Antibacterial and Antioxidant Properties of Selected Medicinal Plants from Law Land Nepal

Abstract

Medicinal plants , as source of remedies, are widely used as alternative therapeutic tool for the prevention or treatment of many diseases The aim of the present study was to evaluate the antibacterial and antioxidant activity of the methanolic extract of selected medicinal plants of central Nepal. Twelve medicinal plants were studied on the basis of their ethnobotanical uses in the treatment of various ailments especially diarrhoea and dysentery. Antibacterial screening against four pathogenic microbes‟ viz., Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillius substilis was determined by agar well diffusion method and zone of inhibition was observed. Out of twelve plants tested for antimicrobial activity, eight plant species showed antibacterial activity by inhibiting one or more microorganisms. The methanolic extract of Mangifera indica, Bombax ceiba, Bauhinia vahlii, Cassia fistula, Syzygium cumini, showed significant inhibition against all the tested bacteria while, Psidium guajava, Elephantopus scaber and Azadirachta indica showed inhibition against few pathogenes. But medicinal plants such as Cassia occidentalis, Uraria lagopoides, Moringa oleifera and Costus speciosus did not show antibacterial activity against selected bacteria. Total phenolic and flavonoid content were determined by Folin-Ciocalteu and aluminium chloride calorimetric method respectively. The antioxidant activity was determined by 2, 2diphenyl-1-picrylhyrazyl (DPPH) free radical and ascorbic acid was taken as standard. Syzygium cumini, Bombax ceiba, Elephantopus scaber, Uraria lagopoides and Bauhinia vahlii showed lower IC 50 value than standard ascorbic acid where as Cassia occidentalis, Mangifera indica, Moringa oleifera, Azadirachta indica, Cassia fistula, Psidium guagava and Costus specious showed higher value than standard ascorbic acid. Moringa oleifera showed the highest phenolic content whereas all the plant extracts showed comparable amount of Flavonoid content. The results of the present study suggest that the selected plants can be used as a source of antioxidants and antibacterial for pharmacological preparations as very well evidenced by the present work.