Biological Activity of Acetylated Phenolic Compounds
Elizabeth Fragopoulou, Tzortzis Nomikos, Haralabos C. Karantonis, Constantinos Apostolakis, Emmanuel Pliakis, Martina Samiotaki, George Panayotou, and Smaragdi Antonopoulou*
Department of Science of Nutrition-Dietetics, Harokopio University of Athens, 17671 Athens, Greece, and Protein Chemistry Laboratory B.S.R.C. "Alexander Fleming", Athens, Greece
Received for review September 22, 2006. Revised manuscript received November 6, 2006. Accepted November 8, 2006.
In recent years an effort has been made to isolate and identify biologically active compounds that are included in the Mediterranean diet. The existence of naturally occurring acetylated phenolics, as well as studies with synthetic ones, provide evidence that acetyl groups could be correlated with their biological activity. Platelet activating factor (PAF) is implicated in atherosclerosis, whereas its inhibitors seem to play a protective role against cardiovascular disease. The aim of this study was to examine the biological activity of resveratrol and tyrosol and their acetylated derivatives as inhibitors of PAF-induced washed rabbit platelet aggregation. Acetylation of resveratrol and tyrosol was performed, and separation was achieved by HPLC. Acetylated derivatives were identified by negative mass spectrometry. The data showed that tyrosol and its monoacetylated derivatives act as PAF inhibitors, whereas diacetylated derivatives induce platelet aggregation. Resveratrol and its mono- and triacetylated derivatives exert similar inhibitory activity, whereas the diacetylated ones are more potent inhibitors. In conclusion, acetylated phenolics exert the same or even higher antithrombotic activity compared to the biological activity of the initial one.
Keywords: HPLC separation; acetylation; platelet activating factor; electrospray mass spectrometry; resveratrol; tyrosol