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Tetra-acetylajugasterone a new constituent of Vitex cienkowskii with vasorelaxant activity |
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| Institution: | 1. Department of Animal Biology, Faculty of Science, University of Douala, P.O. Box 24157, Douala, Cameroon;2. Department of Chemistry, University of Dschang, P.O. Box 371, Dschang, Cameroon;3. Institute of Forestry, Tribhuvan University, Pokhara Campus, P.O. Box 43, Pokhara, Nepal;4. Institute of Pharmacology and Toxicology, Technical University of Munich, Biedersteiner Str. 29, 80802 Munich, Germany;5. Chemistry Department, Organic and Bioorganic Chemistry, Bielefeld University, P.O. Box 100131, 33501 Bielefeld, Germany;6. Institute of Pharmaceutical Biology, Butenandt Str. 5 - 13 B, 81377 Munich, Germany;1. J. Heyrovsky Institute of Physical Chemistry, v.v.i., Academy of Sciences of the Czech Republic, Dolejskova 3, CZ-18223 Prague 8, Czech Republic;2. ELMARCO, s.r.o., V Horkach 76/18, CZ-460 07 Liberec, Czech Republic;3. Institute of Chemical Technology, Prague, Technická 5, CZ-166 28 Prague 6, Czech Republic;1. Physics Department, Università degli Studi di Milano, Milan, Italy;2. INFN – Section of Milan, Italy;3. Energy Department, Politecnico di Milano, Milan, Italy;4. Department of Neutron Physics, Research Centre Rez, Ltd., Czech Republic;1. Department of Microbiology (LD, AC), All India Institute of Medical Sciences, New Delhi, India |
| Abstract: | Tetra-acetylajugasterone C (TAAC) was found to be one of the naturally occurring compounds of the Cameroonian medicinal plant Vitex cienkowskii which is responsible for a vasorelaxant activity of an extract of this plant. The evaluation of the underlying mechanisms for the relaxing effect of TAAC was determined using aortic rings of rats and mice. TAAC produced a concentration-dependent relaxation in rat artery rings pre-contracted with 1 μM noradrenaline (IC50: 8.40 μM) or 60 mM KCl (IC50: 36.30 μM). The nitric oxide synthase inhibitor l-NAME (100 μM) and the soluble guanylate cyclase inhibitor ODQ (10 μM) significantly attenuated the vasodilatory effect of TAAC. TAAC also exerted a relaxing effect in aorta of wild-type mice (cGKI+/+; IC50 = 13.04 μM) but a weaker effect in aorta of mice lacking cGMP-dependent protein kinase I (cGKI?/?; IC50 = 36.12 μM). The involvement of calcium channels was studied in rings pre-incubated in calcium-free buffer and primed with 1 μM noradrenaline prior to addition of calcium to elicit contraction. TAAC (100 μM) completely inhibited the resulting calcium-induced vasoconstriction. The same concentration of TAAC showed a stronger effect on the tonic than on the phasic component of noradrenaline-induced contraction. This study shows that TAAC, a newly detected constituent of Vitex cienkowskii contributes to the relaxing effect of an extract of the plant. The effect is partially mediated by the involvement of the NO/cGMP pathway of the smooth muscle but additionally inhibition of calcium influx into the cell may play a role. |
| Keywords: | Tetra-acetylajugasterone C Aortic smooth muscle Relaxation Nitric oxide cGMP cGKI |
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