Quantitative estimation of tannins, phenols and antioxidant activity of methanolic extract of Imperata cylindrica

Abstract

The aim of present study was to evaluate the antioxidant activity of the Methanolic root extract of Imperata cylindrica (MEIC) by using various in-vitro models of antioxidant activity. The extract was comprised to phytochemical screening and quantitative determination of tannins and total phenols by spectrophotometric methods. Scavenging of nitric oxide by MEIC was estimated by using Gries's reagent. Reducing the ability of MEIC was studied by using FeCl₃ reagent. Ascorbic acid was used as standard in all the three methods. The extract showed the IC₅₀ value for nitric oxide scavenging method as 400.15± 1.934 µg/ml as compared to the standard ascorbic acid with IC₅₀ value 269.75± 0.852 µg/ml. The extract was found to have been strong reducing power and the activity was comparable to the standard ascorbic acid. The hydrogen peroxide scavenging capacity of MEIC was reported as IC₅₀ value of 185.6± 1.551µg/ml as compared to the IC₅₀ value of the standard ascorbic acid 128.5 ± 0.683µg/ml. MEIC showed significant antioxidant activity in all the three antioxidant models comparable to the standard. The phytochemical screening of the MEIC revealed the presence of carbohydrates, glycosides, triterpenoids, phenolic compounds/tannins, flavonoids, proteins and volatile oils. The tannin content of MEIC was found to be 12.53 ± 0.56mg tannic acid equivalent g^-1 extracted powder. The total phenolic content was found to be 7.09 ± 0.14mg gallic acid equivalent g^-1 extracted powder. The antioxidant potential of the methanolic extracts of Imperata cylindrica may be due to the presence of tannins and phenolic compounds.