Cyclofarnesane sesquiterpenoids from the fungus Sanghuangporus sp.

An antibacterial activity-guided phytochemical investigation of the fungus Sanghuangporus sp. resulted in the isolation of two new cyclofarnesane sesquiterpenoids, (4 S ,6 S)-4-hydroxy-gamma-ionylideneacetic acid (1) and (4 R ,5 R ,6 S)-5,14-dihydro-4-hydroxy-gamma-ionylideneacetic acid (2), together with three known compounds, gamma-io-nylideneacetic acid (3), 1 S-(2 E)-5-[(1R)-2,2-dimethyl-6-methylidenecyclohexyl]-3-methylpent-2-enoic acid (4), and D-mannitol (5). Their structures were elucidated using extensive spectroscopic data (IR, 1D and 2D NMR) and mass spectrometry. The absolute configurations of compounds 1 and 2 were identified by NOESY and comparisons of their experimental and calculated electronic circular dichroism spectral data. Compounds 1 , 3 , and 4 were evaluated for antibacterial activity against five bacterial strains (Staphylococcus aureus MSSA 2933, S. aureus MRSA 20651, Bacillus cereus ATCC 11778, Escherichia coli 25922, and Shigella dysenteriae 15110).