title: Characterization of the antiplatelet effects of (2S)-5-methoxy-6-methylflavan-7-ol from Draconis Resina.
abstract: (2S)-5-methoxy-6-methylflavan-7-ol (MMF) was purified from Draconis Resina and its in vitro effects on various aspects of platelet reactivity were examined. Results indicated that MMF dose dependently inhibited aggregation of washed rabbit platelets induced by collagen, arachidonic acid, ADP, U46619 or platelet-activating factor (PAF), with IC50) values of 17.2, 49.8, 179.8, 109.6, and 189.2 microM, respectively. Concomitantly, MMF also dose dependently suppressed ATP release by platelets activated by these stimulants. The increase in intracellular free calcium ([Ca2+]i), elicited by these activating agents, was inhibited by MMF as reflected by fura-2 fluorescence measurements. However, MMF had no effects on the cyclic AMP level of platelets. In addition, MMF inhibited the arachidonic acid-induced thromboxane B2 and prostaglandin D2 formation in intact platelet suspensions or homogenized platelet lysates. This study provided evidence that MMF is an antiplatelet agent whose activity is likely related to cyclooxygenase inhibition and suppression of [Ca2+]i increase.
authors.affiliation: National Research Institute of Chinese Medicine, Taipei, Taiwan. wjtsai@cma23.nricm.edu.tw
authors.forename: W J
authors.initials: WJ
authors.lastname: Tsai
authors.forename: H T
authors.initials: HT
authors.lastname: Hsieh
authors.forename: C C
authors.initials: CC
authors.lastname: Chen
authors.forename: Y C
authors.initials: YC
authors.lastname: Kuo
authors.forename: C F
authors.initials: CF
authors.lastname: Chen
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D005419:Flavonoids / Q000302:isolation & purification / Q000494:pharmacology*; D008315:Malondialdehyde / Q000378:metabolism; D010946:Plants, Medicinal / Q000737:chemistry*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D015230:Prostaglandin D2 / Q000096:biosynthesis; D011817:Rabbits; D013929:Thromboxane B2 / Q000096:biosynthesis
chemical_list: C113397:5-methoxy-6-methylflavan-7-ol; D005419:Flavonoids; D010975:Platelet Aggregation Inhibitors; D008315:Malondialdehyde; D013929:Thromboxane B2; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D015230:Prostaglandin D2; D002118:Calcium