Jagroop Indera Anita
Academic Department of Surgery, Division of Surgical and Interventional Science, Royal Free Campus, University College London Medical School, University College London (UCL), Pond Street, London, NW3 2QG, UK,
Purinergic Signal. 2014;10(2):233-9. doi: 10.1007/s11302-013-9393-0. Epub 2013 Nov 5.
Adenosine diphosphate (ADP) plays a pivotal role in platelet activation. Platelet hyperactivity is associated with vascular disease and also has a key role in haemostasis and thrombosis. ADP activates platelets through three purinoceptor subtypes, the G(q)-coupled P2Y(1) receptor, G(i)-coupled P2Y(12) receptor and P2X(1) ligand-gated cation channel. Platelet ADP purinergic receptors are therefore suitable targets for antiplatelet drugs. Thienopyridines such as clopidogrel and ticlopidine, as well as other ADP receptor antagonists like prasugrel, ticagrelor, cangrelor and elinogrel have demonstrated clinical benefits via the inhibition of the selective purinergic ADP receptor, P2Y(12). However, they still have limitations in their mode of action and efficacy, like increased risk of bleeding. Thus, the ongoing pursuit to develop newer and more effective antiplatelet agents continues. There is a growing interest in the purinergic antiplatelet properties exhibited by plant extracts. This article considers the following: pomolic acid isolated from Licania pittieri, brazilin isolated from the heartwood of Caesalpinia sappan L, phylligenin isolated from the twigs of Muraltia vulpina, bark oil of Gonystylus velutinus, seed and bark extracts from Aesculus hippocastanum L. and red wine phenolics and catechins isolated from green tea. Moreover, the method used to investigate platelet purinergic receptors should be considered, since using a more sensitive, high-resolution platelet sizer can sometimes detect platelet variations when the light transmission method was not able to do so. The exact mechanisms by which these plant extracts work need further investigation. They all however inhibit ADP-induced activation in human platelets. This could explain, at least in part, the protective effect of plant extracts as antiplatelet agents.
二磷酸腺苷（ADP）在血小板激活过程中起关键作用。血小板活性过高与血管疾病相关，并且在止血和血栓形成中也起关键作用。ADP通过三种嘌呤受体亚型激活血小板，即G(q)偶联的P2Y(1)受体、G(i)偶联的P2Y(12)受体和P2X(1)配体门控阳离子通道。因此，血小板ADP嘌呤能受体是抗血小板药物的合适靶点。噻吩并吡啶类药物如氯吡格雷和噻氯匹定，以及其他ADP受体拮抗剂如普拉格雷、替格瑞洛、坎格雷洛和依利格雷，已通过抑制选择性嘌呤能ADP受体P2Y(12)显示出临床益处。然而，它们在作用方式和疗效方面仍有局限性，如出血风险增加。因此，开发更新、更有效的抗血小板药物的研究仍在继续。人们对植物提取物所展现的嘌呤能抗血小板特性的兴趣与日俱增。本文探讨了以下几种物质：从皮氏石梓中分离出的波摩酸、从苏木的心材中分离出的巴西苏木素、从伏地卷耳的嫩枝中分离出的叶igenin、绒毛白木香的树皮油、七叶树的种子和树皮提取物，以及从绿茶中分离出的红酒酚类和儿茶素。此外，应考虑用于研究血小板嘌呤能受体的方法，因为使用更灵敏、高分辨率的血小板大小分析仪有时能够检测到光透射法无法检测到的血小板变化。这些植物提取物发挥作用的确切机制尚需进一步研究。然而，它们均能抑制ADP诱导的人血小板激活。这至少可以部分解释植物提取物作为抗血小板药物的保护作用。
