ABSTRACT
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.
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.
