Phaeosphspirone (1/1'), a pair of unique polyketide enantiomers with an unusual 6/5/5/6 tetracyclic ring from the desert plant endophytic fungus Phaeosphaeriaceae sp.

Phaeosphspirone, an undescribed polyketide with a unique 6/5/5/6-fused tetracyclic system, and two known analogues, herbarin and O-methylherbarin, were purified from the endophytic fungus Phaeosphaeriaceae sp. isolated from the desert plant Bassia dasyphylla. The connectivity and relative configuration of phaeosphspirone was elucidated by comprehensive HR-ESI-MS and NMR analysis together with a computer-assisted structure elucidation (CASE) method.

Stereochemical determination of four 10-membered ring resorcylic acid lactones from the desert plant endophytic fungus Chaetosphaeronema hispidulum.

Four 10-membered ring resorcylic acid lactones (RALs) including a new compound hispidulactone F (1) and three known analogs hispidulactone B (2), 2 R, 4R-sonnerlactone (3), and 2 R, 4S-sonnerlactone (4) were isolated from the special bioenvironmental desert plant endophytic fungus Chaetosphaeronema hispidulum. The structure of the new compound hispidulactone F (1) was determined by extensive spectra analysis including HR-ESI-MS, NMR (H, C, H-H COSY, HSQC, and HMBC). Hispidulactone F (1) and hispidulactone B (2) were a pair of stereoisomers at C-3, whereas 2 R, 4R-sonnerlactone (3) and 2 R, 4S-sonnerlactone (4) were another pair of stereoisomers at C-4.