In vitro Morphogenesis of nodes and Bioactivities of different Part extracts of Rubia manjith Roxb. Ex Fleming

Abstract

Rubia manjith, a perennial herbaceous climber is one of the important medicinal and dye plants that have been prioritized for research and development as well as categorized as a vulnerable plant (CAMP 2001) in Nepal. This is a significant plant used for medicine, cosmetic and dye purpose. Locally this plant is being used by various communities to cure different diseases. It is heavily exploited unsustainably and exported in a large amount. All these factors are leading to it’s the depletion of its population in nature and hence it becomes necessary to study its potentials and conserve in situ and ex situ. Single nodes as an explant of R. manjith were cultured in Murashige and Skoog (MS) medium supplemented with plant growth regulators, BAP and NAA. The highest mean shoot number 5.33±0.33 was observed on MS media without any growth regulators followed 4.33±0.33 mean shoots on 0.1 mg/L BAP and 1.0 mg/L BAP. The highest mean root number 8.00±1.00 was also observed in MS media without any growth regulators. Highest shoot length 14.33±1.54cm was observed in 0.1 mg/L BAP followed by MS media 14.13±1.12cm whereas the highest root length 6.80±1.27 in 2.0 mg/L BAP. High amount of callus (+++) were observed in 2.0 mg/L NAA, 0.1 mg/L BAP + 1.0 mg/L NAA, 0.1 mg/L BAP + 2.0 mg/L NAA and 1.0 mg/L BAP + 1.0 mg/L NAA. For the analysis of phytoconstituents and their bio-activities, methanol, dichloromethane and hexane extract of the root, stem and leaves were prepared by fractionation. Total phenolic content was estimated using FC-reagent and the highest TPC was found in dichloromethane extract of root with 77.5±0.01 µg GAE/mg phenols. Brine shrimp lethality assay was performed to examine the toxic activity of plant and highest toxicity was found in the hexane extract of the stem, with an LC value of 194.99±34.58 g/mL. DPPH assay was done to analyze the antioxidant activities and strong antioxidant activity was exhibited by hexane extract of root, dichloromethane extract of root and methanol extract of stem with an IC 50 value 16.92±2.97 μg/mL, 35.17±1.42 μg/mL and 46.49±0.85 μg/mL respectively. Rubia manjith showed high TPC, antioxidant and toxic activities in the hexane fraction, especially in the stem and root, suggesting that the nonpolar compounds and essential oils present in the species may play a role in their active bioactivities, which can be further used in several pharmaceutical and other applications. It can be cultivated easily in vitro from the nodes and utilized on a large scale if needed to maintain its population sustainability. vi