Pharmaceutical Sciences I.
Kamilla Varga, Virág Kovács, Eszter Torma, Dimitrisz Patakfalvi, Éva Szökő, Tamás Tábi
Department of Pharmacodynamics
Introduction: Resveratrol has a potential as drug candidate based on its reported beneficial pharmacological effects. However, because of its poor bioavailability and unclear mechanism of action a demand for analogues with improved properties has also emerged.
Aim: We aimed at studying the cytoprotective effect and its possible mechanism. Mitochondrial effects and autophagy induction of resveratrol analogues with different oxidation states were aimed at analyzed.
Method: Apoptosis was triggered by serum deprivation in primary mouse embryonal fibroblasts cells. Caspase 3 activity, mitochondrial membrane depolarization, reactive oxygen species (ROS) production and autophagy were determined by their fluorescent indicators and western blot analysis of specific autophagy related proteins.
Results: Resveratrol and monomethylated resveratrol protected cells against apoptosis in a more effective manner than trimethylated resveratrol, while oxyresveratrol showed intermediate potency. Resveratrol and monomethyl resveratrol induced significant mitochondrial depolarization however, the ROS production did not increase. On the contrary trimethyl resveratrol caused a more considerable mitochondrial depolarization and significant ROS production, while oxyresveratrol showed no mitochondrial effects. Resveratrol, monomethyl and trimethyl resveratrol increased both ULK1 phosphorylation and LC3 lipidation, while oxyresveratrol did not induce autophagy. With serum deprivation the analogues did not alter the level of p62.
Conclusion: Our results revealed a structure dependence of the cytoprotective effect of resveratrol analogues. We hypothesize that free hydroxyl groups are necessary for effective antiapoptotic action, because it could provide the antioxidant effect needed to balance out the mitochondrial membrane depolarization, however, oxyresveratrol revealed that too strong antioxidant effect can also be disadvantageous. Resveratrol and monomethyl resveratrol have a preconditioning-like effect by simultaneously inducing mitochondrial damage and facilitating elimination of ROS thus promoting stress resistance mechanisms. Or results also point to the paramount importance of bulk autophagy initiated at an early phase.
Funding: The project was funded by Semmelweis 250+ Excellence PhD Scholarship (EFOP-3.6.3-VEKOP-16-2017-00009).