and examined using Titrimetric analysis, atomic absorption spectroscopy and x-ray diffraction (XRD) methods. The results show that sample C1RJ has the highest copper concentration (2.20% by titration and 1.64% by AAS) among the test samples, indicating that the collected samples contain extractable amounts of copper in that location. The XRD results confirms the ores are auzurite, malachite, cuprite and chalcocite. However, further research is required to carry out the quality of the copper deposit.
Status of arsenic contamination in the groundwater of nawalparasi west district and Remediation Using ZnCL2 Activated sugarcane bagasse as bioadsorbent
(2024-06) Ghimire, Khag Raj; : Dr. Bhoj Raj Poudel
Groundwater sources contaminated by arsenic represent a global threat to the environment and living organisms, including humans. Exposure to arsenic for a long period would have a severe health impact. Various conventional techniques are being applied to treat arsenic contaminated water, which are either expensive or less efficient. So, there is a need to develop cost-effective alternative technologies for the removal of arsenic. This research will investigate the possibility of using agro-waste like sugarcane bagasse as a readily available, affordable, eco-friendly bioadsorbent for remediation of toxic pollutants from water. The main target of this study is to develop a novel adsorbent from sugarcane bagasse by ZnCl2 activation. As it is reported that Nawalparasi West district in Lumbini Province has a high concentration of arsenic in ground water, the performance of bio-adsorbent will be examined by 30 different samples from arsenic contaminated area of Nawalparasi. The material which will be developed in this research from sugarcane bagasse is supposed to be efficient and selective for specified arsenic. The batch experiment will be carried out under varying experimental conditions. The kinetics of the adsorption reaction and the adsorption isotherm will be studied. The experimental results will be applied to the treatment of ground water samples from Ramgram municipality, Nawalparasi west district.
Green synthesis of Silver nanoparticles using Rudraksha extracts:characterization and its applications for antimicrobial activities
(Institute of Science & Technology, 2024-06) Jha, Gautam Kumar; Dr. BHOJ RAJ POUDEL
Different methods are reported for synthesis of AgNPs. In this research green synthesis of AgNPs is used as it is simple, economical, environmentally friendly and nontoxic process. Leaves extract of Rudraksha plant has been used for synthesis of AgNPs. Rudraksha and AgNPs both have antimicrobial activity. Green Reduction Ag+ was carried out. Phytochemicals present in leaves extract was studied at room temperature. The Synthesized AgNPs was characterized using techniques UV -visible Spectral analysis, XRD, and FTIR followed by assessment of antimicrobial property against some bacteria and fungus of extract, AgNPs and their composite 1:1 mass ratio. The size of synthesized AgNPs was about 11.93nm. The antimicrobial activity of AgNPs was enhanced by leaf extract of Rudraksha.
Analisys of Bioactive Phytochemicals and Study of Antimicrobial Activity From Methanolic Extract of Roots of Streptopus streptopoides
(Institute of Science & Technology, 2024-06) Subedee, Anup; Dr. Deval prasad Bhattarai
Traditional practice of using medicinal plants have been the foundation of modern medicine. Streptopus streptopoides is a plant of traditional medicinal value. This report focuses in the phytochemical analysis of root parts of Streptopus streptopoides collected from Gorkha and study of biological activity of the extract. Methanolic extract of root was used for the analysis. Herein, three hundred grams of dried powder of the root of the plant was processed to extraction using methanol. The extract of S. streptopoides root solution was subjected to primary phytochemical screening. Methanol extract method revealed the presence of various phytochemicals. Total flavonoid content (TFC) in methanol has been reported to be 1.92±0.36 mg QE/g. It indicated the prescence of very low content of flavonoid in the plant sample. The total phenolic content (TPC) in methanol extract has been quantified to be 50.37 ± 0.44 mg GAE/g. Nauplii started dying at the concentration of 50 ppm. 50% (or more) of the tested nauplli died at the highest concentration of 100 ppm. Hence, LC50 of methanol extract is at 100 ppm (100 µg/mL).
Photocatalytic degradation of commonly used organic dye in Nepal using nanoparticles
(Institute of Science & Technology, 2024-04) Shrestha Pradhanang, Situ; Prof. Dr. Rajesh Pandit
The utilization of organic dyes across various industries has significantly contributed to the vibrant colors in fabrics, papers, and wools. However, the release of these dyes into water bodies poses a significant environmental challenge due to their persistent nature as pollutants. To address this issue, researchers have been exploring different methods for the removal of dye pollutants from water, with nanoparticles emerging as promising catalysts for degradation processes under light exposure. In this research work, zirconia (ZrO2) and hydroxyapatite (HAp) nanomaterials were investigated as photocatalysts for degrading methylene blue, a prevalent dye in Nepal. Employing an eco-friendly green synthesis route, both nanomaterials were successfully prepared and characterized using techniques such as X-ray diffraction (XRD), Fourier Transmission-Infrared spectroscopy (FT-IR), and UV- Visible spectroscopy. FTIR analysis confirmed the successful green synthesis of zirconia and hydroxyapatite, while XRD results indicated their nanometric size range. The degradation of methylene blue was conducted using the synthesized nanomaterials under sunlight exposure, with degradation efficiency dependent on nanoparticle dosage and dye concentration. Notably, both ZrO2 and HAp nanoparticles exhibited significant efficacy in dye degradation, with ZrO2 demonstrating superior performance at low dye concentrations and HAp exhibiting remarkable effectiveness at higher nanoparticle doses. This research underscores the promising potential of ZrO2 and HAp nanoparticles as efficient catalysts for mitigating organic dye pollution in water bodies, offering a sustainable approach to address this pressing environmental challenge.
Exploration of Antidiabetic, Antioxidant and Anticancer Potential of Zanthoxylum armatum, Sarcococca wallichii and Sarcococca coriacea from Nepal
(Institute of Science & Technology, 2024-01) Baral, Janaki; Dr. Achyut Adhikari
The present research aims to explore the bioactive potential of extracts, fractions, and selected compounds from the plants' Zanthoxylum armatum DC as well as Sarcococca coriacea and Sarcococca wallichii. The extract of Z. armatum fruit pericarp from Pyuthan district was subjected to bioassay-guided isolation, in vivo antidiabetic, in vivo toxicity studies, and anticancer activities. Bioassay-guided isolation from Z. armatum yielded seven compounds: tambulin (1), prudomestin (2), cinnamic acid (3), cinnamic ester (4), isovanillic acid (5), isoquercetin (6), and ducosterol (7). The structures of the compounds were elucidated using mass spectrometry and 1D-and 2D-NMR spectroscopy techniques. Bioactivities including anti-inflammatory, antioxidant, and anticancer properties, were investigated for extracts, fractions, and compounds, particularly focusing on flavonoids 1 and 2 due to their higher yield. Essential oil extraction was carried out using the Clevenger apparatus through hydro-distillation from the fruit pericarp collected from three major commercial sites, and their GCMS analysis was used to examine volatile components and enantiomeric composition. The antioxidant activities, measured using DPPH, showed increasing activities with IC50 values of ethanolic extract 174.00 ± 1.01, methanolic extract 169.85 ± 0.244, Ethylacetate fraction 42.94 ± 1.19, compound 1 and 2 as 32.65 ± 0.31, 26.96 ± 0.19 µg/mL respectively. Likewise the reactive oxygen species inhibition activities was found potent of ethanolic extract (IC50= 20.7 ± 0.4 µg/mL), methanolic extract (IC50= 27.7 ± 0.7 µg/mL), hexane fraction (IC50= 26.3 ± 1.1 µg/mL), ethyl acetate fraction (IC50 =17.8 ± 1.1 µg/mL), and compounds 1 and 2 (IC50= 7.5 ± 0.3 and 1.5 ± 0.3) µg/mL, respectively as compared to standard ibuprofen (IC50= 11.2 ± 1.9 µg/mL). Molecular docking study of compounds 1 and 2 with cyclooxygenase-2 exhibited optimal binding affinity, with binding energies of -8.4 and -8.6 kcal/mol, respectively compared to standard ibuprofen (-7.7 kcal/mol). Drug likeliness and ADMET analyses indicated superior gastrointestinal absorption for compounds 1 and 2 without any discernible toxic effects. Both the extracts’, hexane fraction, and cinnamic acid (3) possess activity against breast cancer cell line (MCF-7) while extract and hexane fraction were also active against cervical cancer HeLa as measured through MTT assay. Compounds 1 and 2 demonstrated the highest insulin secretion activities at 200 mM and 50 mM, respectively at optimal stimulatory glucose (11-25 mM). Molecular docking and simulation studies of compound 2 with an insulin-secreting target were performed and found to be binding with excellent stability. The GC-MS analysis of essential oil indicated linalool as the major constituent. The hexane fraction’s odorant and olfactory sensory molecules exhibited the qualities of a bio-pesticide. Acute toxicity results showed an LD50 value of 565.68 mg/kg body weight in the case of healthy Swiss albino mice and the histopathological studies indicated inflammatory changes and polymorphs in the pancreas and kidney, and liver necrosis in higher doses. The extract was nontoxic to healthy Long Evans Rats. In vivo antidiabetic studies on Long Evans Rats revealed significant results in lowering blood glucose at (p<0.041, p<0.023, and p<0.003) 25 mg/Kg, 50 mg/Kg, and the standard drug respectively. A dose of 25 mg/Kg significantly (p<0.02) increased hepatic glycogen while 50 mg was significant in hyperlipidemia and in increasing HDL. Bioassay-guided isolation of Sarcococca wallichii Staph. dichloromethane fraction yielded four different compounds Na-Methylepipachysamine D (8), taraxerol (9), beta-sitosterol (10), and oleanolic acid (11). Hydro-methanoic extract of S. coriacea leaf Sc-A, steam Sc-S, and chloroform fraction of S. wallichii at pH 7 (Sw-D) were evaluated for various bioassays and found to be good to potent active. Specifically, Sc-A exhibited notable inhibition against digestive enzymes α-glucosidase (IC50= 39.92 ± 2.52 μg/mL) and α-amylase (IC50= 224.3 ± 1.87 μg/mL), while Sw-D inhibited α-amylase (IC50= 2.116 ± 0.058 μg/mL) exceeding the standard acarbose (IC50= 6.18 ± 0.97μg/mL). Furthermore, antioxidant activities were observed in Sc-A (IC50= 24.56±3.3 μg/mL), Sc-S (IC50= 28.90 ± 5.22 μg/mL) and Sw-D (IC50= 53.79 ± 2.50 μg/mL). Cytotoxicity assessment against breast cancer (MCF-7) revealed an (IC50= 11.50 ± 0.50 μg/mL) for a basic fraction (Sc-B) of S. coriacea while its neutral chloroform fraction (Sc-N) exhibited an (IC50 =68.42±5 μg/mL). Anticancer activity against cervical cancer (HeLa) was observed for Sc-B (IC50 =36.33 ± 10) and Sc-N (IC50 =85.5 ± 5). Sc-B also possesses remarkable antibacterial activities against S. aureus, E. coli, Salmonella typhi. यस् विद्यावारीधी सोधकार्र्यको उद्देश्य वनस्पति जान्थोक्साइम आर्माटम डिसि,सार्कोकोका वालिची स्टाफ र सार्कोकोका कोरिएसि हुक एफ मा रहेका जैविक क्रियाशीलता बिषेसगरी एन्टीडाइबेटीक, एन्टीअक्सीडेन्ट र एन्टीक्यान्सर गुणको खोज गर्नु हो। प्युठान जिल्लाबाट संकलन गरिएको बिज निकालिएको टिमुरको दानाबाट मिथानोलिक र इथानोलिक एक्स्ट्रायाक्ट बनाईएको थियो उत्त इथानोलिक एक्स्ट्रायाकलाई बिभिन्न पोलारिटीको रसाइनिक तत्वमा घोलेर बिभाजन गरियो। उक्त बिभाजनबाट बायोएसे निर्देशनमा इथाइलएसिटेट फ्राक्सनको कोलम क्रोम्याटोग्राफी गरी बिभिन्न सात यौगिकहरु प्राप्त भए । ती यौगिकहरु क्रमसः टाम्बुलिन (१), प्रुडोमेस्टिन (२),सिनामिक एसिड (३), सिनामिक एस्टर (४), इसोव्यानिलिक एसिड (५), इसोक्वर्सेटिन (६),र ड्यूकोस्टेरोल(७) रहेका छन् । यी यौगिकहरुको संरचनाहरुलाई मास स्पेक्ट्रौमेट्री र १–डी र २–डी–एनएमआर स्पेक्ट्रोस्कोपी उपकरण द्वारा पत्ता लगाइयको थियो । एक्सट्रयाक्टहरु, भागहरु र फ्लाभोनोइड यौगिकहरु १ र २ को उच्च मात्राको कारणले थप जैव गतिविधिहरु, गरिएको थियो । तीन मुख्य व्यापारिक स्थलहरु म्याग्दी, सुर्खेत, र सल्यानबाट संकलन गरिएको टीमुरको बिज निकालिएको बोक्राबाट तेल निकाल्नका लागि क्लेभेन्जर उपकरणको प्रयोग गरिएको थियो । सो तेलको जीसीएमएसको माध्यमबाट उद्वेगी यौगिकहरु र एनान्सियोमेरिक संरचना परीक्षण गरिएको थियो। डीपीपीएचद्धारा मापन गरिएको एन्टीआँक्सिडेन्ट एक्टिभिटि,क्रमसः एथानोलिक एक्सट्रयाक्ट आइसि फिप्टी भ्यालु १७४.००±१.०१ माइक्रोग्राम प्रति मि.लि., मेथानोलिक एक्सट्रयाक्टको आइसि फिफ्टी भ्यालु १६९.८५ ± ०.२४४ माइक्रोग्राम प्रति मि.लि., इथाइलेसेटेट फ्रायाक्शनको आइसि फिफ्टी भ्यालु ४२.९४± १ माइक्रोग्राम प्रति मि.लि. तथा योगिक १ र २ को आइसी फिफ्टीभ्यालु क्रमस (३२.६५±०.३१, २६.९६ ±०.१९) माइक्रोग्राम प्रति मि.लि. पाईयो । त्यसैगरी, रिएक्टिभ अक्सीजन स्पेसिस (आरओएस्) गतिविधिमा एथानोलिक एक्सट्रयाक्ट प्रवल पाईयो, आइसी फिफ्टी भ्यालु २०.७ ±०.४ माइक्रोग्राम प्रति मि.लि., मेथानोलिक एक्सट्रयाक्टको आइसी फिफ्टी भ्यालु २७.७ ± ०.७ माइक्रोग्राम प्रति मि.लि., हेक्सेन फ्रायाक्शनको आइसी फिफ्टी भ्यालु २६.३ ± १.१ माइक्रोग्राम प्रति मि.लि., इथाइलेसेटेट फ्र्याक्शनको आइसी फिफ्टी भ्यालु १७.८± १.१ माइक्रोग्राम प्रति मि.लि., र सो एक्टीभिटी बढीप्रदर्सन गर्नेहरुमा क्रमस योगिक १ र २ पाईयो आइसी फिफ्टी भ्यालु ७.५±०.३ र १.५± ०.३० माइक्रोग्राम प्रति मि.लि. भने स्टैण्डर्ड आइब्रोफनको आइसी फिफ्टी भ्यालु ११.२ ± १.९ माइक्रोग्राम प्रति मि.लि. थियो। यौगिकहरु १ र २ को साइक्लोआँक्सीजनेज २ (सीओएक्स–२) सँगको मोलेकुलर डोकिङ्ग अध्ययनले श्रेष्ठ बाइनिडङ एफिनिटि पदर्शन गरेकोमा यौगिकहरु १ र २ को बाइन्डिङ ऊर्जा –८.४ र –८.६ किलोक्यालोरिेप्रति मोल देखायको थियो, जवकी आइब्रोफेनको -७.७ किलोक्यालोरी प्रति मोल थियो। ड्रगलाईकलिनेस् र एडमेट बिश्लेषणले पनि यि दुबै यौगिकहरु १ र २ लाई औसधिय तत्वमा सामेल गर्न निर्देसित गरेको थियो। उत्त एक्स्ट्रायकहरु, हेक्सेन बिभाजन र सिनामिक एसिडले (३) स्तनको क्यान्सर (एमसीएफ–७) बिरुद्ध साइटोटोक्सिक गतिबिधि देखाए। एक्स्ट्रायकहरु, र हेक्सेन बिभाजनले गर्भाशयको क्यान्सर (होला) बिरुद्ध पनि राम्रो गतिबिधि देखाए । योग १ र २ ले सिर्स इन्सुलिन सेक्रेसन गतिबिधिहरु २०० मिमो र ५० मिमोमा उत्तम प्रेरित गुल्कोज(११–२५) मिमोमा देखाए । यौगिक २ सँग इन्सुलिन सेक्रेसनको मोलेकुलर डोकिङ र सिमुलेसन अध्ययनले उत्कृष्ट स्थिरतासहित बाइन्डिङ गरेको देखायो । प्रसोधन गरिएको तेलको जीसी–एमयस बिश्लेषणले लिनालुललाई प्रमुख घटकको रुपमा देखाएको थियो । हेक्सेन भागको सुगंध र अणुहरुले बायो–कीटनाशकको गुण प्रदर्शन गरेको थियो। ऐक्युट बिषमता परीक्षणका परिणामले स्वास्थ्य स्विस आल्बिनो माइसहरुमा शरीरभारको ५६५.६८ मिलीग्राम प्रतिकिलोग्रामको एलडीफिफ्टी भ्यालु प्रदर्शन गरेको थियो, र हिस्टोप्यथोलोजिकल अध्यययनले पेनक्रीयाज र कलेजोमा सुजन रहेको तथा कलेजोमा नेक्रोसिस देखाएको थियो । एक्सट्रयाक्टको असर स्वस्थ लङ इभान्स मुसामा देखीएन । लङ इभान्स डाइबेटिक मुसाहरुमा गरेको इन भिभो अध्ययनले २५ मिग्राप्रतिकिलो, ५० मिग्राप्रतिकिलो मिथानोलिक एक्सट्रयाक्ट र स्ट्यान्डर्ड ग्लीकाजाइडले रक्त ग्ल्युकोजमा क्रमसः कमी गरेको थियो (पि < ०.०४१, पि < ०. ०२३, र पि < ०.००३) । २५ मिग्राप्रतिकिलो डोजले हेपाटिक ग्लाइकोजन उच्च परिणाम प्रदर्शन गरेको थियो (पि <०.०२), जवकी ५० मिग्राप्रतिकिलोले हाइपरलिपिडेमिया र एच्.डी.एल.वृद्धिमा प्रमुख भुमिका देखाएको थियो । पूर्वअध्ययनको आधारमा रहेर अनुसन्धान सुचारु गरीएको वनस्पति सार्कोकोका कोरिएसि हुक एफ, र सार्कोकोका वाल्लिची स्टाफ ले उत्कृष्ट गतिबिधिहरु जस्तै एन्टीडायबेटिक, एन्टीआँक्सीडेन्ट, साइटोटोक्सिक र एन्टीब्याक्टीरियल देखाए।सार्कोकोक्सा वालिची स्टाफ डीसिएम भागको कोलम् क्रोमाटोग्राफीद्वारा चार बिभिन्न यौगहरु, एनए-मेथाइलइपिपासस्यामिन डी (८), टारक्सेरोल (९),बेटा-साइटोस्टेरोल (१०), र ओलिएनोलिक एसिड (११) प्रदान गरेको थियो । एस्. कोरिएसि, एस्–ए र एस्– बीएसको पात र डाँठको हाइड्रौ मेथानोइक एक्सट्रयाक्ट र एस् कोरिएसि क्लोरोफर्म फ्राक्सन् पिएच् सात र एस् वालिचिको डीसीएम् फ्राक्सन् (एस् डबलु डि) लाई बिभिन्न गतिबिधिहरुको मापन गर्दा राम्रो तथा उत्कृस्ट देखियो । खासगरी एस्सि ए ले पाचन प्रकृयाको इन्जायम् अल्फाग्ल्यूकोसिडेज बिरुद्ध आईसि फिफ्टी भ्यालु ३९.९२ ± २.५२ माइक्रोग्राम प्रति मि.लि. र एल्फाअमाईलेज बिरुद्ध आईसि फिफ्टी भ्यालु २२४.३ ± १.८७ माइक्रोग्राम प्रति मि.लि. अवरोध देखाए जवकि, एस्डब्लू डीले एल्फाअमाईलेज बिरुद्ध आईसि फिफ्टी भ्यालु २.११६ ± ०.०५८ माइक्रोग्राम प्रति मि.लि. र स्टान्डरड एकारबोजको आईसि फिफ्टी भ्यालु ६.१८ ± ०.९७ माइक्रोग्राम प्रति मि.लि. थियो । एन्टीआँक्सीडेन्ट मापनले देखायको प्रतिफल अनुसार एस्सि ए आईसि फिटि भ्यालु २४.५६±३.३ माइक्रोग्राम प्रति मि.लि एस्सी बिएस आईसि फिफ्टी भ्यालु २८.९० ± ५.२२ माइक्रोग्राम प्रति मि.लि. र एसडब्लु डीले आईसि फिफ्टी भ्यालु ५३.७९ ± २.५० माइक्रोग्राम प्रति मि.लि. मा प्रदर्शन गरेको थियो । स्तनको क्यान्सर (एमसीएफ–७) बिरुद्ध साइटोटोक्सिक अध्ययनले एससी बी भागले आईसि फिफ्टी भ्यालु ११.५० ± ०.५० माइक्रोग्राम प्रति मि.लि. र तत्कालीन न्यूटर्ल क्लोरोफर्म भागले आईसि फिफ्टी भ्यालु ६८.४२±५ माइक्रोग्राम प्रति मि.लि. प्रदर्शन गरेको थियो । गर्भाशयको क्यान्सर (होला) बिरुद्ध को अनुसन्धानले एससी बीको आईसि फिफ्टी भ्यालु ३६.३३ ± १० र एससी एनले आईसि फिफ्टी भ्यालु ८५.५ ±५ प्रदर्शन गरेको थियो । एस. बी. ले राम्रो आन्टिबक्टरियल गतिबिदी देखियो बिशेस गरी बाक्टएरिया अ एस. औरेअस्, ई. कोली, र सल्मोनेल्ल टाईय्फी बक्टएरियाहरुमा ।
Functionalization of nanocarbons of different dimensionalities and study the physical properties of their nanocomposites with the thermosetting polymer
(Institute of Science & Technology, 2024-01) Sonam Tamang; Dr. Sabita Shrestha
The epoxy/nanocarbon (EP/NCs) nanocomposites were prepared by incorporating NCs of different dimensionalities (such as multiwalled carbon nanotubes; MWCNTs (1D), graphite nanoplatelets; GnP (2D) and nanodiamond; ND (0D), aiming at enhancing their physical and electrical properties thus making them useful in various applications. The NCs were functionalized to a different extent and added to the EP matrix. The functionalization of NCs was confirmed by spectroscopic, thermal and diffraction techniques. The prepared nanocomposites were further characterized by different spectroscopic, thermal and microscopic methods. The electrical and surface wetting properties of those materials were discussed in correlation to their morphologies. The chemical modifications of the NCs were confirmed by Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy showing different oxygen containing functional and increased intensity ratio of D and G band value indicating a high degree of graphitization. The increase in interlayer distance was observed after the acid treatment and the thermal degradation of the acid-treated nanocarbons occurred at lower temperatures also evidencing their successful functionalization. The structural and morphological analysis of the nanocomposites confirmed that there was an effective dispersion between the NCs and epoxy (EP) matrix. In addition to this the hydroxyl functional group was also observed in the case of the acid-treated samples of CNTs, microscopic investigations displayed the brittle nature of the neat epoxy and the addition of nanocarbons on epoxy prevented cracks from propagating, increased the area of the fractured surface and provided a high resistance to fracture. The well-dispersed and cluster-free dispersion of CNTs in the EP/pCNT nanocomposite was observed and the pull-out of the CNTs was also witnessed in the epoxy nanocomposites with pristine CNTs. The thermal stability of EP/NCs composites containing separately pristine and acid-treated nanocarbons was improved slightly in the range of 5-13 ℃. The resistivity of EP/pCNT nanocomposites was found to be decreased as high as about 40 times compared to acid-treated nanocomposites. The higher resistivity of Ep/mCNT was attributed to the shortening of CNT length thereby altering its aspect ratio on acid treatment. On the contrary, acid-treated graphite showed as high as about 35 times decrease in resistivity than that of the pristine graphite because of the well dispersion of graphite particles on the EP matrix. However, in terms of surface wetting properties surface modification of NCs enhances hydrophilicity and wettability of EP/NCs nanocomposites प्रस्तुत अनुसन्धान कार्यमा मुलत: विभिन्न आयामिकतायुक्त नानोकार्बनहरु (जस्तै एक आयामिक कार्बन नानोट्यूब, द्वैआयामिक ग्राफाइट नानोप्लेटलेट तथा सुन्यआयामिक नानोडायमंड) लाई एपोक्सी रेजिन नामक थर्मोसेटिङ् पोलिमरसँग बिभिन्न अनुपातमा मिलाएर नानोकम्पोजिटका नमुनाहरु तयार गरि तिनिहरुको भौतिक एवं विद्युतीय लक्षणहरु जस्ता व्यवहारोपयोगी गुणहरुको अध्ययन प्रसतुत गरिएको छ। यसका लागि प्रत्येक नानोकार्बनको सतहमा उपयुक्त विधिद्वारा विभिन्न परिमाणमा रासायनिक क्रियाशिलताको उद्भब गराई त्यासलाई एपोक्सी रेजिन भित्र समानरुपले घुलाइएको थियो। नानोकार्बनको सतहमा आरोपित रासायनिक क्रियाशिलताको पुष्टिका खातिर प्रकाशपटिय (Spectroscopy), तापिय (Thermal) तथा विवर्तन (Diffraction) विधिहरूको सहयोग लिइएको थियो। अनुसन्धान कार्यका दौरान तयार पारिएका नानोकम्पोजिटहरूका विभिन्न गुणहरूको अवलोकनार्थ पनि प्रकाशपटिय, तापिय, विवर्तन तथा सुक्ष्मदर्शक यन्त्रिय विधिहरूको प्रयोग गरिएको थियो। साथै आन्तरिक शुक्ष्म वनोटको आधारमा ति बस्तुहरुका विद्युतीय एवं सतह संबन्धित गुणहरूको व्याख्या गरिएको थियो। नानोकार्बनहरुको सतहमा रासायानिक परिवर्तन भए नभएको फोरिएर ट्रान्स्फर्म ईन्फ्रारेड (FTIR) तथा रमण स्पेक्ट्रोस्कोपीद्वारा निधो गरिएको थियो। त्यसवाट क्रमशः नानोकणिकाको सतहमा विभिन्न अक्सिजनयुक्त प्रतिक्रियात्मक समुहहरु जोडीएका तथा डि (D) र जी (G) ब्याण्डको तिव्रताको अनुपात (जसलाई नानोकणिकाको ग्राफाईटमा रुपान्तरण भएको सुचकको रुपमा लिइन्छ) पनि केही हदसम्म बढेको पाईयो । अम्लसंगको संसर्गपछि नानोकणिकाका आपसि तहहरु विचको दूरीमा वृद्धि भएको तथा तिनिहरुको उच्च तापक्रममा तताउंदा तौल ह्रास हुने तापमानमा पनि गिरावट आएकोवाट ति कणको सतहमा प्रतिक्रियात्माक समुहहरु जोड्ने कार्य सफल भएको निर्क्यौल गरिएको थियो। नानोकम्पोजिटहरूको संरचनात्मक र रुपात्मक विश्लेषण गर्दा एपोक्सि रेजिन थर्मोसेटीङ्ग पोलिमर र नानोकणिकाहरु बीच प्रभावकारी अन्तरवन्धन (intertwine) भएको पुष्टी भयो । यसका साथै नानोकणिकाहरुको अम्लसंग प्रतिकृया गरेपस्चात तिनिहरुको सतहमा हाइड्रोक्सिल समूहहरु पनि जोडीएका तथा सुक्ष्मदर्शक यन्त्रद्वारा गरिएको अध्ययनले विसुध्द एपोक्सि रेजिनले ब्रिटल प्रकृति देखाए पनि नानोकार्वन पोलिमरसंग मिसाए पश्चात यिनीहरुले यान्त्रिक वलद्वारा उत्पन्न हुन सक्ने शुक्ष्मदरार (Microcrack) लाई रोक्ने तथा शक्ति शोषक सतहको क्षेत्रफल बढाएर उक्त पदार्थको तात्कालिक बिघटनलाई प्रतिरोध गर्ने क्षमतालाई समेत बढाएको पाईयो। एक आयामिक नानोकार्वन, कार्बन नानोट्यूब, को पोलिमरको भित्रि आयतनसम्म राम्रोसंग फैलावट भएको तथ्य त्यसको एपोक्सि रेजिनसंगको मिश्रणको शुक्ष्म अध्ययनमा राम्रोसँग देख्न पाईन्छ। साथै शुद्ध अवस्था र अम्लसँग प्रतिक्रिया पस्चात प्राप्त भएको नानोकार्वन प्रयोग गरी तयार गरिएका नानोकम्पोजिटहरूको थर्मल स्थिरतामा ५-१३ ℃ तापक्रमले वृद्धि भएको पाइयो। शुद्ध नानोकार्बन प्रयोग गरी बनाइएको नानोकम्पोजिटहरूको विद्युतीय प्रतिरोधात्मकता अम्लसँग प्रतिक्रिया पश्चात प्राप्त भएको भन्दा लगभग ४० गुणाले कम भएको पाइयो। प्राप्त नतिजाहरुको विश्लेषणबाट यो निस्कर्षमा पुगिन्छ कि नानोकार्वनको अम्लसँग प्रतिक्रिया गराउँदा यीनिहरुको वनोटलाई खन्डित भई आस्पेक्ट अनुपात परिवर्तन हुन्छ र कम्पोजिटको विद्युतीय गुणमा नकारात्मक असर गर्दछ। यसको विपरीत अम्लसँग प्रतिक्रिया गरेका द्वैआयामिक नानोकार्वन (जस्तै ग्राफाइट नानोप्लेटलेट) एपोक्सि रेजिनसंग राम्रोसँग फैलिएर बनेको हुनाले नानोकम्पोजिटको विद्युतीय प्रतिरोधात्मकता शुद्ध अवस्थाको नानोकार्वन भएको नानोकम्पोजिटको तुलनामा लगभग ३५ गुणाले कम भएको देखियो। नानोकम्पोजिटहरूले आफ्नो सतहमा जलाकर्षण गर्ने गुणहरुलाई केलाउने क्रममा भने रासायानिक रुपमा परिमार्जीत तीनै प्रकारका सूक्ष्म कणहरुले सकारात्मक भूमिका खेलेको पाईयो।
Chemical Characterization, Enantiomeric Distribution, and Bioactivity Analysis of Essential Oil from the Selected Lamiaceae Plants of Nepal and Their Application in Topical Formulation
(Department of Chemical Science and Engineering School of Science Kathmandu University, 2023-12) Prem Narayan Paudel; Prof. Dr. Rajendra Gyawali ; Supervisor
Essential oils (EOs) are complex mixtures of biologically active volatile compounds that have been utilized for a long time as flavoring agents, preservatives, and natural ingredients in many commercial products. In recent years, they have drawn great attention due to their increasing demand for food, cosmetics, and pharmaceuticals. Since many studies have revealed the good antimicrobial, antioxidant, and toxicity activities of essential oils, it is very important to characterize them based on their chemical profiles. In the present study, some selective plants from the Lamiaceae family of Nepal were collected to determine the chemical composition, enantiomeric distribution, and biological activities. The hydro-distilled essential oils were characterized for volatile compounds by Gas Chromatography and Mass Spectrometry (GC-MS), GC-Flame Ionization Detection (GC-FID), and enantiomeric composition by Chiral GC-MS. The chemometric analysis was applied to identify the chemotaxonomic relationship among Lamiaceae essential oils. The antimicrobial property was evaluated by the microbroth dilution method using some ATCC bacterial and fungal strains. The antioxidant activity was determined by DPPH and ABTS radical-scavenging assays. The in vitro cytotoxicity was evaluated in human breast cancer (MCF-7) and fibroblast (NIH-3T3) cell lines by using the Cell Counting Kit-8 kit assay. The antioxidant-rich essential oils were blended into the cream formulation. The results revealed the variation in the yield of essential oils with harvesting seasons. The species showed higher essential oil yield in the summer season and tropical regions than others. Ocimum tenuiflorum L. had the highest concentration (1.68±0.13%), and Leucosceptrum canum Sm. had the lowest yield among the samples (0.15±0.05%). The average essential oil yield obtained from the Lamiaceae plant species in Nepal was about 0.76%. Oxygenated monoterpenes were the dominant class of terpenoids present in most of the essential oil samples, with concentrations above 49%. Mentha pulegium L. showed the highest proportion of oxygenated monoterpenes (91.63%), followed by Mentha spicata L. (85.3%) and Perilla frutescens (L.) (83.05%). The lowest yield of oxygenated monoterpenes was found in Colebrookea oppositifolia Sm. at 0.89%. The single compound, carvone, was detected in the highest concentration for Mentha spicata L. oil (68.51%). The seasonal variations in the chemical composition of essential oils were also detected among the Lamiaceae samples. Origanum majorana L. comprises linalool and terpinen-4-ol as major compounds, with 13.8% and 32.1% in spring, and 15.37% and 33.35% in summer. Similarly, the carvone of M. spicata L. was not much influenced by seasonal variation, with 51.96% in winter and 68.51% in summer. Major constituents of O. tenuiflorum L., eugenol (32.15 to 34.95%), and trans-β-elemene (29.08 to 32.85%) were not much influenced by seasonal variation except minor ones. The same result was also detected in O. basilicum L., where methyl chavicol (62.16–64.42%) and linalool (26.92–27.09%) were not variable during the winter and summer seasons. A minor seasonal variation in the major compounds was observed for M. pulegium L. In contrast, the major constituents of L. canum Sm. were highly influenced by seasonal variations. The leading compound, β-pinene, of L. canum Sm. was found at 29.07% in winter, which decreased to 15.21% during summer. Similarly, another leading compound, β-caryophyllene, of L. canum Sm. was found at 13.29% in winter, which increased to 33.51% during summer, thereby indicating the seasonal variation in the chemical composition of Lamiaceae essential oils. In the chemometric analysis, agglomerative hierarchical cluster analysis for Lamiaceae essential oil showed two main groups of volatile classes: the first dominated by oxygenated monoterpenes and the second by sesquiterpene hydrocarbons. Both principal component analysis and clustered heat maps confirmed the two distinct groups of volatile components as assigned by HCA. The chiral GC-MS revealed several chiral compounds in the essential oil samples. The α-thujene, αpinene, sabinene, β-pinene, camphene, limonene, 1-octen-3-ol, linalool, α-terpineol, cis-sabinene hydrate, menthone, β-caryophyllene, terpinen-4-ol, germacrene D, borneol, β-bisabolene, δcadinene, (E)-β-ionone, and (E)-nerolodol were common chiral compounds in the EO, dominating in the levorotatory form (62.4%). In the DPPH assay, O. tenuiflorum L. exhibited relatively good antioxidant activity (IC50 69.2382.99 µg/mL), when compared to the standards (ascorbic acid, IC50 6.37 µg/mL and BHT, IC50 12.46 µg/mL), and in the ABTS aasay, this essential oil exhibited the strongest activity (IC50 5.88-17.69 µg/mL), when compared to the standards (ascorbic acid, IC50 1.98µg/mL and quercetin, IC50 7.79 µg/mL). The least activity was noted in M. pulegium L. from Nuwakot during the summer with an IC50 value of 646.58 µg/mL in the DPPH assay and with an IC50 value of 145.35 µg/mL in the ABTS assay. The antioxidant activity M. spicata L., P. frutescens (L.), L. canum Sm., and O. majorana L. The essential oils obtained in the summer was higher as compared to the essential oils collected during the winter. In contrast, O. ameicanum L., O.ameicanum L., O. basilicum L., and O. tenuiflorum L. The essential oils collected during winter exhibited higher antioxidant activity than those from the summer. The present study also revealed that the seasons and environmental conditions may influence the photochemistry of plants, thereby affecting their antioxidant properties. Samples from tropical zones had better antioxidant activities than the other parts. The effect of these essential oil samples on the viability of human breast cancer (MCF-7) and fibroblast NIH-3T3 cell lines was also found to be significant. Among the Lamiaceae essential oils, P. frutescens (L.) (IC50 7.41 and 8.14 µg/mL), C. umbrosum (M. Bieb.) C. Koch (IC50 21.70 and 12.53 µg/mL), M. longifolia L. (IC50 23.76 and 12.12 µg/mL), and O. tenuiflorum L. (23.43 µg/mL) samples were highly cytotoxic as compared to other species against both cell lines. While M. pulegium L., M. spicta L., P. glabar Benth., and O. basilicum L. essential oils displayed the least toxicity, with the IC50 values varying from 99.64 to 90.56 µg/mL. Among the essential oil studied against fungal strains, O. majorana L., M. pulegium L., and O. tenuiflorum L. were more effective against Candida albicans and Aspergillus niger (MIC, 78.1 µg/mL). O. majorana L. essential oil exhibited a broad spectrum of antimicrobial activity, with a MIC value of at least 156.3 to 312.5 µg/mL for all tested organisms. For anti-bacterial activity, only slight inhibition of these oils was found against all the tested bacterial strains. Similarly, the essential oils of O. majorana L., O. tenuiflorum L., and O. basilicum L. were utilized for the formulation of cream, which showed the retention of their best efficacy after extensive investigation of several pharmacological parameters. Hence, the present study concluded that the chemotaxonomic profiles of many essential oil samples from the Lamiaceae family of Nepal were prepared. They also exhibited excellent and varied biological efficacies, which can be useful in bioprospecting for the benefit of human health. Keywords: Lamiaceae, Essential Oil, GC-MS, Chemical Composition, Enantiomer, Antioxidant, Antimicrobial, Cytotoxicity, Formulation.
Characterization of the Cellulosic Fiber Obtained from Nepalese Lokta Bushes and Explore its Novel Applications
(Institute of Science and Technology, 2024-05) Aryal , Girja Mani
In Nepal, Handmade papers (HPs) are made from fibrous biomass of several plant species. Paper fabricated from fibrous biomass obtained from Lokta bushes following the traditional eco-friendly method is called Lokta paper or Nepal Kagaj. Handmade paper fabricated from Lokta bushes is being used to fabricate value-added products. The paper is traditionally believed to be durable and bug and mold-resistant. However, a systematic study on the material properties of this paper is not reported yet. Additionally, material properties of Lokta fiber retted under different conditions; which help to understand the performance of Lokta fiber-derived products is not mentioned in the literature. To increase, trade value it is also equally important to find next generation applications of the Lokta paper. This dissertation work was aimed at understanding the material properties of Lokta paper and fiber, and the fabrication of Lokta paper-derived nanocomposite mat for antimicrobial application. It was found that the mean caliper, apparent density, Cobb 60, grammage, brightness, opacity equilibrium moisture content, tensile strength, and tensile index values in the paper samples collected from local enterprises (n=10) ranged from ~90‒700µm, 0.2‒0.4 g/cm3, 50‒150 g/m2, 4‒7%, 50‒400 g/m2, 56‒67 %, 83‒98 %, 30‒2900 N/m, and 1‒27 Nm/g; in that order. These data recommended that Lokta paper is a light weight paper having intermediate to high strength, high caliper variation and relatively low brightness. All paper samples exhibited considerably increased tensile strength across the length axis (p<0.05). Distinctive characteristics of hemi‒cellulose, cellulose, and lignin were spotted in the FTIR spectra of all the samples. The amorphous and crystalline cellulosic segments were detected in X‒ray diffraction (XRD) data. Most importantly, electron microscopic showed a properly cross-linked web of entire fibers organizing a parallel layout of microfibrils. These morphological qualities could be responsible for delivering strength and durability to the paper samples. A comprehensive analysis of material properties of Lokta fiber subjected to 1-9% NaOH (w/v) concentrations at ambient temperature was also performed. The alkali resulted in significant shrinkage of lignin and hemicellulose; thereby increasing the cellulose content. On alkali treatment, fiber width and equilibrium moisture content decreased whilst fiber density, crystallinity index, tensile strength, and thermal stability increased. These changes can be assigned to the deduction of cementing materials from fiber bundles. These findings suggested that processing conditions greatly affect the fiber properties and to get Lokta paper of optical performance fiber chemistry needs to be properly tailored. Finally, Lokta paper-making process was mimicked in laboratory settings and the physico-chemical properties of lab-made Loka paper were compared with commercially available paper. The Ag/ZnO and Cu nanoparticles were doped in the Lokta paper following hydrothermal and chemical reduction methods. The Lokta paper nanocomposite mat showed promising antimicrobial activity contrary to two bacteria (Escherichia coli and Bacillus subtilis) and a fungal strain (Candida Albicans). These observations suggested that the Lokta paper-derived nanocomposite mat can find potential applications as an antimicrobial packaging material.
Preparation of amperometric glucose biosensor by means of electropolymerisation of polyaniline onto graphite
(Department of Chemistry, 2013) Bhusal, Suresh Prasad
In this study, an amperometric glucose biosensor with immobilization of glucose oxidase enzyme on electrochemically polymerized polyaniline film onto graphite surface has been prepared. The immobilization of the enzyme glucose oxidase has been accomplished via the physical entrapment technique. Electropolymerization of aniline onto the suface of the graphite was carried out by cyclic voltammetry (potential range of -0.4V to 1.2V, scan rate 100mV/sec, 10 cycles) by using standard calomel electrode (SCE) as reference and platinum wire as counter. Characterization of the PANi/Graphite was carried out with the aid of cyclic voltammetry in 1M HCl, obtaining three couple of peaks from which the two pair were distinct, having proved the electro-activity of the PANi film. The enzyme was potentiostatically immobilized onto the surface from 0.1M phosphate buffer of pH 6.0 with 200U/mL glucose oxidase (GOx) enzyme. The amperometric response was studied by using hydrodynamic amperometric mode. Determination of glucose was carried out by the measurement of amperometric response obtained during the reduction of enzymatically produced hydrogen peroxide at - 0.4 V vs calomel electrode and platinum wire as counter in phosphate buffer of pH 6.0. Biosensor was found to be responsive within the concentration range of 0.01ML -1 -0.1ML -1 . All experiments were carried out at room temperature.
Synthesis, Characterization, and Antibacterial Evaluation of Metal Complexes of Surfactant Based Schiff Bases
(Institute of Science & Technology, 2024-03) Adhikari, Janak
Modern pharmaceutical science needs more efficient drug delivery systems (DDSs) that permit poorly aqueous soluble drugs to work effectively. Consequently, medications function effectively. Pharmacological science has found Surfactants to be an invaluable alternative for enhancing the potential of conventional drugs and improving the efficacy of drugs with poor water solubility. Solid drugs can be solubilized more easily when surfactant molecules are added and membrane permeability can be increased in lipid layers as a result. In the last few years, the synthesis of transition metal complexes of Schiff bases has drawn a lot of interest as an alternative to coordination compounds for the creation of chelating agents. Metal chelates have suitable biological activities. This research aims to design and develop surfactant-containing Schiff bases and their metal complexes, which can serve as a drug to solve the problems with antibiotic resistance and drug delivery. The study has focused on the structural modification of compounds under study (Pyrrole-2-carboxaldehyde, Pyrrole-3-carboxaldehyde, and Dodecylamine) by forming the Schiff bases and metal complexes and their correlation with bio-functional activities. Given this, two new Schiff bases [DDAP2C and HL (DDAP3C)] have been prepared and further complexed with four transition metal ions, Co2+, Ni2+, Cu2+, and Zn2+. The newly prepared metal complexes and Schiff bases were fully characterized by elemental microanalysis, conductivity measurement, melting point measurement, 1HNMR, 13CNMR, FT-IR, UV/Vis, ESI-mass, MALDI-TOF-mass spectrometry, and magnetic susceptibility, studies. The conductivity data were used to calculate the synthesized compounds' critical micelle concentration (CMC), which was further utilized to derive the Gibbs free energy of micellization (ΔG°m). Thermal stability and kinetic properties of the complexes were determined using thermogravimetric and differential thermal analysis (TGA/DTA). The Coats-Redfern method was used to extract thermodynamic parameters that describe the kinetic activity of the complexes. Most complexes showed high thermal stability and non-spontaneous decomposition steps. The powder X-ray diffraction study was conducted to verify the crystalline nature of the complexes. The Origin and X'pert high score software were used to analyze PXRD data, and the diffractograms were carefully analyzed to get information about the nature of complexes. Most of the complexes were found to crystalline with nanocrystalline size. Scanning electron microscopy (SEM) studies enabled the characterization of the surface morphology of Schiff bases and complexes and revealed their different surface textures. Molecular modeling has provided additional support for the geometry of the complexes determined by spectroscopic methods. The structure optimization was achieved by running the proposed molecular structures in CsChemOffice Ultra 16 and Argus Lab 4.0.1 software with MM force field calculation. The standard Kirby-Bauer paper disk diffusion technique demonstrated the antibacterial potency of the Schiff bases and metal complexes. Several clinical strains of both gram-positive and gram-negative bacteria have been isolated and cultured in laboratories to achieve this objective. They have interacted with synthesized complexes solution prepared in DMSO at variable concentrations. These were further quantified more precisely by performing a minimum inhibitory concentration (MIC) test. In most biological studies, the free Schiff bases and compounds under study were found to have lower antibacterial efficacy than the Schiff base metal complexes. The copper complexes of both the Schiff bases showed excellent antibacterial activity. आधुनिक औषधि विज्ञानलाई अझ प्रभावकारी औषधि वितरण प्रणालीको आवश्यकता छ, जसको उपलब्धताले खराब जलीय घुलनशील औषधिलाई पनि प्रभावकारी रुपमा कार्य गर्ने बाटो खुल्न जान्छ। परिणामस्वरुप औषधिहरूले अझ प्रभावकारी ढंगले आफ्नो कार्य सम्पादन गर्दछन्। फार्माकोलोजिकल विज्ञानले परम्परागत औषधिहरूको प्रभावकारीता बढाउन, खराब जलीय घुलनशिलता एवम् औषधिहरूको प्रभावकारीतामा सुधार गर्न सर्फेक्टेन्टहरूलाई अमूल्य विकल्प को रुपमा पहिचान गरेको छ। जब औषधिहरूमा सर्फेक्टेन्ट अणुहरू थपिन्छ, ठोश औषधिहरूको घुलनशिलतामा बृध्दि हुन जान्छ फलस्वरुप लिपिड तहहरुमा झिल्ली पारगम्यता बढ्न गई औषधिहरूको प्रभावकारीता बढ्न जान्छ। पछिल्ला केही वर्षहरुमा शिफ बेशहरुबाट धातु कमप्लेक्सहरुको सश्लेषण हुने तथ्यले चेलेटिंग एजेन्टहरूको सिर्जनाको लागि समन्वय यौगिकहरुको विकल्पको रुपमा अधिक ध्यान आकर्षण गरेको छ। धातु चेलेटहरुमा उपयुक्त जैविक गतिविधिहरु विद्यमान हुन्छन्। यस अनुसन्धानले सर्फेक्टेन्ट्युक्त शिफ बेशहरु र तिनीहरुका धातु कमप्लेक्सहरुका डिजाइन र विकाश गर्ने लक्ष्य राखेको छ, जसले एन्टिवायोटिक प्रतिरोध र औषधि वितरणको समस्याहरु समाधान हेतु औषधिको रुपमा कार्य सम्पादन गर्न सक्छन्। यो अध्ययनले शिफ बेशहरु र धातु कमप्लेक्सहरु निर्माण पश्चात, अध्ययनमा लिइएका यौगिकहरुको संरचनात्मक परिमार्जन र जैविक-कार्यात्मक गतिविधिहरुसँग तिनीहरुको अन्तर सम्बन्धका बारेमा ध्यान केन्द्रित गरेको छ। यस तथ्यलाई हृदयङ्गम गर्दै, दुई नयाँ शिफ बेशहरु तयार गरी, तिनीहरुको चार धातु आयनहरुसँग (Co2+, Ni2+, Cu2+, & Zn2+) थप धातु कमप्लेक्सहरु बनाइएको छ। नयाँ तयार गरिएका शिफ बेशहरु र धातु कमप्लेक्सहरुलाई सम्पूर्ण रुपमा Elemental microanalysis, चालकता मापन, पग्लने बिन्दु मापन, 1HNMR, 13CNMR, FT-IR, UV-Vis, ESI-mass, MALDI-TOF-mass Spectrometry र चुम्बकीय संवेदनशीलता अध्ययनहरु द्वारा चरित्र चित्रण गरिएको थियो। चालकता तथ्याङ्क सश्लेषित यौगिकहरुको महत्वपूर्ण मिसेलि एकाग्रता (CMC) को गणनाको लागि प्रयोग गरिएको थियो, जुन गिब्स फ्री एनर्जी अफ माइसलाइजेशन (ΔG°m) प्राप्त गर्न पुन: प्रयोग गरिएको थियो। थर्मोग्राभीमेट्रिक र विभेदक थर्मल विश्लेषण प्रयोग गरेर तापीय स्थिरता र कमप्लेक्सहरुको गति सम्बन्धित गुणहरु निर्धारण गरिएको थियो। कोट्स-रेडफर्न (Coats-Redfern) विधि प्रयोग गरी थर्मोडायानामिक प्यारामिटरहरु निकालिएको थियो, जसले कमप्लेक्सहरुको काइनेटिक गतिविधि वर्णन गर्दछन् । धातु कमप्लेक्सहरुले उच्च तापीय स्थिरता र गैर-स्वस्फूर्त विघटन चरणहरु देखाएका थिए। पाउडर एक्सरे विवर्तन (PXRD) अध्ययन, कमप्लेक्सहरुको क्रिस्टलीय प्रकृति प्रमाणित गर्न प्रयोग गरिएको थियो। Origin र X’ Pert High Score Software हरु प्रयोग गरी PXRD तथ्याङ्कहरुको विश्लेषण गरिएको थियो र कमप्लेक्सहरुको प्रकृतिबारे जानकारी प्राप्त गर्न तिनीहरुको Diffractograms हरुलाई सावधानीपूर्वक विश्लेषण गरिएको थियो। कमप्लेक्सहरु नैनोक्रिस्टलाइन प्रकृतिका थिए। स्क्यानिङ्ग इलेक्ट्रोन माइक्रोस्कोपी (SEM) अध्ययनद्वारा शिफ बेशहरु र कमप्लेक्सहरुको सतह उजागर गरिएको थियो र तिनीहरुको विभिन्न सतहगत बनावट पाइएको थियो। आणविक मोडेलिंगले, स्पेक्ट्रोस्कोपिक विधिद्वारा निर्धारित कमप्लेक्सहरुको ज्यामितीको लागि अतिरिक्त समर्थन प्रदान गरेको छ। CsChem Office Ultra 16 र Argus Lab 4.0.1 Software मा MM Force field गणनाको साथै प्रस्तावित आणविक संरचनाहरुलाई चलाएर, संरचना अनुकूलन हासिल गरिएको थियो। मानक किर्बी-बाउर पेपर डिस्क प्रसारण प्रविधिले शिफ बेश र धातु कमप्लेक्सहरुको जीवाणुरोधी शक्ति प्रदर्शन गरिएको थियो। यो उदेश्य हासिल गर्न प्रयोगशालामा ग्राम-पजिटिभ र ग्राम-नेगेटिभ व्याक्टेरियाका धेरै क्लिनिकल स्ट्रेनहरुलाई पृथकीकरण एवम् संवर्धन गरिएको थियो। तिनीहरुले विभिन्न एकाग्रता का DMSO मा तयार गरिएको सश्लेषित यौगिकहरुको घोलसँग अन्तरक्रिया गरेका थिए। सश्लेषित यौगिकहरु को जीवाणुरोधी सक्रियता थप सटिक रुपमा न्यूनतम अवरोध एकाग्रता (MIC) परीक्षण गरेर प्रमाणित गरिएको थियो। जैविक अध्ययनहरुमा, अध्ययन अन्तर्गतका यौगिकहरु र शिफ बेशहरु, तिनीहरुका धातु कमप्लेक्सहरुभन्दा कम जीवाणुरोधी क्षमताका पाइएका थिए।
Corrosion behavior of sputter-deposited W-Mo alloys in NaOH solutions
(Department of Chemistry, 2010) Khadka, Arun
The corrosion behavior of the sputter-deposited nanocrystalline WMo alloys is studied after immersion for 24-29 h in different concentrations of NaOH solutions at 25 o C, open to air by using corrosion tests and open circuit potential measurements. Molybdenum metal acts synergistically with tungsten in enhancing the corrosion resistance of the sputter-deposited W-Mo alloys so as to show the lower corrosion rates than those of alloyconstituting elements (that is, tungsten and molybdenum) after immersion for 24-29 h in NaOH solutions. In general, the open circuit potentials of all the examined W-Mo alloys are shifted to the more positive (noble) direction with increasing the molybdenum content in the alloys. The stability of the spontaneous passive films of the binary W-Mo alloys is decreased with increasing the concentrations of NaOH solutions. However, the corrosion rates of all the examined W-Mo alloys are almost independent of concentrations of NaOH solutions (that is, 0.01 M, 0.1 M and 1 M NaOH).

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