Metabolomics study of Danggui Buxue Tang on treatment of type 2 diabetes mice using UHPLC-Q-TOF-MS / 中国中药杂志

In this paper, ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry(UHPLC-Q-TOF-MS)-based metabolomics approach was used to explore the mechanism of Danggui Buxue Tang(DBT) in treating type 2 diabetes mellitus(T2 DM). T2 DM mice model was induced by high-sugar and high-fat fodder and streptozotocin(STZ). The routine indexes such as body weight, blood glucose, plasma insulin, IL-6 and related organ indexes were determined. The UHPLC-Q-TOF-MS technique was used to analyze the metabolism profile of serum samples between the control group and model group, and multiple statistical analysis methods including principal component analysis(PCA) and orthogonal partial least squares discriminant analysis(OPLS-DA) were used to screen and identify biomarkers. Metabolic profiling revealed 16 metabolites as the most potential biomarkers distinguishing mice in model group from those in control group. The metabolomics pathway analysis(MetPA) was used to investigate the underlying metabolic pathways. Seven major metabolic pathways such the valine, leucine and isoleucine biosynthesis, glycerophospholipid metabolism, primary bile acid biosynthesis, taurine and hypotaurine metabolism, phenylalanine metabolism, fatty acid metabolism and biosynthesis of unsaturated fatty acid. Eleven metabolites such as taurocholic acid and palmitic acid were down-regulated in T2 DM mice, and five metabolites such as L-leucine and leukotriene E4 were up-regulated. Moreover, the sixteen biomar-kers of each administration group had a trend of returning to mice in control group. The significantly-altered metabolite levels indicated that DBT can improve the progression of type 2 diabetes by increasing insulin sensitivity, regulating sugar and lipid metabolism disorders, and relieving inflammation.

A Medipix quantum area detector allows rotation electron diffraction data collection from submicrometre three-dimensional protein crystals.

When protein crystals are submicrometre-sized, X-ray radiation damage precludes conventional diffraction data collection. For crystals that are of the order of 100 nm in size, at best only single-shot diffraction patterns can be collected and rotation data collection has not been possible, irrespective of the diffraction technique used. Here, it is shown that at a very low electron dose (at most 0.1 e(-) Å(-2)), a Medipix2 quantum area detector is sufficiently sensitive to allow the collection of a 30-frame rotation series of 200 keV electron-diffraction data from a single ∼100 nm thick protein crystal. A highly parallel 200 keV electron beam (λ = 0.025 Å) allowed observation of the curvature of the Ewald sphere at low resolution, indicating a combined mosaic spread/beam divergence of at most 0.4°. This result shows that volumes of crystal with low mosaicity can be pinpointed in electron diffraction. It is also shown that strategies and data-analysis software (MOSFLM and SCALA) from X-ray protein crystallography can be used in principle for analysing electron-diffraction data from three-dimensional nanocrystals of proteins.

Imaging protein three-dimensional nanocrystals with cryo-EM.

Flash-cooled three-dimensional crystals of the small protein lysozyme with a thickness of the order of 100 nm were imaged by 300 kV cryo-EM on a Falcon direct electron detector. The images were taken close to focus and to the eye appeared devoid of contrast. Fourier transforms of the images revealed the reciprocal lattice up to 3 Å resolution in favourable cases and up to 4 Å resolution for about half the crystals. The reciprocal-lattice spots showed structure, indicating that the ordering of the crystals was not uniform. Data processing revealed details at higher than 2 Å resolution and indicated the presence of multiple mosaic blocks within the crystal which could be separately processed. The prospects for full three-dimensional structure determination by electron imaging of protein three-dimensional nanocrystals are discussed.

Characterization of structure-antioxidant activity relationship of peptides in free radical systems using QSAR models: key sequence positions and their amino acid properties.

Antioxidative peptides have attracted increasing attention from researchers because of their antioxidant properties as natural materials in functional food and for applications in medicine. However, the relationship between structure and activity (SAR) remains unclear, especially in antioxidative peptides in free radical systems. Antioxidative peptides with different lengths were obtained from the literature, measured using different methods, and were organized into three databases, namely, Trolox-equivalent antioxidant capacity (TEAC), oxygen radical absorption capacity (ORAC), and superoxide radical (SOR). After the peptides were processed using the two-terminal position numbering method, quantitative SAR modeling was performed on antioxidative peptides in the three databases. The vectors of hydrophobic, steric, and electronic properties (VHSE) and the divided physicochemical property scores descriptors (DPPS) were selected from 17 physicochemical descriptors to express electronic, hydrophobic, and steric properties (or hydrogen bonding) of the three (or four) external amino acids in the N-terminal and C-terminal positions. Models were estimated using partial least squares regression and validated through full cross-validation and external validation (R(2)>0.7, Q(2)>0.5 for TEAC; R(2)>0.9, Q(2)>0.5 for ORAC and SOR). The results found a relationship between the physicochemical properties of the C-terminal and N-terminal regions and antioxidant potency. The properties of amino acids at C-terminal regions were more important than those at the N-terminal regions for predicting antioxidant activity. The properties of amino acids at C(2)>C(1) for TEAC, C(3)>C(4)>C(1) for ORAC, and C(4)>C(1)>N(1) for SOR were highly correlated with antioxidant activity. Although electronic property most significantly contributed to antioxidant activity in the three free radical systems, it had complex effects at each position. Bulky hydrophobic amino acids at the C-terminal were related to the antioxidant activity of peptides in the three free radical systems. For peptides in the TEAC database, the relationship between the N-terminal segment (N(2), N(3)) and the activity increased when longer peptides were included, which reflects the likely influence of stericity. This study contributes to the ongoing research on antioxidants in food and its application in medicine.

Structure-activity relationship study of antioxidative peptides by QSAR modeling: the amino acid next to C-terminus affects the activity.

Screening, isolation and in vitro assays have been used for characterization of antioxidative peptides derived from food proteins, and incompatible deductions of structural characteristics derived from the isolated peptides have been brought forward. However, there is still little information concerning the structure-activity relationship of antioxidative peptides. QSAR modeling was performed, respectively, on synthetic tripeptides and tetrapeptides related to LLPHH. According to cumulative squared multiple correlation coefficients (R(2)), cumulative cross-validation coefficients (Q(2)) and relative standard deviation for calibration set (RSD(c)), two credible models for tripeptide and tetrapeptide databases, respectively, have been built with partial least squares (PLS) regression (R(2) for models of tripeptide and tetrapeptide are 0.744 and 0.943, Q(2) are 0.631 and 0.414, and RSD(c) are 0.323 and 0.111, respectively). Meanwhile, according to the cumulative multiple correlation coefficient for the predictive set (R2(ext)) and the relative standard deviation for the predictive set (RSD(p)), the predictive ability of the model for tripeptides also is excellent (R2(ext)) and RSD(p) are 0.719 and 0.450, respectively). Hydrogen bond property and hydrophilicity of the amino acid residue next to the C-terminus, and the hydrophobicity as well as electronic propertyof the N-terminus are more significant; meanwhile, the electronic property of the C-terminus is beneficial for antioxidant activity. The structural characteristics we found are very useful in understanding and predicting the peptide structures responsible for activity and development of functional foods with peptides as active compounds, or antioxidative peptides as alternatives to other antioxidants.

Alkaloid and sesquiterpenes from the root tuber of Curcuma longa / 药学学报

One new quinoline alkaloid and seven known bisabolane sesquiterpenes: 2-(2'-methyl-1'-propenyl)-4, 6-dimethyl-7-hydroxyquinoline (1), 2, 5-dihydroxybisabola-3, 10-diene (2), 4, 5-dihydroxybisabola-2,10-diene (3), turmeronol A (4), bisacurone (5), bisacurone A (6), bisacurone B (7) , bisacurone C (8), as well as dehydrozingerone (9) and zingerone (10) were isolated from the root tuber of Curcuma longa. Their structures were identified by spectral evidence. Compound 1 is a new compound, compounds 6 -8 were isolated from this plant for the first time and compounds 9 - 10 from Curcuma for the first time.