Study of Antioxidant and Larvicidal Properties of Selected Medicinal Plants of Fringe Villages of Manas National Park, Assam, India

Background: Mosquito-borne diseases are among the major ailments of world affecting billions of people living in economically poor and developing countries. The development of insecticide resistance in mosquito vectors has forced the global community to look into alternative sources of medicines with better efficacy and less side effects. Plants with rich sources of metabolites have been explored extensively for mosquitocidal activity. The present study explored the antioxidant and larvicidal activities of five important plants traditionally used as mosquito repellent by tribal communities of fringe villages of Manas National Park of Assam. Methods: Methanolic crude extracts were prepared for all the plants following standard protocols. Phytochemical and antioxidant study was performed following the protocol published in recent publications. Larvicidal bioassay was carried out as per WHO protocol. Results: The study observed considerable phytochemical and antioxidant activity. Phenolics, flavonoid and antioxidant activity, were found to be highest in Cinnamomum tamala. The phenolic and flavonoid value ranged from 9.89 to 147.15µgGAE/mg and 4.32 to 28.43µgQE/mg plant extract, respectively. The IC50 for various antioxidant activities ranged from 27.94 to 114.15µg/mL (DPPH), 15.05 to 707.74µg/mL and 40.23 to 338.91µg/mL (TBARS). Similarly, C. tamala showed the strongest larvicidal activity with LC50 value of 3.11mg/mL in Aedes aegypti larvae. Conclusion: The present study observed that C. tamala leaves could be a good source of phytochemicals and antioxidant and larvicidal activity.