Marnix Roseboom

A highly luminescent Ag⁺ doped Pt cluster is reported. Compared to the original platinum thiolate complex, the inclusion of silver ion has boosted photoluminescent quantum yield by 18 times. The LUMO, which has the main contribution from the Ag s‐orbital and Pt d‐orbitals, plays a critical role in suppressing the structural distortion at the excited state.

Abstract

There has been controversy surrounding the roles of the metal core (metal–metal interaction) and the shell (metal–ligand interaction) in photoluminescence of ligand‐protected metal nanoclusters. We have discovered aggregation‐induced room‐temperature phosphorescence of a platinum–thiolate complex and its silver ion inclusion complex (a silver‐doped platinum sub‐nanocluster). The inclusion of silver ion boosted the photoluminescent quantum yield by 18 times. Photophysical measurements indicate that the rate of nonradiative decay was slower for the silver‐doped platinum sub‐nanocluster. DFT calculations showed that the LUMO, which had the main contribution from Ag s‐orbital and Pt d‐orbitals, played a critical role in suppressing the structural distortion at the excited state. This work will hopefully stimulate more research on designing strategies based on molecular orbitals of atomicity‐precise luminescent multimetallic nanoclusters.

A reagent‐directed diverse synthesis of three skeletally distinct frameworks, involving ring expansion and intramolecular cyclization strategies, has been achieved from tri‐O‐benzyl‐D‐glucal.

A reagent‐directed divergent synthesis of three skeletally distinct compounds, namely, amino‐substituted indolizidine alkaloids, decahydropyrazino[2,1,6‐cd]‐pyrrolizine triols and (–)‐pochonicine stereoisomers have been accomplished from a single precursor. Tri‐O‐benzyl‐d‐glucal was converted into a diastereomeric mixture of homoallylic alcohols through a seven‐step sequence developed earlier in our lab. Intramolecular iodo‐amination of the homoallylic alcohols proceeded through a 5‐exo‐tet ring opening of initially formed iodonium ion to give the iodo‐substituted pyrrolizidine {[5,5‐]‐fused} derivatives. Upon exposure to AgOAc, these iodo‐pyrrolizidines underwent a ring enlargement under the reaction condition and delivered polyhydroxylated indolizidine {[5,6]‐fused} derivatives as the main products. On the other hand, when the iodo‐pyrrolizidines were treated with NaH, a smooth intramolecular substitution reaction took place resulting in the formation of novel decahydropyrazino[2,1,6‐cd]pyrrolizine triols in good yields. Diversely, epoxidation of the homoallyic alcohols followed by intramolecular ring opening and subsequent synthetic transformations delivered stereoisomers of (–)‐pochonicine. The structure and stereochemistry of the final compounds were established through detailed 2D‐NMR analysis.

Molecules, Vol. 25, Pages 1225: Antiproliferation Activity and Mechanism of c9, t11, c15-CLNA and t9, t11, c15-CLNA from Lactobacillus plantarum ZS2058 on Colon Cancer Cells

Molecules doi: 10.3390/molecules25051225

Authors: Qing Ren Bo Yang Guangzhen Zhu Shunyu Wang Chengli Fu Hao Zhang R. Paul Ross Catherine Stanton Haiqin Chen Wei Chen

Conjugated linolenic acid (CLNA) is a type of ω-3 fatty acid which has been proven to have a series of benefits. However, there is no study about the function of Lactobacillus-derived CLNA isomer. Lactobacillus plantarum ZS2058 has been proven to manifest comprehensive functions and can produce CLNA. To investigate the specific functions of CLNA produced by this probiotic bacterium, two different conjugated α-linolenic acid (CLNA) isomers were successfully isolated. These isoforms, CLNA1 (c9, t11, c15-CLNA, purity 97.48%) and CLNA2 (c9, t11, t15-CLNA, purity 99.00%), both showed the ability to inhibit the growth of three types of colon cancer cells in a time- and concentration-dependent manner. In addition, the expression of MDA in Caco-2 cells was increased by CLNA1 or CLNA2, which indicated that lipid peroxidation was related to the antiproliferation activity of CLNAs. An examination of the key protein of pyroptosis showed that CLNA1 induced the cleavage of caspase-1 and gasdermin-D, while CLNA2 induced the cleavage of caspase-4, 5 and gasdermin-D. The addition of relative inhibitors could alleviate the pyroptosis by CLNAs. CLNA1 and CLNA2 showed no effect on caspase-3, 7, 9 and PARP-1, which were key proteins associated with apoptosis. No sub-diploid apoptotic peak appeared in the result of PI single staining test. In conclusion, CLNA1 activated caspase-1 and induced Caco-2 cell pyroptosis, whereas CLNA2 induced pyroptosis through the caspase-4/5-mediated pathway. The inhibition of Caco-2 cells by the two isomers was not related to apoptosis. This is the first study on the function of Lactobacillus-derived CLNA isomer. The inhibition pathway of Lactobacillus-derived CLNA isomer on colon cancer cells were proved.