Effects of tomato extract on human platelet aggregation in vitro

Among all fruits tested in vitro for their anti-platelet property, tomato h ad the highest activity followed by grapefruit, melon, and strawberry, wher eas pear and apple had little or no activity. Tomato extract (20-50 mul of 100% juice) inhibited both ADP- and collagen-induced aggregation by up to 7 0% but could not inhibit arachidonic acid-induced platelet aggregation and concomitant thromboxane synthesis under similar experimental conditions. Th e anti-platelet components (MW <1000 Da) in tomatoes are water soluble, hea t stable acid are concentrated in the yellow fluid around the seeds. The ac tive fractions were separated using gel filtration and HPLC. The aqueous fr action (110 000xg supernatant) of tomatoes containing anti-platelet activit y was subjected to gel filtration column chromatography (Biogel P2 column), The activity was fractionated into two peaks, peak-3 and peak-ii (major pe ak). Subsequently, peak-4 was further purified by HPLC using a reversed-pha se column. NMR and mass spectroscopy studies indicated that peak F2 (obtain ed from peak 4) contained adenosine and cytidine, Deamination of peak F2 wi th adenosine deaminase almost completely abolished its anti-platelet activi ty, confirming the presence of adenosine in this fraction. In comparison, d eamination of peak-4 resulted in only partial loss of inhibitory activity w hile the activity of peak-3 remained unaffected. These results indicate tha t tomatoes contain anti-platelet compounds in addition to adenosine. Unlike aspirin, the tomato-derived compounds inhibit thrombin-induced platelet ag gregation. All these data indicate that tomato contains very potent anti-pl atelet components, and consuming tomatoes might be beneficial both as a pre ventive and therapeutic regime for cardiovascular disease.