Endophytic fungal compounds active against Cryptococcus neoformans and C. gattii

Infections with Cryptococcus are invasive mycoses associated with significant morbidity and mortality, mainly in immunosuppressed patients. Several drugs have been introduced to combat these opportunistic infections. However, resistance of this organism to antifungal drugs has increased, causing difficulties in the treatment. The goal of this work was to evaluate the antifungal activity of ethanol extracts from endophytic fungi isolated from plants collected from different Brazilian ecosystems and to perform the fractionation of the most promising extract. Four-hundred fungal extracts were investigated by microdilution broth assays against Cryptococcus neoformans and Cryptococcus gattii at a concentration of 500 μg ml(-1). Among them, the extract of Mycosphaerella sp. UFMGCB 2032, an endophytic fungus isolated from the plant Eugenia bimarginata DC. (Myrtaceae) exhibited outstanding antifungal activity against C. neoformans and C. gattii, with MIC values of 31.2 μg ml(-1) and 7.8 μg ml(-1), respectively. The fractionation of this extract using liquid-liquid partitioning and semi-preparative HPLC afforded two eicosanoic acids with antifungal activity, compound 1, (2S,3R,4R)-(E)-2-amino-3,4-dihydroxy-2-(hydroxymethyl)-14-oxoeicos-6,12-dienoic acid with MIC values ranging from 1.3-2.50 μg ml(-1), and compound 2, known as myriocin, with MIC values of 0.5 μg ml(-1) against C. neoformans and C. gattii. These compounds are reported for the first time in the Mycosphaerella genus.