The effect of VB1 and its derivatives on the respiration of the isolated rat liver mitochondria.

The effect of thiamine and its various derivatives on the respiratory control of rat liver mitochondria was examined. Except TDP all other thiamine derivatives tested were shown to damage mitochondrial respiration. In these experiments DCET and T A TD are shown to be strong inhibitors. It was noted that thiamine and its derivatives except TDP have aldehyde group in their chemical structure. Because formaldehyde and acetalhyde are inhibitors to the respiration of the isolated rat liver mitochondria, the aldehyde group in chemical structure is speculated to have some relation to their action on liver mitochondria. Further studies are necessary concerning the mechanism of the inhibitory actions of thi!lmine derivatives. INTRODUCTION Many thiamine derivatives are at present widely used in Japan by clinicians in place of thiamine. Except thiamine diphosphate, thiamine derivatives used in Japan have an aldehyde group in their chemical structure. It is well known that formaldehyde and acetaldehyde are inhibitors to the respiration by isolated rat liver mitochondria1>. The effect of thiamine derivatives on the mitochondrial functions must be an interesting problem to be studied. Muraoka has reported that TPD and TTFD decreased respiratory control of the isolated rat liver mitochondria. He suspected that Pi in the reaction medium and SH group in their chemical structure have some relation to this effect 2>. In the present report we examined the effect of thiamine and its seven derivates including TPD and TTFD on the respiration of isolated rat liver mitochondria and we recognized that all derivatives except TDP impaired Jl9f 3Z ~ Received for publication September 8, 1972. Thiamine: Bt TDP : Thiamine diphosphate TPD : Thiamine propyldisulfide TTFD BUTDS BTMP DCET TATD Thiamine tetrahydrofurfuryl disulfide o-butyroyl thiamine disulfide s-benzoyl thiamine monophosphate o, s-diethoxycarbonyl thiamine Thiamine methyl-6-acetyl-dihydrothioacetate disulfide