Free radical scavenging and metal chelation by Tinospora cordifolia, a possible role in radioprotection.

Aqueous extract of T. cordifolia inhibited Fenton (FeSO 4 ) reaction and radiation mediated 2-deoxyribose degradation in a dose dependent fashion with an IC 5 0 value of 700 μg/ml for both Fenton and radiation mediated 2-DR degradation. Similarly, it showed a moderate but dose dependent inhibition of chemically generated superoxide anion at 500 μg/ml concentration and above with an IC 5 0 value of 2000 μg/ml. Aqueous extract inhibited the formation of Fe 2 + -bipiridyl complex and formation of comet tail by chelating Fe 2 + ions in a dose dependent manner with an IC 5 0 value of 150 μg/ml for Fe 2 + -bipirydyl formation and maximally 200 μg/ml for comet tail formation, respectively. The extract inhibited ferrous sulphate mediated lipid peroxidation in a dose-dependent manner with an IC 5 0 value of 1300 μg/ml and maximally (70%) at 2000 μg/ml. The results reveal that the direct and indirect antioxidant actions of T. cordifolia probably act in corroboration to manifest the overall radioprotective effects.