Cipacinoids A–D, Four Limonoids with Spirocyclic Skeletons from <i>Cipadessa cinerascens</i>

Abstract

Four limonoids, cipacinoids A–D (<b>1</b>–<b>4</b>), with spirocyclic skeletons were isolated from <i>Cipadessa cinerascens</i>. It is particularly notable that compounds <b>1</b>–<b>3</b> had a 17<i>S</i>-configuration for the first time in the limonoid family. Their structures with absolute configurations were assigned by spectroscopic data, X-ray crystallography, and CD analysis. Compound <b>1</b> showed moderate protein tyrosine phosphatase 1B (PTP1B) inhibition