Brazilian propolis (AF-08) inhibits collagen-induced platelet aggregation without affecting blood coagulation

Brazilian propolis (AF-08) is a dietary supplement containing a variety of flavonoids. It is used worldwide as a folk medicine. Flavonoids and a diet of fruits and vegetables containing them have been shown to reduce the risk of cardiovascular diseases (CVDs). Most of CVDs are caused by arterial thrombus formation. A thrombus is formed by the interaction between adhesion and aggregation of platelets to damaged blood vessels and blood coagulation consisting of extrisic and intrinsic pathways. Platelet aggregation and blood coagulation are closely linked to thrombosis. Therefore, we evaluated the effectiveness of AF-08 or its component flavonoids against thrombosis by examining their inhibition of platelet aggregation and blood coagulation. Human platelet-rich plasma was incubated with serial dilutions of AF-08 for 10 min to assess its inhibitory effect on platelet aggregation caused by collagen. The inhibitory effect of AF-08 on blood coagulation was evaluated by the prothrombin time (PT) and activated partial thromboplastin time (APTT), which reflect the coagulation function of extrinsic and intrinsic pathways, respectively. AF-08 significantly inhibited collagen-induced platelet aggregation but not PT and APTT, indicating that AF-08 inhibited platelet aggregation but not blood coagulation. Among three flavonoids contained in AF-08, apigenin and chrysin obviously inhibited platelet aggregation but the inhibitory effect of kaempferol was less effective. The three flavonoids did not affect PT and APTT. The inhibitory activity of AF-08 on human platelet aggregation without affecting blood coagulation was suggested to be partially due to apigenin and chrysin. AF-08 may be effective in suppressing platelet-based arterial thrombus formation and reducing the risk of CVDs.