Two new bioactive metabolites produced by Colletotrichum gloeosporioides, an endophytic fungus of Michelia champaca L

Plant-associated microorganisms are known to produce a variety of metabolites with novel structures and interesting biological activities and the claimed medicinal properties and biological activities of some plant species have been attributed to the microorganisms living in association with these plants [1,2]. As part of our ongoing efforts to understand plant-microbial interactions and to discover small molecule natural products with novel structures and/or biological activities from plant-associated microorganisms [1], we have investigated the fungal strain Colletotrichum gloeosporioides, an endophytic fungus isolated from Michelia champaca. The strain P. gloeosporioides was selected for chemical and biological investigation because of the strong antifungal activity against the phytopatogenic fungi Cladosporium sphaerospermum and C. cladosporioides. Fractionation of the crude EtOAc extract by flash chromatography column on reversed-phase C-18 silica, followed by reversed-phase HPLC, led the isolation of a two new indole derivative, 1 and 2. The structures of these compounds were elucidated through a series of 1D and 2D NMR experiments. The compounds 1–2 were assayed against the phytopathogenic fungi C. cladosporioides and C. sphaerospermum, as well as for acetylcholinesterase inhibition. Compound 1 and 2 displayed strong antifungal activity against both fungi at 10µg, and 50µg, respectively and showed weak acetylcholinesterase inhibition at 200µg.

Acknowledgements: Suported by BIOTA/FAPESP grant n ^o 03/02176–7

References: 1. Gunatilaka, A. A. L. et al. (2007) Phytochemistry 68: 368–372.

2. Clardy, J. et al. (2000)J. Nat. Prod. 63: 1447–1448