Investigation of in vitro and in vivo antioxidant potential of secoisolariciresinol diglucoside

The present study was designed to evaluate the in vitro and in vivo ameliorative antioxidant potential of secoisolariciresinol diglucoside (SDG). In vitro antioxidant activity of synthetic SDG was carried out using DPPH, reducing power potency, and DNA protection assays. Wistar albino rats weighing 180–220 g were used for in vivo studies and liver damage was induced in the experimental animals by a single intraperitoneal (I.P.) injection of CCl₄ (2 g/kg b.w.). Intoxicated animals were treated orally with synthetic SDG at (12.5 and 25 mg/kg b.w.) and Silymarin (25 mg/kg) for 14 consecutive days. The levels of catalase (CAT), superoxide dismutase (SOD), peroxidase (POX), and lipid peroxidase (LPO) were measured in liver and kidney homogenates. The synthetic SDG exerts high in vitro antioxidant potency as it could scavenge DPPH at a IC₅₀ value of 78.9 μg/ml and has dose-dependent reducing power potency and protected DNA at 0.5 mg/ml concentration. Oral administration of synthetic SDG at 12.5 and 25 mg/kg b.w. showed significant protection compared to Silymarin (25 mg/kg) and the activities of CAT, SOD, and POX were markedly increased (P < 0.05), whereas LPO significantly decreased (P < 0.001) in a dose-dependent manner in liver and kidney in both pre- and post-treatment groups when compared to toxin-treated group. The results of in vitro and in vivo investigations revealed that synthetic SDG at 25 mg/kg b.w. is associated with beneficial changes in hepatic enzyme activities and thereby plays a key role in the prevention of oxidative damage in immunologic system.