Antibacterial bisabolane sesquiterpenoids and isocoumarin derivatives from the endophytic fungus Phomopsis prunorum

A pair of new phenolic bisabolane-type sesquiterpenoid enantiomers (+/-)-phomoterpenes A and B [(+/-)-1 ] and two known analogues (2 and 3), together with two new isocoumarins, phomoisocoumarins C-D (4 -5), were isolated from an endophytic fungus Phomopsis prunorum (F4-3). Their structures were elucidated by compre-hensive spectroscopic analysis. The enantiomeric separation for (+/-)-1 were achieved by chiral-HPLC, and their absolute configurations were assigned by electronic circular dichroism (ECD) calculation. Compounds (+)-1 and 5 exhibited moderate antibacterial activity against plant pathogenic bacteria Pseudomonas syringae pv. Lachrymans with MIC values of 15.6 mu g/mL.