Objective: Silybum marianum L. Food Supplements that contain silymarin is widely used as a therapeutic agent in liver diseases. Many brands are available on the market in USA, Egypt, Europe and other countries. The objective of this study was to compare the biological activity in different preparations of silymarin available on the market in USA and Egypt using paracetamol-induced oxidative stress injury on primary cultured rat hepatocytes.
Methods: Forty four silymarin samples available on the market were collected from USA (24) and Egypt (20) and tested for hepat protective antioxidant effects on primary cultured rat hepatocytes. Cytotoxicity was measured by MTT [3-(4, 5-dimethyl-thiazol-2)-2,5-diphenyl tetrazolium bromide] assay and lactate dehydrogenase (LD) leakage into culture medium. Antioxidant effects were determined by glutathione reductase (GR), and Nitric oxide (NO) assays in silymarin, pretreated rat hepatocytes for 2 h followed by incubation with 25 mM paracetamol over a period of 1 h. Therapeutic index was calculated for each tested sample for comparative analysis.
Results: Silymarin preparations significantly decreased toxicity induced by paracetamol in rat hepatocytes, decreased lactate dehydrogenase leakage and prevented GSH depletion (P<0.01) and returned NO to basal levels in rat hepatocytes. The therapeutic index was 80, 40 and 20 for samples No. 20, 19 and 5 respectively.
Conclusions: The 44 different silymarin preparations tested in this study exhibited variation in antioxidant capacity and in reducing nitric oxide produced as a result of paracetamol injury. This variation in biological activity did not always correspond to the amount of silymarin recorded on samples
