W1, a Novel Oral Antiplatelet Agent With Less Resistance Than Clopidogrel.

Clopidogrel (CLO) is a clinical antiplatelet agent, about which there are major concerns because its antiplatelet efficiency decreases with insufficient metabolic activation, leading to "clopidogrel resistance." We aimed to determine the antiplatelet effects of W1, a novel molecule composed of 2-O-clopidogrel and aspirin (1:1 ratio), on platelet aggregation ex vivo and thrombus formation in vivo, and its susceptibility to CLO resistance in combination with other therapies in rats. Platelets were prepared, and an arteriovenous shunt thrombosis model was established using Wistar rats to measure platelet aggregation and thrombus formation, respectively. W1 markedly inhibited adenosine 5'-diphosphate (ADP)-induced platelet aggregation and thrombus formation dose dependently (0.3, 1, and 3 mg/kg). W1 (3 mg/kg) acted rapidly at 0.5 hours and lasted for 72 hours. W1 prolonged bleeding and clotting times in mice, confirming its antithrombotic properties. Compared with CLO 10 mg/kg, the positive control, W1 3 mg/kg exerted equivalent effects on the above specifications. In addition, cyclic adenosine monophosphate levels, measured in rat platelets, increased rapidly after prostaglandin E1 (alprostadil) stimulation of the vehicle control (0.5% methyl cellulose suspension) and W1 (3 mg/kg)-treated groups. ADP (50 µm) reduced the control levels more remarkably than W1 did (P < 0.05 in 3 minutes or P < 0.001 at 5 minutes), suggesting that W1 suppressed ADP-induced cyclic adenosine monophosphate reduction. This was associated with a significant platelet reactivity inhibition measured using the vasodilator-stimulated phosphoprotein assay. CLO or W1 coadministration with or without omeprazole and amlodipine to rats to investigate the pharmacodynamic interactions revealed that W1 exhibited more stable and potent antithrombotic effects than CLO did. In conclusion, both W1 and CLO showed antiplatelet and antithrombotic effects, while the former exhibited less CLO resistance in combination with omeprazole or amlodipine, 2 drugs that inhibit CLO metabolism. Therefore, this study implies that W1 may be a promising oral antiplatelet agent for reducing CLO resistance after percutaneous coronary intervention.

Kojic acid protects C57BL/6 mice from gamma-irradiation induced damage.

The radioprotective effects of a single administration of kojic acid (KA) against ionizing radiation were evaluated via assessment of 30-day survival and alterations of peripheral blood parameters of adult C57BL/6 male mice. The 30-day survival rate of mice pretreated with KA (75 or 300 mg/kg body weight, KA75 or KA300) subcutaneously 27 h prior to a lethal dose (8 Gy, 153.52 cGy/min) of gamma irradiation was higher than that of mice irradiated alone (40% or 60% vs 0%). It was observed that the white blood cell (WBC) count/the red blood cell (RBC) count, haemoglobin content, haematocrit and platelet count of mice with or without KA pretreatment as exposed to a sub-lethal dose (4 Gy, 148.14 cGy/min) of gamma irradiation decreased maximally at day 4/day 8 post-irradiation. Although the initial WBC values were low in KA300 or WR-2721 (amifostine) groups, they significantly recovered to normal at day 19, whereas in the control group they did not. The results from the cytotoxicity and cell viability assays demonstrated that KA could highly protect Chinese hamster ovary (CHO) cells against ionizing radiation with low toxicity. In summary, KA provides marked radioprotective effects both in vivo and in vitro.