Radioprotective role of uric acid: evidence from studies in Drosophila and human dermal fibroblast cells

Exposure to ionizing radiation (IR) is a common phenomenon during medical diagnosis and treatment. IRs are deleterious because cellular exposure to IR can cause a series of molecular events that may lead to oxidative stress and macromolecular damage. Radiation protection is therefore essential and significant for improving safety during these procedures. Over decades several antioxidant molecules have been screened to explore their potential as radio-protectors with little success. Therefore, the current study was carried out to confirm the role of uric acid (UA)-a putative antioxidant molecule in radioprotection using radio-resistant insect Drosophila and human dermal fibroblast (HDF) cells. Here, we demonstrate the depleted levels of UA in the mutant flies of Drosophila melanogaster-rosy and by targeting xanthine oxidase (XO an enzyme involved in UA metabolism), through maintaining flies on an allopurinol mixed diet. Allopurinol is a drug that reduces UA levels by inhibiting XO; it reduces the survival percentage in D. melanogaster compared to wild type flies following gamma irradiation at a dose of 1000 Gy. Enzymatic antioxidants such as superoxide dismutase (SOD), catalase, D. melanogaster glutathione peroxidase (DmGPx) and levels of non-enzymatic antioxidants were measured to evaluate the importance of UA. The results indicate that lack of UA reduces the total antioxidant capacity. The activity of SOD was lowered in male flies. Furthermore, we show that supplementation of UA to HDFs cells in media improved their survival rate following gamma irradiation (2 Gy). From the present study we conclude that UA is a potent antioxidant molecule present in high levels among insects. Also, it appears that UA contributes to the radiation resistance of Drosophila flies. Hence, UA emerges as a promising molecule for mitigating radiation-induced oxidative damage in higher organisms.