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Silkworm silk protein fibroin is widely exploited to develop novel silk-based biomaterials due to its stable b-sheetstructure, providing high crystallinity and tensile strength. The polymorphic behaviour of silk fibroin provides awindow to modulate its structural transitions during self-assembly for different functional outcomes. Most studiesare therefore mainly focused on formation of well-developed b-sheet structure and self-assembly of silk fibroinwhich are regulated by many parameters. Glyoxal, a highly reactive a-oxoaldehyde, reacts with different proteinsto form advanced glycation end products (AGEs) following Maillard-like reaction. Considering the significanceof protein modification by glyoxal-derived AGEs, in the present study the effect of glyoxal (250, 500 and1000 lM) on the structure of silk fibroin has been investigated. CD and fluorescence studies reveal that higherconcentrations of the a-oxoaldehyde induce considerable alterations of secondary and tertiary structure of theprotein leading to aggregation following incubation with for 3 weeks. The aggregates exhibit fibrillar morphologywith amyloidal nature as evident from SEM, FTIR and XRD experiments. The findings highlight that glycationinduced modification can be a possible approach for modulating the conformation of the silk protein which may berelevant in connection to clinical, biomedical or synthetic biology based applications.
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Objective To establish a quality assessment method for Ermiao Pills (EP) based on HPLC fingerprint and qualitatively analyze the chemical constituents. Methods The chromatographic column Shiseido C18 (250 mm × 4.6 mm, 5 μm) was used, acetonitrile-0.1% formic acid as mobile phase with gradient elution at the flow rate of 1.0 mL/min, and the detection wavelength was 330 nm. The standard chromatographic fingerprint was synthesized from chromatogram of the mixed standard herbs of Phellodendron Rupr. and Atractylodes DC, and the similarity evaluation of Ermiao Pills samples was carried out by the Similarity Evaluation System for Chromatographic Fingerprints of TCM (Chinese Pharmacopoeia Commission, version 2012A). Ultra high-performance liquid chromatography coupled with linear ion trap-Orbitrap Elite mass spectrometer (UPLC-LTQ-Orbitrap) was used to characterize the chemical constituents of Ermiao Pills. A Thermo Scientific Syncronis C18 (100 mm × 2.1 mm, 1.9 μm) column and a gradient elution of acetonitrile-0.1% formic acid were used for UPLC separation. The combination of ESI-LTQ-Orbitrap mass analyzer with a linear ion trap was applied for high resolution mass spectrometry and collision-induced dissociation (CID). Results The chromatographic fingerprints were generated with 10 common peaks. The similarity scores of 20 samples between each material batch and the reference fingerprint ranged from 0.869-0.992. Twenty-one components were identified via referring to reference components and literatures and analyzing MS data, they were neo-chlorogenic acid, magnocurarine, xanthoplanine, magnoflorine, 3-O-feruloylquinic acid, menisperine, demethyleneberberine, oxyberberine, columbamine, jatrorrhizine, berberubine, palmatine, berberine, syringic acid, caffeic acid, (E)-4-(3-hydroxyprop-1-en1yl)-2-methoxyphenol, atractylenolide II, acetosyringone, atractylenolide I, selina-4(14), 7(11)-dien-8-one, and atractylodin. Conclusion The established method of fingerprint is specific, combined with LC-MS qualitative analysis, can be used for the quality evaluation of Ermiao Pills, giving support to quality control comprehensively.
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Objective: To determine the optimal concentration of hormone and hygromycin for seedling regeneration of Rehmannia glutinosa. Methods: Using the young leaf of sterile plantlet from R. glutinosa as explants, we conducted the transformation mediated by Agrobacterium tumefaciens, analyzed the efficiency of hygromycin and acetosyringone (AS) on resistant callus induction and plant regeneration. Results: The concentration of hygromycin had greatly affected the production of resistant callus and seedlings. The critical concentration of hygromycin on the resistant callus induction and shoot regeneration were 9 and 6 mg/L, respectively. The optimal concentration of hygromycin for the genetic transformation of Wen 85-5 was 12 mg/L. Adding 100 μmol/L AS could greatly improve the transformation efficiency of R. glutinosa. It was confirmed by PCR detection of hpt gene and GUS staining that the foreign gene was integrated into the genome of R. glutinosa. Conclusion: The stable genetic transformation system of R. glutinosa is established, which lays the foundations for the research on molecular pharmacognosy and genetic improvement.