The tea of flowers of M. caesalpiniifolia promotes hypotension and tachycardia, whereas ethanolic extract (MC-EtOH) promotes hypotension and bradycardia involving the participation of the muscarinic and ganglionic pathways, as well as vasorelaxant action involving the Ca(2+) influx inhibition blockade.

The antihypertensive and antioxidant effects of α‐terpineol on hypertensive rats were evaluated in this study. Hypertension was induced in male Wistar rats by oral administration of the NG‐nitro‐L‐arginine methyl ester (L‐NAME) 50 mg/kg body weight/day) in drinking water for 1 week. Rats with mean arterial pressure > 140 mmHg were considered hypertensive. In order to evaluate the α‐terpineol effect on haemodynamic parameters, rats were treated once a day with different doses of α‐terpineol (25, 50, or 100 mg/kg/day) or vehicle for one week. After this time, blood samples were collected and activities of antioxidant enzymes were assessed. Furthermore, the vasorelaxant effect of α‐terpineol was also assessed in mesenteric artery rings. Oral administration of α‐terpineol was able to reduce mean arterial pressure in up to 38.15 ± 8.7 mmHg. In mesenteric artery rings, α‐terpineol (10−9–10−2 M) induced vascular endothelium independent vasodilatation. In addition, rats treated with α‐terpineol showed alterations in biochemical parameters indicating an antioxidant effect. Such results suggest that α‐terpineol is able to reduce arterial pressure, possibly due to a decrease of vascular resistance, and restore enzymatic antioxidants in L‐NAME‐induced hypertensive rats. Copyright © 2013 John Wiley & Sons, Ltd.

The Protium heptaphyllum species, also known as Almécega, produces an oily resin, used in folk medicine as an analgesic and anti-inflammatory agent, in healing, and as an expectorant, which is rich in pentacyclic triterpenes and essential oils. In this study, the essential oil obtained by hydrodistillation of Almécega's resin was analyzed by gas chromatography-triple quadrupole mass spectrometry and evaluated for chemical composition and vasorelaxant activity in rat superior mesenteric artery. The main constituents determined by gas chromatography-triple quadrupole mass spectrometry were limonene, p-cineole, and o-cymene. In intact rings precontracted with phenylephrine (Phe 1 μM), EOPh (3–750 μg/mL) induced relaxation, and the essential oil had a concentration-dependent vasorelaxant effect, without involvement of endothelial mediators.

The study evaluated the vasorelaxant effect induced by the ethanolic extract of the leaves of Zanthoxylum rhoifolium Lam (EEtOH-Zr/leaves). Wistar rats were treated with the leaf extract containing a single dose of 2,000 mg / kg, v.o. After 14 days, the animals were anesthetized for blood collection and subsequent analysis of the biochemical parameters; they were then euthanized (sodium pentobarbital-100 mg/kg, i.p.) for the removal and morphological analysis of the heart, lung, liver and kidney. The vasorelaxation activity the and vascular reactivity of EEtOH-Zr/leaves were evaluated on artery mesenteric rings isolated from rats. The extract showed no signs of toxicity and no significant difference in the values of the biochemical parameters between the control group and the group of treated animals. In the evaluation of pharmacological activity in the smooth muscle, the EEtOH-Zr/leaves caused vasorelaxant effect on the tonic contraction induced by phenylephrine in mesenteric artery preparations in the presence (pD2=2.17±0.05 µg/mL; Emax=99.8±5.2%) and absence (pD2=2.14±0.05 µg/mL; Emax=95.3±6.4%) of the vascular endothelium. Oral administration of EEtOH-Zr/leaves reduced the contraction induced by the cumulative addition of PHE. It is concluded that the EEtOH-Zr/leaves promote vasorelaxation and reduce vascular reactivity of adrenergic alpha-1 agonist in the mesenteric artery. The results did not show toxic effects of the extract.