1: J Nat Prod. 2007 Jun;70(6):910-7. Epub 2007 Jun 5. Vasorelaxant activity of diterpenes from Croton zambesicus and synthetic trachylobanes and their structure-activity relationships. Baccelli C, Navarro I, Block S, Abad A, Morel N, Quetin-Leclercq J. Laboratoire de Pharmacognosie, Unité d'Analyse Chimique et Physico-Chimique des Médicaments et Pharmacognosie, Université Catholique de Louvain, UCL 72.30-CHAM, Avenue E. Mounier 72, 1200 Bruxelles, Belgium. Chiara.Baccelli@cham.ucl.ac.be The diterpenes previously isolated from the leaves of Croton zambesicus were tested to evaluate their vasorelaxant activity on the Wistar rat aorta. Their vasorelaxant effect was compared to a series of synthetic trachylobanes and related polycyclic compounds on KCl- or noradrenaline-induced contractions in order to evaluate structure-activity relationships. We demonstrate the vasorelaxant properties of some pure trachylobane diterpenes at low concentration (IC50 < 10 microM) on KCl-induced contractions, but none have a significant effect in noradrenaline-induced contractions. Comparing structures and activity we observed that a C-14 carbonyl group associated with a C-15 hydroxy or ketone function or a C-3 carbonyl associated with a hydroxymethyl group plays an important role in the vasorelaxant activity of trachylobane diterpenes. We also observed that the absolute configuration or the cleavage of the C13-C16 cyclopropane bond does not have a marked effect on the activity. The cytotoxicity of all of these compounds has also been evaluated on HeLa cells in order to verify that the vasorelaxant activity was not correlated with general cytotoxicity. PMID: 17547457 [PubMed - indexed for MEDLINE] Related Links Diterpenes isolated from Croton zambesicus inhibit KCl-induced contraction. [Planta Med. 2005] PMID:16320205 Diterpenes from the leaves of Croton zambesicus. [Phytochemistry. 2004] PMID:15110699 New diterpenes from Croton insularis. [J Nat Prod. 2004] PMID:15104505 ent-trachyloban-3beta-ol, a new cytotoxic diterpene from Croton zambesicus. [Planta Med. 2002] PMID:12143003 A validated method for the quantification of pimarane and trachylobane diterpenes in the leaves of Croton zambesicus by capillary gas chromatography. [Phytochem Anal. 2005] PMID:16223091