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Lin AC, Salpietro SJ, Deretey E, Csizmadia IG. Multidimensional conformational analysis of allyl methyl disulfide: a key component of garlic. CAN J CHEM 2000. [DOI: 10.1139/v00-020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Organosulfur compounds in garlic, like allyl methyl disulfide, have been found to be involved in antimutagenic, anticarcinogenic, antithrombotic, and lipid-lowering activities, and it has also been found to act as an antioxidant. Ab initio molecular computations were performed on dihydrogen disulfide (1) with respect to torsional angle τ1 = τ(H·S-S·H), hydrogen methyl disulfide (2) with respect to torsional angle τ1 = τ(H·S-S·CH3), and allyl methyl disulfide (3) with respect to torsional angles τ1 = τ(H3C2·CH2·S-S·CH3), τ2 = τ(H3C2·CH2-S·S·CH3), and τ3 = τ(H3C2-CH2·S·S·CH3). Potential energy curves (PEC) were obtained from 1 and 2, i.e., E = E(τ1), from which optimized structures were obtained at the HF/6-31G* level of theory. These optimized structures were used to investigate the potential energy hypersurface surface (PEHS) of 3, i.e., E = E(τ1,τ2,τ3). One-dimensional scans along τ2 and τ3 (where τ1 = ±90°; τ1 = 180°) were performed at the HF/3-21G* level of theory. From these scans, six lower energy pairs of enantiomeric minima (i.e., [g+g+g+| g-g-g-], [g+ag- | g-ag+], [g+g-g+ | g-g+g-], [g+g+g-| g-g-g+], [g+ag- | g-ag+], and [g+g-g-| g-g+g+]) as well as 3 higher energy minima (i.e., [g+g+s | g-g-s], [g+as | g-as], and [g+g-s | g-g+s]) were optimized at τ1 = ±90° at the HF/6-31G* and B3LYP/6-31G* levels of theory. The global minimum was determined to be the [g+g-g+ | g-g+g-] enantiomeric pair of conformers, and the fully symmetrical anti-anti-anti [a a a] structure was determined to be a second-order saddle point on the PEHS of 3. Although there are no stereocentres in 3, there is chirality in the conformational twist with respect to the [a a a] conformation through τ1 = τ2 = τ3 = 180°. Based on the energies and MO diagrams of the HUMO and LUMO +1 of 3, the anticarcinogenic and cholesterol lowering activity mechanism of 3 is presented.Key words: ab initio MO computations, allyl methyl disulfide, multidimensional conformational analysis (MDCA), anticarcinogenic, cholesterol lowering.
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Brown I, Davies D. Vicinal fluorine nuclear coupling constants in fluoroethanes: self-consistent perturbation theory calculations. Chem Phys Lett 1972. [DOI: 10.1016/0009-2614(72)80213-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Cavalli L. The NMR spectra and rotational isomerism of some 1,2-disuhstituted-tetrafluoroethanes. ACTA ACUST UNITED AC 1972. [DOI: 10.1016/0022-2364(72)90103-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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