Anhydro-7-chlortetracycline

The participation of anhydrotetracyclines as intermediates was discovered relatively early due to the ready availability of these compounds by chemical degradation of the tetracyclines. McCormick and co-workers (I962) found that anhydro-7-chlortetracycline was converted to 7-chlorotetracychne by a wide variety of blocked mutants of S. aureofaciens as was true also of the conversion of anhydrotetracycline to tetracycline. 

Tetracyclines including doxycycline (DC) and oxytetracycline (OTC) and degradation products, like 4-epitetracycline (ETC), chlortetracycline (CTC), 4-epianhydro-tetracycline (EATC), anhydro-tetracycline (ATC), can also be separated on silica gel HPTLC plates (Merck), that have been predeveloped with a saturated aqueous Na2EDTA solution, dried at room temperature for Ih and activated at 130°C for 2h (47). In this method, 100 nl of the reference solutions (10 mg/ml methanol) were applied. The following solvents are used ... 

For the assay and purity control of chlortetracycline and demeclocycline a densitometric method has been published (55). With the solvent dichloromethane/methanol/water (60 35 5) for CTC and (59 35 6) for DMC and silica gel layers (Macherey-Nagel), previously sprayed with 10% Na2EDTA, adjusted to pH 8.0, all major impurities of CTC or DMC are separated from the main components and from each other. The less important anhydro derivatives of CTC or DMCTC were better separated on RP2 (20 X 20 cm) and RP 8 (10 x 10 cm, Merck both) with a mobile phase of methanol/acetoni-trile/0.5 M oxalic acid pH 2.0 (1 1 6) and methanoI/acetonitrile/0.5 m oxalic acid 2.0 (1 1 4), respectively. The coefficient of variation for the determination of the main component is 2%. The correlation with HPLC-resuIts is excellent (r = 0.9999). 

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See also in sourсe #XX -- [ ]

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