Isoindolium-Based Allenes: Reactivity Studies and Applications in Fluorescence Temperature Sensing and Cysteine Bioconjugation.

The reaction of a series of electron-deficient isoindolium-based allenes with sulfhydryl compounds has been studied, leading to the formation of isoindolium-based vinyl sulfides. The vinyl sulfides generated could be readily converted into the corresponding indanones and amines upon heating at 30-70 °C with good yields up to 61 %. The thermal cleavage reaction of vinyl sulfides was further studied for developing temperature-sensitive systems. Notably, a novel FRET-based fluorescent temperature sensor was designed and synthesized for temperature sensing at 50 °C, giving a 6.5-fold blue fluorescence enhancement. Moreover, chemoselective bioconjugation of cysteine-containing peptides with the isoindolium-based allenes for the construction of multifunctional peptide bioconjugates was investigated. Thermal cleavage of isoindoliums on the modified peptides at 35-70 °C gave indanone bioconjugates with up to >99 % conversion. These results indicated the biocompatibility of this novel temperature-sensitive reaction.

Iridium-catalyzed enantioselective alkynylation and kinetic resolution of alkyl allylic alcohols.

Herein, we report an efficient kinetic resolution of alkyl allylic alcohols enabled by an iridium-catalyzed enantioselective alkynylation of alkyl allylic alcohols with potassium alkynyltrifluoroborates. A wide range of chiral 1,4-enynes bearing various functional groups and unreacted enantioenriched allylic alcohols were obtained with excellent enantioselectivities and high kinetic resolution performance (s-factor up to 922). Additionally, this method is particularly effective for preparing some useful optically pure alkyl allylic alcohols, such as the key components towards the synthesis of prostaglandins and naturally occurring matsutakeols, which are difficult to access via other asymmetric reactions. Mechanistic studies revealed that the efficient kinetic resolution might be due to the significant distinction of the η 2-coordination between the (R)- and (S)-allylic alcohols with the iridium/(phosphoramidite, olefin) complex.

Intermolecular Metal-Free Cyclopropanation and Aziridination of Alkenes with XH2 (X=N, C) by Thianthrenation.

Three-membered cyclic structures are widely existing in natural products and serve as enabling intermediates in organic synthesis. However, the efficient and straightforward access to such structures with diversity remains a formidable challenge. Herein, a general and practical protocol to aziridines and cyclopropanes synthesis using free XH2 (X=C or N) with alkenes by thianthrenation is presented. This metal-free protocol features the direct aziridination and cyclopropanation with unprotected XH2 . Free sulfonamides, amides, carbamates, amines, and methylene with acidic protons, are good precursors, providing an attractive alternative for straightforward synthesis of aziridines and cyclopropanes from easily available starting materials.

Optical resolution of 1,16-dihydroxytetraphenylene by chiral gold(iii) complexation and its applications as chiral ligands in asymmetric catalysis.

We report herein a novel approach involving optical resolution of (±)-1,16-dihydroxytetraphenylene (DHTP) by chiral gold(iii) complexation. This method features several key advantages, i.e., recyclability of chiral resolution reagents, feasibility of scaling up to gram quantities, and operational simplicity. On the basis of this method, which led to optically pure DHTP, a library of 2,15-diaryl (S)-DHTPs and several (S)-DHTP-derived phosphoramidite ligands were synthesized. Finally, the superior performance of a (S)-DHTP phosphoramidite ligand was demonstrated by efficient iridium-catalyzed asymmetric allylic alkynylation reactions.

Synthesis of 1H-isoindoliums by electrophile-mediated cascade cyclization/iodination of propargylamine-based 1,6-diynes.

A highly regio- and chemoselective synthesis of 1H-isoindoliums through a facile and novel cascade cyclization reaction of propargylamine-based 1,6-diynes under mild conditions has been developed. Different functional groups were compatible under the optimized reaction conditions, giving the corresponding products in up to 94% yields. Upon treatment with a base, the alkyne moiety of 1H-isoindoliums could be further transformed to allenes in excellent yields.

8-prenylgenistein exerts osteogenic effects via ER α and Wnt-dependent signaling pathway.

8-prenylgenistein (8PG) was previously reported to exert stronger osteogenic activity than genistein, a well-known soy phytoestrogen. However, the molecular mechanism underlying the actions of 8PG on osteoblasts was far from clear. In the present study, the osteogenic effects and mechanisms of 8PG and genistein were studied using human BMSC and murine pre-osteoblast MC3T3-E1 cells. Our results indicated that the stimulatory effects of 8PG and genistein on osteoblast differentiation were abolished by co-incubation with MPP (10-6 M, an ERα antagonist), but not PHTPP (10-6 M, an ERß antagonist). Molecular docking indicated that the binding mode of 8PG toward ERα was similar to that of genistein and therefore could not account for their differential osteogenic actions. In silico target profiling identified the involvement of glycogen synthase kinase-3ß (GSK-3ß), a key mediator of Wnt/ß-catenin pathway, in the actions of 8PG. However, instead of directly inhibiting GSK-3ß enzymatic activities, 8PG and genistein were found to induce GSK-3ß phosphorylation at Serine-9 in osteoblastic MC3T3-E1 cells. 8PG exerted more potent effects than genistein in stimulating expressions of LRP5, ß-catenin, Runx2, osteocalcin, alp, opg, major protein and gene markers involved in Wnt signaling pathway in MC3T3-E1 cells. Moreover, the inhibition of Wnt signaling by DKK1 could be restored by treatment with 8PG and genistein. However, 8PG, but not genistein, stimulated ERα-dependent ß-catenin protein expression in MC3T3-E1 cells. Furthermore, the increase in ALP activity, LRP5 and phospho-Akt/Akt expression by 8PG and genistein were abolished by co-treatment with LY294002 (10-5 M, a PI3K pathway inhibitor). Collectively, our results suggested that the osteogenic activities of 8PG was mediated by GSK-3ß phosphorylation through the induction of Wnt/ß-catenin and ERα-associated PI3K/Akt signaling.

Selective modification of alkyne-linked peptides and proteins by cyclometalated gold(III) (C

Alkyne is a useful functionality incorporated in proteins for site-selective bioconjugation reactions. Although effective bioconjugation reactions such as copper(I)-catalyzed and/or copper-free 1,3-dipolar cycloadditions of alkynes and azides are the most common approaches, the development of new alkyne-based bioconjugation reactions is still an ongoing interest in chemical biology. In this work, a new approach has been developed for selective modification of alkyne-linked peptides and proteins through the formation of arylacetylenes by a cross-coupling reaction of 6-membered ring cyclometalated gold(III) (C^N) complexes (HC^N = 2-arylpyridines) with terminal alkynes. Screening of the reaction conditions with a series of cyclometalated gold(III) complexes with phenylacetylene gave an excellent yield (up to 82%) by conducting the reaction in slightly alkaline aqueous conditions. The reaction scope was expanded to various alkynes, including alkyne-linked peptides to achieve up to >99% conversion. Using fluorescent dansyl (1l) and BODIPY (1m)-linked gold(III) complexes, alkyne-linked lysozyme has been selectively modified.

Analysis of Long Non-Coding RNA Expression Profile and Functional Study of LOC389332 in Early Gastric Cancer.

BACKGROUND Long non-coding RNAs (LncRNAs) could potentially function as diagnostic markers for gastric carcinoma. Nevertheless, the expression profile and biological feature of LncRNAs in early gastric cancer (EGC) remains to be explored. MATERIAL AND METHODS LncRNA expression microarray analysis was performed on 6 paired EGC tissues. One deregulated LncRNA, LOC389332, was validated using a quantitative reverse-transcription polymerase chain reaction (qRT-PCR) assay using independent tissue samples and cell lines. The Cell Counting Kit-8 (CCK-8) assay and wound healing assay were conducted to evaluate its influences on the proliferation and migration of gastric cancer cells. LncRNA expression microarray and gene ontology (GO) analysis were also performed on the LOC389332 knockdown cell line model to explore the molecular feature of LOC389332 in gastric carcinoma. RESULTS The LncRNA expression profiling showed that 72 LncRNAs were significantly differentially expressed in EGC tissues. The results in the validation phase revealed that LOC389332 was remarkably overexpressed in gastric carcinoma tissues, precancerous lesions, and gastric cancer cells. Functional study showed that knockdown of LOC389332 expression could inhibit cell proliferation and migration. LncRNA expression microarray on the LOC389332 knockdown cell line model revealed that 393 mRNAs were differentially expressed. The GO enrichment analysis indicated that the downregulated genes were mainly associated with cell membrane function, signal transmission process, and cell adhesion process. CONCLUSIONS The LncRNA expression profile between EGC and gastritis tissues was significantly different. LOC389332 was potential non-coding oncogenes in gastric cancer, and it may perform its function through altering cell membrane function, signal transmission, and cell adhesion.

Chiral Cyclometalated Oxazoline Gold(III) Complex-Catalyzed Asymmetric Carboalkoxylation of Alkynes.

Asymmetric catalysis by using novel chiral O,O'-chelated 4,4'-biphenol cyclometalated oxazoline gold(III) complexes has been developed. A high yield (≤89%) and a high enantioselectivity (≤90% ee) were achieved in asymmetric carboalkoxylation of alkynes. Enantioselectivity could be significantly improved from 19% to 90% ee by increasing the steric size of the substituent on the chiral oxazoline ligand. Catalytically active AuIII species and the origin of chiral induction are proposed.

C,O-Chelated BINOL/Gold(III) Complexes: Synthesis and Catalysis with Tunable Product Profiles.

Unprecedented stable BINOL/gold(III) complexes, adopting a novel C,O-chelation mode, were synthesized by a modular approach through combination of 1,1'-binaphthalene-2,2'-diols (BINOLs) and cyclometalated gold(III) dichloride complexes [(C^N)AuCl2 ]. X-ray crystallographic analysis revealed that the bidentate BINOL ligands tautomerized and bonded to the AuIII atom through C,O-chelation to form a five-membered ring instead of the conventional O,O'-chelation giving a seven-membered ring. These gold(III) complexes catalyzed acetalization/cycloisomerization and carboalkoxylation of ortho-alkynylbenzaldehydes with trialkyl orthoformates.

Cyclometalated gold(III) complexes for chemoselective cysteine modification via ligand controlled C-S bond-forming reductive elimination.

Modular assembly of cyclometalated gold(III) complexes by choosing appropriate bidentate C,N-donor ligands and ancillary ligands for chemoselective cysteine modification of peptides and proteins via C-S bond-forming reductive elimination has been achieved.

Bis-cyclometallated gold(III) complexes as efficient catalysts for synthesis of propargylamines and alkylated indoles.

Stable bis-cyclometallated gold(III) complexes were developed as efficient catalysts for organic transformation reactions by using two strategies: (1) construction of distorted square planar gold(III) complexes and (2) dual catalysis by gold(III) complexes and silver salts.

The apoptotic effect and associated signalling of HSP90 inhibitor 17-DMAG in hepatocellular carcinoma cells.

Primary liver cancer is one of the highly malignant tumours. The traditional surgery, chemotherapy and radiation therapy only established 6% of 5-year survival rate in HCC (hepatocellular carcinoma). Therefore there is an urgent need to develop new therapeutic strategies. HSP90 (heat shock protein 90) is one of the important molecular chaperones and was identified with high expression in the primary liver cancer. In this study, we evaluated the therapeutic effect of specific HSP90 inhibitor 17-DMAG (17-dimethylaminoethylamino-17-demethoxy geldanamycin) in HCC cells. The time and concentration effects of 17-DMAG were investigated in HCC cells. Cell proliferation was measured by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide] assay and cell counting. Apoptosis was detected by flow cytometry with staining of Annexin V-FITC/PI (propidium iodide). The protein levels of survivin, cyclin D1, p53 and NF-κB (nuclear factor κB) were measured by Western blotting. 17-DMAG inhibited the proliferation of HCC cells in a time- and concentration-dependent manner. Treatment with 400 nmol/l 17-DMAG for 48 h significantly induced early-stage apoptosis (22.4%). Conversely, it induced less late-stage apoptosis (3.03%). The 5 mg/l of cisplatin induced significantly less early-stage apoptosis (6.5%), but similar proportion of late-stage apoptosis (4.89%) compared with 17-DMAG. Inhibition of HSP90 activity by 400 nmol/l 17-DMAG decreased protein levels of survivin, cyclin D1 and NF-κB protein levels, whereas increased p53 protein level. HSP90 plays a key role in HCC cell growth and survival through regulation of survivin, cyclin D1, p53 and nucleus NF-κB protein levels and the specific HSP90 inhibitor 17-DMAG can play a therapeutic role in HCC treatment.