Structural and Vibrational Investigation on Alkaloid N-methylcytisine using FTIR spectroscopy and DFT calculations

FANNY C. ÁLVAREZ ESCALADA; A E. LEDESMA; ELIDA ROMANO; BRANDÁN, S.A.

Congreso; XLVIII Reunión Anual de la Sociedad Argentina de Biofísica; 2019

N-methylcytisine is a quinolizidine alkaloid obtained from plants that is widely used in in the treatment of multiple diseases, such as migraine, insomnia, asthma, or cough. The quasi-aromatic ring in cytisine structure, with similar properties than nicotine, shows an affinity towards the specific subunits of nicotine acetylcholine receptors nAChRs. FTIR spectroscopy combining with Mechanical-Quantum Calculations (DFT level) can be used as tools in the analysis of the structure activity relationship. In this work, we present the analysis of two isomeric forms of N-methylcytisine in gas and aqueous solution phases by using hybrid B3LYP/6-311++G** calculations. The infrared spectrum in solid phase and the UV-Visible spectrum in aqueous solution were registered and the structural analysis was carried out using the Gaussian 09 program. The complete assignments of the IR spectrum and the corresponding force fields in both media were performed by using scaled SQMFF methodology. The reactivities of both forms were predicted in aqueous solution while their charge transference interactions were also characterized in both media by using Natural Bond Orbitals (NBO) calculations.