维生素类清除自由基机理的密度泛函理论计算
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摘要
抗氧化剂是一种重要的食品添加剂,对人类健康至关重要。它是指具有传递电子作用、与氧化剂发生氧化--还原反应,从而清除自由基或抑制自由基形成的物质(还原剂)。量子化学是以量子力学为基础,利用量子力学的原理和方法来研究化学中的问题的一门理论科学。从量子化学理论出发,人们能对化学物质的结构、功能、反应做出新的设计和预测。采用密度泛函理论方法的量子化学计算是当前量子化学计算中应用最为广泛的方法。
     维生素是具有化学活性的非酶类抗氧化剂。维生素A能够维持人类正常的视觉反应、维持上皮组织的正常形态与功能、以及维持正常的骨骼发育,对人体健康有着极大的作用。运用HPERCHEM7.5上的AM1半经验量子化学计算方法进行初步的分子结构优化,得到化合物的一些理化参数。接着运用Gaussian03量子化学程序,利用密度泛函理论方法B3LYP对维生素A进行分子结构优化并进行了振动频率计算。结果显示计算的振动频率无虚频,维生素A的偶极矩和脂水分配系数较大,可以看出其为脂溶性的物质,从前线轨道电子云分布可以看出,维生素A容易失去共轭双键和羟基的电子从而表现出还原性,从而发挥抗氧化作用。
     大多数类胡萝卜素是维生素A原,类胡萝卜素分子结构中含有一个共轭大π键,可能是这种特殊的结构使它容易与自由基发生反应,形成无害的产物。运用密度泛函理论方法对虾青素、β-胡萝卜素、玉米黄素和叶黄素分子进行了分子结构优化和单点能计算。研究表明,分子的共轭效应使C-C单双键的键长均匀化,同时降低了分子的能量,最高占据轨道与最低空轨道能级间隔⊿ E (LUMO-HOMO)变小,光谱移至可见区,从而使各种类胡萝卜素显出不同的颜色。从原子的NBO电荷值,前线轨道⊿E方面分析可见,抗氧化活性高低次序理论上应为:虾青素>玉米黄素≈β-胡萝卜素>叶黄素。此外,玉米黄素和叶黄素结构中的羟基会增强其与水溶性或脂溶性氧化物反应,导致其清除自由基的能力大于β-胡萝卜素。
     运用密度泛函理论方法优化计算了维生素C的分子结构及其红外光谱。从分子中O-H的键长、O-H上H原子的正电荷值、以及分子和自由基的生成能、前线分子轨道结构特征等方面讨论了维生素C的抗氧化活性位点和还原性特征。抗氧化剂清除自由基的活性与O-H键的强度成反比,O-H的键的强度越弱则抗氧化剂的活性越高。对比维生素C分子的前线轨道能量和其去掉H原子以后的自由基前线轨道能量,可以看出失去H原子后,导致其电子最高占据轨道能级降低,从而使其失电子能力降低,即还原性降低。从理论上得出维生素C分子具有还原性的特征是由于它容易失去H自由基。
     运用Gaussian03进行构型优化和频率计算,得到维生素C分子及其去掉H原子以后的自由基的红外光谱。对计算的LVC分子的光谱、标准LVC分子及水溶液中测定的LVC分子的红外光谱进行了对比;对计算的几种自由基的红外光谱与标准LVC分子红外光谱也进行了对比。结果表明,只有失去H18或者H19后得到的自由基的红外光谱与标准维生素C红外光谱频率最为相近,可以预测标准维生素C最可能的存在形式是失去H18或者H19后的自由基。
As important food additive, antioxidant is essential to human health. It can eliminate free radicals by transmitting electron and form harmless products (reducing agent). Quantum chemistry, a kind of theoretical sciences, is based on the principles of quantum mechanics to study the chemical problems. On the basis of quantum chemical theory, people can make new designs of chemical reactions and predictions on chemical substances structures and functions. Now the Density Functional Theory is the most popular method used in quantum chemistry calculations.
     Vitamin is a kind of antioxidants which owns biologic activity but not enzymes. Vitamin A plays an important role in human health. Vitamin A can sustain human normal visual response, maintain the normal form and function of the epithelial tissue, and maintain the normal growth of bone. First, the semi-empirical quantum chemistry calculation method AM1in HPERCHEM was used to optimize the molecular structure of Vitamin A, and some quantum chemical parameters of the compound were obtained. The results showed that the dipole moment and lipid-water partition coefficient of Vitamin A are both very large, so it is fat-soluble substance. Then, the Density Functional Theory B3LYP method in Gaussian03 was used to optimize its geometry structure ulteriorly and calculate its vibration frequencies. The results showed that the compound can exist stably for no imaginary vibrational frequencies appearing in its IR spectrum. Based on the structure property of the frontier molecular orbital, one can see that vitamin A can lose its electrons of the conjugateπbond and hydroxide easily. That is just the reason of Vitamin A showing reductive and anti-oxidative properties.
     It is well-known that there is a conjugatedπbond in the carotenoid molecular structure. It can eliminate free radicals in the organisms by reacting with free radicals through the conjugatedπbond to form harmless products or destroy the chain reaction of involving radicals. In this work, the Density Functional Theory was adopted to optimize the molecular structures of astaxanthin,β-carotene, zeaxanthol and lutein, and then B3LYP / 6-311 (d) method was applied to calculate their Single Point Energys (SPEs). The carotenoids’molecular structure, total energy, NBO charge value of the atoms and the structures of the frontier molecular orbitals were analyzed in detail. The results showed that in the conjugated system, the molecular conjugated effects make the C-C bond lengths unified, the total energy and the energy differences⊿E (LUMO-HOMO) reduced, and the absorptive spectrum shifted to the visible spectrum area. Based on the electronic parameters of the NBO charges and the structures of the molecular frontier orbitals, one can concluded theoretically that the antioxidation activity goes along with the series as astaxanthin >β-carotene≈zeaxanthol > lutein. But the hydroxide radicals in the structures of zeaxanthol and lutein enhance their hydrophilicity and make them easy to react with water-soluble or fat-soluble oxides. So their ability of eliminating free radicals is higher than that ofβ-carotene.
     The structures and its several free radicals losing one H atom of O-Hs of Vitamin C were optimized by using Density Functional Theory (DFT) B3/LYP method at 6-311++G (2d, p) basis set. The reductive feature and active sites of the vitamin C were investigated based on the length of O-H bonds, the charge value on the H atoms of the O-H, the total energies of the Vitamin C molecule and its free radicals, and the structures of their frontier orbital. The results showed that the activity of antioxidant to scavenge free radicals in organism is negative to the strength of the O-H bonds. The lower the O-H bond strength is, the higher the anti-oxidative activity is. For the highest occupied orbital energy of the free radicals is lower than that of Vitamin C, their ability of losing electron is lowered, it means that the reducibility of Vitamin C decreases. So it can be concluded theoretically that the vitamin C possesses the reductive ability due to its losing H atom easily.
     The IR spectrum of the vitamin C molecule and its free radicals after losing H atoms were calculated in this work yet. The infrared spectrums of the LVC molecular calculated, spectrums of standard LVC sample, and spectrums of LVC measured in aqueous solution were compared. Also, the infrared spectrums of several free radical molecules calculated were compared with the standards LVC IR. The results showed that only the infrared spectra of the free radicals by losing H18 or H19 were most similar to that of the standard vitamin C. So we guessed that the vitamin C usually exists in the form of free radicals by losing H18 or H19.
引文
[1]汪秋安.天然抗氧化剂及其在食品中的应用[J].粮油食品科技, 2000, 1: 33-35.
    [2]徐学兵.油脂化学[M].北京:中国商业出版社, 1993.
    [3] A. Bendich. The antioxidant role of vitamine [J]. CadvFree Biol Med., 1986, 8(2): 419-419.
    [4]翟惠敏,李亚洁.氧自由基对脑损伤的作用和维生素的防护作用[J].南方护理学报, 2001, 8(1): 18-18.
    [5]徐开来,谢代前,鄢国森. SnCl4和DMF作用下1一三氯锡烷基一2,3一丁二烯与甲醛反应机理的理论研究[J].化学学报, 2004, 62(20): 2003-2006.
    [6] M. M. Riad, F. E. Laurence. DFT and ab Initio Study of the Unimolecular Decomposition of the Lowest Singlet and Triplet States of Nitromethane [J]. Journal of Physical Chemistry A, 1998, 102(48): 9884-9889.
    [7]卫海燕,王凡,陈志达.密度泛函理论研究顺式与反式构型的Mn(II)一NITR2自由基配合物的磁交换作用[J].中国科学(B辑), 2005, 35(2): 110-120.
    [8]李浩宏,陈之荣,黄长沧.一种新颖有机/无机杂化配位聚合物[(C7Hl8N)(Ag2I3)]n的合成、结合及量子化学计算[J].无机化学学报, 2005, 21(6): 933-937.
    [9]史福强,徐志成,安静仪,等.呋喃-乙酸分子间相互作用的量子化学研究[J].化学学报, 2005, 63(4): 283-288.
    [10] X. H. Lu, Y. X. Wang. Theoretical Studies on Mechanisms of Cycloaddition Reaction between Dichlorovinylidene and Formaldehyde: Concerted and Stepwise [J]. Journal of Physical Chemistry A, 2003, 107(39): 7885-7890.
    [11]王炳武,徐光宪,陈志达.无机类似富勒烯分子[Cu—Cl]20[Cp*FeP5]12[Cu(CH2CN)2+Cl-]5中Cu的共价和化学键的密度泛函[J].中国科学(B辑), 2004, 34(1): 1-7.
    [12]刘朋军,常鹰飞,孙昊,等. HODD与CH( 2π)双自由基反应微观动力学的理论研究[J].高等学校化学学报, 2005, 26(4): 723-726.
    [13] U. Burkert, N. L. Allinger. Molecular Mechanics. American Chemical Society [M], Washington D C, 1982.
    [14] A R. Leach. Molecular Modeling: Principles and Application.London: Addison Wesley Longman Limited, 1996.
    [15] W. J. Hehre, L. Radom, P. V. R., Schleyer, et a1. Ab initio Molecular Orbital Theory[M]. NewYork: John Wiley& Sons, 1986.
    [16] S. Hoyau, G. Ohanessian. Interaction of alkali metal cations (Li+-Cs+) with glycine in the gas phase: A theoretical study [J]. Chemistry-A European Journal, 1998, 4: 1561-1569.
    [17] G. Nandini, D. N. Sathyanarayana. Ab initio studies on geometry and vibrational spectra of N-methyl formamide and N-methylacetamide [J]. Journal of Mo1ecular Structure: THEOCHEM, 2002, 579(1-3): 1-9.
    [18] O. J. James, J. G. Sean, B. Ajit, et al. A theoretical study of As4O6: vibrational analysis, infrared and Raman spectra [J]. Journal of Molecular Structure: THEOCHEM, 2003, 644: 145-156.
    [19] R. G. Parr, W. Yang. Density-Functional Theory of Atoms and Molecules [M]. Oxford Universiy Press: Oxford, UK, 1989, Vol: 16.
    [20] P. Hohenberg, W. Kohn. Inhomogeneous electron gas [J]. Physical Reviews, 1964, 136: B864-871.
    [21] W. Kohn, L. J. Sham. Self-consistent equations including exchange and correlation effects [J]. Physical Reviews, 1965, 140: A1133-A1138.
    [22] A. D. Becke. Density-functional thermochemistry.iii.the role of exact exchange [J]. Journal of Chemical Physics, 1993, 98(7): 5648-5652.
    [23] C. Lee, W. T. Yang, R. G. Parr. Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density [J]. Physical Review, 1988, 37(2): 785-789.
    [24] M. J. Frisch, G. W. Trucks, H. B. Schlegel et al, Gaussian 03, Revision C.02, Gaussian, Inc., Wallingford CT, 2004.
    [25] X. H. Chen. Introduction to Gaussian 03 Package [M]. Chemistry Department, New York Univer- sity. January, 2006.
    [26]邹玉秋.维生素A的功能及应用[J] .养殖技术顾问, 2009, 3.
    [27]孙定人,张石革.维生素A (视黄醇)缺乏症(夜盲症)与补充维生素A[C].中国药房, 2003, 14(10).
    [28]谢岩黎,周惠明.维生素A抗氧化作用研究进展[J].粮食与油脂, 2006, 3.
    [29] G. Fatih, H. Hicran. Renal deterioration caused by carcinogens as a consequence of free radical mediated tissue damage: a review of the protective action of melatonin [J]. Arch Toxicol, 2007, 81 (10): 675-681.
    [30]李桂星,杨振宇.类维生素A研究进展[J].国外医学临床生物化学与检验学分册2004, 3 25 (2):152-154.
    [31] A. Palacios, V. A. Piergiacomi, A. Catala. Vitamin A supplementation inhabits chemilumine scence and lipid peroxidation in isolatedrat liver microsomes and mitochondria [J]. Mol Cell Bioch, 1996, 154:77-81.
    [32]吕庆章,卢雁,王键吉.铁卟琳和氯化四苯基铁卟琳的密度泛函量子化学计算研究[J].计算机与应用化学, 2005, 22(10): 33-38.
    [33] Aynur BSNE. Determination of in vitro antidiabetice effects. Antioxidant activities and phenol contents of some herbal teas. Plant Foods Hum Nutr, 2008, 63:27-33.
    [34]张跃华,张曙光,雷武,夏明珠,王风.云蔡类衍生物荧光发射光谱的密度泛函理论研究[J].计算机与应用化学, 2005, 22(10): 33-38.
    [35] D C.Yong. Computational Chemistry, A practical guide for applying techniques to real world problems [M]. New York: John Wiley &Sons, Inc, Publication, 2001: 32~41.
    [36]王维国.原子轨道与分子轨道[M ] .北京:高等教育出版社, 1986, 417~424.
    [37]林梦海.量子化学计算方法与应用[M].北京:科学出版社, 2004, 116-153.
    [38]福井谦一.化学反应与电子轨道[M].北京:科学出版社, 1985: 96-100.
    [39] B. Delley. Analytic energy derivatives in the numerical local-density—functional approach [J]. J Chem Phys, 1991, 94: 7245-7253.
    [40]杨颇,高孝恢.性能一结构一化学键[M].北京:高等教育出版社, 1987.
    [41] W. G. Richards. Quantum pharmacology [M]. New York: Butterworth& Co Ltd, 1983: 48-52.
    [42] Ei Agamey. Ali, Lowe. GM. Carotenoid radical chemistry and antioxidant/pro-oxidant proerties. Archives of Biochemistry and Biophysics, 2004, 430(1): 37-48.
    [43] S. H. Lee, D. B. Min. Effects, quenching mechanisms and kinetics of carotenoids in chlorophyl1 -sensitised photooxidation of soybean oil [J]. J Agric Food Chem, 1990, 38(8): 1630-1634.
    [44]惠伯棣.类胡萝卜素化学及生物化学[M].北京:中国轻工业出版社, 2003.
    [45] F. J. Pashkow, D. G. Watumull, C. L. Campbell. Astaxanthin: a novel potential treatment for oxidative stress and inflammation in cardiovascular disease [J]. Am. J Cardiol, 2008, 101(10): 58–68.
    [46] B. S. Kamath., B. M. Srikanta, S. M. Dharmesh, R. Sarada, et al. Ulcer preventive and antioxidative properties of astaxanthin from Haematococcus pluvialis [J]. Eur. J. Pharmacol, 2008, 590 (1–3):387–395.
    [47] G. Hussein, H. Goto, S. Oda, et al. Antihypertensive potential and mechanism of action of astaxanthin: III. Antioxidant and histopathological effects in spontaneously hypertensive rats[J]. Biol. Pharm. Bull, 2006, 29(4): 684–688.
    [48]徐泽枫,吕斯濠,范洪波.玉米中类胡萝卜素的研究进展.广东化工, 2009, 36(3): 119-121.
    [49]郭志有,高翠玲,宋儒等.叶黄素的功能及应用.河北农业科学, 2010, 14(2): 52-53.
    [50] H Y.Zhang. Theoretical methods used in elucidating activity differences of phenolic antioxidants [J]. J Am Oil Chem Soc, 1999, 76:745-748.
    [51] H Y.Zhang, Y M.Sun, X L.Wang. Substituent effects on O—H bond dissociation enthalpies and ionization potentials of catechols: a DFT study and its implications in rational design of phenolic antioxidants and elucidation of structure activity relationships for flavonoid antioxidants[J] . Chem-Eur J, 2003, 9:502-508.
    [52]陈凯先,蒋华良,嵇汝运.计算机辅助药物设计—原理、方法及应用[M].上海:科技出版社,2000.
    [53]张红雨,陈德展.表征O—H解离能参数的AMI计算[J ] .有机化学,2001 ,21 (1) :66-70.
    [54]周公度,段连运.结构化学基础[M].北京:高等教育出版社, 2008.
    [55]潘道皑,赵成大,郑载兴.物质结构[M].北京:高等教育出版社, 1989.
    [56]范晓岚,杨军,糜漫天,杨慧.β-胡萝卜素的抗氧化作用与疾病[J].预防中国公共卫生, 2003, 19(4): 479-480.
    [57]孙震,姚惠源.叶黄素,玉米黄素分子结构修饰对抑制肿瘤细胞增殖活性的影响[J].食品科学, 2007, 28(4): 296-301.
    [58] Woodall AlanA, Britton George, Jackson MalcolmJ. Carotenoids and protection of phospholipids in solution or in liposomes against oxidation by peroxyl radicals: Relationship between carotenoid structure and protective ability. Biochimica Biophysica Acta, 1997, 1336(3): 575-586.
    [59] A. Bendich. The antioxidant role of vitamine [J]. Cadv Free Biol Med, 1986, 8(2): 419-419.
    [60]翟惠敏,李亚洁.氧自由基对脑损伤的作用和维生素的防护作用[J].南方护理学报, 2001, 8(1): 18-18.
    [61] Z. Daide, H. Chenshi, Y. Feng. Tea polyphenols and querce—tin preventing the heart, brain and liver from the injury by freeradicals in comparison with ascorbic acid [J]. Chin J Nat Med, 2004, 2(4):223-233.
    [62]杜毅,孙传花.维生素C的临床应用进展[J].中华实用中西医杂志, 2005, 18(16): 749-749.
    [63]刘珊,孙贵范,宛超等.维生素C对香烟烟雾的氧化应激作用的影响[J].中国公共卫生, 2004, 20(8): 938-938.
    [64]马文涛.维生素C对应激大鼠脑内超氧化物歧化酶含量的影响[J].中国心理卫生杂志, 2002, 16(12): 809-809.
    [65]陆洋,杨波涛,陈凤香.五种天然抗氧化剂Rancimat法对食用油的抗氧化效果评析[J].食品工业, 2009, 5(3): 4-4.
    [66]阿吉姑·阿布都热西提,买尔旦·马合木提,马合木提·乌斯满等.维生素C清除自由基能力3种检测方法的比较[J].新疆医科大学学报, 2008, 31(5): 578-579.
    [67] David C.Young.Computational Chemistry [M]. John Wiley & Sons, New York, 2001.
    [68] SABE Van Acker,LMH Koymans,A Bast.Molecular pharmacology of vitamin E:structural aspects of antioxidant activity[J].Free Rad Biological Medicine,1993,15(2):311-328.
    [69]雷英杰,陈宝泉,丁玫.生物活性物质大豆苷元的量子化学研究[J].天津化工, 2006, 20(5): 22-23.
    [70]邓琴英,刘岚,邓慧敏.波谱分析教程.科学出版社[M].北京: 2003.
    [71] M. Plazane, N. Fukshima. The Virational Spectrum ofCrystalline Benzoic Caid:Lnelaslic Neutron Scatteringand Density Functional Theory calcu1ations[J]. Journal of Chemical Physics, 2001, 115(7): 32-41.
    [72] M. Joost, M. A. Bakker. The Infrared Absorpotion Spectrum of The gas Phase Neutralbenzoic Acid M onom erand Dimmerl, [J]. Journal of Chemical Physics, 2003, 119(21): l1-l8.
    [73] M. R. Johnson, H. P. Trommsd. Dispersion of Vibrational Modes in Benzoic Acid Crystals [J]. Chemical Physics Letters, 2002, 364: 34-38.
    [74]杜冬梅,付爱萍,周正宇,等.丙酮酸分子结构与振动光谱的密度泛函理论研究[J].化学物理学报, 2000, 13(4): 442-448.
    [75]杜冬梅,付爱萍,陈起凤,等.甲醚的分子结构及振动光谱的理论研究[J].曲阜师范大学学报, 2002, 28(3): 73-76.
    [76]肖继军,张骥,杨栋,等.杂环硝胺结构和性能的DFT比较研究[J].化学学报, 2002, 60(12): 2110-2114.
    [77]周梅,正确补充维生素C[J].杭州食品科技, 2007, 87(4): 31-31.
    [78]贾君. 5种水果中维生素C含量的测定研究[J].冷饮与速冻食品工业, 2004. 6: 33-34.
    [79]贝拉米. LJ.复杂分子的红外光谱[M].北京:科学出版社, 1975.
    [80]国家药典委员会编.药品红外光谱集[M].第一卷.北京:化学工业出版社, 1995: 159.
    [81]陈立军.抗坏血酸氧化还原反应的红外光谱分析[J].重庆师范学院学报, 2000: 17(1): 40-442.
    [82]王勇健.当心维生素变毒药.家庭医学,2007,9(4):42-45.

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