Chemical properties

The reactions that tetracyclines undergo are generally of a sophisticated nature, dictated by the complex functionality and the sensitivity of the molecules to mild reaction conditions (acid, base, heat) [8].

• Acidic conditions
  When exposed to dilute acid conditions, tetracycline undergoes dehydration to yield anhydrotetracycline. Anhydroterramycin suffers further cleavage and lactonization to apoterramycin:
  
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  Diluted acid promotes epimerization at C-4 as well.

• Basic conditions
  Mild alkali attacks 11a carbon of tetracycline, which is transformed to isotetracycline:
  
  

  

• Formation of complexes
  Tetracycline possesses a great tendency to form complexes with a number of chemical species, due to its B- and C-ring oxygen atoms:
  
  

  
  It complexes most readily with Fe³⁺, Fe²⁺, Cu²⁺, Ni²⁺, Co²⁺, Zn²⁺, Mn²⁺, Mg²⁺, Ca²⁺, Be²⁺, Al³⁺ among metal ions, phosphates, citrates, salicylates, p-hydroxybenzoates, saccharin anion, caffiene, urea, thiourea, polivinylpyrrolidone, serum albumin, lipoproteins, globulins, and RNA [11].