title: The vasorelaxant effect of 8(17),12E,14-labdatrien-18-oic acid involves stimulation of adenylyl cyclase and cAMP/PKA pathway: Evidences by pharmacological and molecular docking studies.
abstract: The relaxant effect of 8(17),12E,14-labdatrien-18-oic acid (LBD) was investigated on isolated aortic rings and compared with forskolin (FSK), a standard and potent activator of adenylyl cyclase (AC) with relaxing effect. The presence of potassium channel blockers, such as glibenclamide (ATP-blocker), apamin (SKCa-blocker), charybdotoxin (BKCa-blocker) did not significantly affect either the LBD or FSK concentration-response curves. However, in the presence of 4-aminopyridine (KV-blocker), the relaxant effect for both diterpenes was significantly attenuated, with reduction of its relative potencies. Moreover, the relaxation induced by 8-Br-cAMP, an analog of cAMP, was also significantly attenuated in the same conditions, i.e., in the presence of 4-aminopyridine. The presence of aminophylline, a nonselective phosphodiesterase inhibitor, caused a significant increasing in the potency for both LBD and FSK. On the other hand, the presence of Rp-cAMPS, a selective PKA-inhibitor, significantly attenuated the relaxant effect of LBD. In this work, in the same experimental conditions, both labdane-type diterpenes presented remarkably similar results; FSK, however, presented a higher potency (100-fold) than LBD. Thus, the hypothesis that LBD could be a novel AC-activator emerged. To assess that hypothesis, computational molecular docking studies were performed. Crystallographic structure of adenylyl cyclase/forskolin complex (1AB8) was obtained from RSCB Protein Data Bank and used to compare the modes of interaction of the native ligand and LBD. The computational data shows many similarities between LBD and FSK concerning the interaction with the regulatory site of AC. Taken together, the results presented here pointed to LBD as a novel AC-activator.
authors.affiliation: Colegiado de Farmácia (CFARM), Universidade Federal do Vale do São Francisco (UNIVASF), Av. José de Sá Maniçoba, S/No, Campus Centro, P.O. Box 252, CEP:56304-205, Petrolina, PE, Brazil; Programa de Pós-Graduação em Recursos Naturais do Semiárido (PGRNSA), Universidade Federal do Vale do São Francisco (UNIVASF), 56304-205, Petrolina, PE, Brazil. Electronic address: luciano.ribeiro@univasf.edu.br.
authors.forename: Luciano A A
authors.initials: LAA
authors.lastname: Ribeiro
authors.affiliation: Colegiado de Farmácia (CFARM), Universidade Federal do Vale do São Francisco (UNIVASF), Av. José de Sá Maniçoba, S/No, Campus Centro, P.O. Box 252, CEP:56304-205, Petrolina, PE, Brazil.
authors.forename: Edilson B
authors.initials: EB
authors.lastname: Alencar Filho
authors.affiliation: Curso de Graduação em Farmácia, Universidade Federal do Vale do São Francisco (UNIVASF), 56304-205, Petrolina, PE, Brazil.
authors.forename: Maisa C
authors.initials: MC
authors.lastname: Coelho
authors.affiliation: Universidade Federal da Paraíba, Laboratório de Tecnologia Farmacêutica-Campus I. Cidade Universitária, 58051-970, Joao Pessoa, PB, Brazil.
authors.forename: Bagnólia A
authors.initials: BA
authors.lastname: Silva
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000201:enzymology; D001665:Binding Sites; D020134:Catalytic Domain; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004224:Diterpenes / Q000378:metabolism / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D020536:Enzyme Activators / Q000378:metabolism / Q000494:pharmacology*; D008297:Male; D062105:Molecular Docking Simulation; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000201:enzymology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000201:enzymology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D011485:Protein Binding; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017208:Rats, Wistar; D015290:Second Messenger Systems / Q000187:drug effects*; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000378:metabolism / Q000494:pharmacology*
chemical_list: C000609173:8(17),12E,14-labdatrien-18-oic acid; D004224:Diterpenes; D020536:Enzyme Activators; D026902:Potassium Channel Blockers; D047428:Protein Kinase Inhibitors; D014665:Vasodilator Agents; D005576:Colforsin; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D000262:Adenylyl Cyclases
keywords: Adenylyl cyclase; Diterpenes; Forskolin; Molecular docking; Potassium channels; Smooth muscle