Negundoside, an iridiod glycoside from leaves of Vitex negundo, protects human liver cells against calcium-mediated toxicity induced by carbon tetrachloride

Figure 6 Protective effect of NG and silymarin against stimulated lipid peroxidation. A: Anti-lipid peroxidative effect of NG and silymarin in vitro. Liver microsomes (1 mg protein/mL, 0.15 mol/L NaCl, pH 7.0) were incubated for 20 min at 37°C in the absence (control) and presence of 100 mmol/L FeSO₄ +/50 mmol/L H₂O₂ (stimulated). In identically set-up Fe²⁺/H₂O₂-stimulated incubations, NG and silymarin (20 mg/L to 100 mg/L, in 30% DMSO) were added (test C). Control incubations received vehicle only; B: HuH-7 cells were pre-incubated for 1 h with medium containing test materials (NG and silymarin) at different concentrations (5 mg/L to 100 mg/L). The cells were further incubated in absence or presence of 2 mmol/L CCl₄ (stimulated) for further 24 h. The cells were harvested by scraping and assayed for the production of MDA using TBARS assay, as described under materials and methods section. Reaction was terminated by the addition of 2.0 mL TCA-TBA reagent (15% TCA, 0.375% TBA in 5mol/L HCl) and LPO content determined as nmol MDA formed/mg protein. Data are expressed as mean ± SD and are from representative experiments repeated twice and conducted in triplicate. Statistical significance, ^bP < 0.01 vs the untreated control. ^dP < 0.01; ^aP < 0.05; ^fP < 0.001 and NS: Non-significant vs stimulated (FeSO₄ + H₂O₂ and CCl₄ treatments).