Phytochemicals and elucidation of polyphenol compounds of aqueous-methanol fraction of Desmodium velutinum stem using high performance liquid chromatography

The aim of this study was to analyze and identify phytochemicals and bioactive constituents present in Desmodium velutinum stem. Fresh stems of Desmodium velutinum were air dried at room temperature for 3 days. The stems were pulverized into fine powder, which was extracted with methanol (80% v/v). The concentrated extract was fractionated using ethyl acetate, n-hexane and aqueous methanol. Phytochemical analyses and bioactive composition were done using standard methods and HPLC. The fractionation of 40 g of Desmodium velutinum stem methanol extract using ethyl acetate gave a percentage yield of 11 %, 40 g of n-hexane yielded 8 % and 40 g of aqueous methanol gave a 16 % percentage yield. The phytochemical analyses showed the presence of tannins, flavonoids, phenolics and alkaloids with concentrations 5.02±1.22 mg/g, 2.64±0.01 mg/g, 7.02±1.18 mg/g and 3.61±0.04 mg/g respectively. The high-performance liquid chromatography (HPLC) analysis of the aqueous fraction of Desmodium velutinum stem showed the presence of different constituents of flavonoids, phenols, and tannins in varying concentrations. The flavonoids include gallic acid, chlorogenic acid, rutin hydrate, caffeic acid and apigenin and two (2) unidentified flavonoid compounds with different retention time. The phenols identified were ascorbic acid, p-coumaric acid, rutin, ferrulic acid, and apigenin while the tannins identified were tannic acid and gallotannin as well as eight (8) unidentified tannic compounds with different retention time. These phytochemicals identified in Desmodium velutinum stem possess antioxidant properties which may be used in preventing and alleviating diseases. Desmodium velutinum may therefore be a potential source of new drugs in orthordox medicine.