Microbial Degradation of Disinfectants: Two New Aromatic Degradation Products of Chlorhexidine, Chlorhexidine Aromatic Degradation Product (CHADP)-4 and CHADP-6, Produced by Pseudomonas sp. Strain No. A-3

To clarify the degradation pathway of chlorhexidine by a microbe, Pseudomonas sp. Strain No. A-3, the isolation and identification of microbial chlorhexidine degradation products were attempted. Two aromatic degradation products of chlorhexidine, named chlorhexidine aromatic degradation product (CHADP)-4 and CHADP-6, were isolated by column chromatography using Diaion HP-10, and purified by column chromatography using Diaion HP-20SS and Sephadex LH-20. The chemical structures of both compounds were examined by infrared, 1H NMR, 13C NMR and fast atom bombardment (FAB) mass spectra studies. Based on the spectroscopic data, CHADP-4 (molecular weight 335) and CHADP-6 (molecular weight 377) were found to be direct degradation products of chlorhexidine and were thought to be cleavage partners of p-chlorophenylurea (CHADP-5) and p-chloraniline (p-CA), respectively. Antimicrobial activity of CHADP-6 are similar to that of chlorhexidine, but antimicrobial activity of CHADP-4 decreased to 1/5-1/10 that of chlorhexidine.