Pharmaceuticals (Oct 2022)

Vasorelaxant Effects of <i>Syzygium samarangense</i> (Blume) Merr. and L.M.Perry Extract Are Mediated by NO/cGMP Pathway in Isolated Rat Thoracic Aorta

  • Noura A. Hassan,
  • Mohamed A. O. Abdelfattah,
  • Yasmine M. Mandour,
  • Assem M. El-Shazly,
  • Mansour Sobeh,
  • Mona F. Mahmoud

DOI
https://doi.org/10.3390/ph15111349
Journal volume & issue
Vol. 15, no. 11
p. 1349

Abstract

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Syzygium samarangense (Blume) Merr. and L.M.Perry is utilized widely in traditional medicine. We have reported previously a wide array of pharmacological properties of its leaf extract, among them anti-inflammatory, antioxidant, hepatoprotective, antidiabetic, antiulcer, and antitrypanosomal activities. We also annotated its chemical composition using LC-MS/MS. Here, we continue our investigations and evaluate the vasorelaxant effects of the leaf extract on aortic rings isolated from rats and explore the possible underlying mechanisms. S. samarangense extract induced a concentration dependent relaxation of the phenylephrine-precontracted aorta in the rat model. However, this effect disappeared upon removing the functional endothelium. Pretreating the aortic tissues either with propranolol or NG-nitro-L-arginine methyl ester inhibited the relaxation induced by the extract; however, atropine did not affect the extract-induced vasodilation. Meanwhile, adenylate cyclase inhibitor, MDL; specific guanylate cyclase inhibitor, ODQ; high extracellular KCl; and indomethacin as cyclooxygenase inhibitor inhibited the extract-induced vasodilation. On the other hand, incubation of S. samarangense extract with aortae sections having their intact endothelium pre-constricted using phenylephrine or KCl in media free of Ca2+ showed no effect on the constriction of the aortae vessels induced by Ca2+. Taken together, the present study suggests that S. samarangense extract dilates isolated aortic rings via endothelium-dependent nitric oxide (NO)/cGMP signaling. The observed biological effects could be attributed to its rich secondary metabolites. The specific mechanisms of the active ingredients of S. samarangense extract await further investigations.

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