1H NMR determination of hypericin and pseudohypericin in complex natural mixtures by the use of strongly deshielded OH groups

Tatsis, Evangelos C.; Exarchou, Vassiliki; Troganis, Anastassios N.; Gerothanassis, Ioannis P.

doi:10.1016/j.aca.2007.11.040

Cited by 31 publications

(17 citation statements)

References 45 publications

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“…The quantity of the compounds was calculated from the relative ratio of the integral of these NMR peaks with an internal standard, and the results were comparable with other chromatographic methods of quantification [158]. Similarly for Hypericum perforatum, hypericin and its derivative pseudohypericin were efficiently quantified by 1 H-NMR with the specific detection of strongly de-shielded peri-hydroxyl protons of hypericins in the region of 14 -15 ppm in CD 3 OH solutions [159]. The high-throughput analysis of 80 phytopreparations of the same plant was also efficiently performed with a near-infrared spectroscopic method.…”

Section: Detection Without Hplc Separationmentioning

confidence: 64%

HPLC in Natural Product Analysis: The Detection Issue

2009

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High-performance liquid chromatography (HPLC) is a very powerful and versatile chromatographic technique for the separation of natural products (NPs) in complex matrices, such as crude extracts for selective detection and quantification or general profiling. The method is widespread and has been adapted to the analysis of a broad range of NPs generally without the need for complex sample preparation. The choice of the appropriate detection method in HPLC is crucial because of the diversity of NPs and the fact that there is no single technique for their efficient detection. In this review both qualitative and quantitative applications of HPLC with UV, DAD, FD, ECD, RID, FID, CL, ESLD, CAD, MS, MS-MS, and NMR are covered to provide a general, rather than an exhaustive, overview. The potential and limitations as well as some new trends in HPLC hyphenation are discusse

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Section: Detection Without Hplc Separationmentioning

confidence: 64%

HPLC in Natural Product Analysis: The Detection Issue

2009

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“…Analysis of plant extracts is an attractive research area which is based on time‐consuming and tedious chromatographic techniques and/or the use of dedicated hyphenated spectroscopic techniques . In the last few years, however, significant effort has been given to the development of NMR methodologies that can be successfully applied for the analysis of various constituents of complex plant extracts without any previous pre‐treatment, separation, and isolation of the individual components . Because of the complex nature of natural extracts, direct in situ NMR monitoring of dynamic changes in composition represents a significant challenge that has been rarely addressed in the current scientific literature.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3] In the last few years, however, significant effort has been given to the development of NMR methodologies that can be successfully applied for the analysis of various constituents of complex plant extracts without any previous pre-treatment, separation, and isolation of the individual components. [4][5][6][7][8][9][10][11][12][13][14] Because of the complex nature of natural extracts, direct in situ NMR monitoring of dynamic changes in composition represents a significant challenge that has been rarely addressed in the current scientific literature. As pointed out by Pauli et al, [15] stability studies, reaction mechanisms, and kinetic studies involving natural products are essentially lacking in the literature up to 2004 with only three publications [16] in the period of 2005-2011.…”

Section: Introductionmentioning

confidence: 99%

Dynamic changes in composition of extracts of natural products as monitored by in situ NMR

Charisiadis

Tsiafoulis

Tzakos

et al. 2014

Magnetic Reson in Chemistry

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The direct in situ NMR observation and quantification, based on the aldehyde -CH chemical shift region, of the inter-conversion of secoiridoid derivatives due to temperature and solvent effects is demonstrated in complex extracts of natural products without prior isolation of the individual components. The equilibrium between the aldehyde hydrate form and the dialdehyde form of the oleuropein aglycon of an olive leaf aqueous extract in D(2)O was shown to be temperature dependent. The resulting thermodynamic values of the Van't Hoff plot with ΔH(o) = -26.34 ± 1.00 kJ mol(-1) and TΔS° (298 K) = -24.70 ± 1.00 kJ mol(-1) demonstrate a significant entropy term which nearly compensates the effect of enthalpy at room temperature. The equilibrium between the two diastereomeric hemiacetal forms and the dialdehyde form of the oleuropein 6-O-β-d-glucopyranoside aglycon of an olive leaf aqueous extract in CD(3) OD was also shown to be strongly temperature dependent again because of the significant entropy term (TΔS° (298 K) = -26.50 ± 1.39 kJ mol(-1)) compared with that of the enthalpy term (ΔH(o) = -36.64 ± 1.46 kJ mol(-1)). This is the first demonstration of the significant role of the entropy parameter in determining the equilibrium of chemical transformations in complex mixtures of natural products due to solvent and temperature effects.

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“…With HPLC coupled to MS, there is no need to derivatize compounds prior to the analysis. HPLC separations are better suited for the analysis of non‐volatile polar and non‐polar compounds in their native form 40. LC/MS is also capable of analyzing large numbers of compounds that cannot be analyzed by GC/MS.…”

Section: Introductionmentioning

confidence: 99%

Ultra‐performance liquid chromatography coupled to mass spectrometry as a sensitive and powerful technology for metabolomic studies

Wang

Sun

Zhang

et al. 2011

J of Separation Science

136

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Metabolomics is the comprehensive assessment of endogenous metabolites of a biological system. These large-scale analyses of metabolites are intimately bound to advancements in ultra-performance liquid chromatography-electrospray (UPLC) technologies and have emerged in parallel with the development of novel mass analyzers and hyphenated techniques. Recently, the combination of UPLC with MS covers a number of polar metabolites, thus enlarging the number of detected analytes in the widely used separation sciences. This technology has rapidly been accepted by the analytical community and is being gradually applied to various fields such as metabolomics and traditional Chinese medicine (TCM). Given the power of the technology, metabolomics has become increasingly popular in drug development, molecular medicine, traditional medicine and other biotechnology fields, since it profiles directly the phenotype and changes thereof in contrast to other "-omics" technologies. Hyphenated UPLC/MS technique is becoming a useful tool in the study of body fluids, represents a promising hyphenated microseparation platform in metabolomics and has a strong potential to contribute to disease diagnosis. This review describes the applications of UPLC/MS in metabolomic research, and comparison role of HPLC/MS, NMR and GC/MS, highlights its advantages and limitations with certain characteristic examples in the life and TCM sciences.

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1H NMR determination of hypericin and pseudohypericin in complex natural mixtures by the use of strongly deshielded OH groups

Cited by 31 publications

References 45 publications

HPLC in Natural Product Analysis: The Detection Issue

HPLC in Natural Product Analysis: The Detection Issue

Dynamic changes in composition of extracts of natural products as monitored by in situ NMR

Ultra‐performance liquid chromatography coupled to mass spectrometry as a sensitive and powerful technology for metabolomic studies

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