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 μM) against phosphodiesterase-4 (PDE4), a drug target for the treatment of asthma and chronic obstructive pulmonary disease.