Mechanism of Calf thymus DNA radioprotection by sucrose: A combined effect of scavenging action and altered water
International Journal of Radiation Research
Development of safe radioprotector is a challenging task. In this study radioprotecve effect of sucrose has been demonstrated in calf thymus DNA (CtDNA). Sucrose is a free radical scavenger and also acts as osmolyte and therefore can influence the water acvity around DNA and effects of radiaon on DNA. Hoechst 33258 was used to probe the possible alteraon in physicochemical properes due to altered hydraon induced by sucrose in irradiated CtDNA. Materials and Methods: Calf thymus DNA (CtDNA),
... ose and Hoechst 33258 were obtained from Sigma Chemicals, USA. 60 Co Gamma source (Gamma5000, BRIT India) was used for irradiaon. Radiaon induced structural destabilizaon was monitored spectrophotometrically (Cary Bio 100, Varian, Australia) by measuring CtDNA melng temperature. Changes in physicochemical properes (altered water acvity, minor groove binding characteriscs) were invesgated using absorpon and fluorescence spectroscopic properes of Hoechst 33258-CtDNA interacons in presence of sucrose. Results: The CtDNA melng temperature data suggest that sucrose reduced the effect of γ-irradiaon on CtDNA. Thermodynamics of binding interacon of Hoechst 33258 with irradiated CtDNA suggested favorable energecs accompanied by displacement of water molecules. Binding affinity in presence of sucrose was altered marginally at low concentraon (<0.5Osm). The marginal changes in absorpon and fluorescence spectroscopic properes of Hoechst 33258-CtDNA interacons at higher concentraon of sucrose suggested unaltered funconal capability of CtDNA. Conclusion: This study suggests that sucrose can provide structural protecon in γ irradiated CtDNA. Both scavenging and altered water acvies by sucrose contributed in the observed radioprotecon. These physicochemical properes of sucrose can be considered for designing beer radioprotector. The observaons at low concentraons of sucrose appears important lead for further validaon studies.