Antimicrobial constituents from three endophytic fungi

To evaluate the antimicrobial potential of extracts of the endophytic fungi Plectophomella sp., Physalospora sp., and Crataegus monogyna (C. monogyna) and study the tentative identification of their active constituents.

Crude extracts and isolated compounds were screened for antimicrobial activity using the agar well diffusion method. Four compounds were purified from three endophytic fungi using column chromatography and their structures have been assigned based on their (1)H and (13)C nuclear magnetic resonance spectra.

Plectophomella sp., Physalospora sp., and C. monogyna extracts showed promising antifungal, antibacterial and herbicidal properties. (-)-Mycorrhizin A was isolated from Plectophomella sp. while cytochalasins E and K were isolated from Physalospora sp. Similarly radicinin was purified from the endophytic fungus C. monogyna. The ethyl acetate extract of Plectophomella sp. showed significant antifungal activity towards Ustilago violacea (U. violacea) and Eurotium repens (E. repens) and significant antibacterial activity against Bacillus megaterium. Interestingly, the ethyl acetate extracts of Physalospora sp. and C. monogyna showed strong herbicidal and antifungal activities towards Chlorella fusca, U. violacea, E. repens, Mycotypha microspora (M. microspora), Fusarium oxysporum, Escherichia coli, and Bacillus megaterium. (-)-Mycorrhizin A showed significant antifungal activity towards U. violacea and E. repens. Cytochalasins E and K showed strong antifungal activity against E. repens and M. microspora especially towards fungal Mycotypha microspora. Similarly cytochalasins E and K showed good herbicidal activity towards Chlorella fusca. Radicinin showed strong antifungal activity against E. repens and M. microspora.

Antimicrobial activities demonstrated by the extracts of the endophytic fungi Plectophomella sp., Physalospora sp., and C. monogyna and four isolated compounds clearly demonstrate that these fungi extracts and active compounds present a great potential use in the food, cosmetic and pharmaceutical industries.