Effects of tomato extract on human platelet aggregation in vitro

Abstract

Among all fruits tested in vitro for their anti-platelet property, tomato had the highest activity followed by grapefruit, melon, and strawberry, whereas pear and apple had little or no activity. Tomato extract (20-50 microl of 100% juice) inhibited both ADP- and collagen-induced aggregation by up to 70% but could not inhibit arachidonic acid-induced platelet aggregation and concomitant thromboxane synthesis under similar experimental conditions. The anti-platelet components (MW <1000 Da) in tomatoes are water soluble, heat stable and are concentrated in the yellow fluid around the seeds. The active fractions were separated using gel filtration and HPLC. The aqueous fraction (110 000 xg supernatant) of tomatoes containing anti-platelet activity was subjected to gel filtration column chromatography (Biogel P2 column). The activity was fractionated into two peaks, peak-3 and peak-4 (major peak). Subsequently, peak-4 was further purified by HPLC using a reversed-phase column. NMR and mass spectroscopy studies indicated that peak F2 (obtained from peak 4) contained adenosine and cytidine. Deamination of peak F2 with adenosine deaminase almost completely abolished its anti-platelet activity, confirming the presence of adenosine in this fraction. In comparison, deamination of peak-4 resulted in only partial loss of inhibitory activity while the activity of peak-3 remained unaffected. These results indicate that tomatoes contain anti-platelet compounds in addition to adenosine. Unlike aspirin, the tomato-derived compounds inhibit thrombin-induced platelet aggregation. All these data indicate that tomato contains very potent anti-platelet components, and consuming tomatoes might be beneficial both as a preventive and therapeutic regime for cardiovascular disease.

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“…In summary, these results demonstrating the actions of tAF on different platelet functions were all consistent with potential effects mediated partly through polyphenols and PDI and partly through nucleosides elevating cAMP and cGMP levels in platelets [13, 67]. Effects on TF binding suggested that tAF components could have a larger effect on some aspects of the coagulatory response, such as thrombin generation, than previously imagined.…”

“…The antiaggregatory effects of different aqueous fruit extracts on human platelets in vitro have been published previously [13]. The maximum inhibitory effect (70–75 %) was found to be with tomato and kiwi fruit extracts, whereas apple and pear had very little activity (2–5 %).…”

“…Grapefruit, melon and strawberry had intermediate activities on platelet aggregation (33–44 %). The antiplatelet potential of the fruits tested appeared to have no relationship with their antioxidant activity [13]. These antiplatelet compounds in tomato had a molecular mass less than 1000 Da and were highly water soluble and stable to boiling.…”

“…The compounds of interest were concentrated into an aqueous extract produced by homogenizing fresh tomatoes, removing particulate matter and delipidating. The delipidated aqueous extract was then further fractioned by gel filtration using a Biogel P2 column [13]. Adenosine, a known antiplatelet factor, was identified in one fraction, but its removal from the whole extract did not substantially decrease the antiplatelet activity, indicating the presence of additional, different antiplatelet agents.…”

“…We therefore systematically investigated the effects of bioactive compounds in fruits and vegetables on human blood platelet aggregation and utilized the findings to characterize the mechanisms involved in this process, in the hope of identifying potential dietary antiplatelet components. In a variety of studies, it was demonstrated that water-soluble components of tomatoes are capable of inhibiting platelet aggregation both in vitro and in vivo [13–16]. These water-soluble tomato components were also found to inhibit angiotensin-converting enzyme (ACE) and to relax the vascular endothelium, the other important limbs of the cardiovascular system [17, 18].…”