Gonçalves Roberta L, Lugnier Claire, Keravis Thérèse, Lopes Miguel J, Fantini Fernando A, Schmitt Martine, Cortes Steyner F, Lemos Virginia S
Department of Physiology and Biophysics, ICB, Federal University of Minas Gerais, Belo Horizonte, Brazil.
Eur J Pharmacol. 2009 Oct 12;620(1-3):78-83. doi: 10.1016/j.ejphar.2009.08.008. Epub 2009 Aug 15.
The inhibitory effect of the flavonoid dioclein was assessed on purified vascular cyclic nucleotide phosphodiesterase isoforms (EC 3.1.4.17, PDE1-5) in comparison with 8-methoxymethyl-isobutylmethylxanthine (8-MM-IBMX) and vinpocetine which are currently used as PDE1 inhibitors. The mechanism underlying the vasorelaxant effect of dioclein was investigated in human saphenous vein. Dioclein inhibited PDE1 more selectively than vinpocetine and 8-MM-IBMX, with IC(50) values of 2.47+/-0.26 and 1.44+/-0.35 microM, respectively in basal- and calmodulin-activated states. Dioclein behaved as a competitive inhibitor for cGMP hydrolysis by PDE1 in basal- and calmodulin-activated states (K(i)=0.62+/-0.14 and 0.55+/-0.07 microM, respectively), indicating this inhibitory effect to be independent of calmodulin interactions. In addition, dioclein induced a concentration-dependent relaxation of human saphenous vein which was independent on the presence of functional endothelium (EC(50) values of 7.3+/-3.1 and 11+/-2.7 microM, respectively with and without endothelium). 8-MM-IBMX relaxed human saphenous vein with an EC(50)=31+/-16 microM, whereas vinpocetine did not cause any vasorelaxation at concentrations up to 100 microM. Rp-8-pCPT-cGMPS, which inhibits cGMP-dependent protein kinase (PKG), blocked the vasodilator effect of dioclein, whereas H-89, which is a cAMP-dependent protein kinase (PKA) inhibitor, had a minor inhibitory effect. Our data show that dioclein is a potent calmodulin-independent selective inhibitor of PDE1 and that inhibition of PDE1 is involved in the PKG-mediated vasorelaxant effect of dioclein in human saphenous vein. Furthermore, dioclein may represent a new archetype to develop more specific PDE1 inhibitors.
与目前用作磷酸二酯酶1（PDE1）抑制剂的8 - 甲氧基甲基 - 异丁基甲基黄嘌呤（8 - MM - IBMX）和长春西汀相比，评估了黄酮类化合物二氢杨梅素对纯化的血管环核苷酸磷酸二酯酶同工型（EC 3.1.4.17，PDE1 - 5）的抑制作用。在人隐静脉中研究了二氢杨梅素血管舒张作用的潜在机制。二氢杨梅素比长春西汀和8 - MM - IBMX更具选择性地抑制PDE1，在基础和钙调蛋白激活状态下，其半数抑制浓度（IC50）值分别为2.47±0.26和1.44±0.35微摩尔。在基础和钙调蛋白激活状态下，二氢杨梅素对PDE1水解环磷酸鸟苷（cGMP）表现为竞争性抑制剂（抑制常数Ki分别为0.62±0.14和0.55±0.07微摩尔），表明这种抑制作用与钙调蛋白相互作用无关。此外，二氢杨梅素诱导人隐静脉浓度依赖性舒张，这与功能性内皮的存在无关（有和无内皮时的半数有效浓度EC50值分别为7.3±3.1和11±2.7微摩尔）。8 - MM - IBMX使人类隐静脉舒张，半数有效浓度EC50 = 31±16微摩尔，而长春西汀在浓度高达100微摩尔时未引起任何血管舒张。抑制环磷酸鸟苷依赖性蛋白激酶（PKG）的Rp - 8 - pCPT - cGMPS阻断了二氢杨梅素的血管舒张作用，而作为环磷酸腺苷依赖性蛋白激酶（PKA）抑制剂的H - 89具有较小的抑制作用。我们的数据表明，二氢杨梅素是一种有效的、与钙调蛋白无关的PDE1选择性抑制剂，并且PDE1的抑制参与了二氢杨梅素在人隐静脉中由PKG介导的血管舒张作用。此外，二氢杨梅素可能代表一种开发更特异性PDE1抑制剂的新原型。
