Tetracyclines chelating groups

Tetracyclines have similar chelating groups in their stmcture. Therapeutic chelators are used in syndromes where there is metal ion overload. EDTA (ethylenediaminetetraacetic... 

Degradation of Tetracyclines Tetracyclines are relatively stable under acidic conditions but not under alkaline conditions. They form complexes with chelating agents such as divalent metals, proteins, and silanol groups (Oka et al., 2000 ... 

The tetracyclines Form an important group of antibiotics. The activity appears to result from their ability to chelate metal ions since the extent of antibacterial activity parallels the ability to form stable chelates. The metal in question appears to be magnesium or calcium since the addition of large amounts of magnesium can inhibit the antibiotic effects. In addition, it is known that in blood plasma the tetracyclines exist as calcium and magnesium complexes.,JS... 

Another instability leading to a dramatic decrease of antibacterial action, to which all clinically used tetracyclines are subject, is epimerization of the natural 4-a-dimethy-lamino group A to the p-epimer B (Eq. 6.11). Under acidic conditions a 1 2 equilibrium is established in solution within a day. This occurs in a variety of solvents, especially acetic acid. Anions also tend to support this process. Divalent ions that chelate tetracyclines, particularly Ca2+, facilitate the reversal of the epimerization from the epi to the natural isomer. 

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