Selaginpulvilins A–D, New Phosphodiesterase‑4 Inhibitors with an Unprecedented Skeleton from <i>Selaginella pulvinata</i>

Abstract

Selaginpulvilins A–D (<b>1</b>–<b>4</b>), four new phenols with an unprecedented 9,9-diphenyl-1-(phenylethynyl)-9<i>H</i>-fluorene skeleton, together with four known selaginellins (<b>5</b>–<b>8</b>) were isolated from <i>Selaginella pulvinata</i>. Their structures were elucidated by spectroscopic analysis and chemical correlation. The structure of <b>1</b> was confirmed by single-crystal X-ray diffraction. Compounds <b>1</b>–<b>8</b> 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