Seven strains capable of utilizing 18 beta -glycyrrhetinic acid (18 beta -GRA) as a sole carbon and energy source were isolated from soil samples by enrichment culture technique. One of these strains, named strain G5, was identified as Sphingomonas paucimobilis. When this strain grew on 18 beta -GRA, several metabolites were detected in the culture broth. A major metabolite, tentatively named M-A, was isolated and its chemical structure was determined by nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry (GC-MS).