Effects of DK-002, a synthesized (6aS,cis)-9,10-Dimethoxy-7,11b-dihydro-indeno[2,1-c]chromene-3,6a-diol, on platelet activity

Abstract In the present study, the mechanism of antiplatelet activity of DK-002, a synthesized (6aS, cis )-9,10-Dimethoxy-7,11b-dihydro-indeno[2,1- c ]chromene-3,6a-diol, was investigated. DK-002 inhibited the thrombin, collagen, and ADP-induced rat platelet aggregation in a concentration-dependent manner, with IC 50 values of 120, 27, and 47 μM, respectively. DK-002 also inhibited thrombin-induced dense granule secretion, thromboxane A 2 synthesis, and [Ca 2+ ] i elevation in platelets. DK-002 did not show any significant effect on ADP-induced inhibition of cyclic AMP elevation by prostaglandin E 1 , but DK-002 was confirmed to inhibit ADP-induced [Ca 2+ ] i elevation and shape change. DK-002 inhibited 4-bromo-A23187-induced [Ca 2+ ] i elevation in the presence of creatine phosphate/creatine phosphokinase (CP/CPK, a ADP scavenging system) and indomethacin (a specific inhibitor of cyclooxygenase). DK-002 also inhibited Ca 2+ mobilization in thrombin- or 4-bromo-A23187-stimulated platelets through its inhibitory effects on both Ca 2+ release from intracellular stores and Ca 2+ influx, in the presence of CP/CPK and indomethacin. Taken together, the present study shows that DK-002 has inhibitory effects on stimulation of platelets, and suggests that its antiplatelet activity might be related to the inhibitory mechanism on Ca 2+ mobilization in stimulated platelets.