In vitro anti-platelet aggregative effect of procyanidins isolated from grape seeds

AIM: To study the possible anti-platelet aggregative mechanisms of procyanidins (PC) isolated from grape seeds in vitro. METHODS: Platelet-rich plasma (PRP) and platelet-poor plasma (PPP) were prepared from the blood of healthy volunteers. PC,diphenylene iodonium(DPI,a nonspecific NADPH oxidase inhibitor) and apocynin (a specific NADPH oxidase inhibitor) were used to observe the effects on collagen-induced platelet maximum aggregation rate using platelet aggregometer. The influences of PC on platelet NADPH oxidase activity, NO content and superoxide anion (O₂^-·) level were evaluated by chemiluminescence spectrometer. The role of PC in the expression of activated platelet markers (PAC-1 and CD62P) was observed by flow cytometry. RESULTS: PC (100 μmol/L), apocynin (10 μmol/L) and DPI (100 μmol/L) significantly inhibited collagen-induced maximum platelet aggregation rate (P<0.01). In collagen-activated platelets, NO content reduced and O₂^-· level increased,both of which were recovered by PC at concentration of 100 μmol/L (P<0.05). PC also obviously inhibited NADPH oxidase activity (P<0.01), and significantly down-regulated PAC-1 and CD62P expression (P< 0.05) in platelets. CONCLUSION: Procyanidins isolated from grape seeds have the anti-platelet aggregation function through inhibiting NADPH oxidase activity, further influencing platelet NO and O₂^-· levels.