COMPARATIVE STUDY BETWEEN TOPICAL APPLICATIONS OF LIPOSOMALLY ENTRAPPED DNA REPAIR ENZYMES AND THYMIDINE DINUCLEOTIDES AS RADIOPROTECTORS

The delivery of active agents to the skin by liposome carriers is of great interest during the last three decades, based on their potential to enclose various types of biological materials and to deliver them to diverse cell types. Purpose: is to compare between topical application of DNA repair enzymes and thymidine dinucleotide which is a photoprotective agent against non-ionizing radiation through induction of DNA repair. Materials and Methods: thirty six Albino rats were treated by either thymidine dinucleotides or liposomally entrapped DNA repair enzymes topically, 24 hours after they were irradiated with Cobalt-60(60Co) gamma radiation with different doses (0.5 and 3Gy), and they were evaluated with histolopathologically by H&E stain and computerized image analyzer using Masson’s trichrome stain. Results: Gamma radiation produced epidermal thinning and dermal inflammatory cells together with collagen fragmentation and clumping in a dose-like manner. Thymidine dinucleotides gave a better response with both (0.5& 3 Gy) than liposomally entrapped DNA repair enzymes, the epidermis was preserved of with no inflammatory cells and also it maintained the normal architecture of collagen bundles. Conclusion: The effects of gamma radiation on the skin could be minimized by the use of certain dinucleotides