Agrawala, P KAdhikari, J S2011-12-162011-12-162009-11Agrawala P K, Adhikari J S. Modulation of radiation-induced cytotoxicity in U 87 cells by RH-3 (a preparation of Hippophae rhamnoides). Indian Journal of Medical Research. 2009 Nov; 130(5): 542-549.http://imsear.searo.who.int/handle/123456789/135935Background & objectives: Hippophae rhamnoides L. has been widely exploited for medicinal purposes and an extract of its whole berries coded as RH-3 has been found to render radioprotection. Effect of pre-irradiation treatment of up to 10 μg/ml RH-3 was studied in U 87 cells using MTT assay. This study aims at unraveling the mechanism of action of RH-3 in amelioration of radiation-induced cytotoxicity in vitro. Methods: Most effective doses selected were studied further for the elucidation of radiomodifying properties of RH-3, especially with respect to early and late events of apoptosis. Results: RH-3 at concentrations of 7.5 and 10 μg/ml (-15 min) were found most effective in protecting against 2 Gy induced cytotoxicity in terms of MTT reducing ability in U 87 cells. RH-3 was observed to mitigate radiation-induced cellular and mitochondrial free radicals. Mitochondrial membrane potential depletion (studied up to 12 h) was prevented by RH-3 pre-irradiation administration. It could also restore the level of antiapoptotic protein Bcl-2 at 24 and 48 h comparable to the control value. RH-3 also prevented radiation-induced increase in mitochondrial mass at 48 and 72 h post-treatment and the values were comparable to that of control cells. Annexin-V-FITC assay at 12 and 24 h time intervals indicated significant protection against radiation-induced apoptosis by RH-3 pre-irradiation treatment. Interpretation & conclusion: Our findings showed that probably RH-3 acts as an antioxidant preventing cellular and mitochondrial free radical generation that could contribute to its ability to inhibit radiationinduced apoptosis and cytotoxicity.enApoptosisflow cytometryfree radicalsHippophae rhamnoidesmitochondriaradioprotectionAntioxidants --pharmacologyApoptosis --drug effectsApoptosis --radiation effectsCell LineCell Survival --drug effectsCell Survival --radiation effectsFree Radicals --metabolismGamma Rays --adverse effectsHippophaeHumansMembrane Potential, Mitochondrial --drug effectsMembrane Potential, Mitochondrial --radiation effectsPlant Extracts --pharmacologyPlants, MedicinalRadiation-Protective Agents --pharmacologyArticle