Effect of Armagnac fractions on human platelet aggregation in vitro and on rat arteriovenous shunt thrombosis in vivo probably not related only to polyphenols

Previous studies showed that alcohol-free extracts of Armagnac, an oak cask aged spirit rich in polyphenols, inhibit human platelet function in vitro and in vivo, in an experimental rat arteriovenous shunt thrombosis model and in human healthy volunteers. To identify active compounds, we fractionated a freeze-dried extract of a 10-year-old Armagnac using successively chloroform, diethyl ether and ethyl acetate. The 4 resulting fractions were tested on in vitro human platelet aggregation induced by ADP and in vivo on arteriovenous shunt thrombosis after 10 days oral treatment in rats. Active components were found mainly in fractions 1 and 3: at the highest concentration (2.4 10(-2) g/l), in vitro ADP-induced aggregation was inhibited by 62.7 +/- 2.1% and 51.2 +/- 3.8% for F1 and F3, respectively, vs 18.9 +/- 2.4% and 13.9 +/- 0.4% for fractions 2 and 4 and 33.6 +/- 1.5% for the crude extract. There was a significant decrease in thrombus weight with the crude extract and at[ fractions tested after 10 days treatment with 2.5 mg/kg/day orally, greatest with fraction 1. Characterisation of phenol content showed that fraction 1, the most biologically active, was essentially devoid of ellagic acid and ellagitannins, the polyphenols initially thought responsible for the effect, whereas fraction 2 which was mostly inactive, was the richest in polyphenols. Conclusion: The antiptatetet and antithrombotic activity of Armagnac seems mostly unrelated to polyphenols. (c) 2006 Elsevier Ltd. All rights reserved.