Studies on desmodium velutinum (Willd.) DC. leaf extract's polyphenol profile, in-vitro antioxidant capacity, and anti-proliferative activity of A549 cell lines

Abstract

In African and Asian ethnomedicinal studies, Desmodium velutinum (Willd) has been used in the treatment of tooth and head aches, diarrhoea, cancer, and haematuria and as repellent and aphrodisiac. The study is aimed at determining polyphenol profile and antioxidant activities of D. velutinum methanol leaf extract and its ethyl acetate and butanol fraction. The study also investigated the effect of this plant on lung adenocarcinoma (A549) cell line. The polyphenol constituents in D. velutinum were evaluated with the U-HPLC technique. While, the antioxidant activities of the methanol plant extract and its fractions were assessed with the DPPH, metal chelating, reducing power and DNA nicking assays. MTT assay was employed to analyse the effect of the plant on A549 cell line. Kaempferol is the principal polyphenol in the leaf extract/fraction of D. velutinum. Conversely, its ethyl acetate fraction possessed a higher concentration of catechin than kaempferol. Total phenolic content (TPC) result was directly proportional to the antioxidant activities of extract and fractions, a higher TPC value was obtained in ethyl-acetate fraction (787.1 ± 21.4 mg GAE/g) than the crude methanol extract (710.9 ± 24.5 mg GAE/g) and its n-butanol fraction (759.2 ± 1.3 mg GAE/g), thus, ethyl acetate fraction performed best in the antioxidant assays. D. velutinum also inhibited oxidative damage to supercoiled plasmid DNA and suppressed the proliferation of A549 cells in a dose-dependent manner. This study shows that D. velutinum does have potentials to protect against many diseases linked with reactive oxygen species.