Abstract
1. It was confirmed by bioautography that S-benzoyl derivatives of thiamine, i, e., S-benzoylthiamine O-monophosphate (BTMP), S-benzoylthiamine (SBT) and O, S-dibenzoylthiamine (DBT), were converted to thiamine monophosphate (TMP), thiamine and O-benzoylthiamine (OBT), respectively, by de-S-benzoylation with the L-cysteine contained in MaciasR's medium.
2. Both BTMP and SBT are as effective as thiamine on L. fermenti in this medium. However, it is not due to the biological activities of these compounds per se. DBT failed to show the thiamine activity on this organism.
3. BTMP, SBT, DBT and OBT become active even without L-cysteine by autoclaving. Therefore, it must be careful, when the biological activity of the compound is in question.
