Bioprospecção de compostos de microalgas contra espécies do gênero Leishmania

Abstract

Leishmaniasis, a neglected tropical disease, is caused by protozoa of the genus Leishmania and can clinically manifest in cutaneous, mucocutaneous, and visceral forms. Current therapies face several challenges, including undesirable side effects, high costs, and invasive administration methods. In this context, there is an urgent need to develop new therapeutic options.Microalgae, due to their high biotechnological potential, have emerged as a promising source for the discovery of therapeutic biomolecules. This study aimed to evaluate the leishmanicidal potential of extracts from eight microalgae species: IBLC 015, IBLC 007, IBLC 002, IBLC 017, IBLC 105, IBLC 103, IBLC 106 e IBLC 118, obtained from the Microalgae Bank of LABBIOTEC, against three species of the Leishmania genus.The microalgae were cultured in Conway and LC Oligo media to obtain biomass, which was subsequently centrifuged and lyophilized. Compound extraction was carried out using absolute ethanol, followed by extract concentration through rotary evaporation.Leishmania promastigotes were cultured in supplemented Schneider's medium (for L. amazonensis and L. braziliensis) or supplemented 199 medium (for L. infantum). The leishmanicidal activity of the extracts was evaluated using the alamarBlue™ cell viability assay and direct counting in a Neubauer chamber. In all tests performed, the extracts demonstrated inhibitory activity against promastigote forms of Leishmania. IC50 and CC50 values were determined, with notable results for extract IBLC 015, which showed an IC50 of 62.95 µg/mL against L. amazonensis and 76.09 µg/mL against L. braziliensis, and for extract IBLC 118, with an IC50 of 69.15 µg/mL against L. infantum. These results indicate distinct biological activities against different Leishmania species. The cytotoxicity of the extracts varied in RAW macrophage cell lines, with IBLC 103 (CC50 = 736.5 µg/mL) and IBLC 017 (CC50 = 579.4 µg/mL) standing out for having the best selectivity profiles. Based on these data, the most promising extracts (IBLC 103 and IBLC 017) were fractionated. Extract IBLC 017 revealed an active fraction (F4), with an IC50 of 275.9 µg/mL. Extract IBLC 103 presented two fractions with significant activity: F2 (IC50 = 53.73 µg/mL) and F4 (IC50 = 272 µg/mL). These findings reinforce the potential of the studied microalgal extracts as promising candidates for the development of new therapies against different Leishmania species.