抄録
A titration method of tube assay for lipoic acid with Streptococcus faecalis 10C1 described by Wada et al. who introduced the Stokstad's assay media to a titration method was investigated. The composition and pH of the assay media were slightly modified, with which growth of the microbes were more accelerated and incubation time was reduced. A suitable standard response curve after 24 hours incubation was ranged from 0.5 to 5 mμg/ml. The lipoic acid contents in non-hydrolyzed natural materials were measured. Recoveries of added DL-lipoic acid were sufficient in urine samples, though those in blood and tissues were sometimes more than theoretical values. These values were compared with those measured turbidimetrically in the samples which were treated to remove some interfering substances.
