USING QUANTUM-CHEMICAL PARAMETERS FOR PREDICTING ANTI-RADICAL (НО∙) ACTIVITY OF RELATED STRUCTURES CONTAINING A CINNAMIC MOLD FRAGMENT. I. DERIVATIVES OF CINNAMIC ACID, CHALCON AND FLAVANON

Abstract

45 compounds uniting 3 groups of derivatives of cinnamic acid, chalcone and flavanone, have been studied. Each of them includes 15 substances. The analyzed compounds contain a common structural fragment, which is a cinnamic acid residue (cinnamoyl fragment).The aim is to study the quantum-chemical parameters of the listed groups of the compounds in order to predict possible ways of their interaction with the most aggressive and dangerous of the active oxygen species (ROS) – a hydroxyl radical.Materials and methods. For the analyzed structures, the Mulliken charges (a.u.), bond numbers (Nμ), unsaturation index (IUA), and electron density values on all 9-carbon atoms of the cinnamoyl fragment have been determined. The calculations have been carried out on a workstation with an Intel Xeon E5-1620 3.5 GHz processor, 20 GB of RAM. The semi-empirical method PM7 was used (WinMopac 2016 program). The ORCA 4.1 program was used to calculate the energies of homolytic cleavage of the O – H bond.Results. The analysis of Mulliken charges (a.u.), bonded numbers (Nμ), unsaturation indices (IUA), and electron density revealed a number of regularities on the basis of which it can be concluded, that taking into account the nature of the substituent, the most probable for addition in the aryl residueare positions C-1, C-2, C-3, C-4 and C-5. In the propenone fragment, the radical НО∙ first attacks position 8, then 7. For the hydroxy-substituted, the energy of the homolytic breaking of the H – O bond has been determined and it has been established that the spatial difficulty of phenols (compounds 13k, 13x, 13f, 14k, 14x, 14f) H-O bonds are the smallest and on average are -160.63 kJ/mol. It has also been established that the higher the positive Mulliken charge on the carbon atom with which the phenolic hydroxyl is bound, the lower the energy of the homolytic breaking of the H – O bond and the more stable the resulting phenoxy radicalis.Conclusion. The carried out quantum chemical calculations allow us to conclude that the studied classes of compounds can be used to bind the hydroxyl radical formed in the body, causing various kinds of mutations, leading, among other things, to the development of oncological diseases.

Keywords

• гидроксильный радикал
• производные коричной кислоты
• халконы
• флаваноны
• малликеновские заряды
• связевые числа
• индекс ненасыщенности
• электронная плотность