Proteins and enzymes are the basic regulatory units in living systems. Radiation-induced damages in protein
and enzyme structure can lose their regulatory and biocatalytic properties lead to radiation induced structural and thus
functional impairment. In the present study we report in vitro radioprotective efficacy of semiquinone glucoside derivative
(SQGD) isolated from a radioresistant bacterium Bacillus sp. INM-01. Radiation induced damage in Bovine Serum
Albumin (BSA) and its protection by SQGD pre-treatment was evaluated by UV-Vis, Circular Dichroism (CD)
spectroscopic and SDS-PAGE analysis. Protection to functional activity of restriction enzyme (Hind III) by SQGD was
analysed through agarose gel electrophoresis. While antioxidant activities of SQGD was analyzed by fluorescence
spectro-photometeric analysis using fluorescein as oxidized adduct and 2,2'-azobis(2-amidino-propane) dihydrochloride
(AAPH) as oxidizing agent. Significant increase in absorption maxima represented oxidation of BSA with irradiated (600-
1200Gy) samples was observed. Whereas, no such increase in absorption maxima in the irradiated BSA pretreated with
SQGD was observed. Circular Dichroism (CD) spectroscopic analysis showed dose dependent upward shift in the spectra
of BSA upon irradiation. While, pre-treatment by SQGD, shift the BSA spectra towards control. NATIVE-PAGE analysis
showed a clear smearing in irradiated BSA, which was found to be abolished upon SQGD pre-treatment. Further,
significant loss of functional activity of Hind III endonulease was observed upon irradiation, while SQGD pretreatment
helps to protect catalytic activity of irradiated Hind III. Thus, in view of above, present study was suggested that SQGD
carries excellent radioprotective activities and protects enzymes and proteins against ionizing radiation-induced oxidative
damage. In conclusion, SQGD can be used as protector of vital proteins, vitamins, enzymes and other important
radiosensitive food supplements during radiosterilization process of food and meat industries.
BSA, circular dichroism spectroscopy, radioprotection, restriction enzymes.
Radiation Biotechnology Group, Radiation Biosciences Division, Institute of Nuclear Medicine and Allied Sciences, Brig. S. K. Mazumdar Road, Delhi, 110054, India.