Biological Nature Of Platelet Inhibitors From Allium Cepa, Allium Sativum And Auricularia Polytrica
Several lines of evidence indicate that extracts of onion (Allium cepa), garlic (Allium sativum) or Chinese black tree fungus (Auricularia polytrica) inhibit platelet aggregation both in-vitro and in-vivo.A systematic study showed that aqueous extracts of these vegetables produced a dose-dependent inhibition of ADP, arachidonic acid (AA) or collagen-induced platelet aggregation. Onion and garlic juices were extracted sequentially into petroleum ether and diethyl ether. The anti-platelet activity in the aqueous phases was completely inactivated by purified adenosine deaminase. The activity in the petroleum ether layer was further characterised by its effects on the metabolism of 14C-AA by platelets. This oily fraction of onion and garlic suppressed thromboxane synthesis completely and induced a redistribution in the products of the lipoxygenase pathway. Adenosine and allicin (found in the ether layer) inhibited aggregation without affecting AA metabolism. Preparative GC and GC/MS studies showed that the activity of the oily fraction was due principally to paraffinic polysulfides (PPS) of which dimethyl trisulfide was one of the most active. Authentic samples of dimethyl trisulfide duplicated the effects of onion and garlic oils on both aggregation and AA metabolism.