New isolates from leaves of Nicotiana tabacum and their biological activities.

Three new isolates (1-3) including one new sterol and two new flavonoids together with three known sterols (4-6) were isolated from the leaves of Nicotiana tabacum. Their structures were determined mainly by spectroscopic methods, including extensive 1D and 2D NMR techniques. All compounds were evaluated for their anti-tobacco mosaic virus and cytotoxic activities. The results showed that compounds 2 and 3 exhibited high anti-TMV activity with inhibition rate of 34.2 and 33.4%, respectively, which were roughly equivalent to that of positive control. The cytotoxicities of compounds 1 and 4-6 against five human tumour cell lines were also tested, and tested compounds showed weak inhibitory activities against some tested human tumour cell lines.

Rapid simultaneous determination of major isoflavones of Pueraria lobata and discriminative analysis of its geographical origins by principal component analysis.

INTRODUCTION: Isoflavones are main bioactive components of Pueraria lobata (Willd.) Ohwi. Puerarin has been used as the marker compound in herb quality evaluation in the Chinese Pharmacopoiea. However, it is also important to include the other isoflavones present in the herb, such as daidzin, daidzein, genistin and genistein, in the evaluation as they also contribute to the overall bioactivity of the herb. OBJECTIVE: To develop a rapid and reliable method for simultaneous quantitation of isoflavones for P. lobata herb quality evluation. METHODOLOGY: The chromatographic separation was performed on an Agilent rapid resolution liquid chromatographic system through gradient elution. The developed method for the quantification of puerarin, daidzin, daidzein, genistin and genistein was fully validated. When it was applied to analyse the extracts of P. lobata, baseline separation was obtained within 10 min. RESULTS: The amounts of puerarin, daidzin, daidzein and genistin varied greatly among the samples although their chromatographic fingerprints were similar to each other. The 19 samples studied were classified into three clusters (I-III) by principal component analysis based on the amounts of puerarin, daidzin, daidzein and genistin. CONCLUSION: The classification result can be related to herbal origins, but the classification outcome from the chromatographic fingerprinting similarity approach did not provide any geographical origin information. This shows that bioactive constituents can reflect the intrinsic quality of P. lobata more accurately.

Fingerprinting alterations of secondary metabolites of tangerine peels during growth by HPLC-DAD and chemometric methods.

Tangerine peels are herbal materials of two coupled traditional Chinese medicines, Pericarpium Citri Reticulatae (PCR) and Pericarpium Citri Reticulatae Viride (PCRV). In this paper, high-performance liquid chromatographic fingerprints of tangerine peels during growth were firstly measured for deliberately collected 34 samples from three species (Citrus reticulata 'Chachi', Citrus reticulata 'Dahongpao' and Citrus erythrosa Tanaka). After sixteen characteristic components which have similar change trends in the grown process were screened out with the help of heuristic evolving latent projection (HELP) method, score plots of principal component analysis (PCA) successfully presented the grown footprints of tangerine peels. It implied that July might be the best harvest time for PCRV, November and December were better for PCR. Furthermore, hesperidin, nobiletin and tangeretin were screened as chemical markers by loadings of PCA. The HPLC-HELP-PCA strategy has shown its potential in optimization of harvest time and chemical markers' screening, which will have wide perspective in the analysis of "coupled TCMs".

The analysis of Radix Angelicae Sinensis (Danggui).

Radix Angelicae Sinensis, known as Danggui in China, is one of the most popular traditional Chinese medicines (TCMs), which is contained by more than 80 composite formulae. Modern researches indicate that phthalides, organic acids and their esters, polysaccharides are main chemical components related to the bioactivities and pharmacological properties of Danggui. Some of them, such as Z-ligustilide and ferulic acid, are selected as marker compounds to evaluate the quality of Danggui frequently. Because of the diversity of chemical structures and characters of these components, analytical methods of Danggui are various, including GC-MS, HPLC-DAD-MS, TLC, CE-DAD, and so on. Besides that, the development of analytical technology makes the quality control of Danggui more effective and reliable. Quality evaluation is from single or several components' analysis to fingerprinting, or in combination. Furthermore, bioactive components screening of Danggui has also attracted much attention, which will help us evaluate the selected marker components to some extent. In this paper, the literatures about the major phytoconstituents of Danggui, quality control and bioactive components screening methods have been reviewed. Main attention is given to the different methodologies developed to perform chemical analysis, including separation, detection and identification.

Calibration model transfer for near-infrared spectra based on canonical correlation analysis.

In order to solve the calibration transformation problem in near-infrared (NIR) spectroscopy, a method based on canonical correlation analysis (CCA) for calibration model transfer is developed in this work. Two real NIR data sets were tested. A comparative study between the proposed method and piecewise direct standardization (PDS) was conducted. It is shown that the transfer results obtained with the proposed method based on CCA were better than those obtained by PDS when the subset had sufficient samples.

Comparative analysis of essential oil components in Pericarpium Citri Reticulatae Viride and Pericarpium Citri Reticulatae by GC-MS combined with chemometric resolution method.

The similarities and differences of essential oil components in Pericarpium Citri Reticulatae Viride (PCRV) and Pericarpium Citri Reticulatae (PCR) were investigated by GC-MS combined with a chemometric method, named alternative moving window factor analysis (AMWFA). Furthermore, temperature-programmed retention indices (PTRIs) were used together with mass spectra for identification of the essential oil components. A total of 61 and 59 compounds in the essential oils of PCRV and PCR from three Citrus species were identified, which represented 98.15-99.66% and 97.6-99.84% of their total relative contents, respectively. The essential oils from PCRV and PCR significantly differed both qualitatively and quantitatively. The main compound in the essential oils from PCRV and PCR was d-limonene accounting for 65.61-83.14%. The comparative analysis indicates that AMWFA greatly enhanced the accuracy of quantitative and qualitative results by utilizing information from chromatography and mass spectra. The results obtained may be helpful to find out the possibly bioactive compounds of PCRV and PCR.

Simultaneously quantitative measurement of comprehensive profiles of esterified and non-esterified fatty acid in plasma of type 2 diabetic patients.

Fatty acids, having intimate relationship with type 2 diabetes mellitus (DM2), are not only the main energy source as nutrients, but also signaling molecules in insulin secretion. In this work, we developed a two-step rapid method to comprehensive profiling of esterified fatty acid (EFA) and non-esterified fatty acid (NEFA) using KOH-CH3OH to methylate EFA followed by H2SO4-CH3OH to methylate NEFA. Its applications to fatty acids profiling of type 2 diabetic patients and health controls were also presented. The t-test results informed that 16 NEFAs and 7 EFAs had distinct differences between type 2 diabetes and health controls. Furthermore, quantitative alterations of fatty acids in plasma of type 2 diabetic patients treated with rosiglitazone were obtained by this method. Our research results indicated that the dynamic changes of NEFAs are various. Some decreased linearly, such as C18:0, C18:3n-6 and C22:6, and some changed nonlinearly, such as C18:3n-3 and C22:4. All results informed that fatty acid profiles could provide comprehensive and accurate information for not only discrimination between DM2 patients and health controls, but also evaluation alterations of fatty acids during therapeutic process.

Quality control and discrimination of pericarpium citri reticulatae and pericarpium citri reticulatae viride based on high-performance liquid chromatographic fingerprints and multivariate statistical analysis.

High-performance liquid chromatographic (HPLC) fingerprints of pericarpium citri reticulatae (PCR) and pericarpium citri reticulatae viride (PCRV) were firstly measured for deliberately collected 39 authentic samples and 21 commercial samples. Both correlation coefficients of similarity for chromatograms and absolute peak areas of characteristic compounds were calculated for quantitative expression of the HPLC fingerprints. After principal component analysis (PCA) successfully distinguished the 'mixed peels' samples from authentic samples, partial least squares-linear discrimination analysis (PLS-LDA) was then effectively applied to class separation between authentic PCR and PCRV. Furthermore, the unequivocally determined compounds, hesperidin, nobiletin and tangeretin, were screened out by loadings plots of PCA and PLS-LDA. The results indicated that they could be used as chemical markers for discrimination among different groups of samples. The proposed method shows an efficient strategy for quality control of PCR and PCRV, which cannot only distinguish the 'mixed peels' but also discriminate authentic PCR and PCRV. This method has potential perspective for quality control of traditional Chinese medicine (TCM).

Conversion of programmed-temperature retention indices from one set of conditions to another.

In order to make programmed-temperature retention index (PTRI) data be shared by other chromatographers and laboratories, conversion of PTRI from one set of experimental conditions to another is investigated in detail in this work. It was found that the differences between the PTRIs at different heating rates are structurally dependent, especially the number of ring in molecules. Thus, with the help of molecule constitutional descriptors, equations of PTRI conversion to certain initial temperature, heating rate, and stationary phase were obtained with high correlation coefficients and low standard deviations. Calculation errors of PTRI conversion between different heating rates and between different initial temperatures were from 1.1 to 2.9 retention index units (i.u.), which is in the same order with experiment errors. It is well known that reproducibility of PTRI on a polar column is not as good as that on an apolar column because of the apolarity of the n-alkane homologues. Thus, topological descriptors were used for PTRI conversion between two columns with different polar stationary phases, giving better results than those obtained by constitutional descriptors. This shows that topological descriptors could provide more molecular structural information than constitutional descriptors. However, as constitutional descriptor has the advantages of clear physical meaning and very simple calculation, it is our first selection when the PTRI calculation accuracy is satisfied. The method developed is simple in calculation, easy to be performed with high accuracy.

Plasma fatty acid metabolic profiling and biomarkers of type 2 diabetes mellitus based on GC/MS and PLS-LDA.

Metabolic profiling has increasingly been used as a probe in disease diagnosis and pharmacological analysis. Herein, plasma fatty acid metabolic profiling including non-esterified fatty acid (NEFA) and esterified fatty acid (EFA) was investigated using gas chromatography/mass spectrometry (GC/MS) followed by multivariate statistical analysis. Partial least squares-linear discrimination analysis (PLS-LDA) model was established and validated to pattern discrimination between type 2 diabetic mellitus (DM-2) patients and health controls, and to extract novel biomarker information. Furthermore, the PLS-LDA model visually represented the alterations of NEFA metabolic profiles of diabetic patients with abdominal obesity in the treated process with rosiglitazone. The GC/MS-PLS-LDA analysis allowed comprehensive detection of plasma fatty acid, enabling fatty acid metabolic characterization of DM-2 patients, which included biomarkers different from health controls and dynamic change of NEFA profiles of patients after treated with medicine. This method might be a complement or an alternative to pathogenesis and pharmacodynamics research.