H. Li,D. Zhang,L.-H. Tan,B. Yu,S.-P. Zhao,W.-G. Cao
In this study, Dipsacus asperoides was separately extracted in three solvents (water, methanol and acetone), and the antioxidant activities of each extract were investigated through assays of DPPH, ABTS, β-carotene/linoleic acid system and reducing power. The total phenolic acids, flavonoids and saponins in each solvent extract were calculated for a correlation analysis. The phenolic compounds in the extracts were identified by LC-ESI-QTOF-MS–MS. The results showed that the three extracts exhibited antioxidant effects in a concentration-dependent manner, and the water extracts exerted the highest antioxidant activity effect followed by the methanol and acetone extracts. The correlation analysis indicated that the total phenolic components presented the greatest contribution to the antioxidant activities. Fifteen main phenolic compounds were identified in the water extracts, and three of these compounds had not been previously identified in D. asperoides . The results suggest that water extraction of D. asperoides is a promising source of natural antioxidants.
Lulu He,Jianqin Qian,Peixi Zhu,Weifeng Yang,Yuanbin She
A simple and sensitive method was developed for separation and characterization of seventeen impurities from commercial latamoxef sodium for injection by liquid chromatography combined with electrospray ionization and QTOF mass spectrometer (LC-ESI-QTOF MS). The chromatographic separation was performed on a Boston Green ODS-AQ C18 column (250 mm × 4.6 mm, 5 μm) under gradient mode using binary mobile phase: (A) ammonium acetate (10 mM)-methanol (99:1, v/v) and (B) ammonium acetate (10 mM)-methanol (70:30, v/v). Based on tandem multistage MS and high resolution MS data, the molecular formulas and structures of unknown impurities were inferred. A plausible formation mechanism of impurities was also proposed. In addition, the fragmentation regularity of degraded impurities in positive-ion mode was summarized.
We aimed to identify antibacterial peptides from Maillard reaction products of half-fin anchovy hydrolysates/glucose. Seven peptides from the active fraction of P3-2 derived from DEAE-Sepharose™ CL-6B chromatography and PL aquagel-OH 30 on HPLC system were identified by liquid chromatography-electrospray ionization/multi-stage mass spectrometry, and five peptides were selected for further synthesis on the basis of peptide sequences. The anionic peptide FFTQATDLLSR adopted an α-helical structure, as predicted by Network Protein Sequence @ analysis and helical wheel projection, and further determined using circular dichroism assay. The cationic peptide WLPVVR exhibited stronger inhibition effects against Escherichia coli than other peptides at similar concentration. Furthermore, differential sizes of hydrodynamic diameters of anionic 1,2-dimyristoyl-sn-glycero-3-phosphocholine liposome vesicles treated with peptides were observed, suggesting the clustering and decomposition of peptide on liposome vesicles. To the best of our knowledge, this is the first study that reports antibacterial peptides derived from the MRPs of half-fin anchovy hydrolysates.
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