Search results for "Lactone"
showing 10 items of 335 documents
The hydrolysis of 6-phosphogluconolactone in the second step of pentose phosphate pathway occurs via a two-water mechanism.
2018
Hydrolysis reaction marks the basis of life yet the mechanism of this crucial biochemical reaction is not completely understood. We recently reported the mechanisms of hydrolysis of nucleoside triphosphate and phosphate monoester. These two reactions hydrolyze P-O-P and P-O-C linkages, respectively. Here, we present the mechanism of hydrolysis of δ-6-phosphogluconolactone, which is an important precursor in the second step of the pentose phosphate pathway. Its hydrolysis requires the cleavage of C-O-C linkage and its mechanism is hitherto unknown. We report three mechanisms of hydrolysis of δ-6-phosphogluconolactone based on density functional computations. In the energetically most favorab…
Alternariol induce toxicity via cell death and mitochondrial damage on Caco-2 cells
2015
Alternariol (AOH), a mycotoxin produced by Alternaria sp, appears as food contaminant in fruit, vegetables and cereal products. Its toxicity has been demonstrated, but the mechanisms involved have not been elucidated yet. In this study, the pathways triggered by AOH and degradation products generated on Caco-2 cells were evaluated. Cells were exposed to AOH sub-cytotoxic concentrations of 15, 30 and 60 μM. Cell cycle disruption, the induction of apoptosis/necrosis and changes in mitochondrial membrane potential (Δψm) after 24 and 48 h was asses by flow cytometry. Also, AOH and its degradation products were evaluated after 24 and 48 h by high-performance liquid chromatography with tandem mas…
Influence of the Fabrication Accuracy of Hot-Embossed PCL Scaffolds on Cell Growths
2020
Polycaprolactone (PCL) is a biocompatible and biodegradable polymer widely used for the realization of 3D scaffold for tissue engineering applications. The hot embossing technique (HE) allows the obtainment of PCL scaffolds with a regular array of micro pillars on their surface. The main drawback affecting this kind of micro fabrication process is that such structural superficial details can be damaged when detaching the replica from the mold. Therefore, the present study has focused on the optimization of the HE processes through the development of an analytical model for the prediction of the demolding force as a function of temperature. This model allowed calculating the minimum demoldin…
3D printing of hybrid biomaterials for bone tissue engineering: Calcium-polyphosphate microparticles encapsulated by polycaprolactone.
2017
Abstract Here we describe the formulation of a morphogenetically active bio-ink consisting of amorphous microparticles (MP) prepared from Ca 2+ and the physiological inorganic polymer, polyphosphate (polyP). Those MP had been fortified by mixing with poly-e-caprolactone (PCL) to allow 3D-bioprinting. The resulting granular PCL/Ca-polyP-MP hybrid material, liquefied by short-time heating to 100 °C, was used for the 3D-printing of tissue-like scaffolds formed by strands with a thickness of 400 µm and a stacked architecture leaving ≈0.5 mm 2 -sized open holes enabling cell migration. The printed composite scaffold turned out to combine suitable biomechanical properties (Young’s modulus of 1.60…
Evaluation of Alternaria mycotoxins in strawberries: quantification and storage condition
2016
Alternariol (AOH), alternariol methyl ether (AME) and tentoxin (TEN) are Alternaria mycotoxins produced by the most common post-harvest pathogens of fruits. The production of these metabolites depends on several environmental factors, mainly temperature, water activity, pH and the technological treatments that have been applied to the product. In this study, the occurrence of AOH, AME and TEN was evaluated in strawberries samples stored at different temperatures ranges (at 22 ± 2 or 6 ± 2°C) and different periods (up to 1 month) simulating the current practice of consumer's storage conditions. Sample extraction was performed using a liquid-liquid extraction method prior to LC-MS/MS analysis…
Transcriptome analysis revealed that a quorum sensing system regulates the transfer of the pAt megaplasmid in Agrobacterium tumefaciens.
2016
Background Agrobacterium tumefaciens strain P4 is atypical, as the strain is not pathogenic and produces a for this species unusual quorum sensing signal, identified as N-(3-hydroxy-octanoyl)-homoserine lactone (3OH,C8-HSL). Results By sequence analysis and cloning, a functional luxI-like gene, named cinI, has been identified on the At plasmid of A. tumefaciens strain P4. Insertion mutagenesis in the cinI gene and transcriptome analyses permitted the identification of 32 cinI-regulated genes in this strain, most of them encoding proteins responsible for the conjugative transfer of pAtP4. Among these genes were the avhB genes that encode a type 4 secretion system (T4SS) involved in the forma…
Colletotrin: a sesquiterpene lactone from the endophytic fungus Colletotrichum gloeosporioides associated with Trichilia monadelpha
2017
Abstract A new sesquiterpene lactone, namely colletotrin (1), together with two known fungal metabolites (2, 3), was obtained from a rice culture of Colletotrichum gloeosporioides, an endophytic fungus isolated from the stem bark of Cameroonian medicinal plant Trichilia monadelpha (Meliaceae). The structure of the new compound was established on the basis of extensive NMR analysis (1H, 13C, heteronuclear single-quantum coherence and heteronuclear multiple-bond correlation) completed by high-resolution electrospray ionization mass spectroscopy results and by comparison of these data with those of related compounds described in the literature. Their cytotoxic and antibacterial activities agai…
Phytoagent Deoxyelephantopin and Its Derivative Inhibit Triple Negative Breast Cancer Cell Activity through ROS-Mediated Exosomal Activity and Protei…
2017
A novel plant sesquiterpene lactone derivative, DET derivative (DETD)-35, originating from parental deoxyelephantopin (DET) was previously observed to effectively suppress human triple negative breast cancer (TNBC) MDA-MB-231 cell activity and tumor growth in mice. In this study, the mechanisms underlying the activity of DETD-35 were elucidated. DET and DETD-35 induced reactive oxygen species (ROS) which caused structural damage and dysfunction of mitochondria and increased cytosolic calcium level, subsequently evoking exosome release from the cancer cells. Intriguingly, exosomes induced by both compounds had an atypical function. Cancer cell-derived exosomes commonly show metastatic potent…
A Standardized Wedelia chinensis Extract Overcomes the Feedback Activation of HER2/3 Signaling upon Androgen-Ablation in Prostate Cancer
2017
Crosstalk between the androgen receptor (AR) and other signaling pathways in prostate cancer (PCa) severely affects the therapeutic outcome of hormonal therapy. Although anti-androgen therapy prolongs overall survival in PCa patients, resistance rapidly develops and is often associated with increased AR expression and upregulation of the HER2/3-AKT signaling pathway. However, single agent therapy targeting AR, HER2/3 or AKT usually fails due to the reciprocal feedback loop. Previously, we reported that wedelolactone, apigenin, and luteolin are the active compounds in Wedelia chinensis herbal extract, and act synergistically to inhibit the AR activity in PCa. Here, we further demonstrated th…
Enhanced adhesion and in situ photothermal ablation of cancer cells in surface-functionalized electrospun microfiber scaffold with graphene oxide
2017
The physicochemical characteristics of a biomaterial surface highly affect the interaction with living cells. Recently, much attention has been focused on the adhesion properties of functional biomaterials toward cancer cells, since is expected to control metastatic spread of a tumor, which is related to good probability containing the progression of disease burden. Here, we designed an implantable poly(caprolactone)-based electrospun microfiber scaffold, henceforth PCLMF-GO, to simultaneously capture and kill cancer cells by tuning physicochemical features of the hybrid surface through nitrogen plasma activation and hetero-phase graphene oxide (GO) covalent functionalization. The surface i…