Isolation and structure elucidation of (−)-idescarparide, a new spiro compound from Idesia polycarpa

(−)-Idescarparide, a new spiro compound possessing a tetrahydrobenzodioxole structure from the fruit of Idesia polycarpa Maxim. was identified to be a dimer of (−)-idescarpin by spectroscopic analysis. The absolute configuration of (−)-idescarpin was firstly determined to be of S form by using single-crystal X-ray diffraction. The absolute configuration of (−)-idescarparide was confirmed by comparison with semi-synthetic (−)-idescarparide, achieved via triethylamine-catalyzed dimerization of (−)-idescarpin. (−)-Idescarparide significantly reduced lipid production in 3T3-L1 cells.