Basic studies on ursodeoxycholyl-para-aminobenzoic acid for evaluation of intestinal microflora

Area of Science:

• Microbiology
• Gastroenterology
• Biochemistry

Background:

• Assessing the composition and activity of intestinal microorganisms is crucial for understanding gut health.
• Current methods for evaluating enteric bacteria can be complex, expensive, or involve radioisotopes.

Purpose of the Study:

• To investigate the suitability of a novel ursodeoxycholic acid conjugate with para-aminobenzoic acid (PABA-UDCA) for evaluating enteric bacteria.
• To determine if PABA-UDCA can be used as a non-invasive biomarker for gut microbial activity.

Main Methods:

• Synthesized PABA-UDCA and tested its deconjugation by various enzymes and microorganisms.
• Administered PABA-UDCA orally to rats and measured urinary PABA excretion under different conditions (intestinal stagnant loop, antibiotic treatment, dietary variations).
• Evaluated PABA-UDCA in human volunteers, comparing urinary PABA excretion in control and antibiotic-treated groups.

Main Results:

• PABA-UDCA was deconjugated by cholylglycine hydrolase and by most microorganisms that split glycocholic acid, but was resistant to pancreatic and intestinal enzymes.
• Urinary PABA excretion in rats was significantly altered by intestinal stagnant loops, various oral antibiotics, and dietary changes (high-fiber vs. control vs. high-protein-high-fat).
• Human volunteers showed reduced urinary PABA excretion when pretreated with polymixin B and tinidazole, confirming the compound's utility in vivo.

Conclusions:

• PABA-UDCA serves as a reliable substrate for evaluating the activity of intestinal microorganisms.
• The compound's deconjugation and subsequent PABA release provide a sensitive indicator of gut bacteriologic status.
• PABA-UDCA represents a promising, simple, and rapid method for assessing intestinal microorganisms without specialized equipment or radioisotopes.