A novel thin-layer chromatography-based method for Brazilin quantification

JPC – Journal of Planar Chromatography – Modern TLC - Brazilin, a constituent of the Chinese medicine heartwood, exhibits pronounced anti-tumor effects. To date, brazilin quantification...     

Contradictory effect of gold nanoparticle-decorated molybdenum sulfide nanocomposites on amyloid-β-40 aggregation

The effect of gold nanoparticle-decorated molybdenum sulfide (AuNP-MoS₂) nanocomposites on amyloid-β-40 (Aβ₄₀) aggregation was investigated. The interesting discovery was that the effect of AuNP-MoS₂ nanocomposites on Aβ₄₀ aggregation was contradictory. Low concentration of AuNP-MoS₂ nanocomposites could enhance the nucleus formation of Aβ₄₀ peptides and accelerate Aβ₄₀ fibrils aggregation. However, although high concentration of AuNP-MoS₂ nanocomposites could enhance the nucleus formation of Aβ₄₀ peptides, it eventually inhibited Aβ₄₀ aggregation process. It might be attributed to the interaction between AuNP-MoS₂ nanocomposites and Aβ₄₀ peptides. For low concentration of AuNP-MoS₂ nanocomposites, it was acted as nuclei, resulting in the acceleration of the nucleation process. However, the structural flexibility of Aβ₄₀ peptides was limited as the concentration of AuNP-MoS₂ nanocomposites was increased, resulting in the inhibition of Aβ₄₀ aggregation. These findings suggested that AuNP-MoS₂ nanocomposites might have a great potential to design new multifunctional material for future treatment of amyloid-related diseases.     

Oxidation of aromatic sulfides with molecular oxygen: Controllable synthesis of sulfoxides or sulfones

The recent development of selective oxidation of aromatic sulfides with molecular oxygen was highlighted. The sulfoxides and sulfones could be obtained by simply switching the reaction media, i.e., bis(2-butoxyethyl)ether (BBE) or poly(ethylene glycol)dimethyl ether (PEGDME). The application of the high-boiling-point polyether as an initiator and green media can eliminate the need of large quantities of additives and volatile solvents. This strategy represents an economic and eco-friendly method that could find potential applications.     

Catalytic transfer hydrogenation of biomass-derived furfural to furfuryl alcohol with formic acid as hydrogen donor over CuCs-MCM catalyst

Catalytic transfer hydroge nation(CTH) of furfural(FF) to furfu ryl alcohol(FFA) has received great intere st in recent years.He rein,Cu-Cs bimetallic supported catalyst,CuCs(2)-MCM,was developed for the CTH of FF to FFA using formic as hydrogen donor.CuCs(2)-MCM achieved a 99.6% FFA yield at an optimized reaction conditions of 170℃,1 h.Cu species in CuCs(2)-MCM had dual functions in catalytically decomposing formic acid to generate hydrogen and hydrogenating FF to FFA.The doping of Cs made the size of Cu particles smaller and improved the dispersion of the Cu active sites.Impo rtantly,the Cs species played a favorable role in enhancing the hydrogenation activity as a promoter by adjusting the surface acidity of Cu species to an appropriate level.Correlation analysis showed that surface acidity is the primary factor to affect the catalytic activity of CuCs(2)-MCM.     

Site-Specific Detection of Free Radicals in Membranes Using an Amphiphilic Spin Trap

The detection of free radicals and related species has attracted considerable attention in recent years due to their critical roles in physiological and pathological processes. Among the various methods for the detection of free radicals, electron spin resonance coupled with spin-trapping technique has been an effective approach for the characterization and quantification of free radicals due to its high specificity. In this study, we designed and synthesized a novel amphiphilic spin trap, 2-(diethoxyphosphoryl)-2-heptadecanyl-3,4-dihydro-2H-pyrrole-1-oxide (DEPHdPO), from 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide with a long hydrocarbon chain at the C-5 position of the pyrroline ring, providing the amphiphilic character. The free-radical-trapping ability of DEPHdPO was evaluated by capturing hydroxyl radicals (^·OH), superoxide anions (\( {\text{O}}_{2}^{ \cdot - } \)), and carbon-centered free radicals in a model membrane prepared from sodium dodecyl sulfate (SDS). The results indicate that the hydrophobic hydrocarbon chain of DEPHdPO can be inserted into the inner core of SDS micelles, and the hydrophilic nitronyl functional moiety is located on the surface layer. Thus, various free radicals, including ^·OH radicals, \( {\text{O}}_{2}^{ \cdot - } \) anions, and carbon-centered radicals could be site-specifically detected near the membrane surface. Moreover, DEPHdPO could be successfully located on the surface of thylakoid membranes, and the nearby photo-initiated \( {\text{O}}_{2}^{ \cdot - } \) anions could be trapped site-specifically.