The cyclitol bornesitol is the main constituent of the leaves from the antihypertensive medicinal plant Hancornia speciosa. This study aimed to investigate the ability of bornesitol to reduce blood pressure and its mechanism of action. Normotensive Wistar rats were divided into control group and bornesitol groups treated intravenously with bornesitol (0.1, 1.0 and 3.0 mg/kg). Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were recorded in non-anesthetized awake animals. Nitric oxide (NO) and angiotensinconverting enzyme (ACE) were measured in plasma by using colorimetric methods. Vascular reactivity study was performed in rat aorta rings and the involvement of nitric oxide synthase (NOS), calcium-calmodulin complex and phosphatidylinositol-3-kinase (PI3K)/Akt pathway in the vasodilator effect was investigated. Administration of bornesitol significantly reduced the SBP, increased the plasmatic level of nitrite, and decreased ACE activity in normotensive rats. In the rat aorta, bornesitol induced endothelium-dependent vasodilatation, which was abolished by NOS blockade. While calcium-calmodulin complex inhibition decreased the vasodilator effect of bornesitol, the inhibition of PI3K/Akt pathway did not alter it. Bornesitol reduced the blood pressure by a mechanism involving an increased production or bioavailability of NO, inhibition of ACE, and by an endothelium-and NO-dependent vasodilator effect. The present results support the use of bornesitol as an active marker for the cardiovascular activity of Hancornia speciosa.

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D-pinitol is a cyclitol present in several edible plant species and extensively investigated for the treatment of metabolic diseases in humans, as food supplement, and demonstrated protective effects in the cardiovascular system. For these reasons, the present work aimed at investigating the mechanisms involved in the vascular effects of D-pinitol in mouse mesenteric artery. Mesenteric arteries from male C57BL/6 mice were mounted in a wire myograph. Nitrite was measured by the 2,3-diaminonaphthalene (DAN) method. Protein expression and phosphorylation were measured by Western blot. The systolic blood pressure (SBP) was measured by tail-cuff plethysmography. D-pinitol induced a concentration-dependent vasodilatation in endothelium-intact, but not in endothelium-denuded arteries. Nω-Nitro-L-arginine methyl ester (300 μM) abolished the effect of D-pinitol, while 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 10 μM) shifted the concentration-response curve to the right. KN-93 (1 μM) blunted the vasodilator effect of D-pinitol, but H-89 (0.1 μM) did not change it. 1-[2-(Trifluoromethyl) phenyl]imidazole (300 μM), indomethacin (10 μM), celecoxib (5 μM), wortmannin (1 μM), ruthenium red (10 μM), tiron (10 μM), MnTMPyP (30 μM), MPP (0.1 μM), PHTPP (0.1 μM), and atropine (1 μM) did not change the effect of D-pinitol. D-pinitol increased the concentration of nitrite, which was inhibited by L-NAME and calmidazolium (10 μM). D-pinitol increased the phosphorylation level of eNOS activation site at Ser1177 and reduced the phosphorylation level of its inactivation site at Thr495. In normotensive mice, the intraperitoneal administration of D-pinitol (10 mg/kg) induced a significant reduction of the SBP after 30 min. The present results led us to conclude that D-pinitol has an endothelium- and NO-dependent vasodilator effect in mouse mesenteric artery through a mechanism dependent on the activation of eNOS by the calcium-calmodulin complex, which can explain its hypotensive effect in mice.