Steroids produced by Cladosporium anthropophilum, an endophytic fungus Isolated from Avicennia marina (Forssk.) Vierh and Their Antibacterial Activity

This work was conducted to isolate the steroid compounds from an endophytic fungus Cladosporium anthropophilum and determine their effects against 4 strains of bacteria. The fungi were afforded from a mangrove plant Avicennia marina (Forssk.) Vierh of Acanthaceae family, growing in West Java, Indonesia. The fermentation and isolation of C. anthropophilum yielded 3 ergostane-type steroids including a highly oxidized one, identified as penicisteroid A (1), ergosterol (2), and ergosterol-5,8-peroxide (3), together with 2 stigmastanes, characterized as stigmasterol (4), and stigmasterol-5,8-peroxide (5). The elucidation structure of all isolated steroids was performed by extensive spectroscopic measurements (MS, IR, 1D, and 2D NMR) and supported by a comparison of previously reported spectral data. Subsequently, the potential of the 5 steroids as well as methanol, n-hexane, and ethyl acetate extracts were evaluated against 2 Gram-positive bacteria, Staphylococcus aureus ATCC 29213 and Enterococcus faecalis ATCC 29212 and 2 Gram-negative bacteria, Vibrio harveyi ATCC 5339 and Escherichia coli ATCC 25922. The results showed that none of the isolated steroids were active, while the 3 extracts exhibited significant inhibition against all the tested bacteria’s growth and enabled us to propose the synergistic effects between active compounds in these extracts and their antibacterial activity. HIGHLIGHTS An isolated and identified endophytic fungus, Cladosporium anthropophilum, from a mangrove plant Avicennia marina (Forssk.) Vierh yielded five steroids. A chromatography technique and spectroscopic method were utilized for separation processes and structure determination, respectively. An antibacterial assay against two Gram-positive bacteria ( aureus and E. faecalis) and two Gram-negative bacteria (V. harveyi and E. coli) implied the synergistic effects between five isolated steroids and their parent extracts. A further investigation is highly recommended to explore the possibility of these five steroids as a potential source of active compounds. GRAPHICAL ABSTRACT