Nicotine as a Catalyst for Chlorination Promoted by Hypochlorous Acid: Experimental and Theoretical Studies

Autor(es)

Ximenes, Valdecir F. ; Pavan, Nathalia M. ; de Souza, Aguinaldo R. ; Barros, Gabriel A. ; Morgon, Nelson H.

• Tipo de documento: Artigo Científico
• Fonte: Journal of the Brazilian Chemical Society; v. N/A, p. 6-pg., 2022-06-27.

Resumo

There is robust evidence of the hypochlorous acid (HClO)-mediated damage in biomolecules, and nicotine boosts the chlorination potency of HClO. We present experimental and theoretical evidence of the mechanism by which nicotine catalyzes the chlorination of pyranine. The rate constants for chlorination of pyranine by HClO were measured in the presence (5.3 x 10(5) mol(-1) L s(-1)) and absence of nicotine (4.2 x 10(3) mol(-1) L s(-1)), revealing the catalytic effect of the alkaloid. Density functional theory (DFT) calculations, based on B3LYP-GD3(BJ)/6-311++G(3df,2p)/SMD(Water)//B3LYP-GD3(BJ)/6-311++G(2d,p)/SMD(Water) level of theory, were performed and showed a decreased activation energy for chlorine transfer and hydrogen abstraction when nicotine chloramine intermediated the reaction. The atomic polar tensor (APT) charges on the chlorine atom of HClO (+0.084) were lower than the chlorine of nicotine chloramine (+0.149), revealing the higher electrophilic character of nicotine chloramine. In conclusion, the increased electrophilic nature of HClO provoked by nicotine explains its catalytic effect. (AU)

• Processo FAPESP: 19/18445-5 - Síntese, estudos e aplicações de sondas fluorescentes e circular dicroicas para caracterização de interações com proteínas, DNA e determinação de atividade enzimática
• Beneficiário: Valdecir Farias Ximenes
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 19/12294-5 - Cálculos teóricos de espectros eletrônicos (UV-Vis, fluorescência e dicroísmo circular) de moléculas de interesses farmacológico e aplicado
• Beneficiário: Nelson Henrique Morgon
• Modalidade de apoio: Auxílio à Pesquisa - Regular