A DFT study of molecular structure and 1H NMR, IR, and UV‐Vis spectrum of Zn(II)‐kaempferol complexes: A metal‐flavonoid complex showing enhanced anticancer activity

• Published in: International journal of quantum chemistry 2018-12, Vol.118 (23), p.n/a
• Main Authors: De Souza, Leonardo A., Soeiro, Malucia M., De Almeida, Wagner B.
• Format: Article
• Language: English
• Subjects: 1H NMR IR UV‐Vis spectrum; Anticancer properties; Binding sites; Cancer; Chemistry; Coordination compounds; Density functional theory; DFT; Flavonoids; Infrared spectroscopy; kaempferol; Liquid phases; Molecular structure; NMR; Nuclear magnetic resonance; Organic chemistry; Physical chemistry; Quantum chemistry; Quantum physics; Zinc; Zn(II) complex
• ISSN: 0020-7608; 1097-461X
• DOI: 10.1002/qua.25773

The polyphenol compound Kaempferol, a relevant member of the class of flavonoids, is a good example where coordination to Zn(II) ion was found to improve the anticancer effects compared to the free ligand. Determination of the metal‐complex molecular structure (and binding sites on Kaempferol) in the liquid phase is fundamental for an understanding of biological activities. Experimental UV‐Vis and EPR data only provide indirect evidence or limited structural information. Therefore, theoretical study of structural and spectroscopic properties of the metal‐polyphenol complex, using computational quantum chemistry methods, is certainly relevant as starting point for the investigation of mechanism of action at a molecular level. In this article, we used the density functional theory (DFT) methodology to predict the molecular structure of [Zn(Kaempferol)(H2O)n]+ and [Zn(Kaempferol)2(H2O)n] complexes (n = 0, 2, or 4) and B‐ring nonplanar conformation of flavonoid using as strategy the best match between theoretical and experimental 1H NMR, IR, and UV‐Vis spectroscopic data in solution. These are valuable information for further studies involving structure‐activity relationship. Kaempferol, a flavonoid extracted from the Camellia sinensis, has several biological activities. According to the literature, Zn(II)‐kaempferol complexes exhibit higher antitumor activity than free flavonoid. Therefore, the elucidation of the complex structure in solution constitutes one of the main properties to study its mechanism of interaction with DNA. This article shows unpublished results obtained through a DFT study of the structures and their 1H NMR spectra in solution of different geometries for this complex.