| Caffeic acid phenethyl ester derived from propolis, is one of its main active ingredient. It is reported that it has many biological activities, such as antiviral, antibacterial, antioxidant, immunomodulatory, antitumor, preventing from myocardial ischemia and reperfusion injury and other physiological activities. It has been used as medicine for a long history in folk, mainly in the Middle East. Propolis can protect the liver as a natural product. There are O-dihydroxyphenyl and two phenolic hydroxyl groups on the molecular structure of caffeic acid phenethyl ester. The forward group can eliminate the free radicals and the latter groups are easily oxidized. Based on previous studies, this article investigated mechanisms of antiplatelet aggregation activity of caffeic acid p-nitro phenethyl ester which is a derivative of caffeic acid phenethyl ester.This paper studied the antiplatelet aggregation activity of caffeic acid p-nitro phenethyl in vitro. Compared the control group, positive control group (caffeic acid phenethyl ester) and he experimental group (caffeic acid p-nitro phenethyl ester) anti-platelet aggregation activities are different. It researched their effects on physiological metabolic processes of collagen-stimulated platelet, such as changes in platelet aggregation. To further describe mechnisms of antiplatelet aggregation activity of caffeic acid p-nitro phenethyl ester induced by collagen, this paper investigated that the release of nitric oxide, changes of cyclic guanosine monophosphate (cGMP), the formation of thromboxane A2(TXA2), the activity of cyclooxygenase-1(COX-1) and the release of5-hydroxytryptamine (5-HT) of he post-treatment of platelets. These substances are associated with changes in the signal transduction and metabolism of activated platelets.It was demonstrated that caffeic acid p-nitro phenethyl ester and caffeic acid phenethyl ester inhibited collagen induced rat washed platelets and PRP platelet aggregation in vitro. Caffeic acid p-nitro phenethyl ester (CAPE-NO2) in the1.5-12μM inhibited platelet aggregation in a dose-dependent manner. The rates of platelet aggregation after treament with it were62%,52%,46%and34%. Compared with the control group, the inhibition rate of caffeic acid p-nitro phenethyl ester (12μM)) on platelet aggregation was55%. Inhibition rate of caffeic acid phenethyl ester (1.5μM) was14%. So their activities of antiplatelet aggregation were very good. Platelets NO levels were significantly elevated by caffeic acid p-nitro phenethyl ester in a dose-dependent. It also significantly increased levels of cGMP in the platelet. Caffeic acid p-nitro phenethyl ester at a concentration of1.5,3,6,12μM inhibited the generation of thromboxane B2, respectively,9.5%,23%,40%,51%. But caffeic acid phenethyl ester (1.5μM) was18%. It also inhibited cyclooxygenase activity at concentrations of1.5-12μM.5-HT release are454μg/L,435μg/L,408μg/L and376μg/L after treatment with different concentrations (1.5,3,6,12μM) of caffeic acid p-nitro phenethyl ester. The inhibition of5-HT was87%at12μM. And the inhibition of1.5μM caffeic acid phenethyl ester was19%. It may involve the following mechanisms of antiplatelet aggregation. Caffeic acid p-nitro phenethyl ester activated NO/cGMP signaling pathway, increased release of NO and cGMP generation process, inhibited activity of cyclooxygenase-1, resulting in the reduction of thromboxane B2. Finally Caffeic acid p-nitro phenethyl ester decreased5-serotonin secretion from activated platelets.A high-performance liquid chromatography method was established for simultaneous determination of caffeic acid p-nitro phenethyl ester in rat plasma after intramuscular injection and studied its pharmacokinetics. The samples were chromatographed on a SepaxHP-C18(4.6mm×250mm,5μm) column with a mobile phase consisting of acetonitrile-water (55:45). The detection wavelength was329nm. The flow rate was1mL·min-1. The temperature of column was30℃. The injection volume was20μL. Excellent liner relationship was obtained in the range of50-2000ng·mL-1(r=0.9999), and the lower limit of qauntification was0.05μg·mL-1. The data was analysised by DAS3.0. The concentration-time profiles of CAPE-NO2fitted in with two-compartment models. The main pharmacokinetic parameters were as follow:Cmax=976.66μg·L-1, tmax=1h, t1/2α=0.95h, t1/2β=5.51h, AUC0-t=2649.77μg·h-L-1, AUC0-∞=2837.77μg·h-L-1. |
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