Thiamine

Benfotiamine

Metabolism of Benfotiamine appears to depend on GSH in erythrocytes:

Their results suggested that benfotiamine (given orally) is first dephosphorylated to S-benzoylthiamine by the ecto-alkaline phosphatase present in the brush borders of intestinal mucosal cells.

The more lipophilic S-benzoylthiamine then diffuses through the membranes of intestinal and endothelial cells and appears in the venous mesenteric blood.

A significant part of S-benzoylthiamine is captured by erythrocytes and converted to free thiamine through a slow non-enzymatic transfer of the S-benzoyl group to SH groups of glutathione.

In the liver, the remainder can be enzymatically hydrolyzed to thiamine and benzoic acid by thioesterases present in the hepatocytes.

On the other hand, thiamine disulfide derivatives require a reduction either enzymatically in the liver by glutathione or non enzymatically in blood by glutathione and possibly other substrates. (R1)