Synthesis of thioesters using an electrochemical three-component reaction involving elemental sulfur.

An electrochemical three-component reaction involving elemental sulfur is disclosed for achieving a metal-free, oxidant-free synthesis of thioesters in a high atom-economical, step-economical and chemoselective manner. A mechanistic investigation indicates that the use of elemental sulfur to trap acyl radical derived from radical umpolung of α-keto acid with an electrochemical design can efficiently generate a carbonyl thiyl radical, which can further be captured by diazoalkane to afford various thioesters.

Synthesis of vinyl-1,2,3-triazole derivatives under transition metal-free conditions.

Herein, we describe a novel and green route for the direct synthesis of vinyl triazole derivatives with alkynes and triazoles promoted by an inorganic base under transition metal-free conditions. The base shows great catalytic activity for the anti-Markovnikov stereoselective hydroamination of alkynes. Moreover, good yields with excellent functional group tolerance are successfully achieved for a range of substrates, including aryl and heteroaryl groups, terminal alkynes and internal alkynes, and various triazole derivatives. This work presents an advanced concept for the synthesis of alkenyl triazole with a versatile and cost-efficient approach.

MEG3 promotes proliferation and inhibits apoptosis in osteoarthritis chondrocytes by miR-361-5p/FOXO1 axis.

BACKGROUND: This study aimed to investigate the role of long non-coding RNA (lncRNA) maternally expressed 3 (MEG3) and related molecular mechanisms, in osteoarthritis (OA). METHODS: Cartilage tissues of OA patients and healthy volunteers were isolated and cultured. After transfection with the appropriate constructs, chondrocytes were classified into Blank, pcDNA3.1-NC, pcDNA3.1-MEG3, si-NC, si-MEG3, pcDNA3.1-NC + mimics NC, pcDNA3.1-MEG3 + mimics NC, pcDNA3.1-NC + miR-361-5p mimics and pcDNA3.1-MEG3 + miR-361-5p mimics groups. qRT-PCR was used to detect the expression of MEG3, miR-361-5p and FOXO1. Western blot, luciferase reporter assay, RIP, CCK-8, and flow cytometry analysis were performed to reveal the morphology, proliferation, and apoptotic status of cartilage cells. Histological analysis and immunostaining were conducted in the OA rat model. RESULTS: Expression of MEG3 and FOXO1 was significantly decreased in OA compared with the normal group, while the expression of miR-361-5p was increased. MEG3 might serve as a ceRNA of miR-361-5p in OA chondrocytes. Moreover, using western blot analyses and the CCK-8 assay, MEG3 was shown to target miR-361-5p/FOXO1, elevate cell proliferation, and impair cell apoptosis. Functional analysis in vivo showed that MEG3 suppressed degradation of the cartilage matrix. CONCLUSION: MEG3 can contribute to cell proliferation and inhibit cell apoptosis and degradation of extracellular matrix (ECM) via the miR-361-5p/FOXO1 axis in OA chondrocytes.

Mitomycin C induces apoptosis in rheumatoid arthritis fibroblast-like synoviocytes via a mitochondrial-mediated pathway.

BACKGROUND/AIMS: Rheumatoid arthritis (RA) is a systemic chronic inflammatory disease characterised by prominent synoviocyte hyperplasia and a potential imbalance between the growth and death of fibroblast-like synoviocytes (FLS). Mitomycin C (MMC) has previously been demonstrated to inhibit fibroblast proliferation and to induce fibroblast apoptosis. However, the effects of MMC on the proliferation and apoptosis of human RA FLS and the potential mechanisms underlying its effects remain unknown. METHODS: Cell viability was determined using the Cell Counting Kit-8 assay. Apoptotic cell death was analysed via Annexin V-FITC/PI double staining and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labelling. The production of intracellular reactive oxygen species (ROS) was assessed via flow cytometry, and the changes in mitochondrial membrane potential (ΔΨm) were visualized based on JC-1 staining via fluorescence microscopy. The expression of apoptosis-related proteins was determined via Western blot. RESULTS: Treatment with MMC significantly reduced cell viability and induced apoptosis in RA FLS. Furthermore, MMC exposure was found to stimulate the production of ROS and to disrupt the ΔΨm compared to the control treatment. Moreover, MMC increased the release of mitochondrial cytochrome c, the ratio of Bax/Bcl-2, the activation of caspase-9 and caspase-3, and the subsequent cleavage of poly(ADP-ribose) polymerase. CONCLUSION: Our findings suggest that MMC inhibits cell proliferation and induces apoptosis in RA FLS, and the mechanism underlying this MMC-induced apoptosis may involve a mitochondrial signalling pathway.

Potential risk of mitomycin C at high concentrations on peripheral nerve structure.

Although the local application of mitomycin C may prevent epidural adhesion after laminectomy, mitomycin C can induce neurotoxicity in optic and acoustic nerves at high concentrations. To determine the safe concentration range for mitomycin C, cotton pads soaked with mitomycin C at different concentrations (0.1, 0.3, 0.5, and 0.7 mg/mL) were immediately applied for 5 minutes to the operation area of rats that had undergone laminectomy at L1. Rat sciatic nerves, instead of dorsal nerves, were used in this study. The results showed that mitomycin C at 0.1-0.5 mg/mL did not damage the structure and function of the sciatic nerve, while at 0.7 mg/mL, mitomycin C significantly reduced the thickness of the sciatic nerve myelin sheath compared with lower concentrations, though no functional change was found. These experimental findings indicate that the local application of mitomycin C at low concentrations is safe to prevent scar adhesion following laminectomy, but that mitomycin C at high concentrations (> 0.7 mg/mL) has potential safety risks to peripheral nerve structures.

Effect of topical application of mitomycin-C on wound healing in a postlaminectomy rat model: an experimental study.

The aim of this study was to investigate the effects of topical application mitomycin-C (MMC) on wound healing after laminectomy. 60 adult male SD rats were equally and randomly divided into five groups. Laminectomy was performed at the level of L1 in all rats. After hemostasis was achieved, cotton pads soaked with saline and MMC (0.1mg/ml, 0.3mg/ml, 0.5mg/ml and 0.7mg/ml) were directly subjected to the exposed dura for 5min in each group. Two weeks after laminectomy all the rats were killed. The vertebral column including the back scar tissue and muscles was obtained to make paraffin sections. The hematoxylin-eosin staining and Masson staining were performed with the obtained paraffin sections. The number of the fibroblast and the capillary density were counted by the hematoxylin-eosin staining slice. The extent of epidural fibrosis and the expression of vascular endothelial growth factor (VEGF) were evaluated by the immunohistochemical slice through a computer image analysis system. Our data showed that the number of fibroblast, capillary density and fibrotic tissue in the 0.5 and 0.7mg/ml MMC groups was significantly lower than the control, 0.1 and 0.3mg/ml MMC groups; while the expression of VEGF in control and 0.1mg/ml MMC groups was notably higher than 0.3, 0.5 and 0.7mg/ml MMC groups. Topical application of MMC above the concentration of 0.3mg/ml could affect all steps of the wound healing process via inhibiting the angiogenesis and fibroblast proliferation, thus delayed the wound healing after laminectomy.

Study on the optimal concentration of topical mitomycin-C in preventing postlaminectomy epidural adhesion.

There is increasing evidence that topical application of mitomycin-C can be beneficial in reducing epidural scar adhesion. However, the ideal concentration of mitomycin-C is unknown. The purpose of this study was to verify its efficacy for preventing epidural adhesion and the immediate electrophysiological responses caused by it in a laminectomy model. Seventy rats underwent laminectomy at L-1 and L-2. Cotton pads soaked with saline and various concentrations of mitomycin-C (0.1 mg/ml, 0.3 mg/ml, 0.5 mg/ml and 0.7 mg/ml) were applied to the exposed dura for 5 min. Spine somatosensory evoked potentials (SSEP) were monitored in preoperative and the immediate electrophysiological responses of mitomycin-C used. Four weeks postlaminectomy the rats were killed. The area of epidural scar tissue and degree of epidural adhesion were determined by 7.0 T Micro MR imaging. Macroscopic evaluations were performed according to the Rydell standard. The results showed that severe epidural adhesion was formed in the saline group and no dural adherence or incomplete adhesions were found in the mitomycin-C group. The Rydell classification and the degree of epidural adhesion and the area of the scar in 0.5 mg/ml group and 0.7 mg/ml mitomycin-C group revealed a significant decrease compared with the control group and 0.1 mg/ml group and 0.3 mg/ml mitomycin-C group. The spine sensory evoked potentials did not alter obviously in both preoperative and the immediate electrophysiological responses of mitomycin-C used. In conclusion, locally applied mitomycin-C in a concentration of 0.5 mg/ml and 0.7 mg/ml mitomycin-C may be the optimal concentration in preventing postlaminectomy epidural adhesion.

EIF2alpha and caspase-12 activation are involved in oxygen-glucose-serum deprivation/restoration-induced apoptosis of spinal cord astrocytes.

Astrocytes play an important role in protecting neurons during ischemia and reperfusion in the central nervous system. Although many studies have shown that oxygen-glucose deprivation (OGD) can induce astrocyte apoptosis, the role of PERK/eIF2 alpha/ATF4 integrated stress response (ISR) in astrocyte apoptosis mediated by oxygen-glucose-serum deprivation (OGSD)/restoration remains uncertain. Astrocytes were subjected to a combination of oxygen, glucose, and serum deprivation for 8h followed by restoration. Hoechst 33342 staining was performed to quantify apoptotic astrocytes and cell viability was assessed with Cell Counting Kit-8 (CCK8). Immunocytochemical analysis and Western blotting for some related molecules, including pancreatic ER stress kinase (PERK), p-PERK, eukaryotic initiation factor 2 alpha (eIF2 alpha), p-eIF2 alpha, activating transcription factor 4 (ATF4), caspase-12, were examined. Caspase activation and apoptosis were detected in neonatal rat astrocytes from spinal cord subjected to OGSD/restoration. We also observed an increase in cytoplasmic staining of p-eIF2 alpha in astrocytes (8h OGSD/15 min restoration) compared with that of non-treated cells. In addition, we found the sequential activation of PERK, eIF2 alpha, and ATF4 during OGSD/restoration by Western blotting. These results indicate that both the PERK/eIF2 alpha/ATF4 ISR and activation of caspase-12 may be involved in apoptosis of spinal cord astrocytes induced by OGSD/restoration.