Radioprotective properties of Hippophae rhamnoides (sea buckthorn) extract in vitro.

BACKGROUND: Hippophae rhamnoides, a high altitude habitat plant, has been extremely used in traditional medicinal practices for treating a variety of ailments. Recently, an extract (RH-3) prepared from berries of Hippophae rhamnoides has been reported to exhibit significant radioprotection against whole body lethal irradiation. OBJECTIVE: Present study was undertaken to elucidate the DNA binding ability of an extract (RH-3) prepared from berries of Hippophae rhamnoides and its role in modulating radiation induced frank and clustered DNA damage. METHOD: Agarose gel electrophoresis was employed as method to understand DNA binding potential and DNA protective ability of RH-3. RESULTS: RH-3 in a dose dependent fashion interacted with plasmid DNA (pUC18) reducing the mobility of supercoiled form and increasing the amount of the complex in the well indicating its ability to interact with plasmid DNA. RH-3 at higher concentrations (> 0.4 mg/ml) almost completely prevented the migration of supercoiled form without interfering with mobility of open circular form indicating its ability to selectively interact with supercoiled form. Studies done with supercoiled or open circular form also revealed the binding specificity of RH-3 for supercoiled form of plasmid. Both inhibited radiation induced strand breaks and DNA interaction by RH-3 were found to be dependent upon pH and the order of efficacy was found to be acidic pH> neutral pH > alkaline pH. RH-3 in a dose dependent manner inhibited radiation induced frank single, double strand breaks as well as endonuclease IV detectable abasic sites (clusters) and maximum reduction was observed at a concentration of 200 μg/ml. CONCLUSION: Results obtained in this study suggest that the ability of RH-3 to interact with DNA could be playing a significant role in preventing radiation induced DNA damage.