Antiparasitic activity of lipid extracts from the subantarctic macroalgae Iridea cordata against Trichomonas vaginalis

In this study, we demonstrate the promising antiparasitic activity of natural extracts as an alternative treatment for trichomoniasis. We evaluated the in vitro and in silico antiparasitic activity of Iridea cordata extracts, obtained in two distinct development phases: Iridea cordata tetrasporaphyte phase (IFT) and Iridea cordata cystocarp phase (IFC). To determine the minimum inhibitory concentration (MIC) and 50% inhibitory concentration (IC50), we tested five concentrations of the extracts against Trichomonas vaginalis (ATCC 30236). To gain insights into the mechanisms underlying the antiparasitic activity and possible adverse effects, the extracts were subjected to cytotoxicity assays in VERO and human vaginal epithelial (HVMII) cells, gene expression analyses, and their components’ interactions with T. vaginalis proteins were analyzed through molecular docking. In the in vitro biological assay, IFT and IFC exhibited a MIC of 600 μg/mL while showing an IC50 of 150 μg/mL and 300 μg/mL and inhibiting 80% and 97% of T. vaginalis trophozoites, respectively. Importantly, no cytotoxic effects were observed on VERO and HMVII cells for IFC and IFT at 600 μg/mL, indicating their safety. IFC and IFT induced significant differences in gene expression compared to the negative control, DMSO, and metronidazole, suggesting their potential modulation of T. vaginalis genes. Moreover, in silico analysis revealed that constituents of both extracts interacted, with significant free-binding energy, with proteins that are important for T. vaginalis survival. Overall, this study provides evidence of the antiparasitic activity of Iridea cordata extracts against T. vaginalis and supports further evaluation of its extracts as a promising treatment for trichomoniasis.