cyclic-gmp and propargylglycine

The present research aimed to isolate the non-polar secondary metabolites that produce the vasodilator effects induced by the dichloromethane extract of Prunus serotina (P. serotina) fruits and to determine whether the NO/cGMP and the H2S/KATP channel pathways are involved in their mechanism of action. A bioactivity-directed fractionation of the dichloromethane extract of P. serotina fruits led to the isolation of ursolic acid and uvaol as the main non-polar vasodilator compounds. These compounds showed significant relaxant effect on rat aortic rings in an endothelium- and concentration-dependent manner, which was inhibited by NG-nitro-L-arginine methyl ester (L-NAME), DL-propargylglycine (PAG) and glibenclamide (Gli). Additionally, both triterpenes increased NO and H2S production in aortic tissue. Molecular docking studies showed that ursolic acid and uvaol are able to bind to endothelial NOS and CSE with high affinity for residues that form the oligomeric interface of both enzymes. These results suggest that the vasodilator effect produced by ursolic acid and uvaol contained in P. serotina fruits, involves activation of the NO/cGMP and H2S/KATP channel pathways, possibly through direct activation of NOS and CSE.

Topics: Alkynes; Animals; Aorta; Cyclic GMP; Cystathionine gamma-Lyase; Endothelium, Vascular; Enzyme Activation; Fruit; Glyburide; Glycine; Hydrogen Sulfide; KATP Channels; Male; Molecular Docking Simulation; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase Type III; Plant Extracts; Protein Binding; Prunus avium; Rats; Triterpenes; Ursolic Acid; Vasodilation; Vasodilator Agents

Recent studies have demonstrated that hydrogen sulfide (H(2)S) is produced within the vessel wall from L-cysteine regulating several aspects of vascular homeostasis. H(2)S generated from cystathione γ-lyase (CSE) contributes to vascular tone; however, the molecular mechanisms underlying the vasorelaxing effects of H(2)S are still under investigation.. Using isolated aortic rings, we observed that addition of L-cysteine led to a concentration-dependent relaxation that was prevented by the CSE inhibitors DL-propargylglyicine (PAG) and β-cyano-l-alanine (BCA). Moreover, incubation with PAG or BCA resulted in a rightward shift in sodium nitroprusside-and isoproterenol-induced relaxation. Aortic tissues exposed to PAG or BCA contained lower levels of cGMP, exposure of cells to exogenous H(2)S or overexpression of CSE raised cGMP concentration. RNA silencing of CSE expression reduced intracellular cGMP levels confirming a positive role for endogenous H(2)S on cGMP accumulation. The ability of H(2)S to enhance cGMP levels was greatly reduced by the nonselective phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine. Finally, addition of H(2)S to a cell-free system inhibited both cGMP and cAMP breakdown.. These findings provide direct evidence that H(2)S acts as an endogenous inhibitor of phosphodiesterase activity and reinforce the notion that this gasotransmitter could be therapeutically exploited.

Topics: 1-Methyl-3-isobutylxanthine; Alanine; Alkynes; Animals; Aorta, Thoracic; Clone Cells; Cyclic AMP; Cyclic GMP; Cystathionine gamma-Lyase; Cysteine; Endothelial Cells; Glycine; Humans; Hydrogen Sulfide; In Vitro Techniques; Male; Phosphodiesterase Inhibitors; Rats; Rats, Wistar; RNA, Small Interfering; Vasodilation

H2S is an important gasotransmitter with a vasorelaxant property. The modulation of endogenous H2S generation from different tissues and the functional consequence of this modulation are not clear. In the present study, the production of H2S from vascular tissues as well as the liver and ileum of rats was measured. The H2S production rate was significantly greater in rat liver than rat vascular tissues. H2S production in rat aortae, ileum, and liver tissues was upregulated by sodium nitroprusside in a cGMP-dependent fashion. Amino-oxyacetate (AOA) (1 mM) abolished H2S production in liver tissues and partially inhibited H2S production in the ileum, while D,L-propargylglycine (PPG) at a similar concentration only slightly inhibited H2S production in liver. Intraperitoneal injection PPG, but not AOA, significantly suppressed H2S production in liver, aorta, and ileum tissues. The systolic blood pressure of rats was significantly increased 2-3 weeks after i.p. injection of PPG. It is concluded that the endogenous production of H2S could be modulated by NO. AOA and PPG have different capacities in regulating the endogenous production of H2S in different types of tissues.

Topics: Alkynes; Aminooxyacetic Acid; Animals; Aorta; Blood Pressure; Carbon-Oxygen Lyases; Cyclic GMP; Cystathionine beta-Synthase; Glycine; Hydrogen Sulfide; Ileum; In Vitro Techniques; Injections, Intraperitoneal; Liver; Male; Nitric Oxide; Rats; Rats, Sprague-Dawley