1999 年 18 巻 2 号 p. 73-80
A novel bifidogenic growth stimulator (BGS) was present in the cell-free filtrate and in methanol extract fraction of the starter (Propionibacterium freudenreichii) cells for the manufacture of Swiss-type cheese. After purification of the BGS isolated from the lyophilized cells, the mass (217.037) was determined by high-resolution electron impact mass spectrometry (MS) and liquid chromatography-MS spectra. Various experimental analyses indicated that the chemical structure of the BGS was 2-amino-3-carboxy-1, 4-naphthoquinone (ACNQ). We examined the activity of the P. freudenreichii ET culture containing the BGS on a gut bacterial composition using an anaerobic continuous culture system and found that the BGS seems to enhance the selective utilization of oligosaccharides by bifidobacteria. Furthermore, a placebo-controlled study of the effects of BGS on fecal flora and stool frequency was carried out in healthy human subjects. A drink with the sterilized ET-3 culture was administered once a day for 7 days. Bifidobacterium percentage in the fecal flora and stool frequency were significantly increased by administration of the P. freudenreichii culture. The ACNQ exhibited growth stimulation of bifidobacteria at an extremely low concentration and enhanced the activities of NADH oxidase and NADH peroxidase in bifidobacteria. It was revealed that ACNQ works as a good electron acceptor of NAD (P)H diaphorase. The ACNQred was easily auto-oxidized and also acted as a better electron donor of NAD (P) H peroxidase. These ACNQ-mediated reactions seem to play roles in NAD (P) +-regeneration processes and seem to be responsible for the growth stimulation of bifidobacteria.