Merging gold plasmonic nanoparticles and L-proline inside a MOF for plasmon-induced visible light chiral organocatalysis at low temperature

Light-driven asymmetric photocatalysis represents a straightforward approach in modern organic chemistry. In comparison to the homogeneous one, heterogeneous asymmetric photocatalysis has the advantages of easy catalyst separation, recovery, and reuse, thus being cost- and time-effective. Here, we demonstrate how plasmon-active centers (gold nanoparticles - AuNPs) allow visible light triggering of chiral catalyst (proline) in model aldol reaction between acetone and benzaldehyde. The metal-organic framework UiO-66-NH2 was used as an advanced host platform for the loading of proline and AuNPs and their stabilization in spatial proximity. Aldol reactions were carried out at a low temperature (-20 °C) under light illumination which resulted in 91% ee with a closed-to-quantitative yield, 4.5 times higher than that without light (i.e. in the absence of plasmon triggering). A set of control experiments and quantum chemical modeling revealed that the plasmon assistance proceeds through hot electron excitation followed by an interaction with an enamine with the formation of anion radical species. We also demonstrated the high stability of the proposed system in multiple catalytic cycles without leaching metal ions, which makes our approach especially promising for heterogeneous asymmetric photocatalysis.

Comparative analysis of thymidylate synthase, thymidine phosphorylase and dihydropyrimidine dehydrogenase expression in colorectal cancer and surrounding normal tissue

Thymidylate synthase [TS], thymidine phosphorylase [TP] and dihydropyrimidine dehydrogenase [DPD] play the essential role in the activation and catabolism of the fluoropyrimidines used in cancer therapy. Its expression may influence the antitumor activity or toxicity of these drugs. We studied the expression levels of selected enzymes in colorectal tumors and adjacent normal mucosa. The analysis of TS, TP and DPD gene expression was performed using quantitative Real time PCR technique (Roche) in 15 (TS), 64 (TP) and 12 (DPD) of 64 colorectal cancer patients. The mean gene expression of TS, TP and DPD was found to be 3.29; 3.79 and 8.24 in tumors and 1.88; 3.80 and 19.69 in normal mucosa. The corresponding median gene expression was 1.87; 2.32 and 4.50 for tumors and 2.14; 2.63 and 11.64 for normal tissue. We did not find any significant differences in TS, TP and DPD gene expression between colorectal tumor and surrounding mucosa.

[Influence of feed mixtures supplemented with animal fat on milk yield and milk composition]

Animal fat was administered in fat-supplemented mixtures of concentrates in amounts varying from 0%, 5%, to 10%. The trials were carried out on 12 dairy cows. The best results were obtained with mixed concentrates containing 5% of animal fat. Animals on these food rations produced 6.75% more milk (expressed in units of fat-corrected milk (FCM) and 9.87% more milk fat. Additions of animal fat affected the composition of milk fat in such a way that the milk contained smaller portions of short-chain fatty acids and higher proportions of stearic and oleic acid.