PRO-OXIDANT NATURAL COMPOUNDS REDUCE THE INFECTIVITY OF Trypanosoma cruzi.

GOMEZ J; COLL M; CIFUENTES D; SOSA MA; BARRERA P

Congreso; XXXVIII Reunión Anual de la Sociedad de Biología de Cuyo; 2022

Sociedad de Biología de Cuyo

Trypanosoma cruzi (T. cruzi) is a parasite of medical importance that causes the Chagas disease. During its life cycle, T. cruzi alternates between three stages: epimastigote (non-infective), trypomastigote and intracellular amastigote (both infectives). The establishment of the disease relies on the ability of the parasite to evade the host's immune response, for this T. cruzi has an antioxidant system with enzymes and reducing molecules. Since this system is exclusive to parasites, it could be considered as a potential target for new chemotherapies against Chagas disease. In this sense, we are studying the mechanism of action of a natural compound: Dehydroleucodine (DhL). Presumably, its α-methylene group would be responsible for most of its biological activities and could react with thiol groups present in molecules, inducing an oxidative stress on the cells. In this work, we study the importance of the mentioned group in the trypanocidal activity and the effect of DhL on infected mammalian cells with T. cruzi. To asses this, we have studied comparatively the effect of DhL with 10 semi-synthetic derivatives obtained by chemical substitution on this group, named DC-X2 to DC-X11. Among the derivatives studied, only DC-X6 (IC50 = 8.44 μM at 48 hs; R2: 0.92) and DC-X11 (IC50 = 14 μM at 48 hs; R2: 0.81) displayed an antiproliferative effect on the parasites, although at lesser extent than DhL (IC50 4 μM at 24 h R2: 0.86). Since the derivatives have shown less activity than the native drug, the importance of the methylene group in the biological activity of DhL should be featured. The antiproliferative effect of DhL was blocked by the sulfhydryl group donor glutathione (GSH) added either at 24 h or 48 h, while protection against DC-X6 was exerted just from 48 h incubation and no protection was observed against with DC-X11. The protective effect of GSH could be due to a scavenging of ROS. Regarding the selectivity index (SI) (CC50 /IC50), DhL displayed be 3.67 fold more cytotoxic towards epimastigotes (IC50: 4 μM) than the mammalian cells (CC50: 13.35 μM). Finally, we study the effect of DhL on infected mammalian cells with T. cruzi. The Vero cells were infected with trypomastigotes (24h) and then incubated with the compound (2μM to 13μM) during 24h and 48h. In this experiment we found less amastigotes per cell, as well as an increase of uninfected cells. We conclude that the methylene group of DhL is important for the trypanocidal role, and its mechanism of action could be associated by inducing ROS in the parasites. We consider the antioxidant system of the parasite as an interesting target for the development of new trypanocidal drugs.