No abstract

Present study was undertaken to evaluate the radioprotective ability of total polyphenols extracted from edible portion (epicarp and mesocarp) of apple. Prior administration of apple polyphenols to murine thymocytes significantly countered radiation induced DNA damage (evaluated by alkaline halo assay) and cell death (trypan blue exclusion method) in a dose dependent manner maximally at a concentration of 2 and 0.2 mg/ml respectively. Apple polyphenols in a dose dependent fashion inhibited both radiation or Fenton reaction mediated 2-deoxyribose (2-DR) degradation indicating its ability to scavenge hydroxyl radicals and this activity was found to be unaltered in presence of simulated gastric juice. Similarly apple polyphenols in a dose dependent fashion scavenged DPPH radicals (maximum 69% at 1 mg/ml), superoxide anions (maximum 88% at 2 mg/ml), reduced Fe(3 +) to Fe(2 +) (maximum at 1 mg/ml) and inhibited Fenton reaction mediated lipid peroxidation (maximum 66% at 1.5 mg/ml) further establishing its antioxidative properties. Studies carried out with plasmid DNA revealed the ability of apple polyphenols to inhibit radiation induced single as well as double strand breaks. The results clearly indicate that apple polyphenols have significant potential to protect cellular system from radiation induced damage and ability to scavenge free radicals might be playing an important role in its radioprotective manifestation.

Hippophae rhamnoides or seabuckthorn is used extensively in Indian and Tibetan traditional medicine for the treatment of circulatory disorders, ischemic heart disease, hepatic injury, and neoplasia. In the present study, we have evaluated the radioprotective potential of REC-1001, a fraction isolated from the berries of H. rhamnoides. Chemical analysis of the extract indicated that REC-1001 was approximately 68% by weight polyphenols, and contained kaempferol, isorhamnetin, and quercetin. The effect of REC-1001 on modulating radiation-induced DNA damage was determined in murine thymocytes by measuring nonspecific nuclear DNA damage at the whole genome level using the alkaline halo assay and by measuring sequence/gene-specific DNA damage both in nuclear DNA (beta-globin gene) and in mitochondrial DNA using a quantitative polymerase chain reaction. Treatment with 10 Gy resulted in a significant amount of DNA damage in the halo assay and reductions in the amplification of both the beta-globin gene and mitochondrial DNA. REC-1001 dose-dependently reduced the amount of damage detected in each assay, with the maximum protective effects observed at the highest REC-1001 dose evaluated (250 micro g/ml). Studies measuring the nicking of naked plasmid DNA further established the radioprotective effect of REC-1001. To elucidate possible mechanisms of action, the antioxidant properties and the free-radical scavenging activities of REC-1001 were evaluated. REC-1001 dose-dependently scavenged radiation-induced hydroxyl radicals, chemically-generated superoxide anions, stabilized DPPH radicals, and reduced Fe(3+) to Fe(2+). The results of the study indicate that the REC-1001 extract of H. rhamnoides protects mitochondrial and genomic DNA from radiation-induced damage. The polyphenols/flavonoids present in the extract might be responsible for the free radical scavenging and DNA protection afforded by REC-1001.

The radioprotective action of a preparation from Hippophae rhamnoides berries RH-3, already reported to render >80% survival against whole body 10 Gy gamma irradiation, was further investigated with respect to the testicular system. RH-3 was administered to mice 30 min before gamma irradiation (5 and 10 Gy) and histological parameters such as testis weight, sperm count, frequency of abnormal sperm, repopulation index, stem cell survival index and seminiferous tubular diameter were assessed on the 35th day. RH-3 administration partially countered radiation induced reduction in testis weight, sperm count, repopulation index and stem cell survival index (p < 0.01). The increase in the frequency of abnormal sperm (15.17 +/- 1.046%) caused by irradiation (5 Gy) was counteracted by pre-irradiation treatment with RH-3, which significantly decreased the level of abnormal spermatozoa to 7.99 +/- 0.918% (p < 0.001), i.e. 52% abnormalities in comparison with 5 Gy irradiated group. RH-3 treatment alone did not elicit any toxic or adverse effect on the process of spermatogenesis. The present study suggests that RH-3 treatment protected spermatogenesis by enhancing the spermatogonial proliferation, enhancing the stem cell survival and reducing sperm abnormalities. The presence of polyphenolic flavonoids and tannins in the extract and the radical scavenging activity might be responsible for the radioprotective action of RH-3.

No abstract