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.