Endophytic Fungus Nigrospora oryzae from a Medicinal plant Coccinia grandis, a High Yielding New Source of Phenazine-1-carboxamide

Nigrospora oryzae was isolated as an endophytic fungus from the leaves of Coccinia grandis, a popular medicinal plant used to control diabetes. Fermentation of the fungus in potato dextrose broth and chromatographic purification of the ethyl acetate extracts of the broth and mycelium yielded two phenazine secondary metabolites, which were identified as phenazine-1-carboxylic acid (1) and phenazine-1-carboxamide (2) by comparing their spectral data with those reported in the literature. Compound 2, isolated in high yield (1 g/4 L medium), showed strong antifungal activity against the plant pathogen Cladosporium cladosporioides. This is the first report of the isolation of N. oryzae as an endophytic fungus of C. grandis. These phenazines have never been isolated from any fungal source. Antifungal activity of 2 against C. cladosporioides is reported for the first time.