Selaginpulvilins A-D, New Phosphodiesterase-4 Inhibitors with an Unprecedented Skeleton from Selaginella pulvinata

Selaginpulvilins A-D (1-4), four new phenols with an unprecedented 9,9-diphenyl-1-(phenylethynyl)-9H-fluorene skeleton, together with four known selaginellins (5-8) were isolated from Selaginella pulvinata. Their structures were elucidated by spectroscopic analysis and chemical correlation. The structure of 1 was confirmed by single-crystal X-ray diffraction. Compounds 1-8 exhibited remarkable inhibitory activities (IC50 values in the range of 0.11-5.13 mu M) against phosphodiesterase-4 (PDE4), a drug target for the treatment of asthma and chronic obstructive,pulmonary disease.