Six new metabolites produced by Colletotrichum aotearoa 09F0161, an endophytic fungus isolated from Bredia oldhamii

Six new compounds, colletobredins A-D (1-4) and colletomelleins A and B (5 and 6), along with 12 previously identified compounds, were isolated from the culture broth of Colletotrichum aotearoa BCRC 09F0161, a fungal endophyte residing in the leaves of an endemic Formosan plant Bredia oldhamii Hook. f. (Melastomataceae). The structures of the new compounds were established by spectroscopic methods, including UV, IR, HR-ESIMS and extensive 1D and 2D NMR techniques. The effects of some isolates on the inhibition of nitric oxide (NO) production in lipopolysaccharide-activated murine macrophage RAW264.7 cells were evaluated. All these compounds inhibited NO production in activated macrophages without any cytotoxicity at a concentration of 100M. Of these isolates, 1 showed weak NO inhibitory activity with IC50 value of 182.2M. To the best of our knowledge, this is the first report on isochroman glycoside metabolites (1-4) from the genus Colletotrichum.