The in Vitro Antioxidant Activity and Total Phenolic Content of Four Indian Medicinal Plants

Methanolic extracts of Plumbago zeylanica (Root), Acorus calamus (Rhizome), Hemidesmus indicus (Stem) and Holarrhena antidysenterica (Bark), used in Ayurvedic medicines for number of ailments were evaluated for their antioxidant activity by ferric thiocyanate (FTC) assay and compared with thiobarbituric acid (TBA) method. The order of antioxidant potential according to FTC assay was found to be highest in Plumbago zeylanica followed by Holarrhena antidysenterica, Acorus calamus and Hemidesmus indicus. Whereas there is slightly difference in activities as measured by TBA method. The antioxidant activity of medicinal plants was at par with the commercial antioxidant butylated hydroxy toluene (BHT), L-Ascorbic acid and αtocopherol. Further, the radical-scavenging activity of the extracts was measured as decolourizing activity followed by the trapping of the unpaired electron of DPPH. The percentage decrease of 1, 1-diphenyl-2-picryl hydrazyl radical (DPPH) standard solution was recorded maximum for Hemidesmus indicus (77.0%) followed by Plumbago zeylanica (73.41%), Acorus calamus (20.88%) and Holarrhena antidysenterica (20.06%) extracts at a concentration of 100 μg/ml. Phytochemical analysis revealed the presence of major phytocompounds like alkaloids, glycosides, phenolics and saponins. Moreover, total phenolics concentration equivalents to gallic acid was found in the range of 59.50 to 109.0 mg/g of plant extracts, which correlated with antioxidant activity. The findings indicated promising antioxidant activity of crude extracts of the above plants and needs further exploration for their effective use in both modern and traditional system of medicines.