1. Introduction Plants are the main source of food and medicine of humans since the times of ancient throughout the world. Many synthetic antioxidants such as butylated hydroxyl anisole (BHA) and butylated hydroxyl toluene (BHT) are known to have side effects causing liver damage. The expensive treatments, adverse effects of several allopathic drugs and development of resistance to existing drugs have forced us to look back into nature as a resource for therapeutics to a wide variety of human ailments. Therefore there is a need for isolation and characterization of natural antioxidant having fewer side effects which can be used in foods or medicinal materials to replace damage causing synthetic antioxidants [20]. A very important medicinal …show more content…
Estimation of total Flavonoid content by AlCl3 reagent method The total flavonoid content of methanol extract of leaves of A.malabarica was determined by the AlCl3 reagent method [4]. The extract (500 µg/mL) was mixed with 0.5 mL of 5% NaNO2 solution and allowed to stand for 5 mins. Then 0.3 mL of 10% AlCl3 solution was added and the mixture was allowed to stand for further 5 min. Finally, 1 mL of 1 M NaOH solution was added, and the final volume of the mixture was brought to 5 mL with distilled water. The mixture was incubated for 15 mins at room temperature and absorbance was measured at 510 nm. The total flavonoid content was expressed as quercetin equivalent (µg/mg of extract), which is a common reference standard. 2.4. DPPH radical scavenging assay The DPPH radical scavenging activity of methanol extract of leaves of Anisomeles malabarica was carried out according to the method [1].One mL of Plant extract of various concentrations (50-300 μg/mL) were mixed with 1 mL of 0.1 mM of DPPH solution in methanol. The reaction mixture was kept at room temperature for 30 min. Absorbance was read at 517 nm in spectrophotometer. The percentage of the radical scavenging activity was calculated as follows. % of inhibition = Control – Sample ×