Vasorelaxant properties of acid and neutral fractions of Dimerocostus strobilaceus Kuntze used by Kuna Indians of Panama

Ethnopharmacological relevance: Dimerocostus strobilaceus is used by the Kuna Indians of Panama for the treatment of hypertension and other cardiovascular diseases. Aim of the study: We investigated the vascular effects of acid and neutral fractions obtained from methanol and dichloromethane extracts of Dimerocostus strobilaceus. Materials and methods: The acid and neutral methanol fractions (A-MeOH and N-MeOH) or acid and neutral dichlorometanic fractions (A-DCM and N-DCM) were tested using isolated rat aortic rings with or without endothelium pre-contracted by phenylephrine. We examined the ability of these different fractions at different concentrations to modify vascular responses induced by angiotensin II using endothelium-denuded aortic rings from Spontaneously Hypertensive Rats (SHR). Results: In aortic rings with intact endothelium A-MeOH, N-MeOH and A-DCM fractions produced a concentration-dependent vasorelaxation (62.4 ± 5.2, 64.5 ± 5.0 and 63.7 ± 5.0%, respectively), whereas the N-DCM fraction did not produce any vasorelaxant effect. Maximal relaxation evocated by vasoactive fractions was substantially inhibited on aortic rings without endothelium. Our study demonstrates that A-MeOH, N-MeOH, A-DCM and N-DCM significantly reduce contractile responses induced by angiotensin-II on aortic rings. Conclusions: Our findings may contribute to a better understanding of the potential link between vascular properties observed with Dimerocostus strobilaceus and their ethnobotanical use.