Vasorelaxant Effect of Vitexin, Procyanidin B2 and Isoquercetine on Rat’s Aortic Smooth Muscle

Abstract

Vitexin, procyanidin B₂ and isoquercetine are active compounds found in hawthorn berry fruit. They have several cardioprotective, anti-inflammatory, antioxidant, prooxidant, anti-cancer, antinociceptive, anti-convulsant, and other pharmacological influences; with the possibility of improving memory, anti-diabetic and chemo-preventive properties. The current study looked at the effects of vitexin, procyanidin B₂, and isoquercetine (2x10-6 to 3x10-4 M) on rat aortic smooth muscle cells that had been pre-contracted by phenylephrine (PE). The use of particular inhibitors and blockers to affect induced aortic ring relaxation revealed that the mediated relaxation was dependent on K⁺, Ca²⁺ channels, and several EDHFs such as NO, PGI2, and cGMP. The relaxation induced by vitexin was primarily dependent on Kca channel activation, NO, cGMP, and PGI2 pathways activation, but not on K_ATP, Kir, or Kv channels. Isoquercetine relaxation was mostly dependent on NO. Procyanidin B₂ caused relaxation that was dependent on the L-type Ca2+ channel. According to these findings Vitexin, procyanidin B₂, and isoquercetine all caused concentration-dependent relaxation in rat aortic smooth muscle. Potassium, Ca²⁺ channels, and EDHFs, particularly NO, were involved in the relaxation caused by these compounds. The activation of PKs, as well as the NO released from the endothelium, which activates Kca channels. and causes relaxation in aortic smooth muscle cells