Coumarin antiplatelet activity

GU-7, a 3-arylcoumarin derivative, has been isolated fi om Glycyrrhizae radix, which is a crude herbal medicine. GU-7 caused inhibition of platelet aggregation, phosphorylation of 40K and 20K dalton proteins, inositol 1,4,5-trisphosphate production, intraplatelet calcium increase and phosphodiesterase activity in vitro. The data indicate that GU-7 inhibits platelet aggregation by increasing intraplatelet cAMP concentration. Antiplatelet action may also explain the mechanism by which traditional medicines are effective in diabetic neuropathy [236]. Osthole causes hypotension in vivo, and inhibits platelet aggregation and smooth muscle contraction in vitro. It may interfere with calcium influx and cyclic nucleotide phosphodiesterases [12]. Cloricromene, a synthetic coumarin derivative, also possesses antithrombotic-antiplatelet activity [237]. Some of these properties of cloricromene have been attributed to the inhibition of arachidonate release from membrane phospholipids [12]. 

Quilinggao is a Chinese herbal produet made from a mixture of herbs. The first brand did not contain any herbs suspected to have anticoagulant effects except one with possible antiplatelet activity, but the second brand contained Chinese peony Paeoniae rubra), Poncirus trifoliata and a couple of other herbs known to contain substances with anticoagulant or antiplatelet effects in vitro, but see also Coumarins + Herbal medicines , p.414. 

Several natural products contain substances that have coumarin, salicylate, or exhibit antiplatelet properties. Therefore, a theoretical risk for potentiation of the pharmacological activity of warfarin exists when these herbs are taken with warfarin. Herbs thought to contain coumarin or coumarin derivatives include the following ... 

Coumarin, which was first isolated from tonka bean Dipteryx odorata Wild) in 1820 [36], have been demonstrated to possess anti-inflammatory, antiplatelet aggregation, antidote, antitumor, and AChE inhibitory activities [37]. As a consequence, significant efforts have been devoted to the synthesis of coumarins. 

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