Abstract
Lipoic acid content in animal tissues were estimated by the titration method using Streptococcus faecalis R, described previously. Lipoic acid values estimated in non-hydrolyzed samples showed practically no difference between animal species except mouse liver. The administration of lipoic acid, per os or intravenously, caused an increase of lipoic acid level in blood, however the high level continued for a short time (1〜2 hrs), then it reduced rapidly to a normal level. The determination of total lipoic acid in blood was investigated by autoclaving with H_2SO_4 or HCl and or in the presence of nitrogen gas. The hydrolysis in 6N H_2SO_4 solution was most adequate, however the recoveries of lipoic acid added to the sample gave always high value than the theoretical one. This means that the hydrolyzed blood sampes probably contain some activating factors for growth of the microbes.
