Aqueous extracts of Desmodium adscendens (Fabaceae) possess in vitro antioxidant properties and protect hepatocytes from Carbone tetrachloride-induced injury and Hepatitis C Virus infection

Abstract

Background: Desmodium adscendens (DA) is an herbaceous plant found in Africa and South America and used in traditional medicine against liver-related diseases. In the present study, the aqueous decoctions from DA were tested for their antioxidant and hepato-(protective and curative) properties on CCl₄-induced acute injury on primary culture rat hepatocytes. We also investigated its inhibitory effects on hepatitis C virus (HCV) using genotype 1b subgenomic replicon systems and cell-culture derived HCV particles (HCVcc).

Methods: Five chemical antioxidants assay were used for the evaluation of antioxidant properties of aqueous extract of DA. Hepato-(protective and curative) activities of DA against CCl₄-induced hepatotoxicity in primary rat hepatocytes were assessed by measuring cell viability, alanine aminotransferase (ALT) activity leakage into the incubation medium and malondialdehyde (MDA) content as markers of lipid membrane peroxidation. Antiviral activity against hepatitis C virus (HCV) was performed using HCV genotype 1b sub-genomic replicon cell line LucUbiNeo-ET cells and HCV cell-culture derived particles (HCVcc) by measuring luciferase activity and indirect immunofluorescence respectively. Antioxidant activity was assessed, and cytotoxicity and oxidative injury were determined by assessing cell viability by the 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) and leakage of ALT, a cytosolic enzyme. LucUbiNeo-ET cells were used as HCV genotype 1b replicons systems and were incubated with various concentrations of plant extract. The antiviral activity was assayed by measuring the luciferase activity in cell lysates by reporter gene assay.

Results: Average yield of 4.16 ± 0.44 million cells/g of liver and viability of 90 ± 1.29 % were obtained. Hepatocyte viability was not affected by increasing concentrations of plant extracts. Moreover, treatment of cells with plant extracts at concentrations of 1-1000 µg/mL before and after oxidative injury provided a cytoprotective effect to the cells by increasing the percent of cell viability, reducing ALT leakage and decreasing the formation of malondialdehyde and an antioxidant capacity was noted. A strong activity was observed with D. adscendens harvested before flowering (DA1) compared to its activity after flowering (DA2). DA1 extract was tolerated by LucUbiNeo-ET cells up to the concentration of 500 µg/mL after 24 h of incubation. DA1 extract at 25 µg/mL produced a significant (p<0.01) decrease in HCV infection compared to the DMSO-treated group.

Conclusions: These findings indicate that Desmodium adsccendens aqueous extracts possess promising hepatoprotective effects against CCl₄-induced liver injury and HCV infection. These support its traditional use for the management of some liver diseases.