Diego B. Carvalho

Synthesis and Antitrypanosomastid Activity of 1,4-Diaryl-1,2,3-triazole Analogues of Neolignans Veraguensin, Grandisin and Machilin G

Sixteen 1,4-diaryl-1,2,3-triazole compounds derived from the natural products veraguensin, grandisin and machilin G were synthesized, with yields of 78-92%. Biological activity tests against Leishmania amazonensis promastigotes showed that three of these compounds were the most active, with maximum inhibitory concentration (IC50) values of 1.1, 3.71 and 7.23 µM. One compound was highly active against Leishmania infantum, with an IC50 value of 5.2 µM, and one derivative showed an IC50 value of 28.6 µM against Trypanosoma cruzi trypomastigotes. Regarding structure-activity relationship (SAR), hybrid 1,2,3-triazolic compounds containing a methylenedioxy group, showed the best antileishmanial and antitrypanosomal activities.

Antileishmanial Activity and Structure-Activity Relationship of Triazolic Compounds Derived from the Neolignans Grandisin, Veraguensin, and Machilin G

Sixteen 1,4-diaryl-1,2,3-triazole compounds 4–19 derived from the tetrahydrofuran neolignans veraguensin 1, grandisin 2, and machilin G 3 were tested against Leishmania (Leishmania) amazonensis intracellular amastigotes. Triazole compounds 4–19 were synthetized via Click Chemistry strategy by 1,3-dipolar cycloaddition between terminal acetylenes and aryl azides containing methoxy and methylenedioxy groups as substituents. Our results suggest that most derivatives were active against intracellular amastigotes, with IC50 values ranging from 4.4 to 32.7 µM. The index of molecular hydrophobicity (ClogP) ranged from 2.8 to 3.4, reflecting a lipophilicity/hydrosolubility rate suitable for transport across membranes, which may have resulted in the potent antileishmanial activity observed. Regarding structure-activity relationship (SAR), compounds 14 and 19, containing a trimethoxy group, were the most active (IC50 values of 5.6 and 4.4 µM, respectively), with low cytotoxicity on mammalian cells (SI = 14.1 and 10.6). These compounds induced nitric oxide production by the host macrophage cells, which could be suggested as the mechanism involved in the intracellular killing of parasites. These results would be useful for the planning of new derivatives with higher antileishmanial activities.

Design, synthesis and anti-trypanosomatid activities of 3,5-diaryl-isoxazole analogues based on neolignans veraguensin, grandisin and machilin G

Using bioisosterism as a medicinal chemistry tool, 16 3,5‐diaryl‐isoxazole analogues of the tetrahydrofuran neolignans veraguensin, grandisin and machilin G were synthesized via 1,3‐dipolar cycloaddition reactions, with yields from 43% to 90%. Antitrypanosomatid activities were evaluated against Trypanosoma cruzi, Leishmania (L.) amazonensis and Leishmania (V.) braziliensis. All compounds were selective for the Leishmania genus and inactive against T. cruzi. Isoxazole analogues showed a standard activity on both promastigotes of L. amazonensis and L. braziliensis. The most active compounds were 15, 16 and 19 with IC50 values of 2.0, 3.3 and 9.5 μM against L. amazonensis and IC50 values of 1.2, 2.1 and 6.4 μM on L. braziliensis, respectively. All compounds were noncytotoxic, showing lower cytotoxicity (>250 μM) than pentamidine (78.9 μM). Regarding the structure–activity relationship (SAR), the methylenedioxy group was essential to antileishmanial activity against promastigotes. Replacement of the tetrahydrofuran nucleus by an isoxazole core improved the antileishmanial activity.

Design, Synthesis and Anticancer Biological Evaluation of Novel 1,4-Diaryl- 1,2,3-triazole Retinoid Analogues of Tamibarotene (AM80)

We report herein the design and synthesis via click chemistry of twelve novel triazole retinoid analogues of tamibarotene (AM80) and the evaluation of their anticancer activities against six cancer cell lines: HL60, K562, 786, HT29, MCF7 and PC3. Among the synthesized compounds, two were more potent than tamibarotene against solid tumor cells, and one of them had similar potency to tamibarotene against HL60 cells. The bioisosteric exchange between the amide group and the 1,2,3-triazole core in the retinoid agent tamibarotene (AM80) reported in this work is a valid strategy for the generation of useful compounds against cancer.