Ratiometric electrochemical molecular switch for sensing hypochlorous acid: Applicable in food analysis and real-time in-situ monitoring.

A ratiometric electrochemical molecular sensing platform for real-time quantification of extracellular hypochlorous acid (HClO) production has been developed based on a latent electrochemical probe aminoferrocene thiocarbamate (AFTC 3). The substrate AFTC consist of a masked redox reporter amino ferrocene (AF 4) linked with a dimethylthiocarbamate trigger via hydroxyl benzyl alcohol. The conceptual idea behind the probe design is based on a specific chemical interaction between HClO and dimethylthiocarbamate, which allows only HClO to unmask the probe to releases AF. The scheme was manipulated to establish a highly selective (in presence of various reactive oxygen species, anions and other biological interfering species) and sensitive (detection limit 75 nM) sensing platform not only in lab samples but also in real samples (food samples, and live cells). Real-time in situ quantification platform was developed to profile HClO productions in macrophages, and it did so with great consistency.

Wasted Ganoderma tsugae Derived Chitosans for Smear Layer Removal in Endodontic Treatment.

The objective of this study is to investigate the synergistic effects of acid etching and metal-ion chelation in dental smear layer removal using wasted Ganoderma tsugae derived chitosans. The wasted Ganoderma tsugae fruiting body was used to prepare both acid-soluble fungal chitosan (FCS) and alkali-soluble polysaccharide (ASP). To explore the effective irrigant concentration for smear layer removal, a chelating effect on ferrous ions was conducted. Specimens of various concentrations of EDTA, citric acid, and polysaccharide solutions were reacted with FerroZine™ then the absorbance was examined at 562 nm by a UV-visible spectrophotometer to calculate their metal chelating capability. Twenty extracted premolars were instrumented and individually soaked in the solutions of 15 wt% EDTA, 10 wt% citric acid, 0.04 wt% ASP, 0.04 wt% FCS, and normal saline were randomly divided into five groups (N=4). Next, each tooth was cleaved longitudinally and examined by scanning electron microscopy (SEM) to assay the effectiveness of smear layer removal. The chelating capability for EDTA, FCS, and ASP showed no significant difference over the concentration of 0.04 wt% (p > 0.05). The SEM results showed that 0.04 wt% FCS solution was effective in smear layer removal along the canal wall. These results indicated that Ganoderma tsuage derived FCS in acid solutions could be a potential alternative as a root canal irrigant solution due to its synergistic effect.

Synthetic Fluororutaecarpine Inhibits Inflammatory Stimuli and Activates Endothelial Transient Receptor Potential Vanilloid-Type 1.

The natural product, rutaecarpine (RUT), is the main effective component of Evodia rutaecarpa which is a widely used traditional Chinese medicine. It has vasodilation, anticoagulation, and anti-inflammatory activities. However, further therapeutic applications are limited by its cytotoxicity. Thus, a derivative of RUT, 10-fluoro-2-methoxyrutaecarpine (F-RUT), was designed and synthesized that showed no cytotoxicity toward RAW264.7 macrophages at 20 µM. In an anti-inflammation experiment, it inhibited the production of nitric oxide (NO) and tumor necrosis factor (TNF)-α in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages; cyclooxygenase (COX)-2 and inducible NO synthase (iNOS) induced by LPS were also downregulated. After 24 h of treatment, F-RUT significantly inhibited cell migration and invasion of ovarian A2780 cells. Furthermore, F-RUT promoted expressions of transient receptor potential vanilloid type 1 (TRPV1) and endothelial (e)NOS in human aortic endothelial cells, and predominantly reduced the inflammation in ovalbumin/alum-challenged mice. These results suggest that the novel synthetic F-RUT exerts activities against inflammation and vasodilation, while displaying less toxicity than its lead compound.

Tri-layered chitosan scaffold as a potential skin substitute.

A tri-layered chitosan-based scaffold was successfully made to replicate the striation of a full-thickness skin more accurately than a single- or bi-layered scaffold, which needed weeks of co-culturing of fibroblasts and keratinocytes to achieve similar striation. Chitosan solution was freeze-dried and made into porous disks. Chitosan or chitosan-pectin in acetic acid solution was electrospun onto the chitosan disk to form a nanofibrous layer and a thin film. Examinations based on scanning electron spectroscopy showed that the scaffold was composed of a porous layer (2 mm) to simulate the dermis, a thin film (25-45 µm) to mimic the basement membrane, and a layer of nanofibers (100-200 µm) to serve as the protective epidermis. The tensile strength and modulus of the composite scaffold were significantly higher than those of the chitosan disk (p < 0.01). The composite was able to quickly absorb water and stayed intact throughout the course of the 14-day cell culture tests. The fibroblast cells seeded on both sides of the scaffolds were able to proliferate and stayed separated by the thin film.

A simple electrochemical platform based on pectin stabilized gold nanoparticles for picomolar detection of biologically toxic amitrole.

Amitrole is a biologically toxic nonselective herbicide which contaminates surface and ground waters at unprecedented rates. All reported modified electrodes that detect amitrole within sub-micromolar to nanomolar levels were based on the electro-oxidation of amitrole. Herein, we developed a new conceptual idea to detect picomolar concentrations of amitrole based on calcium cross linked pectin stabilized gold nanoparticle (CCLP-GNP) film modified electrode which was prepared by electrodeposition. When the electrochemical behavior of amitrole was investigated at the CCLP-GNP film, the reduction peak current of the GNPs linearly decreased as the concentration of amitrole increases. We have designed a determination platform based on the amitrole dependent decrease of the GNP cathodic peak. The described concept and high sensitivity of square wave voltammetry together facilitate the great sensing ability; as a result the described approach is able to reach a low detection limit of 36 pM which surpassed the detection limits of existing protocols. The sensor presents a good ability to determine amitrole in two linear concentration ranges: (1) 100 pM-1500 pM with a detection limit of 36 pM; (2) 100 nM-1500 nM with a detection limit of 20 nM. The preparation of CCLP-GNPs is simple, rapid and does not require any reducing agents.

Low-cytotoxic synthetic bromorutaecarpine exhibits anti-inflammation and activation of transient receptor potential vanilloid type 1 activities.

Rutaecarpine (RUT), the major bioactive ingredient isolated from the Chinese herb Evodia rutaecarpa, possesses a wide spectrum of biological activities, including anti-inflammation and preventing cardiovascular diseases. However, its high cytotoxicity hampers pharmaceutical development. We designed and synthesized a derivative of RUT, bromo-dimethoxyrutaecarpine (Br-RUT), which showed no cytotoxicity at 20 µM. Br-RUT suppressed nitric oxide (NO) production and tumor necrosis factor-α release in concentration-dependent (0~20 µM) manners in lipopolysaccharide (LPS)-treated RAW 264.7 macrophages; protein levels of inducible NO synthase (iNOS) and cyclooxygenase-2 induced by LPS were downregulated. Br-RUT inhibited cell migration and invasion of ovarian carcinoma A2780 cells with 0~48 h of treatment. Furthermore, Br-RUT enhanced the expression of transient receptor potential vanilloid type 1 and activated endothelial NOS in human aortic endothelial cells. These results suggest that the synthetic Br-RUT possesses very low cytotoxicity but retains its activities against inflammation and vasodilation that could be beneficial for cardiovascular disease therapeutics.

Inhibition of AMPK-associated autophagy enhances caffeic acid phenethyl ester-induced cell death in C6 glioma cells.

An increasing number of studies show that AMP-activated protein kinase (AMPK) activation can inhibit apoptosis. To clarify the antitumor mechanism of caffeic acid phenethyl ester (CAPE) and achieve increased therapeutic efficiency, we investigated the potential roles of AMPK and autophagy in CAPE treatment against C6 glioma cells. The roles of AMPK and autophagy inhibition in CAPE's cytotoxic action were investigated. Phosphorylation of AMPK and mitogen-activated protein kinases (MAPKs) were observed in tumor cells following CAPE treatment. A combination of CAPE and the AMPK inhibitor, compound C, resulted in augmented cell death. Similar effects of compound C were observed in response to changes in the mitochondrial membrane potential ( ΔΨ(m)). Small interfering RNA-mediated AMPK downregulation increased CAPE-induced cell death. The results suggest that AMPK activation plays a role in diminishing apoptosis. CAPE treatment induced an increase in LC3 conversion as represented by the LC3-II/LC3-I ratio. Enlarged lysosomes and autophagosomes were present according to electron microscopy. The autophagy inhibitor, 3-MA, caused increased CAPE cytotoxicity, which suggests that autophagy induction protected glioma cells from CAPE. The combination of CAPE with autophagy and AMPK inhibitors markedly enhanced the cytotoxicity toward C6 glioma cells. Accordingly, CAPE-triggered activation of AMPK and the autophagic response protected tumor cells from apoptotic death. This provides new insights for combined therapy to enhance the therapeutic potential of cancer treatments.

Hydrophilic ester-bearing chlorogenic acid binds to a novel domain to inhibit xanthine oxidase.

Caffeic acid is a xanthine oxidase (XO) inhibitor that binds to the molybdopterin region of its active site. Caffeic acid phenethyl ester (CAPE) has higher hydrophobicity and exhibits stronger inhibition potency toward XO. Chlorogenic acid is a quinyl ester of caffeic acid that has increased hydrophilicity and also shows stronger XO inhibitory activity compared with caffeic acid. Caffeic acid and CAPE showed competitive inhibition against XO, whereas chlorogenic acid displayed mixed-type inhibition, implying that it binds to sites other than the active site. Structure-based molecular modeling was performed to account for the different binding characteristics of the hydrophobic and hydrophilic esters of caffeic acid. Chlorogenic acid showed weak binding to the molybdopterin region of XO, while it more strongly bound the flavin adenine dinucleotide region than it did the molybdopterin region. These results provide the basis for interactions of caffeic acid analogues with XO via various binding domains.

Isovitexin suppresses lipopolysaccharide-mediated inducible nitric oxide synthase through inhibition of NF-kappa B in mouse macrophages.

Isovitexin exhibits potent antioxidant activities. In this study, the activity of nitric oxide synthase (iNOS) in lipopolysaccharide (LPS)-activated RAW264.7 macrophages after incubation with isovitexin was investigated. Isovitexin was able to reduce the production of hydrogen peroxide induced by LPS in mouse macrophage RAW264.7 cells. The cells incubated with isovitexin had markedly reduced LPS-stimulated NO production with an IC (50) value of 58.5 microM. The expression of iNOS was also inhibited when the cells were treated with isovitexin. A transient transfection experiment showed that isovitexin suppressed the iNOS promoter and NF-kappaB-dependent transcriptional activities. It was also found to inhibit IKK kinase activity and prevent the degradation of IkappaBalpha in activated RAW264.7 cells. Additionally, Western blotting analysis revealed that isovitexin prevented the translocation of NF-kappaB from the cytoplasm to the nucleus. Our results indicate that its ROS scavenger and IKK inhibitory activities also contribute to the suppression of ROS-mediated NF-kappaB activity. These results suggest that isovitexin, a food phytochemical contained in dietary rice products, might have biological significance.

Synthesis and biological evaluation of novel bis-aziridinylnaphthoquinone derivatives.

A series of bis-aziridinylnaphthoquinone derivatives has been prepared. The cytotoxic activities and DNA alkylation abilities of these synthetic bis-aziridinylnaphthoquinone derivatives were investigated. They displayed significant cytotoxicity against human carcinomna cell lines and weak cytotoxic activities against HL60 and skin fibroblast (SF). The bisaziridinylnaphthoquinone 1a was the most potent agent among those tested, with an LD50 value of 0.57 microM against the BC-M1 cell line. It exhibited the weakest activity against SF and HL60 with LD50 values of 5.67 and 20.1 microM, respectively, and it was able to alkylate DNA after chemical reduction in vitro. The analogues without aziridinyl moiety 2a and 3a lack DNA alkylation abilities.