Protective role of new nitrogen compounds on ROS/RNS-mediated damage to PC12 cells

Biological systems are frequently exposed to excessive reactive oxygen (ROS) and nitrogen (RNS) species, causing a disturbance in the cells natural antioxidant defence systems, and resulting in damage to all biomolecules, including nucleic acids. So, there has been a growing interest in developing substances that can act against excessive intracellular free radicals. Here, we studied the protective effects of two new nitrogen compounds, from organic synthesis, FMA762 and FMA796, on ROS/RNS-mediated cell damage. RNS were generated in PC12 cells by the NO donor sodium nitroprusside (SNP). Both FMA762 (37μM) and FMA796 (34μM) effectively decreased SNP-induced cell death (MTT test). This decrease was shown to be mostly due to their RNS scavenging ability, assayed by flow cytometry with the probe DCF. Despite being nitrogenated, the compounds do not work as substrates for NO synthase and do not lead, per se, to an extra production of NO. In addition, they didn’t have any effect on NO synthase, as they didn’t reduce the amount of nitrites produced by SNP (measured by the Griess reaction). On the other hand, the compounds protected cells against t-BHP-induced DNA damage, as assessed by the Comet assay. When added 3h prior to t-BHP addition, this protection is similar to the one produced by quercetin. Besides, a slight effect in DNA repair also seems to occur. Currently, we are assessing the compounds protection in specific DNA lesions, namely at the endogenous base oxidation level. Altogether, these data suggest a good antioxidant potential for the new compounds, with specific effects at the oxidative DNA damage level.

Fundação para a Ciência e a Tecnologia (FCT) - Bolsa SFRH/BD/17174/2004, SFRH/BD/3185/2000.