Cytidine metal complexes

Aqueous solutions of complementary purine and pyrimidine base pairs, when examined by Raman spectroscopy (Lord and Thomas, 1967a), revealed no signs of specific base-pair interactions, although interactions between soluble nucleosides and heavy-metal ions have been detected, e.g., cytidine-HgCl2 complex. Aqueous solutions of RNA derivatives have been examined (Lord and Thomas, 19676). This work represents an application of growing importance, where further progress will be... 

Such sugar-metal complexes as (444) were formed in high yield by electrolysis of the appropriate ligand (see p. 133) in methanolic solution using anodes of the metal (Cu or Ni or Co) and a platinum cathode. The interaction between Cu cations and adenosine, guanosine, cytidine, and uridine in aqueous DMSO at various pH values has been studied by e.s.r. and n.m.r. spectroscopy. Since Cu cations were shown to complex specifically with 0-2 and 0-3 of these nucleosides at pH 8.5-10, complex formation can be used to distinguish 5 -ribonucleotides from 2 - and 3 -ribonucleotides and 2 -deoxyribonucleosides. Under certain conditions, Cu cations can form complexes having as many as four bases bound to the metal. 

Table XIX contains stability constants for complexes of Ca2+ and of several other M2+ ions with a selection of phosphonate and nucleotide ligands (681,687-695). There is considerably more published information, especially on ATP (and, to a lesser extent, ADP and AMP) complexes at various pHs, ionic strengths, and temperatures (229,696,697), and on phosphonates (688) and bisphosphonates (688,698). The metal-ion binding properties of cytidine have been considered in detail in relation to stability constant determinations for its Ca2+ complex and complexes of seven other M2+ cations (232), and for ternary M21 -cytidine-amino acid and -oxalate complexes (699). Stability constant data for Ca2+ complexes of the nucleosides cytidine and uridine, the nucleoside bases adenine, cytosine, uracil, and thymine, and the 5 -monophosphates of adenosine, cytidine, thymidine, and uridine, have been listed along with values for analogous complexes of a wide range of other metal ions (700). Unfortunately comparisons are sometimes precluded by significant differences in experimental conditions.

Certain APIs are susceptible to oxidation, e.g., atorvastatin and cytidine nucleoside analogues. Fumed metal oxides (e.g., fumed silica, fumed titania, and fumed zirconia) can promote such oxidation reactions. These reactions are more complex in some ways, and less easy to predict. 

Zn, Ba, Hg ) ion complexing with adenosine, cytidine and guanosine has been investigated by N-n.m.r. spectroscopy metallated nitrogens are shielded. 

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