Assessment of the genotoxic and photoprotective effects of Phyllanthus mirificus (Phyllanthaceae)

Ultraviolet radiation constitutes a natural physical carcinogen that could induce DNA damage, which, if not repaired, might generate mutations. Plants of the genus Phyllanthus (Phyllanthaceae) are used in traditional medicine worldwide. Recent investigations support their genoprotective activity against chemical and physical mutagens, including UV radiation. The purpose of this work was to evaluate the genotoxic and photoprotective activity of the aqueous extract obtained from Phyllanthus mirificus. Two experimental models were used: ex vivo pCMUT plasmid and Caulobacter crescentus cells. The genotoxicity and genoprotection tests carried out were colony-forming capacity, clastogenicity and SOS Chromotest. UVC was used as an irradiation treatment. The UV absorption capacity and the scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals by the extract were measured. In addition, its phytochemical composition was analyzed. The cytotoxic effect was only statistically significant at 2 mg/ mL; however, it was not genotoxic at any of the concentrations tested. The P. mirificus extract showed antioxidant capacity and good levels of UVC absorbance from 0.1 mg/mL. However, the extract exhibited a low photoprotective capacity. It only reduced the induction of UVC-SOS in C. crescentus cells, at high concentrations (> 1 mg/mL), and did not prevent the generation of plasmid DNA damage. This result suggests that the antioxidant and absorptive properties are not enough to carry out photoprotection.