The rapid evaluation of intestinal bacterial growth using a conjugate of ursodeoxycholic acid with para-aminobenzoic acid.

From the standpoint of utilizing the distinctive feature of para-aminobenzoic acid (PABA) and the metabolism of intestinal bile acid, a conjugate of ursodeoxycholic acid with PABA (PABA-UDCA) was newly synthesized to study whether it can be a good material or not for the evaluation of the activity of intestinal bacterial growth. This compound was efficiently deconjugated in an incubation experiment with cholylglycine hydrolase resulting in the release of PABA. In a cultivation experiment, this compound was deconjugated by the same species of aerobic and anaerobic bacteria that deconjugated glycocholic acid. In an animal experiment, urinary excretions of PABA during 6 h following oral administration of 10 mg PABA-UDCA were determined. The control rat (n = 10) excreted 338.5 +/- 13.8 micrograms (mean +/- S.E.) of PABA. In contrast with this, the rats (n = 10) with intestinal antisepsis by the administration of polymyxin B and tinidazole excreted less PABA (14.0 +/- 2.5 micrograms; p less than 0.001), whereas the rats with intestinal bacterial overgrowth owing to the artificially made enteric blind loop excreted more PABA than the control rats did (673.6 +/- 70.2 micrograms; p less than 0.01). These observations indicate that this new compound is likely to offer a simple and rapid method for evaluation of intestinal bacterial growth.