Recently, we reported that a novel phenolic compound isolated from Cedrus deodara, 3-p-trans-coumaroyl-2-hydroxyquinic acid (CHQA), exhibits a potent antioxidant activity. The present study aimed to evaluate the antibacterial activity of CHQA against eleven food-borne pathogens and to elucidate its mechanism of action against Staphylococcus aureus. The results from minimum inhibitory concentration (MIC) determinations showed that CHQA exhibited moderate inhibitory effects on all of the tested pathogens with MIC values ranging from 2.5-10 mg/mL. Membrane potential measurements and flow cytometric analysis demonstrated that CHQA damaged the cytoplasmic membrane of S. aureus, causing a significant membrane hyperpolarization with a loss of membrane integrity. Moreover, CHQA induced an increase in membrane fluidity and conformational changes in membrane protein of S. aureus, suggesting that CHQA probably acts on the cell membrane by interactions with membrane lipid and protein. Transmission electron microscopic observations further confirmed that CHQA disrupted the cell membrane of S. aureus and caused severe morphological changes, which even led to leakage of intracellular constituents. These findings indicated that CHQA could have the potential to serve as a natural antibacterial agent to control and prevent the growth of pathogens in food and in food-processing environments.

The interactions of inorganic mercury Hg(II), methylmercury (MeHg(I)), ethylmercury (EtHg(I)), and phenylmercury (PhHg(I)) with DNA have been probed by capillary electrophoresis with on-line electrothermal atomic absorption spectrometric detection (CE-ETAAS) in combination with circular dichroism and Fourier transform infrared spectroscopy. The CE-ETAAS assay allows sensitive probing of the level of DNA damage by mercury species, extraction of thermodynamic and kinetic information on the interactions of mercury species with DNA, and provides direct evidence for the formation of mercury species-DNA adducts. The binding affinity of mercury species to DNA increases in order of Hg(II) < EtHg(I) approximately PhHg(I) approximately MeHg(I). The interactions of mercury species with DNA follow a first-order kinetics for mercury species and zero-order kinetics for DNA. Mercury highly covalently coordinates to endocyclic and exocyclic N sites of DNA bases. However, the interactions of DNA with mercuric species cause no transition of the DNA original conformation. The results reveal that organomercuric species exhibit stronger affinity and faster binding to DNA and show more potential damage to DNA than Hg(II) in view of the kinetic and thermodynamic evaluations. Moreover, MeHg(I) exhibits the fastest binding to DNA, suggesting that MeHg(I) enjoys superiority over the other mercuric species for rapid formation of a stable complex with DNA, whereas Hg(II) shows the slowest binding to DNA. The present study provides new evidence and understanding of the binding modality of mercuric species to DNA.

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Carbonaceous mesophases are discotic nematic liquid crystals that are spun into high performance carbon fibers using the melt spinning process. The spinning process produces a wide range of different fiber textures. Planar polar (PP) and planar radial (PR) textures are two ubiquitous ones. This paper presents theory and simulation of the texture formation process using the Landau-de Gennes mesoscopic theory for discotic liquid crystals. The computed PP and PR textures phase diagram, given in terms of temperature and fiber radius, is presented to establish the processing conditions and geometric factors that lead to the selection of these textures. Thin fibers adopt the PR texture, while thicker fibers and higher temperatures adopt the PP texture. The influence of elastic anisotropy to the formation of textures and structure is thoroughly characterized.