The phenolic content and antioxidant effect of the methanol extract of Dennettia tripetala G. Baker leaves (Annonaceae)

Abstract

The present study was carried out to investigate the phytochemicals, phenolic compounds and the in-vitro antioxidant effect of the methanol extract of Dennettia tripetala G. Baker (Annonaceae) leaves collected from Orba in Udenu Local Government Area of Enugu State, Nigeria. The determination of the presence of phytoconstituents was carried out using standard methods. Estimation of the total phenolic content (TPC), total flavonoid content (TFC) and total proanthocyanidins (TPA) were determined using Folin-Ciocalteu, aluminum chloride and vanillin methanol methods respectively. The antioxidant activities was evaluated using various assays; 1,1-diphenyl-2-picrylhydrazyl (DPPH) model, reducing power and scavenging nitric oxide. Phytochemical screening of the methanol extract of Dennettia tripetala (MEDT) revealed the presence of alkaloids, tannins, saponins, flavonoids, terpenoids, steroids, glycosides, reducing sugars, proteins and fats and oils. The MEDT exhibited potent and concentration dependent free radical scavenging activity in all the tested models, which was compared with standard drug ascorbic acid at different concentrations as extract. The multiple antioxidant activity of MEDT was evident as it showed significant reducing power and nitric oxide-scavenging activity. The total phenolic content of MEDT was 296.24 mg gallic acid/g of dry extract. The flavonoid compounds were found to be 107.76 mg of quercetin equivalent [QE] per g of dry extract. All the results of the in vitro antioxidant assays reveal potent antioxidant and free radical scavenging activity of the leaves of D. tripetala equivalent to that of standard ascorbic acid and provide a support for its use in traditional medicine and its further investigation.