Studies on silver nanoparticle-glycyrrhizic acid complex as a radioprotector and an adjuvant in radiotherapy under in vivo conditions.

Silver nanoparticles (SN) of particle size of less than 50 nm were dispersed in an aqueous solution of Pluronic F127 and complexed with the phytoceutical, glyzyrrhizic acid (GLY). Radioprotecting ability of the obtained nanoparticle-glyzyrrhizic acid complex (SN-GLY) was evaluated in an in vivo model using Swiss albino mice. The potential of the complex as an adjuvant during radiotherapy was also analyzed in tumor-bearing mice. The administration of SN-GLY, SN, and GLY protected the hemopoetic and gastrointestinal system against radiation-induced damages as revealed by the total white blood cell count, bone marrow cellularity, endogenous spleen colony formation, levels of cellular antioxidants, and histopathologcal examination of gastrointestinal tract. Oral administration of SN-GLY, SN, and GLY 1 hour before a sublethal dose of radiation exposure reduced the radiation-induced depletion of cellular antioxidants and lipid peroxidation in various tissues of mice. Survival of animals following exposure to a lethal dose of gamma radiation was also improved. It was also found that the oral administration of the complex to tumor-bearing mice before 4 Gy gamma irradiation resulted in a faster tumor regression.