Garcinielliptone FC, a polyisoprenylated benzophenone from Platonia insignis Mart., promotes vasorelaxant effect on rat mesenteric artery.

Polyisoprenylated benzophenones represent a group of chemical compounds commonly identified in Clusiaceae species and are responsible for a large amount of biological activities. In this work, the vasorelaxant effect induced by garcinielliptone FC (GFC) isolated from Platonia insignis Mart. (Clusiaceae), a monotype species from Platonia genus, was investigated. GFC promoted an endothelium-independent vasorelaxation on phenylephrine (PHE, 10(-5) mol L(-1))-induced vasoconstriction, but not on KCl (80 mmol L(-1))-induced vasoconstriction, on rat superior mesenteric artery rings. In addition, a concentration-dependent decrease of PHE- or serotonin-induced cumulative concentration-response curves was observed for GFC, and a slight decrease of pD2 value on CaCl2-induced vasoconstriction. In a Ca(2+)-free medium, GFC interfered in calcium mobilisation from PHE (10(-5) mol L(-1))-sensitive intracellular stores. GFC-induced vasorelaxant effect is probably mediated by a dual effect on mobilisation of calcium intracellular stores and attenuation of transmembrane calcium influx.

Antihypertensive and vasorelaxant effects of ethanol extract of stem barks from Zanthoxylum rhoifolium Lam. in rats.

Administration of ethanol extract of stem bark from Z. rhoifolium (EEtOH-ZR) induced hypotension associated with a dual effect in heart rate in normotensive rats. This response was highlighted in spontaneously hypertensive rats (SHR). In rat superior mesenteric artery rings, the cumulative addition of EEtOH-ZR (0.1-750 microg/mL) on a phenylephrine-induced pre-contraction (10(-5) M) promoted a vasorelaxant effect by a concentration-dependent manner and independent of vascular endothelium. A similar effect was obtained on KCl-induced pre-contractions (80 mM). EEtOH-ZR attenuated contractions induced by cumulative addition of CaCl2 (10(-6)-3 x 10(-2) M) in depolarizing medium without Ca2+ only at 500 or 750 microg/mL. Likewise, on S-(-)-Bay K 8644-induced pre-contractions (10(-7) M), the EEtOH-ZR-induced vasorelaxant effect was attenuated. EEtOH-ZR (27, 81, 243 or 500 microg/mL) inhibited contractions induced by cumulative addition of phenylephrine (10(-9) - 10(-5) M) in endothelium-denuded preparations or by a single concentration (10(-5) M) in a Ca(2+)-free medium. The involvement of K+ channels was evaluated by tetraethylammonium (3 mM); the EEtOH-ZR-induced vasorelaxation was not attenuated. Thus, calcium influx blockade through voltage-operated calcium channels (CavL) and inhibition of calcium release from intracellular stores are probably underlying EEtOH-ZR-induced cardiovascular effects.