Endothelium-Independent Vasorelaxant Effects of Anthocyanins-Enriched Extract from Odontonema strictum (Nees) Kuntze (Acanthaceae) Flowers: Ca2+ Channels Involvement

Aims: We aimed in this study to investigate the mechanisms of the vasorelaxation effect caused by the anthocyanins-enriched extract of Odontonema strictum flowers.

Study Design: Anthocyanins-enriched extract of Odontonema strictum flowers and vasorelaxantes activities of mice aortic rings.

Place and Duration of Study: The flowers of Odontonema strictum (Nees) Kuntze (Acanthaceae) were collected in January 2015 at the “Institut de Recherche en Sciences de la Santé (IRSS)” experimental station in Ouagadougou. The experiments were conducted in October - November 2018 at the department of Medicine and Traditional Pharmacopeia-Pharmacy (MEPHATRA-PH)/IRSS.

Methodology: The extract was enriched in anthocyanins using Amberlite XAD-7 non-ionic resin column. The vasorelaxant activity of anthocyanins-enriched extract of O. strictum flowers (OSF) was tested using isolated organ-chamber technique with mice aorta rings.

Results: OSF showed concentration-dependent relaxant effects on mice endothelium intact or denuded aortic rings pre-contracted with U46619 (10-7 M) and KCl (80 mM). OSF induced relaxation in the mice aortic rings by stimulating smooth muscle cells. The vasorelaxant effect of OSF (10-1000 µg/mL) was similar in endothelium-intact and endothelium-denuded aortic rings. The maximum relaxant effect was 93.78 ± 4.69% and 92.30 ± 3.19% for endothelium-intact and endothelium-denuded aortic rings, respectively. Moreover, after incubation of the aorta rings with OSF (400 µg/mL) or vehicle (0.02% of DMSO) in PSS, OSF blocked the contraction through mechanism involving inhibition of CaCl2 and U46619 effect.

Conclusions: The present study provides a pharmacological evidence for the antihypertensive medicinal use of Odontonema strictum by highlighting its vasorelaxant activity.