Iridoid glycoside from the leaves of clerodendrum volubile beauv. Shows potent antioxidant activity against oxidative stress in rat brain and hepatic tissues

Aim: This study aims at reporting the isolation, structure elucidation, and antioxidant potentials of ajugoside from C. volubile leaves in sodium nitroprusside (SNP)-induced oxidative stressed rat brain and hepatic tissues. Materials and Method: An iridoid monoterpene, ajugoside was isolated from the n-butanol fraction of C. volubile and evaluated for its antioxidant protective potential on brain and liver tissues of male Wister rats in an ex vivo model. Two molar concentrations (6.4 × 10^-4 M and 1.28 × 10 ^-3 M) of the metabolite and SNP were incubated with the tissues homogenate at 37°C for 2 hr prior to the test and assayed for catalase, superoxide dismutase (SOD) activities, and lipid peroxidation. α tocopherol (6.4 × 10^-4 M) was used as standard. Results: Both molar concentrations exhibited high catalase activity in the tissues. However, 6.4 × 10^-4 M ajugoside exhibited a very high SOD activity (liver: 96.45 and brain: 96.30%) and inhibition of lipid peroxidation (liver: 88.11 and brain: 93.27%) compared to the standard. 1.28 × 10^-3 M ajugoside also exhibited good activities but lower than that of the standard and 6.4 × 10^-4 M ajugoside. Discussion and Conclusion: Ajugoside showed potent antioxidant activities as evidenced by the synergistic high activities of SOD and catalase as well as inhibition of lipid peroxidation in the studied tissues.