Structural relationships and vasorelaxant activity of monoterpenes.
OBJECTIVE
The hypotensive activity of the essential oil of Mentha x villosa and its main constituent, the monoterpene rotundifolone, have been reported. Therefore, our objective was to evaluate the vasorelaxant effect of monoterpenes found in medicinal plants and establish the structure-activity relationship of rotundifolone and its structural analogues on the rat superior mesenteric artery.


METHODS
Contractions of the vessels were induced with 10 μM of phenylephine (Phe) in rings with endothelium. During the tonic phase of the contraction, the monoterpenes (10-8 - 10-3, cumulatively) were added to the organ bath. The extent of relaxation was expressed as the percentage of Phe-induced contraction.


RESULTS
The results from the present study showed that both oxygenated terpenes (rotundifolone, (+)-limonene epoxide, pulegone epoxide, carvone epoxide, and (+)-pulegone) and non-oxygenated terpene ((+)-limonene) exhibit relaxation activity. The absence of an oxygenated molecular structure was not a critical requirement for the molecule to be bioactive. Also it was found that the position of ketone and epoxide groups in the monoterpene structures influence the vasorelaxant potency and efficacy.


CONCLUSIONS
The results suggest that the presence of functional groups in the chemical structure of rotundifolone is not essential for its vasorelaxant activity.
Department of Physiology, Federal University of Sergipe, CEP 49100-000, São Cristóvão, Sergipe, Brazil. damiao_desousa@yahoo.com.br.
Tamires
T
Cardoso Lima
Marcelo Mendonça
MM
Mota
José Maria
JM
Barbosa-Filho
Márcio Roberto
MR
Viana Dos Santos
Damião Pergentino
DP
De Sousa