On the Nature of the Reversible Isomerizations Occurring in the Tetracycline Family

Chemical Modification of the Tetracyclines

“…In IN HCI, for instance, 4-epianhydrotetracycline (33) is obtained from (MCCORMICK et al 1956;KELLY 1964). Treating both C4 epimers (32) and (34) with zinc in glacial acetic acid for 6 h at 30 oe gives dedimethylaminotetracycline (35) (MCCORMICK et al 1956).…”

Stability of Tetracycline and Riboflavin

“…A similar method, which is based on the authors' procedure, has been published recently (3). This method allows the simultaneous determination of tetracycline (I), anhydrotetracycline (11), and their corresponding C-4 epimers (111 and IV). Studies were performed at pH 4.5 using MacIlvaine's buffer.…”

“…It was believed, however, that this rapid rate represented catalysis by the citrate buffer (10)(11)(12). To test this hypothesis, studies were performed in nonbuffered solutions in which the pH value was simply adjusted to 4.5 with base.…”

Tetracycline Epimerization Kinetics Utilizing NMR Spectrometry

“…The epimer of I was named Cepitetracycline (11) when the reaction was shown to take place at the C-4 position (2,3). McCormick et al (4) reported that epimerization occurred in aqueous solutions of pH 2-6 in the presence of anions such as phosphate, acetate, and citrate.…”