Abstract

Silymarin is a potent antioxidant agent isolated from milk thistle seeds of Silybum marianum (L.) Gaertn (Family Asteracae), comprised mainly of three isomeric flavonolignans: silibinin, silydianin, and silychristin. The aim of the present study was to evaluate the protective antioxidant effects of silymarin in erythrocytes of fluoride-treated rats. Fifty adult male Wistar rats were divided into five groups of ten each: a normal control group received low fluoride (F) drinking water (DW) and a standard diet throughout the study; a second group received only 600 ppm NaF (271 ppm F ion) in their DW for seven days. A third group received 10 mg silymarin/kg bw intraperitoneally (i.p.) for one week, followed by 600 ppm NaF in their DW for seven days. The fourth group received 20 mg silymarin/kg bw i.p. for one week, followed by 600 ppm NaF in their DW for seven days. The fifth group received 10 mg vitamin C/kg bw i.p. for one week, followed by 600 ppm NaF in their DW for seven days. At the end of the one-week pre-treatment period, the erythrocytes of the rats were isolated; and catalase and superoxide dismutase activities, reduced glutathione, and lipid peroxidation levels were determined. Pre-treatment with 20 mg silymarin (and, to a lesser extent, with 10 mg silymarin and 10 mg vitamin C), prior to NaF intoxication, maintained the basal levels of antioxidant parameters and restored the enzymatic antioxidant activities in the erythrocytes when compared with those in the control group. We conclude that silymarin has a potent ameliorative effect on NaF-induced oxidative stress in rat erythrocytes.