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Abstract Malaria is a disease caused by Plasmodium spp. protozoa. The ability of Plasmodium to develop resistance to current antimalarial drugs makes the study of chemotherapeutic alternatives extremely important. This study aimed to evaluate the antimalarial activity of compound 3286938 (1-(3-benzyloxy-4-methoxy-phenyl)-3-(3,4,5-trimethoxy-phenyl)-propan-1-one), which presents in its structure a 3,4,5-trimethoxyphenyl group, in vitro, using the W2 strain of P. falciparum and against circulating strains of P. vivax and P. falciparum from the state of Rondônia. The compound 3286938 obtained an IC50 of 24.4 µM against the W2 strain of P. falciparum, and against the circulating strains, it presented a median (MD)=38.7 µM for P. vivax and MD=6.7 µM for P. falciparum. As for toxicity, 3286938 showed CC50 > 500 µM for VERO and HepG2 strains with a selectivity index greater than 12.9, a ratio calculated for P. falciparum and P. vivax regarding Vero and HepG2 cells. The compound was not considered hemolytic in in vitro assays, thus indicating the specificity of its antiplasmodial action. Based on the results presented, and considering the unprecedented character of the compound, it can be concluded that 3286938 was shown to be promising for complementary in vitro and in vivo studies aiming to produce effective antiplasmodial action.

Trichomonas vaginalis and Leishmania spp. are protozoal species responsible for millions of cases of parasitic diseases worldwide. Considering the potential of natural products and the need for more effective and less toxic alternatives to treat trichomoniasis and leishmaniasis, this study aimed to evaluate the effect of two series of triterpenes derivatives with different modifications at C-3 and C-28 positions of the ursolic acid (UA) and betulinic acid (BA) against trophozoites of Trichomonas vaginalis and promastigotes forms of Leishmania (L.) amazonensis. The compounds modified just at C-3 were the most active. The 3β-acetyl betulinic acid (1b) reduced the trophozoites viability of T. vaginalis at 74%, followed by the 3-oxo ursolic acid and 3-oxo betulinic acid (3a and 3b) compounds (55% of reduction). The compound 3β-isobutyl ursolic acid (7a) inhibited the viability of L. amazonensis promastigotes by 55%. Therefore, analyzing the structure-activity relationship and the data of literature, it is possible to suppose that the inclusion of polar groups in the skeletons could improve the antiprotozoal activity. Overall, further studies are necessary to develop triterpenic derivatives with more powerful trichomonicidal and leishmanicidal properties.