STUDIES ON FAT-SOLUBLE VITAMIN B6

1. Vitamin B6 activity of both pyridoxine dipalmitate and tripalmitate was determined by assays depending upon the growth of Saccharomyces carlsbergensis (ATCC 9080) and of B6-deficient rats.2. Both the pyridoxine dipalmitate and tripalmitate had no growth-promoting activity to Saccharomyces carlsbergensis.3. When the pyridoxine palmitates were administered orally to B6-deficient rats, the same growth response as with pyridoxine hydrochloride was obtained. On the other hand, when they were injected intraperitoneally, only a slight growth was obtained.4. No increase in total vitamin B6 content in the liver was found in the rats administered intraperitoneally with the pyridoxine palmitates as in the case of the deficient control rats. However, when the pyridoxine palmitates were given orally, the total vitamin B6 content in the liver was increased as in the case of pyridoxine hydrochloride.5. The possibility of the difference in the vitamin B6 activity between the oral and intraperitoneal administrations of the pyridoxine palmitates in the animal experiment was discussed.