Role of a gitogenin-type steroidal saponin (3-O-β-d-glucopyranosyl (1→2)-β-d-glucopyranosyl (1→4)-β-d-galactopyranoside-25R,5α-spirostane-2α,3β-diol), isolated from the leaves of Malvastrum coromandelianum in regulating thyrotoxicosis in rats.

The hitherto unknown role of saponin in the regulation of thyrotoxicosis has been revealed in chemically-induced thyrotoxic rats. l-T4 (l-thyroxine) administration at pre-standardized dose of 500-μg/kg body weight for 12days increased the levels of thyroid hormones, enhanced the activity of hepatic 5'-monodeiodinase I (5'DI) and glucose-6-phosphatase (G-6Pase) as well as lipid peroxidation (LPO) with a parallel decrease in the levels of antioxidative enzymes. However, administration of the isolated saponin for 15days ameliorated the T4-induced alterations in serum thyroid hormones, hepatic LPO, G-6-Pase and 5'DI activity, and improved the cellular antioxidant status, indicating its antithyroidal and antioxidative potential. These effects of the test compound were comparable to a reference antithyroid drug, Propylthiouracil (PTU), suggesting that the test saponin may act as a potent anti-thyroid agent.