Modulation of radiation-induced cytotoxicity in U 87 cells by RH-3 (a preparation of Hippophae rhamnoides).
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Date
2009-11
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Abstract
Background & 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.
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Keywords
Apoptosis, flow cytometry, free radicals, Hippophae rhamnoides, mitochondria, radioprotection
Citation
Agrawala 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.