Zhihong Cheng

Isolation and characterization of two flavonoids, engeletin and astilbin, from the leaves of Engelhardia roxburghiana and their potential anti-inflammatory properties.

Engeletin, a flavonoid compound, was isolated from the leaves of Engelhardia roxburghiana for the first time, along with astilbin, another flavonoid. The chemical structures of engeletin and astilbin were confirmed by (1)H and (13)C nuclear magnetic resonance (NMR) and mass spectrometry (MS) spectra, and their anti-inflammatory activities were studied in lipopolysaccharide (LPS)-stimulated mouse J774A.1 macrophage cells. LPS induced the inflammatory state in macrophage cells and increased mRNA expressions of pro-inflammatory cytokines. Engeletin and astilbin exhibited remarkable inhibitory effects on interleukin (IL)-1β and IL-6 mRNA expression. Significant inhibition of LPS-mediated mRNA expressions were also seen in LPS binding toll-like receptor (TLR)-4, pro-inflammatory cytokine tumor necrosis factor (TNF)-α, IL-10, chemoattractant monocyte chemotactic protein (MCP)-1, and cyclooxygenase (COX)-2 genes. The reduced expression of these cytokines may alleviate immune response and reduce inflammatory activation, indicating that engeletin and astilbin may serve as potential anti-inflammatory agents.

Anti-Inflammatory and antiproliferative activities of trifolirhizin, a flavonoid from Sophora flavescens roots.

Trifolirhizin, a pterocarpan flavonoid, was isolated from the roots of Sophora flavescens, and its chemical structure was confirmed by (1)H and (13)C NMR and MS spectra. Its anti-inflammatory activity was examined in lipopolysaccharide (LPS)-stimulated mouse J774A.1 macrophages. Trifolirhizin not only dose-dependently inhibited LPS-induced expression of pro-inflammatory cytokines including tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) but also inhibited lipopolysaccharide (LPS)-induced expression of cyclooxygenase-2 (COX-2). In addition, trifolirhizin showed in vitro inhibitory effects on the growth of human A2780 ovarian and H23 lung cancer cells. These results suggest that trifolirhizin possesses potential anti-inflammatory and anticancer activities.

Chitosan-coated electrodes for bimodal sensing: selective post-electrode film reaction for spectroelectrochemical analysis.

Electrochemical methods are well suited for chemical detection in hand-held devices because they are simple, fast, and sensitive. However, electrochemical detection methods generally suffer from limitations in selectivity. We report a novel approach that enables electrochemically initiated reactions to generate optical signals that can be used to enhance the discriminating power for the electrochemical analysis of antioxidant food phenols. This spectroelectrochemical approach employs transparent electrodes coated with a film of the aminopolysaccharide chitosan. The phenolic analytes diffuse through the chitosan film to the electrode where they are anodically oxidized into electrophilic intermediates that undergo postelectrode reactions with the chitosan film. The postelectrode reaction was analyzed by FTIR and XPS, and this reaction was observed to impart optical properties (color and UV-visible absorbance) to the otherwise colorless and transparent chitosan film. We demonstrate that the optical signal generated from the postelectrode film reaction is selective for oxidized phenols, compared to that for unoxidized phenols or the nonphenolic antioxidant ascorbic acid. Furthermore, we demonstrate that the optical signal (film absorbance) can be correlated to the electrical signal (charge transferred). Finally, we use simple mixtures to demonstrate that the coupling of information from independent optical and electrical measurement modes can assist in the qualitative analysis of antioxidant phenols. Potentially, the postelectrode film reaction may provide a selective and reagentless alternative to conventional colorimetric methods for detecting antioxidant phenols. In a broader perspective, this work suggests the potential for coupling independent detection modes (optical and electrical) to enhance the information content of sensor measurements.