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Objective: To achieve multiple target fishing hook by efficiently grafting polymers containing benzophenone (BP) groups and photochemically coupling molecules in medicines onto magnetic nanoparticles (MNPs). Methods: MNPs attached carbonyl groups (Fe3O4-COOH) were prepared through a hydrothermal process. Then they were modified with DMSA, forming MNPs with thiol groups (Fe3O4-SH). Fe3O4-SH nanoparticles were grafted with polymer containing BP groups by surface-initiated condensation polymerization. Effects of monomer feed ratios and contents on the amounts of BP groups were investigated. The molecules in medicines were covalently coupled onto MNPs via photochemical reactions of BP groups. The contents of coupled molecules were determined by FT-IR and UV-Vis spectra analyses. Results: MNPs with average size of 100 nm were produced, modified with DMSA, and decorated by grafting polymer containing photosensitive BP groups. When the content of monomer containing BP groups was increased in grafting polymerizations, more BP groups were incorporated onto MNPs. This was conductive to the subsequent photo- coupling. FT-IR and UV-Vis spectra analyses confirmed the coupling of molecules in medicines. The active H and steric hinderance of the molecules affected their coupling. Conclusion: The resultant magnetic target fishing hook is ready as a probe for targets identification of traditional Chinese medicine (TCM).
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OBJECTIVE: To establish an HPLC-MS/MS method to identify the unknown impurities in polymyxin B sulfate. METHODS: The analysis was performed on Agilent 1260-6550 Q/TOF-MS with a Diamonsil Plus C18 column(4.6 mm×250 mm, 5 μm). Mobile phase A was 0.01 mol•L-1 trifluoroacetic acid-acetonitrile(95:5), and mobile phase B was acetonitrile containing 0.1% formic acid. Mobile phase A and B were set at the volume ratio of 79:21 at a flow rate of 1 mL•min-1 under isocratic elution. The detection wavelength was set at 254 nm. ESI source was used. Positive ion scanning was conducted in the range of m/z 50-1 700 for MS and MS/MS. The unknown components were identified by comparing the MS and MS/MS with the known reference standards like polymyxin B1 and B2. The photochemical Paterno-Büchi reaction was performed using a low-pressure mercury lamp as the light source at emission wavelength of 254 nm with acetone/water(50/50, V/V) as the reaction solvent. RESULTS: The structures of seven unknown related substances in polymyxin B sulfate were identified. The most abundant impurity was identified to be vinyl polymyxin B1, for which the double bond was at the end of the fatty acyl residue. CONCLUSION: Vinyl polymyxin B1 is reported for the first time. The method provides a good idea for the identification of related substances in drugs.
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A method of identification of C=C location and relative quantitation of unsaturated phosphatidylcholine ( PC ) isomers in breast cells by online photochemical reaction-pulsed directed current electrospray-tandem mass spectrometry ( PB-pulsed-dc-ESI-MS/MS) was established with benzophenone ( BP) as a photochemical reactant. The three-phase extraction method was used to extract the lipids in the cells, and then the C=C in the unsaturated PC and the carbonyl in BP were specifically cycled under the irradiation of 254 nm ultraviolet light (Paternò-Büchi, PB reaction). The PB products were ionized and mass-isolated for low-energy collision dissociation through the non-contact pulsed-dc-ESI ionization method. The double bond position and the relative content of the location isomers were obtained from the resulting ions in the MS/MS spectrum. The C=C location of 8 kinds of unsaturated PCs in MCF-7 and MCF-10A was detected, and the relative contents of 4 kinds of C=C location isoforms were analyzed. It was found that the relative abundance of △9 isomer in PC 16:018:1 was not significantly different between the two cells. The relative abundance of△9 isomers in PC 18:018:1 and PC 18:118:1 was slightly different. However, there is a big difference of △9 in LPC 18:1 between the cancer cell and normal cell (56. 0% ± 1. 3% vs. 71. 7% ± 6. 8%). The establishment of such a rapid and easy mass spectrometry method can analyze the C=C location and the relative content of location isomers, and it is expected to be a powerful tool to identify different cell states and different disease states.
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[ ABSTRACT] AIM:To investigate the effects of cerebral ischemia and postconditioning on protein kinase R-like endoplasmic reticulum kinase (PERK) and glucose-regulated protein 78 (GRP78) in the hippocampus tissue of tree shrew during endoplasmic reticulum stress and the mechanism of post-conditioning protecting the brain from damage.METH-ODS:The focal cerebral ischemic model was duplicated by photochemical reaction in tree shrew and the postconditioning was induced by alternatively occluding and opening the carotid artery of ischemic side for 3 cycles (5 min each cycle) at 3.5 h after ischemia.The damage and ultrastructural changes of the hippocampal neurons were observed by HE staining. The expression of PERK and GRP78 at mRNA and protein levels in the hippocampal tissue at different time points after cer-ebral ischemia and postconditioning was determined by RT-PCR, immunohistochemistry and Western blot.RESULTS:The injuries of hippocampal neurons were aggravated with prolonged cerebral ischemia, which was most severe at 24 h after ischemia while the postconditioning alleviated these damages correspondingly.The expression of PERK at mRNA and pro-tein levels was upregulated at 4 h, 24 h and 72 h after ischemia (P lated the expressions of GRP78 at IP24 h group (P<0.05).CONCLUSION:The focal thrombotic cerebral ischemia ac-tivates the endoplasmic reticulum stress in ischemic hippocampus of tree shrews, leading to the changes in mRNA and pro-tein expression of PERK in the PERK/eIF2αsignal transduction pathway.The postconditioning treatment alleviates endo-plasmic reticulum stress and neuronal damages by downregulating PERK and upregulating GRP78, thereby protecting the brain from injury.