Eight compounds were obtained from the dry fruits of Piper longum L., and their potential vascular relaxant activities were explored. The present study first revealed the access of Rosin (7) and Piperchabaoside (8) in the medicinal plant Piper longum L. The vessel tension studies showed that Piperine (2), (2E,4E,14Z)-N-isobutyleicosa-2,4,14-trienamide (3), and Piperlonguminine (6) exerted significant inhibitory effects on PE-induced mesenteric artery vasoconstriction. Furthermore, Calcium Imaging studies were applied to observe the effect of Piperine on the intracellular calcium in mesenteric artery smooth muscle cells (MASMCs). Piperine (2) was observed to promote the influx of extracellular calcium in MASMCs, and via an endothelium-independent mechanism involving Ca2+ entry. Piper longum L. might have a great potential to be further studied as a vascular relaxant, even to be a drug candidate of anti-hypertension.
Keywords: Piper longum L; calcium influx; mesenteric artery; piperine; vasoconstriction.