Modulation of radiation-induced cytotoxicity in U 87 cells by RH-3 (a preparation of Hippophae rhamnoides).
OBJECTIVE
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 microg/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 microg/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.


CONCLUSIONS
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 radiation-induced apoptosis and cytotoxicity.
Agrawala
P K
PK
Radiation Biosciences Division, Institute of Nuclear Medicine & Allied Sciences, Delhi, India. pkagrawal@gmail.com
Adhikari
J S
JS
D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D005609:Free Radicals / Q000378:metabolism; D005720:Gamma Rays / Q000009:adverse effects; D031281:Hippophae; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects / Q000528:radiation effects; D010936:Plant Extracts / Q000494:pharmacology; D010946:Plants, Medicinal; D011837:Radiation-Protective Agents / Q000494:pharmacology*
D000975:Antioxidants; D005609:Free Radicals; D010936:Plant Extracts; D011837:Radiation-Protective Agents