This study compared the radioprotective effects of high-molecular-weight poly-gamma-glutamate (γ-PGA, average molecular mass 3,000 kDa) and a reduced form of glutathione (GSH, a known radioprotector) on calf thymus DNA damage. The radiation-induced DNA damage was measured on the basis of the decreased fluorescence intensity after binding the DNA with ethidium bromide. All the experiments used ⁶⁰Co gamma radiation at 1,252 Gy, representing 50% DNA damage. When increasing the concentration of γ-PGA from 0.33 to 1.65 μM, the DNA protection from radiation-induced damage also increased, with a maximum of 87% protection. Meanwhile, the maximal DNA protection when increasing the concentration of GSH was only 70%. Therefore, γ-PGA exhibited significant radioprotective effects against gamma irradiation.
Keywords: DNA damage; DNA protection; Poly-gamma-glutamate; gamma radiation; radioprotective material.