Oxythiamine is a thiamine antagonist that acts as a transketolase inhibitor. As transketolase is a crucial enzyme of the pentose phosphate pathway, inhibition of this enzyme causes suppression of the pentose phosphate pathway and thus deprives cells of the metabolic intermediate (glyceraldehyde-3-phosphate) for ATP generation and of the substrates (NADPH, ribose-phosphate) for macromolecule synthesis. This metabolic inhibition seems to be responsible,nat least in part, for the significant anticancer activity observed in vitro and in vivo.
