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Natural products have been largely explored as treatments for leishmaniasis, neglected diseases with few toxic therapeutic options, as scaffolds for the development of new drugs. Herein, derivatives from the aerial parts of Baccharis trimera (Less.) DC (extract and its fractions) were evaluated against Leishmania amazonensis and macrophage cells. The ethyl acetate extract was fractionated by solid-phase extraction, resulting in eight fractions (F1-F8). Fractions F3-4 were further separated into 149 subfractions; subfraction 148 (IC 50-PRO = 1.56 ± 0.1 μg mL -1 ) was selected for purification and constituent(s) characterization by high-performance liquid chromatography, as well as 1 H and 13 C nuclear magnetic resonance spectroscopy. The flavonoid eupatorin (3',5-dihydroxy-4',6,7-trimethoxyflavone) was identified. This compound was 3.7 times more effective against intracellular amastigotes (IC 50-AMA = 1.6 ± 0.1 μM) than amphotericin B and presented low cytotoxicity (CC 50 > 100 μM), being almost 62 times more selective for the parasite, showing great potential in drug development for cutaneous leishmaniasis treatment.

Leishmaniasis is a group of diseases that have limited and high toxic therapeutic options. Herein, we evaluated the antileishmanial potential and cytotoxicity of hexanic extract obtained from the Antarctic brown alga Ascoseira mirabilis using bioguided fractionation against Leishmania amazonensis and murine macrophages, which was fractionated by SPE, yielding seven fractions (F1-F7). The fraction F6 showed good anti-amastigote activity (IC 50  = 73.4 ± 0.4 μg mL -1 ) and low cytotoxicity (CC 50  > 100 μg mL -1 ). Thus, in order to identify the bioactive constituent(s) of F6, the fraction was separated in a semipreparative HPLC, yielding four fractions (F6.1-F6.4). F6.2 was the most bioactive fraction (IC 50  = 66.5 ± 4.5 μg mL -1 ) and GC-MS analyses revealed that the compounds octadecane, propanoic acid, 1-monomyristin and azelaic acid correspond to 61% of its composition. These data show for the first time the antileishmanial potential of the Antarctic alga A. mirabilis .