1: Br J Pharmacol. 2003 Dec;140(7):1211-6. Epub 2003 Nov 03. 

Characterisation of marrubenol, a diterpene extracted from Marrubium vulgare, as
an L-type calcium channel blocker.

El Bardai S, Wibo M, Hamaide MC, Lyoussi B, Quetin-Leclercq J, Morel N.

Laboratoire de Pharmacologie, Universite catholique de Louvain, UCL 5410, Avenue
Hippocrate, 54, Bruxelles B-1200, Belgium.

The objective of the present study was to investigate the mechanism of the
relaxant activity of marrubenol, a diterpenoid extracted from Marrubium vulgare.
In rat aorta, marrubenol was a more potent inhibitor of the contraction evoked
by 100 mm KCl (IC50: 11.8+/-0.3 microm, maximum relaxation: 93+/-0.6%) than of
the contraction evoked by noradrenaline (maximum relaxation: 30+/-1.5%). In
fura-2-loaded aorta, marrubenol simultaneously inhibited the Ca2+ signal and the
contraction evoked by 100 mm KCl, and decreased the quenching rate of fura-2
fluorescence by Mn2+. Patch-clamp data obtained in aortic smooth muscle cells
(A7r5) indicated that marrubenol inhibited Ba2+ inward current in a
voltage-dependent manner (KD: 8+/-2 and 40+/-6 microm at holding potentials of
-50 and -100 mV, respectively). These results showed that marrubenol inhibits
smooth muscle contraction by blocking L-type calcium channels.British Journal of
Pharmacology (2003) 140, 1211-1216. doi:10.1038/sj.bjp.0705561

PMID: 14597602 [PubMed - in process]