A Comparative Evaluation of the Antioxidant Activity of Some Medicinal Plants Popularly Used in Bangladesh

Background and Objective: The people of the rural area of Bangladesh have a great history of putting into use many indigenous medicinal plants to cure diseases. The attention has focused on phytochemicals as sources of natural antioxidants. Therefore, the study was conducted to investigate phenol, total flavonoid content and antioxidant activities in five medicinal plants namely Neem (Azadirachta indica), Tulsi (Ocimum tenuiflorum), Pudina (Mentha spicata), Ulat kambal (Abroma augusta) and Lemon grass (Cymbopogon citratus). Materials and Methods: Five medicinal plants were collected from the medicinal garden of BIRTAN regional station, Noakhali, Bangladesh. The High-Performance Liquid Chromatography (HPLC) method assessed the phenolic compound. The antioxidant activity (DPPH radical scavenging activity) and total flavonoid content were assessed by the UV spectrophotometer method. Results: Significant differences in natural antioxidants among the species were studied. Antioxidant activity was found to range from 40.483-78.373%. The highest antioxidant activity was observed in Neem (78.373% inhibition), followed by Lemongrass (74.717%) and Pudina (62.483%). The phenolic compound and total flavonoid content ranged from 1.13-1.953 mg GAE/g extract and 97.6-145.203 mg QE/g extract, respectively. Neem leaf extract showed the highest in both flavonoid compounds and antioxidant activity suggesting the good potential of this plant could be considered responsible for conferring antioxidant ability and use for traditional medicine. A positive significant correlation was observed between antioxidant activity with total flavonoid content (0.528*) and an insignificant positive correlation with phenolic compound (0.225). Conclusion: It is possible to suggest that the plant extracts' total phenolic and flavonoid content is the reason for the antioxidant activity. Medicinal plants with good antioxidant activity could serve as potential sources of natural antioxidants.