Colletolides A and B, two new γ-butyrolactone derivatives from the endophytic fungus Colletotrichum gloeosporioides

Two new γ-butyrolactone derivatives, colletolides A and B ( 1 and 2 ), together with three known compounds, sclerone ( 3 ), 3-methyleneisoindolinon ( 4 ) and indole-3-acetamide ( 5 ), were isolated from the culture of the endophytic fungus Colletotrichum gloeosporioides B12, which resides in the medicinal plant Illigera rhodantha Hance. Their structures were characterized by a combination of HR-ESI-MS, NMR and ECD spectra. Compounds 1 and 2 showed moderate antibacterial activity against Xanthomonas oryzae pv. oryzae , X. oryzae pv. oryzicola and Ralstonia solanacearum with the same MIC values of 128 μg/mL.