Tetracycline Epimerization Kinetics Utilizing NMR Spectrometry

The pH dependence of carbon-13 nuclear magnetic resonance shifts of tetracycline. Microscopic dissociation constants

“…Chem., 10, 427 (1973). (14) Unpublished data from this laboratory. (15) E. Wenkert, E. W. Hagaman, and G. E. Gutowski, Biochem.…”

“…Microscopic Dissociation Constants G. L. Asiesen and C. W. Frank* Contribution from the Department of Chemistry, University of Iowa, Iowa City, Iowa 52242. Received November 14,1975 Abstract: Carbon signals of tetracycline hydrochloride were found to be very sensitive to pH in a 50/50 DMSO:water solvent system. The curves obtained by plotting the chemical shift of a signal vs. pH were related to the p values which were determined to be 4.4, 8.1, and 9.8 in the mixed solvent system.…”

Principles of Drug Degradation

“…Epi-tetracyclines have less antibacterial activity than the corresponding tetracyclines. The degradation of tetracycline in aqueous solution at elevated temperature was monitored and the concentrations of both tetracycline and epi-tetracycline were determined [4]:…”

Versatile and Facile Synthesis of Diverse Semisynthetic Tetracycline Derivatives via Pd-Catalyzed Reactions

“…Structure−activity relationships based on observations of antibacterial activity subdivide the tetracycline naphthacene ring into two regions (see figure in Table ): position modifications that when chemically modified decrease or eliminate altogether antibacterial activity, the lower peripheral region spanning carbons C10 to C3, and positions on the ring that may be chemically modified resulting in variable changes of antibacterial activity, the upper peripheral region spanning the C5−C9 carbons , The epimerization process at the C4 position occurs during tetracycline metabolism in vivo, pH changes,6f and under harsh chemical reaction conditions …”