Stereostructure and anti-inflammatory activity of three diastereomers of ocobullenone from Ocotea bullata

A novel diastereomer of ocobullenone. designated as sibyllenone, was isolat ed from the stem bark of mature Ocotea bullata in the course of a search fo r anti-inflammatory compounds from this plant. The stereostructure was esta blished by X-ray crystallography and corroborated by NOESY analysis. Ocobul lenone, obtained previously, was re-isolated and crystallised successfully for X-ray analysis, thus making possible an accurate spatial comparison of ocobullenone. iso-ocobullenone and the new stereoisomer. Tested pharmacolog ically for cyclooxygenase-1 and 2, and 5-lipoxygenase inhibition, sibylleno ne was the only compound from O. bullata which showed good inhibitory activ ity towards 5-lipoxygenase. (C) 2000 Elsevier Science Ltd. All rights reser ved.