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]

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