Spectroscopic studies on distorted structure molecules by using U(2) Lie algebraic method

Resonance Raman spectra of oxygenated and deoxygenated functional erythrocytes are calculated by using Lie algebraic technique at 785 nm. The results are obtained by this method is accuracy with the experimental data. So, the algebraic techniques are appropriate to the Raman spectra of red blood cells.     

Structure Elucidation of Two Acetylated Derivatives of Oligomycin A

Partial acetylation of oligomycin A (1) resulted in the formation of 5,9, 33-tri-O-acetyl (2) and 5,9,13,33-tetraacetyl (3) derivatives whose structures have been established through complete assignments of their H and ¹³C NMR spectra. These derivatives were devoid of inhibitory activity when tested on Aspergillus niger spores.     

Water vapour line assignments in the 9250-26 000 cm frequency range

Line parameters for water vapour in natural abundance have recently been determined for the 9250-13 000 cm⁻¹ region [M.-F. Mérienne, A. Jenouvrier, C. Hermans, A.C. Vandaele, M. Carleer, C. Clerbaux, P.-F. Coheur, R. Colin, S. Fally, M. Bach, J. Quant. Spectrosc. Radiat. Transfer 82 (2003) 99] and the 13 000-26 000 cm⁻¹ region [P.-F. Coheur, S. Fally, M. Carleer, C. Clerbaux, R. Colin, A. Jenouvrier, M.-F. Mérienne, C. Hermans, A.C. Vandaele, J. Quant. Spectrosc. Radiat. Transfer 74 (2002) 493] using a high-resolution Fourier-transform spectrometer with a long-path absorption cell. These spectra are analysed using several techniques including variational line lists and assignments made. In total, over 15 000 lines were assigned to transitions involving more than 150 exited vibrational states of H₂¹⁶O. Twelve new vibrational band origins are determined and estimates for a further 16 are presented.     

Infrared emission spectrum of hot D2O

An emission spectrum of hot D₂O (1500 °C) has been analyzed in the 2077-4323 cm⁻¹ region. A considerable number of new vibration-rotation energy levels have been determined and two new vibrational levels identified. The new (0 4 1) and (0 2 2) vibrational levels have estimated band origins of 7343.93 ± 0.01 and 7826.38 ± 0.02 cm⁻¹, respectively.     

Total assignments of 1H and 13C NMR spectra of biflorin and bis‐biflorin from Capraria biflora

Bis‐biflorin, a new o‐naphthoquinone dimer, and biflorin, 6,9‐dimethyl‐3‐(4‐methyl‐3‐pentenyl)naphtho[1,8‐bc]‐pyran‐7,8‐dione, were isolated from roots of Capraria biflora, a medicinal plant from northeast Brazil. Structural elucidation was made on the basis of spectral data, mainly by high‐field NMR and high‐resolution mass spectrometry. Copyright © 2003 John Wiley & Sons, Ltd.     

Aqueous Capillary Electrophoresis of Peptides Part 2: An Investigation of Quantitative Determinants of Hydration and Solvation Relationships

Summary From the published electrophoretic data for a set of 58 peptides at pH 2.5 we have determined the excess hydration required to correct the deviations of the 31 higher-charged peptides from the Offord plot for the 27 singly-charged peptides. These values of the excess hydration were then used to test physical models by regression analysis. The dominant variable is the total excess positive charge, but the number of excess single positive charges and the number of pairs of positive charges – both at the end and internally – were significant determinants. The effect of acidic side chains was ambiguous throughout the analyses and this was presumed to arise from the ability of carboxy groups to be the sites of additional hydration or to diminish hydration via internal bonding with amino groups. A hydrophobicity index was included in he analysis, but surprisingly this too had little effect. In the last stage of the regressions, we also included coding for secondary structure within the peptides. This increased R² for the plots of the excess hydration versus values calculated from the regression constants (Y) from 0.95 to 0.97. Some solvation relationships were particularly good at modelling the hydration of the smaller, lesser-charged peptides, whilst others excelled in the opposite direction. The final model appeared to deal equally well with both extremes, but is not sufficiently sensitive to allow for all of the variations between peptides. As a result, the excess hydration was modelled very well for many of the peptides (±1–2 waters over the range of excess hydration form 5–276), but poorly for a few (± 100–200%). It was not possible to find another set of peptides that could be independently analysed in a similar fashion and compared. However, the regression constants were applied to an alternative set. Although appearing to fall in a generally reasonable range, various tests of the resultant calculated values indicated that this application was not valid. The second set of peptides were much more hydrophilic and the number of amino acid residues with an extended secondary structure appeared to be a contributing factor.     

1H and 13C NMR structure determination of a new stereoisomer of isoreserpiline pseudoindoxyl from Rauvolfia grandiflora

An NMR study of a new stereoisomer of isoreserpiline pseudoindoxyl alkaloid is described. The complete ¹H and ¹³C NMR assignments of the compound were carried out using COSY, HMQC and HMBC. Stereochemistry at carbons C‐2, C‐3, C‐15, C‐20 and C‐19 was established using values of ¹H chemical shifts, coupling constants and NOESY experiments. Copyright © 2003 John Wiley & Sons, Ltd.     

2D—HOHAHA和ROESY方法归属复杂天然有机化合物的NMR谱线

用同核化学位移相关谱及旋转坐标系中的同核化学位移相关谱和旋转坐标系中的同核NOE实验等新的二维核磁共振方法对首次从西洋参叶中分离出的Ocotillol型皂甙(OTS)的~1H化学位移进行了完全归属,为OTS分子溶液中的三维空间结构研究提供了可靠的结构参数.     

Structure elucidation and total assignment of 1H and 13C NMR data for a new bisdesmoside saponin from Cordia piauhiensis

Extensive 1D (¹H NMR, HBBD‐¹³C NMR, DEPT‐¹³C NMR) and 2D (COSY, TOCSY, NOESY, HMQC and HMBC) NMR analysis was used to characterize the structure of a new bisdesmoside saponin isolated from the methanol extract of stems of Cordia piauhiensis Fresen as 3β‐O‐[α‐L ‐rhamnopyranosyl‐(1 → 2)‐β‐D ‐glucopyranosyl]ursolic acid 28‐O‐[β‐D ‐glucopyranosyl‐(1 → 6)‐β‐D ‐glucopyranosyl] ester. Copyright © 2003 John Wiley & Sons, Ltd.     

尾叶远志中-酰基取代口山酮碳甙的结构

用２ＤＮＭＲ（１Ｈ－１ＨＣＯＳＹ，１Ｈ－１３ＣＣＯＳＹ，ＨＭＢＣ）技术研究了从尾叶远志中分离得到的一个苯甲酰基取代口山酮甙的结构，并对其碳氢信号进行了全归属．