High Sample Throughput LED Reactor for Facile Characterization of the Quantum Yield Spectrum of Photochemically Produced Reactive Intermediates

We describe the growth and characterization of highly fluorescing, near-infrared-emitting nanoclusters made of bimetallic Au25-xAgx cores, prepared using various monothiol-appended hydrophobic and hydrophilic ligands. The reaction uses well-defined triphenylphosphine-protected Au11 clusters (as precursors), which are reacted with Ag(I)-thiolate complexes. The prepared nanoclusters are small (diameter < 2nm, as characterized by TEM) with emission peak at 760 nm and long lifetime (~12 µs). The quantum yield measured for these materials was 0.3 - 0.4 depending on the ligand. XPS measurements show the presence of both metal atoms in the core, with measured binding energies that agree with reported values for nanocluster materials. The NIR emission combined with high quantum yield, small size and ease of surface functionalization afforded by the coating, make these materials suitable to implement investigations that address fundamental questions and potentially useful for biological sensing and imaging applications.

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Photochemical Characterization of Paddy Water during Rice Cultivation: Formation of Reactive Intermediates for As(III) Oxidation

Water Research ◽

10.1016/j.watres.2021.117721 ◽

2021 ◽

pp. 117721

Author(s):

Yu Zeng ◽

Guodong Fang ◽

Qinglong Fu ◽

Dionysios D. Dionysiou ◽

Xiaolei Wang ◽

...

Keyword(s):

Reactive Intermediates ◽

Rice Cultivation ◽

Paddy Water

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Oxypeucedanin is a mechanism-based inactivator of CYP2B6 and CYP2D6

Current Drug Metabolism ◽

10.2174/1389200222666210629114830 ◽

2021 ◽

Vol 22 ◽

Author(s):

Kehan Zhang ◽

Yilin Li ◽

Yao Fu ◽

Tiantian Cui ◽

Qian Wang ◽

...

Keyword(s):

Pain Relief ◽

Liver Microsomes ◽

Reactive Intermediates ◽

Enzyme Inactivation ◽

Time Dependent ◽

Reactive Metabolites ◽

Angelica Dahurica ◽

Dependent Inhibition ◽

Microsomal Incubation

Background: Herbal medicine Angelica dahurica is widely employed for the treatment of rheumatism and pain relief in China. Oxypeucedanin is a major component of the herb. Objectives : The objectives of this study are aimed at the investigation of mechanism-based inactivation of CYP2B6 and CYP2D6 by oxypeucedanin, characterization of the reactive metabolites associated with the enzyme inactivation, and identification of the P450s participating in the bioactivation of oxypeucedanin. Methods : Oxypeucedanin was incubated with liver microsomes or recombinant CYPs2B6 and 2D6 under designed conditions, and the enzyme activities were measured by monitoring the generation of the corresponding products. The resulting reactive intermediates were trapped with GSH and analyzed by LC-MS/MS. Results : Microsomal incubation with oxypeucedanin induced a time-, concentration-, and NADPH-dependent inhibition of CYPs2B6 and 2D6 with kinetic values of KI/kinact 1.82 µM/0.07 min-1 (CYP2B6) and 8.47 µM/0.044 min-1 (CYP2D6), respectively. Ticlopidine and quinidine attenuated the observed time-dependent enzyme inhibitions. An epoxide and/or γ-ketoenal intermediate(s) derived from oxypeucedanin was/were trapped in microsomal incubations. CYP3A4 was the primary enzyme involved in the bioactivation of oxypeucedanin. Conclusion : Oxypeucedanin was a mechanism-based inactivator of CYP2B6 and CYP2D6. An epoxide and/or γ-ketoenal intermediate(s) may be responsible for the inactivation of the two enzymes.

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