Prefeeding-dependent anaerobic metabolization of xenobiotics by intestinal bacteria--methods for acarbose metabolites in an artificial colon

Enzymatic synthesis of a new inhibitor of α-amylases: acarviosinyl-isomaltosyl-spiro-thiohydantoin

Synthesis of acarviosinyl-isomaltosyl-spiro-thiohydantoin in yields up to 20%, has been achieved by Bacillus stearothermophilus maltogenic amylase (BSMA). BSMA is capable of transferring the acarviosine-glucose residue from an acarbose donor onto glucopyranosylidene-spiro-thiohydantoin. Reactions were followed using HPLC and MALDI-TOF MS. 1H and 13C NMR studies revealed that the enzyme reserved its stereoselectivity. Glycosylation took place mainly at C-6 resulting in alpha-acarviosinyl-(1-->4)-alpha-D-glucopyranosyl-(1-->6)-D-glucopyranosylidene-spiro-thiohydantoin. This compound was found to be a much more efficient salivary amylase inhibitor than glucopyranosylidene-spiro-thiohydantoin with kinetic constants of K(EI)=0.19 microM and K(ESI)=0.24 microM.

On the occurrence of free glucose in the caecal contents of rats

Free glucose was assayed in the caecal contents of rats. Whereas control animals had less than 60 nmol glucose per g of caecal contents, 230 nmol glucose/g caecal contents were determined 3 hours after the administration of 300 mg Palatinit by gastric intubation. In contrast to an earlier report (8), caecal fluid thus contained less than 3% of the glucose concentration of 11 mumol/ml claimed to occur after Palatinit administration by these authors (8). Since the anaerobic fermentation capacity for glucose by the caecal contents of rats amounted to at least 630 nmol glucose/min X g fresh weight at 37 degrees C, only the low glucose concentrations reported above are plausible.