Gold nanoparticles as localization markers for direct and live imaging of particle absorption through a Caco-2 cell monolayer using dark-field microscopy

Recently, efforts have been made to reduce the size of food particles containing functional ingredients, since reducing the size is expected to improve intestinal absorption. However, the absorption mechanisms have yet to be fully clarified. Therefore, a microscopy-based method for studying interactions between the particles and intestinal cells is required. We optimized the experimental conditions for observing gold nanoparticles (AuNPs) on the surface of an unfixed Caco-2 cell using dark-field microscopy (DFM). Tight junctions were clearly visible with AuNPs on the cells, producing intense scattered light under DFM. This suggests that AuNPs could be used as localization markers to visualize particle absorption through Caco-2 cells.     

Organocatalytic deprotonative functionalization of C(sp(2))-H and C(sp(3))-H bonds using in situ generated onium amide bases

Onium amides, generated in situ from the combination of aminosilanes and onium fluorides (R(4)PF, R(4)NF), are employed for the first time as bases for catalytic deprotonative functionalization of C(sp(2))-H and activated C(sp(3))-H bonds under mild conditions.     

Trypanocidal constituents in plants 6. 1) Minor withanolides from the aerial parts of Physalis angulata

Further study of the methanol extract of the aerial parts of Physalis angulata (Solanaceae) resulted in the isolation of new withanolides, designated physagulins L, M and N, together with known withanolide, physagulin D and flavonol glycoside, quercetin 3-O-rhamnosyl-(1-->6)-galactoside. The chemical structures of these new withanolides were elucidated by detailed spectroscopic analyses to be (20R,22R)-15alpha-acetoxy-5alpha,6beta,14beta,17beta,27-pentahydroxy-1-oxo-witha-2, 24-dienolide, (20S,22S)-15alpha-acetoxy-5alpha,6beta,14alpha,23beta-tetrahydroxy-1-oxo-witha-2,16,24-trienolide and (20S,22R)-15alpha-acetoxy-5beta,6beta-epoxy-14alpha-hydoxy-3beta-methoxy-1-oxo-witha-16,24-dienolide, respectively. All these compounds showed weak trypanocidal activity against trypomastigotes, an infectious form of Trypanosoma cruzi, the etiologic agent for Chagas' disease. Withanolides obtained in the previous paper showed considerable trypanocidal activity, suggesting the structure-activity relationships.     

Short and practical synthesis of O-(p-biphenoyl)-N-tosyl-allo-threonine-derived oxazaborolidinone catalyst

O-(p-Biphenoyl)-N-tosyl-(L)-allo-threonine methyl ester is synthesized in three steps (65% overall yield) starting from commercially available (L)-allo-threonine methyl ester hydrochloride by N-acylation followed by N,O-acyl migration with inversion of the beta carbinol carbon and N-tosylation. Treatment of the methyl ester with dibromophenylborane gives oxazaborolidinone 1, which can be used as a Lewis acid catalyst for the asymmetric Michael and Diels-Alder reactions.     

Isolation and characterization of microorganisms degrading nylon 4 in the composted soil

Two kinds of microorganisms, a bacterium (KT-1 strain) and a fungus (KT-2 strain), degrading nylon 4 (polyamide 4), which was easily prepared by the anionic ring-opening polymerization of 2-pyrrolidone, were isolated from the composted soil with the utilization of enrichment cultures and the culture using nylon 4 as a carbon source. KT-1 and KT-2 strains were identified as neighboring species to Stenotrophomonas sp. and Fusarium sp., respectively, by their morphological properties and the nucleotide sequences. These strains were confirmed to grow in the culture medium containing nylon 4 powders as a carbon source. In addition, nylon 4 film was decomposed in both mineral media containing KT-1 and KT-2 strains, respectively, and disappeared within two months. The MALDI TOF-MS analysis of nylon 4 recovered during the biodegradation test suggest that the isolated KT-2 strain recognize the acyllactam or carboxy chain end and degrade them or their neighboring amide bond.