Summary
Thiosulfinates (TSs) are sulfur compounds generated through the processing of different
Allium species with antiplatelet property. To further define this platelet inhibitory
effect we studied diallyl-TS (Al2TS), dipropyl-TS (Pr2TS), and dimethyl-TS (Me2TS) on platelet responses. The three TSs inhibited dose-dependent platelet aggregation,
with IC50 values of 15 ± 2, 19 ± 2, and 9 ± 1 μM for Al2TS, Pr2TS and Me2TS, respectively. TSs had no effect on the expression of a platelet procoagulant surface,
measured by flow cytometry as the binding of annexin V-FITC. They inhibited the microparticle
shedding and clot retraction. Since the microparticle shedding is a calpain-activation
dependent step, we assessed calpain activation by analysis of autoproteolysis in shorter
active forms and by talin proteolysis in the presence of TSs. Calpain activation was
inhibited by TSs independently of fibrinogen binding. Thus, TSs represent a new category
of platelet inhibitors, acting on cal-pain-induced events.
Keywords
Allium - calpain - microparticles - platelet aggregation - talin