The interaction of a cobalt porphyrin with cancer-associated nitrosamines

• The cobalt porphyrin was synthesized and characterized.
• The cobalt center with two molecular TSNAs formed the six-coordinate complex.
• Type II interaction mode of porphyrin mental center with nitrosamine was showed.
• The thermodynamic properties of the reaction of cobalt porphyrin with TSNAs was obtained.

A cobalt porphyrin (CY-B) was presented, and its interaction with tobacco-specific nitrosamines (TSNAs) was investigated by UV–Vis spectroscopy and high-resolution mass spectrometry. The results revealed that the stoichiometry of the host–guest interaction was 1:2 and that the binding constant between CY-B and TSNAs was within the range of 0.78 × 108–7.83 × 108 M−2. The coordination strength between CY-B and TSNAs decreased in the sequence of NNN > NAB > NAT > NNK based on the binding constant. The interaction mechanism of CY-B with TSNAs involved a coordination interaction, and the π–π interaction between the porphyrin macrocycle and the aromatic frame of the TSNAs pyridines may also have been a driving force. The measured thermodynamic properties demonstrated that the reaction of CY-B with TSNAs was spontaneous and that the driving force for the interaction was a change in enthalpy. The reaction was exothermic, and an increasing temperature inhibited the interaction. The IR spectrum of the complex revealed that the NNO group of TSNAs and the metal cobalt of CY-B formed the six-coordinate complex.

A cobalt porphyrin was synthesized and its interaction with carcinogenic tobacco-specific nitrosamines (TSNAs) was investigated. The interaction mechanism of cobalt porphyrin with TSNAs was coordination interaction and the center cobalt with the NNO group of TSNAs formed the six-coordinate complex. The results provide an example of Type II interaction of cancer-associated nitrosamine with the metal center in cytochrome P450. The thermodynamic properties of the reaction of cobalt porphyrin with TSNAs was obtained.Figure optionsDownload as PowerPoint slide