PYRIDOXINE-3,4-DIACYLATES IN COSMETICS 355 logical assay was carried out similarly as mentioned above, and the amount of pyridoxine was determined by reference to the standard curves. The results are shown in Fig. 2. Pyridoxine and pyridoxine-hydro- chloride were absorbed immediately, but their content in blood de- creased rapidly. In contrast, the dibutyrate was also absorbed im- mediately, but the blood concentration remained at a constant level. The absorption of the dioctanoate and di-iso-octanoate was delayed, but the blood concentration increased gradually. The absorption of dilaurate and dipalmitate was not studied in this experiment. These 1000' -• 8oo. •o rldorlne • 600- o• Pyrldo lbutMrat " • 400- • /• • Pyridoxlne Dl-I sonic tano • te • 200- • PyrldoxlnDiootan ?lme ( hrs. ) Figure 2. Percutaneous absorption of pyridoxine and its derivative (1% in 0/W cream base) facts might suggest that cosmetics or ointments containing intermediate chain fatty acid diester of pyridoxine maintain higher levels of vitamin B• in the living body for a longer period of time than products containing pyridoxi•e. Hydrolysis of Diacylates in Organs (•) Liver, kidney, intestine, and blood of the mouse were used in this experiment. Liver, kidney, and intestine, from which as much blood as possible was removed, were washed with water. One gram of liver, 0.4 g. of kidney, 0.7 g. of intestine and 0.4 ml. of blood were homogenized with Tyrode's solution. These homogenates were poured into 50 ml. Edenmeyer flasks, and the contents were adjusted to 7 g. with Tyrode's

356 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS TABLE VI Hydrolysis of Pyridoxine-3,4-dibutyrate Sample No. Time for Hydrolysis Amount Hydrolyzed, wt. % Liver Kidney Intestine Blood Average Average Average 1 hr. 0.5 hr. 105.8 98.9 98.9 80.1 94.6 90.9 ... 74.2 95.4 106.8 104.5 81.8 98.6 98.8 101.7 78.7 106.6 108.0 92.8 70.4 ... 97.5 107.6 69.6 98.4 98.9 104.4 66.2 102.5 101.4 101.6 68.7 105.6 106.2 99.2 64.6 89.2 104.8 106.8 71.1 107.9 108.0 88.4 56.7 100.9 106.3 98.1 64.1 TABLE VII Hydrolysis of Pyridoxine-3,4-dioctanoate Sample No. Amount Hydrolyzed, wt. % Ti•ne for Hydrolysis Liver Kidney Intestine Blood Average Average Average 91.5 82.3 82.2 0 2 hr. 87.6 69.2 82.3 0 101.7 79.0 87.2 0 93.6 76.8 83.6 0 74.5 66.8 84.2 0 1 hr. 85.2 85.8 84.2 0 84.7 75.6 82.7 0 83.9 76.1 80.2 0 63.1 72.4 64.1 0 0.5 hr. 62.9 61.6 59.8 0 84.0 76.4 79.9 0 70.0 70.1 67.9 0 TABLE VIII Hydrolysis of Pyridoxine-3,4-dilaurate Sample No. Time for Hydrolysis Liver Amount Hydrolyzed, wt. % Kidney Intestine Average 2 hr. 11.1 0 0.9 7.6 0 1.0 10.1 0 0.8 9.6 0 0.9