Picrotoxane sesquiterpenoids from the stems of Dendrobium nobile and their absolute configurations and angiogenesis effect

Abstract Five picrotoxane sesquiterpenoids belonging to the unusual dendrobine-type ( 1 and 4 ) and the picrotoxinin-type ( 2 , 3 , and 5 ) were isolated from the stems of Dendrobium nobile Lindl. Their structures were established by spectroscopic analyses and physical properties. Compound 1 was a new dendrobine analogue. Although the planar structure of 2 and 3 had been reported, their absolute configurations were first determined by single-crystal X-ray diffraction and circular dichroism. Compound 2 exhibited angiogenesis effect against sunitinib-induced damage on intersegmental blood vessels in Tg (flk1: EGFP) and Tg (fli1: nEGFP) transgenic zebrafish at concentrations of 3.13, 6.25, 12.50, and 25.00 μM.