Studies on the Mechanism of Riboflavin Sparing Action by D-Sorbitol in Rat (Report 2)

Abstract

It was previously confirmed that D-Sorbitol has the riboflavin sparing action in rats. When sorbitol is supplemented in the diet of rats, the almost vitamin synthesis in the intestine of rats occur in cecum.So, it is most important problem to investigate that the vitamin synthesized in cecum exist in what form to confirm the mechanism of vitamin sparing action.Then, in this paper the following experiments have been performed. The diet composition was shown in Table 1. The content of cecum of rats in 15% sorbitol diet group after one month feeding was gently homogenated with mortar. The supernatant and precipitate were obtained by twice centrifuging the homogenate for 30 minutes at 11, 000r.p.m.The combined precipitate was dilluted with water and was treated 80°C, 15 minutes, and after was centrifuged for 20 minutes at 3, 000 r.p.m.The riboflavin content and the three different type of riboflavin in supernatant and precipipate were measured by Yagi's riboflavin assay method, respectively.The results are shown in Table 2-3 and Figure 1.The riboflavin content in supernatant and precipitate are approximately 10μg and 110μg in average, respectively. Only flavin mononucleotide (FMN) was found in supernatant solution, but in precipitate the great amounts of flavin adenine-dinucleotide and flavin mononucleotide and a trace amount of free riboflavin (FR) were found.It is very interesting to be finding only (FMN) in supernatant. It is the important problem to research by what and from what FMN is occurred, or whether FMN in supernatant is directly absorbed from cecum or not.At any rate, the following experiment has been done. The supernatant solution was dialyzed with distilled water by using cellophan tube for 2 day at 0-2°C. The result in table 3 showed that the considerable amounts of FMN was dialyzed. This result seems to indicate that FMN transfered to supernatant in cecum may be absorbed from cecum.