Hsiao George, Chang Ching-Yi, Shen Ming-Yi, Chou Duen-Suey, Tzeng Shu-Hw, Chen Tzeng-Fu, Sheu Joen-Rong
Graduate Institute of Pharmacology and Graduate Institute of Medical Sciences, Taipei Medical University, Taiwan.
J Agric Food Chem. 2005 Jun 29;53(13):5179-86. doi: 10.1021/jf0500738.
The aim of this study was to systematically examine the inhibitory mechanisms of the flavonoid alpha-naphthoflavone (alpha-NF) in platelet activation. In this study, alpha-NF concentration dependently (5-20 microM) inhibited platelet aggregation stimulated by agonists. alpha-NF (5 and 10 microM) inhibited intracellular Ca(2+) mobilization, phosphoinositide breakdown, and thromboxane A(2) formation stimulated by collagen (1 microg/mL) in human platelets. In addition, alpha-NF (5 and 10 microM) markedly increased levels of cyclic GMP and cyclic GMP-induced vasodilator-stimulated phosphoprotein (VASP) Ser(157) phosphorylation. Rapid phosphorylation of a platelet protein of Mr 47,000 (P47), a marker of protein kinase C activation, was triggered by phorbol-12,13-dibutyrate (60 nM). This phosphorylation was markedly inhibited by alpha-NF (5 and 10 microM). However, alpha-NF (5 and 10 microM) did not reduce the electron spin resonance (ESR) signal intensity of hydroxyl radicals in collagen (1 microg/mL)-activated platelets. These results indicate that the antiplatelet activity of alpha-NF may be involved in the following pathways. (1) alpha-NF may inhibit the activation of phospholipase C, followed by inhibition of phosphoinositide breakdown, protein kinase C activation, and thromboxane A(2) formation, thereby leading to inhibition of intracellular Ca(2+) mobilization. (2) alpha-NF also activated the formation of cyclic GMP, resulting in inhibition of platelet aggregation. These results strongly indicate that alpha-NF appears to represent a novel and potent antiplatelet agent for treatment of arterial thromboembolism.
本研究的目的是系统研究类黄酮α-萘黄酮（α-NF）抑制血小板活化的机制。在本研究中，α-NF浓度依赖性地（5-20微摩尔）抑制激动剂刺激的血小板聚集。α-NF（5和10微摩尔）抑制人血小板中由胶原（1微克/毫升）刺激的细胞内Ca(2+)动员、磷酸肌醇分解和血栓素A(2)形成。此外，α-NF（5和10微摩尔）显著增加环鸟苷酸（cGMP）水平以及cGMP诱导的血管舒张刺激磷蛋白（VASP）Ser(157)磷酸化水平。蛋白激酶C激活的标志物、分子量为47,000的血小板蛋白（P47）的快速磷酸化由佛波醇-12,13-二丁酸酯（60纳摩尔）触发。这种磷酸化被α-NF（5和10微摩尔）显著抑制。然而，α-NF（5和10微摩尔）并未降低胶原（1微克/毫升）激活的血小板中羟基自由基的电子自旋共振（ESR）信号强度。这些结果表明，α-NF的抗血小板活性可能涉及以下途径。（1）α-NF可能抑制磷脂酶C的激活，随后抑制磷酸肌醇分解、蛋白激酶C激活和血栓素A(2)形成，从而导致细胞内Ca(2+)动员受到抑制。（2）α-NF还激活环鸟苷酸的形成，导致血小板聚集受到抑制。这些结果有力地表明，α-NF似乎是一种用于治疗动脉血栓栓塞的新型强效抗血小板药物。
