Lupeol acetate isolated from Chrysophyllum cainito L. fruit as a template for the synthesis of N-alkyl-arylsulfonamide derivatives and their synergistic effects with metronidazole against Trichomonas vaginalis.

Pentacyclic triterpenes are found in a great variety of natural products and constitute an organic template for the development of new derivative compounds with therapeutic applications. In the present work, lupeol acetate isolated from Chrysophyllum cainito L. fruit was used as a template for the synthesis of novel N-alkyl-arylsulfonamide derivatives, and their synergistic effects with metronidazole against strains of Trichomonas vaginalis were tested. A library of 18 derivatives was synthesized. Ten compounds exhibited an IC50 < 100 µM against a metronidazole-sensitive strain of T. vaginalis. Only seven of these compounds (12, 15, 18-22) also showed activity against metronidazole-resistant strains. The compounds 20 (N-cyclohexyl-p-chlorobenzenesulfonamidolupeol acetate) and 22 (N-cyclohexyl-p-nitrobenzenesulfonamidolupeol acetate) exhibited a similar IC50 against both susceptible and resistant T. vaginalis strains and enhanced the efficacy of metronidazole in a partial and total synergistic way, respectively. These data provided evidence of the trichomonicidal effect of N-alkyl-arylsulfonamide derivatives of lupeol acetate, representing highly promising novel antiparasitic agents.

Immune Response of BALB/c Mice toward Putative Calcium Transporter Recombinant Protein of Trichomonas vaginalis.

Trichomoniasis is a common sexually transmitted infection caused by Trichomonas vaginalis, which actually does not exist a vaccine for control or prevention. Thus, the identification of new and potent immunogens in T. vaginalis, which can contribute to the development of a vaccine against this parasite, is necessary. Therefore, the aim of this work was to evaluate the potential of a recombinant Transient Receptor Potential-like channel of T. vaginalis (TvTRPV), as a promising immunogen in BALB/c mice. First, TvTRPV was cloned and expressed as a recombinant protein in Escherichia coli BL21 cells and purified by nickel affinity. Next, BALB/c mice were immunized and the antibody levels in mice serum and cytokines from the supernatant of macrophages and from co-culture systems were evaluated. Recombinant TvTRPV triggered high levels of specific total IgG in sera from the immunized mice. Also, a statistically significant increase of cytokines: IL-1ß, IL-6, and TNF-α after stimulation with the corresponding antigens in vitro, was identified. Moreover, co-cultures using CD4+ T cells from immunized mice were able to identify higher levels of IL-10 and IFN-γ. These results were useful to validate the immunogenicity of TvTRPV in BALB/c mice, where IL-10-IFN-γ-secreting cells could play a role in infection control, supporting the potential of TvTRPV as a promising target for vaccine against T. vaginalis.

The Role of Iron Status in the Early Progression of Metronidazole Resistance in Trichomonas vaginalis Under Microaerophilic Conditions.

Trichomonas vaginalis is the etiological agent of human trichomoniasis. Metronidazole has high treatment success rate among trichomoniasis patients. However, metronidazole-resistant T. vaginalis has been reported, contributing in an increasing number of refractory cases. The mechanism of metronidazole resistance in this parasite is still unclear. In the vaginal environment, where the microaerophilic conditions prevail but the iron concentration is constantly fluctuating, the metronidazole resistance profile of T. vaginalis could be altered. In this study, we developed metronidazole-resistant strains of T. vaginalis and evaluate if iron availability is important to the action of the drug. The modulation of iron levels and iron chelation affected the actions of metronidazole both in susceptible and resistant strains. Interestingly, the early resistant strains exhibited minor iron content. The results of transcription analysis in the early resistant strains showed dysregulation in the expression of genes that codified proteins involved in iron transporter, iron-sulfur cluster assemblage, and oxidative stress response, which could not be observed in the late resistant and susceptible strains. Our results indicate that iron content plays an important role in the metronidazole action in T. vaginalis and likely to be related to iron-sulfur proteins involved in metronidazole activation and oxidative stress via Fenton reaction.