Quantum Chemical Study of the Structural Properties of Ascorbic Acid (Vitamin C) in DMSO

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1 2013, TextRoad Publication ISSN Journal of Basic and Applied Scientific Research Quantum Chemical Study of the Structural Properties of Ascorbic Acid (Vitamin C) in DMSO Naser Niazazari PhD student at Yerevan State University, Faculty of Chemistry, Armenia, Yerevan ABSTRACT Ascorbic acid is one of the most significant elements added to foods and dietary supplements. It isa man-made form of the vitamin C naturally found in fruits and vegetables. Ascorbic acid plays a key role in processed foods preparation, and human ingestion of the antioxidant values of vitamin C. Considering the significance of Ascorbic acid the goal of the current paper is to study structural properties of ascorbic acid in DMSO. To achieve the goal, first, quantum chemical method, then, ab intio Hartree Fock methods have been applied to determine the structure and energies of stable conformers as well as vibrational characteristics of various types AA/DMSO complexes in gas phase and solution. The results obtained show that there is a satisfactory correlation between experimental and theoretical predictions. KEYWORDS: Quantum chemical method, ab intio, SCRF, DFT, Ascorbic acid, DMSO. 1. INTRODUCTION Ascorbic acid is almost as valuable as natural vitamin C. The most valuable, perhaps, is its antioxidant value. Antioxidants help to struggle against viruses and infections and strengthen the overall immune system. The problem with natural vitamin C is that it splits easily. That is the reason that Vitamin C in fruits and vegetables loses its effect during cooking. Moreover, vitamin C can also lose its effect merely through storing fruits and vegetables for some period. As a result many people fail getting the required amount of vitamin C, even if they use a lot of fruits and vegetables. Considering the effects of the sensitiveness of vitamin C, food manufacturers add vitamin C qualities into their products applying ascorbic acid. Hence, ascorbic acid (AA) or Vitamin C is very important for life and it has been investigated in several researches [1-10]. It prevents and cures scurvy [11], important in formation and maintenance of connective tissue in the body; essential for normal tooth and bone formation and strength capillary walls [12]. It is important in carbohydrate metabolism and in controlling infective processes and also it is antioxidant agent [13-16]. Dimethyl Sulfoxide (DMSO) has medical significance [17-18]. It can dissolve AA [2] and enhance the effective crypreservation of cells after combination with AA [19]. In the current paper we have studied the structural properties of AA/DMSO complexes by quantum chemical approach. This study can be very important because of its medical and biological significance. METHODOLOGY We performed a plan to study L-ascorbic acid (AA) in dimethylsulfoxide (DMSO) by applying quantumchemical methods. Ab initio Hartree-Fock (HF) methods [10] used to determine the structure (optimized values of bond lengths, angles, Mulliken charges and dipole moments for complexes) and energies of stable conformers as well as vibrational characteristics (vibrational frequencies, infrared intensities) of various types AA/DMSO complexes in gas phase and solution. In the present study density functional theory (DFT) method [20-21] has been used. The G* and G** basis sets level have been used to describe the energy changes in the gas phase, and the self-consistent reaction field (SCRF) [22] have been applied to calculate the effect of DMSO as the solvent on the geometry and energy changes of complexes. For the studying solvent affect the Onsager models have been used [23-28]. Theoretical calculations have been performed with GAUSSIAN 98 software package. The initial molecular geometry is optimized by semi-empirical molecular modeling methods (HYPERCHEM 5.02). To obtain a reasonably accurate geometry of the isolated molecules and bonding of complexes restricted Hartree-Fock (RHF), (SCF) and density functional theory (DFT) levels, which include both diffuse functions and polarization functions [20], have been chosen. The Onsager method use as continuum solvation model. This method replaces the DMSO solution by a continuum dielectric medium, homogeneous and isotropic, characterized by the dielectric constant ( DMSO= 46.7). The solute is then placed in a spherical cavity within the solvation self-consistent reaction field (SCRF). The cavity radii [20] obtained from the GAUSSIAN 98 program. Single ascorbic acid molecule and AA/DMSO complexes further optimized inside the cavities at the RHF *Corresponding Author: Naser Niazazari, PhD student at Yerevan State University, Faculty of Chemistry, Armenia, Yerevan. naser.niazazari@gmail.com 658

2 Niazazari, 2013 and DFT level with the G* and G** basis sets. We performed a geometry optimizations and vibrational frequency calculation of the AA molecule, AA/DMSO complexes in vacuum. Since our interest was the behavior of AA in a DMSO solution, we also did calculations for the AA monomer in a dielectric medium using the Onsager method, as well as for the AA molecule in complexes with DMSO molecules, both in vacuum and in a dielectric medium. RESULTS AND DISCUSSIONS The optimized geometric parameters and interaction energies for various complexes at different theory have been estimated. According to interactions between O-H groups of vitamin C and S=O group of DMSO there are 3 types AA-DMSO complexes that shown in Fig 1. I II III Fig.1: Shapes of 3 types of interaction between AA / DMSO However, there are 3 types AA-DMSO in the air, while in solution there are 2 types of AA-DMSO complexes. In other words, complexes II and III are the samein solution. The self-consistent reaction field has been used to calculate the effect of DMSO as the solvent on the geometry and energy changes of complexes. The solvent effects have been studied by using the Onsager models [24]. According to the method of calculations we have obtained, geometry data (bond, distances and angles) for 3 types of complexes as presented in table 1-3. Table 1: RHF/6-311+G*&RHF/6-31++G** calculations of AA+DMSO (complex I) C 2 =O C 4 =C O 3 -C O 3 -C O 9 -H O 7 -H O 9 -C O 7 -C S 25 =O O H O H < H O 26 =S < H O 26 =S < C 27 -S 25 -C Etot (a.u.) Dipole moment (Debye)

3 Table 2: RHF/6-311+G*&RHF/6-31++G** calculations of AA+DMSO (complex II) C 2 =O C 4 =C O 3 -C O 3 -C O 9 -H O 7 -H O 9 -C O 7 -C S 25 =O O H O H < H O 26 =S < H O 26 =S < C 27 -S 25 -C Etot (a.u.) Dipole moment (Debye) Table 3: RHF/6-311+G*&RHF/6-31++G** calculations of AA+DMSO (complex III) C 2 =O C 4 =C O 3 -C O 3 -C O 9 -H O 7 -H O 9 -C O 7 -C S 25 =O O H O H < H O 26 =S < H O 26 =S < C 27 -S 25 -C Etot (a.u.) Dipole moment (Debye) We have also obtained frequency data and interaction for complexes that are presented in table 4-5. The response of the solvent to the dielectric field generated by the polar solvent located in the cavity [20] is assumed to be linear. The dipole of the solute changes as a response to the reaction field generated by the dielectric medium. Table4: Frequency data for RHF/6-311+G* & G** calculation of AA/DMSO complexes in DMSO Igeom IIgeom IIIgeom Igeom IIgeom IIIgeom C 2 =O C 4 =C O 9 -H O 7 -H S 25 =O

4 Niazazari, 2013 A dipole in the molecule will induce dipole in medium and the electric field applied by the solvent dipole will in turn interact with the molecular dipole, leading to net stabilization of the electrostatic effect of the solvent represented as an additional term in the Hamiltonian of molecule in the gas phase. The results obtained indicate that there is a satisfactory correlation between experimental and theoretical predictions [1, 29]. Conclusion Table5: Eintrraction for AA/DMSO complexes in DMSO(Kcal/mol) After analyzing the results of the theoretical calculations and comparison with the results of experimental ones, we found that this is a good approach for calculations of these categories because of the low expenses and time of calculations and can be used for similar researches [2-4]. In our idea the use of another levels and basis sets of theoretical calculations can lead to better results. Acknowledgments Basis set Complex G* G** I II III I would like to express my greatest gratitude to my scientific supervisor prof. Sh. A. Markarian and the scientific research foundation of Yerevan State University for continuous help and support throughout my project. REFERENCES 1. Zatikyan, A. I., Kazoyan, E. A, Bonora, S. and Markarian,Sh. A.2008.Ascorbic acid vibrational spectra in sulfoxide solvents:journal of Applied Spectroscopy, 75(5): Watanabe Y., Suzuki H., and Ueda T HLB number of Vitamins C, E, coenzyme Q 10 derivatives and their transportation efficiency into skin:vibrational Spectroscopy, 42(2): Paasch,S. and Salzer, R Solution to Spectroscopy Challenge 7: Analytical and Bioanalytical Chemistry, 380(5-6): Liu, H., Xiang, B.and Qu, L Structure analysis of ascorbic acid using near-infrared spectroscopy and generalized two-dimensional correlation spectroscopy:j. of Mol. Structure., 794(1-3): Dimitrova, V Theoretical study of the changes in the vibrational characteristics arising from the hydrogen bonding between Vitamin C (l-ascorbic acid) and H2O:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 63(2): Panicker, C. Y., Varghese, H. T. and Philip,D FT-IR, FT-Raman and SERS spectra of Vitamin C: Spectrochim. Acta, Part A, 65(3): Allen, R. N.,Shukla, M. K., Reed, D. and Leszczynski, J Ab initio study of the structural properties of ascorbic acid (vitamin C):Int. J. Quant. Chem., 106(14): Markarian, S. A.,Gabrielian, L. S., Bonora, S. and Fagnano, C Vibrational spectra of diethylsulfoxide:spectrochim. Acta, Part A, 59(3): Markarian, S. A., Zatikyan, A. L.,Bonora, S. and Fagnano, C Raman and FT IR ATR study of diethylsulfoxide/water mixtures:j. Mol. Struct., 655(2): Al-Laham,M.A. and Peterson,G. A Ab initio study of ascorbic acid conformations: J. of Comp.Chem, 12(1): Barnes,M. J. and Kodicek, E. in: Vitamins and Hormones, Vol. 30(Academic Press, New York, 1972): p Dean, J. A Lange`s Hand book of Chemistry: 15 th edition. McGraw-Hill, US. 13. Smith, F.in: The Vitamins, Vol. 1, cds. W. H. Sebell. Jr and R. S. Harris (Academic Press, New York, 1954): p Weight, M. J., Kotze, J. P.,Deklerk,W. A. and Weight,N The effect of dietary ascorbic acid on cholesterol biosynthesis in vitro: Intern. J. of Biochem., 5(3): Smith, F. in: The Vitamins, Vol. 1, eds. W. H. Sebrell Jr. and R. S. Harris (Academic Press, New York,1954) p Herbert,V. and Jacob,E Destruction of Vitamin B12 by Ascorbic Acid:J. Am. Med. Assoc., 230(2) Jacob,S. W. and Herschler, R Pharmacology of DMSO:Cryobiology, 23(1): Yu,Z. W. and P. J. Quinn Dimethyl sulphoxide: a review of its applications in cell biology. Biosci. Rep., 14(6):

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