CHARACTERIZATION AND THIN-LAYER CHROMATOGRAPHIC QUANTITATION OF HUMAN METABOLITE OF 7-DEOXY-7(S)CHLOROLINCOMYCIN (U-21,251F)

U-21, 251 is 7-deoxy-7(S)-chlorolincomycin. The antimicrobial spectrum of this new antibiotic is extended and it is about twice as active as lincomycin in vivo against gram-positive infections. During routine analysis of biological fluids obtained from test subjects, a bio-activity chromatographically different from the 7-deoxy-7(S)-chlorolincomycin was observed on thin-layer bioauto grams. This metabolite has not been differentiated from the N-demethyl-7 deoxy-7(S)-chlorolincomycin by thin-layer chromatography (TLC). Although we have not recovered sufficient metabolite from urine for unequivocal identi fication, some indirect evidence supporting the structural assignment is pre sented. A TLC quantitative analysis for the 7-deoxy-7(S)-chlorolincomycin and its metabolite has been developed for biological fluids, particularly serum. The analysis is based on the separation of the two activities on silica gel and subsequent quantitation by regression analysis of the zone sizes obtained by bioautography. The regression lines cover the range 0.5 to 0.0038 meg and show a maximum variation of 3.0%, based on intercepts. This variation covers contributions by serum and TLC plates. Samples, which usually required concentration prior to analysis, may be quantitated with a 7.5% standard error. © 1968, JAPAN ANTIBIOTICS RESEARCH ASSOCIATION. All rights reserved.