Abstract
Changes in the blood B_6 levels after oral administration of pyridoxal 5'-n-butyrate (PAL・NB), PAL 5'-isobutyrate (PAL・IB), PAL 5'-benzoate (PAL・BE), PAL 3'-n-butyrate, PAL 3', 4'-diacetate, PAL 5'-acetate and PAL 5'-succinate to rat were followed by fluorometric procedure. The maximum total PAL concentrations were mostly the same as in the case of PAL administration, but higher levels were maintained by PAL 5'-acylates. In the case of PAL・NB, ・IB and ・BE, the areas under the time-blood concentration curve (AUC) were 1.5 times larger than that of PAL administration. Possible hydrolysis of the 5'-acylates in the intestine was suggested in circulation experiments using rat intestine in situ and experiments with homogenate of the intestine in vitro. On the other hand, absorption of the 5'-acylates in their intact forms was also evidenced by fractional determination as well as bioautography using Sacch. carlsbergensis of the blood after administration of PAL・BE and ・NB. In this respect, these 5'-acylates were different from the reported pyridoxine acylate with longer chains. From these results, characteristics of 5'-acylation of PAL molecule are discussed on the view point of drug latentiation and prolongation.
