Joannesialactone and other compounds from Joannesia princeps

Abstract

The novel natural products joannesialactone, (-)-α-barbatenal, 4- hydroxy-10-epirotundone, and the E- and Z-isomers of 2-(4- hydroxyphenyl)ethenyl-α-L-rhamnopyranoside and the 3-O-rhamnosides of the dimeric proanthocyanidins afzelechin-(4α → 8)-epiafzelechin-3-O-vanillate, afzelechin-(4α → 8)-epicatechin-3-O-vanillate, afzelechin-(4α → 8)- epiafzelechin-3-O-syringate and afzelechin-(4α → 8)-epicatechin-3-O- syringate have been isolated from the root bark of Joannesia princeps, along with the antibiotic principle cyperenal, the colouring matter assufulvenal, curcusones C and D and 16 further known compounds. Structure determination was achieved mainly by spectroscopic studies and/or by comparison with authentic substances.