Phytochemical investigation, antimicrobial and hepatoprotective properties of the root of Asparagus africanus Lam.

Abstract

The emergency of resistance pathogens limits the therapeutic uses of many of the drugs that are in the market and undesirable side effects associated to certain antibiotics, thus this study was aimed to search alternative drugs for antimicrobial agent and liver disease from root extracts of Asparagus africanus. The air dried plant materials were ground and extracted sequentially with petroleum ether, chloroform, acetone and methanol by maceration technique at room temperature to give crude extracts of 4 g (0.4%), 13 g (1.3%), 8 g (0.8%) and 50 g (5%), respectively. The phytochemical screening of the extracts revealed the presence of various secondary metabolites such as saponin, terpenoids, flavonoid, tannin and steroids. Two separate columns were prepared for the isolation of compounds, first for the methanol extract (20 g) and second one is for the combined extracts of chloroform (10 g) and acetone (6 g) leading to the isolation of six compounds (AA-1, AA-2, AA-3, AA-4, AA-5, and AA-6) and further purified by gel filtration with Sephadex LH-20. Only two compounds AA-5 and AA-6 were characterized using 1H and 13C NMR, named as stigmasterol and nyasol, respectively. The crude extracts and isolated compounds were evaluated for in vitro antimicrobial activities using disk diffusion assay and the methanolic extract were also evaluated for in vivo hepatoprotective effects on twenty five male Swiss albino mice for 28 days by inducing isoniazide and rifampicin hepatotoxicity. The antimicrobial activity of methanol and acetone extract showed the marginal zone of inhibition against two bacterial strains E. coli (12.5±0.7, 12.5±0.9) mm, B. subtilus (11.8±0.8, 11.8±0.8) mm and one fungal strain C. albicans (12.5 ±1.0, 11.8±0.7) mm, respectively compared to chloroform and petroleum ether extracts. Compounds AA-5 (stigmasterol) and AA-6 (nyasol) were showed a marginal zone of inhibition against two bacterial strains (E.coli, 8.0, 8.0) mm, (S. typhi; 9.0, 8.0) mm and one fungal strains (C.albicanus; 10.0, 8.0) mm, respectively. The in vivo hepatoprotective study showed the elevation of the serum alanine aminotransferase, aspartate transaminase, alkaline phosphatase, total bilirubin level of toxicant drug induced group and decrease the serum albumin compared to normal control group, but both the treatment (200 and 400 mg/kg) groups were significantly maintained the level of serum liver biomarkers to the normal with dose dependent manner P<0.05