Thiosulfinates modulate platelet activation by reaction with surface free sulfhydryls and internal thiol-containing proteins.

TitleThiosulfinates modulate platelet activation by reaction with surface free sulfhydryls and internal thiol-containing proteins.
Publication TypeJournal Article
Year of Publication2007
JournalPlatelets
Volume18
Issue7
Pagination481-90
Date Published2007 Nov
ISSN0953-7104
AbstractThiosulfinates are characteristic flavors of Allium vegetables, with a highly reactive S-S=O group, that we previously showed to inhibit platelet aggregation through calpain-dependent mechanisms. With the aim to clarify the mode of action of these redox phytochemicals, we studied their effect on extracellular free sulfhydryls in relation to their effect on platelet responses (Ca2+ signals, release reaction, and aIIb3 integrin activation state). At the platelet surface, thiosulfinate dose-dependently increased the basal level of free sulfhydryls, independently of protein disulfide isomerase activity. This generation of new free sulfhydryls was associated with: (i) a three fold increase in labeling of resting platelets with an anti ligand-induced binding site antibody and (ii) marked inhibition of subsequent aIIb3 activation by agonists. Thiosulfinates increased the basal intracellular Ca2+ level of platelets. In activated platelets, they markedly inhibited the Ca2+ mobilization independently of the external Ca2+, the calpain-induced SNAP-23 cleavage and the granule release. In platelet free systems, thiosulfinates inhibited the activity of purified calpain and the free sulfhydryl of glutathione without any reducing properties on disulfides. The results demonstrate for the first time that thiosulfinates rapidly interact with sulfhydryls both at the platelet surface and inside the cell on intracellular cysteine-proteins, especially calpain. Inhibition of free cysteine and glutathione in whole blood may also contribute to their anti-aggregant properties. Such sulfur compounds are of interest for the development of a new class of antithrombotic agents.
URLhttp://www.tandfonline.com/doi/full/10.1080/09537100701271828
DOI10.1080/09537100701271828
PubMed Linkhttp://www.ncbi.nlm.nih.gov/pubmed/17852771?dopt=Abstract
Short TitlePlatelets