Hypoglycemic and Vasorelaxant Effect of Passiflora edulis Fruit Peel By-Product.

Passiflora edulis fo. flavicarpa (Passifloraceae) is popularly known as yellow passion fruit and its fruit peels are considered a rich by-product in bioactive compounds which has greatly beneficial health properties. The objective of this study was to evaluate the effects of P. edulis fruit peel extracts in a type 1 diabetes model and the potential vasorelaxant effect. The aqueous and hydroethanolic extracts were obtained from P. edulis fruit peels and orientin and isorientin flavonoids were identified in both extracts through ultra-high performance liquid chromatography. Pectin was only identified in the aqueous extract by high-performance steric exclusion chromatography and nuclear magnetic resonance. Regarding the vascular system, the hydroethanolic extract showed better vasorelaxant effects in the mesenteric artery rings when compared to the aqueous extract. These effects mainly occur by opening the potassium channels. In the type 1 diabetes model, extracts at doses of 400 and 600 mg/kg were able to restore the effect of insulin in diabetic rats which were not responding to its action. The antidiabetic effect was more significant for the aqueous extract. Thus, the results suggest that the hydroethanolic and aqueous extracts have greater potential to be used to treat cardiovascular diseases such as hypertension and as a hypoglycemic agent, respectively. Taken together, P. edulis fruit peel extracts proved to be a source of valuable bioactive raw material to produce nutraceuticals or pharmaceutical products.

Involvement of Potassium Channels in Vasorelaxant Effect Induced by Valeriana prionophylla Standl. in Rat Mesenteric Artery.

Assays in vitro and in vivo were performed on extract from roots and leaves from the Valeriana prionophylla Standl. (VPR and VPF, resp.). In phenylephrine (1 µ M) precontracted rings, VPR (0.01-300 µ g/mL) induced a concentration-dependent relaxation (maximum response (MR) = 75.4 ± 4.0%, EC50 = 5.97 (3.8-9.3) µ g/mL, n = 6]); this effect was significantly modified after removal of the endothelium (EC50 = 39.6 (27.2-57.6) µ g/mL, P < 0.05). However, VPF-induced vasorelaxation was less effective compared to VPR. When rings were preincubated with L-NAME (100 µ M) or indomethacin (10 µ M), the endothelium-dependent relaxation induced by VPR was significantly attenuated (MR = 20.9 ± 2.3%, 34.2 ± 2.9%, resp., P < 0.001). In rings denuded endothelium, precontracted with KCl (80 mM), or in preparations pretreated with KCl (20 mM) or tetraethylammonium (1 or 3 mM), the vasorelaxant activity of VPR was significantly attenuated (MR = 40.0 ± 8.2, n = 5; 50.5 ± 6.0%; 49.3 ± 6.4%; 46.8 ± 6.2%; resp., P < 0.01). In contrast, neither glibenclamide (10 µ M), barium chloride (30 µ M), nor 4-aminopyridine (1 mM) affected VPR-induced relaxation. Taken together, these results demonstrate that hypotension induced by VPR seems to involve, at least in part, a vascular component. Furthermore, endothelium-independent relaxation induced by VPR involves K(+) channels activation, most likely due to BKCa channels, in the rat superior mesenteric artery.