Peipei Yu

Synthesis, Characterization, and Antimicrobial Activity of Kojic Acid Grafted Chitosan Oligosaccharide

A novel water-soluble chitosan oligosaccharide (COS) derivative, chitosan oligosaccharide/kojic acid grafts assigned as COS/KA, was prepared by using the selective partial alkylation of N-benzylidene COS and chlorokojic acid in the presence of dimethyl sulfoxide (DMSO) and pyridine (Py). The derivative was characterized by UV-vis spectroscopy, FTIR, (1)H NMR, TGA, SEM, and XRD techniques, which showed that the alkylation reaction took place at the C-6 and C-3 positions of COS. The results showed that the degree of substitution (DS) for COS/KA was from 0.38 to 1.21, and the product exhibited an excellent solubility in organic solvents and distilled water. The antibacterial results indicated that the antibacterial activity of COS/KA was strengthened relative to COS with the increase of DS for Staphylococcus aureus , Escherichia coli , Aspergillus niger and Saccharomyces cerevisiae . These findings provide important supports for developing new antibacterial agents and expand the scope of application of COS in the food industry.

Effect of kojic acid-grafted-chitosan oligosaccharides as a novel antibacterial agent on cell membrane of gram-positive and gram-negative bacteria.

Our work here, for the first time, reported the antibacterial activity of kojic acid-grafted-chitosan oligosaccharides (COS/KA) against three gram-positive and three gram-negative bacteria. Integrity of cell membrane, outer membrane (OM) and inner membrane (IM) permeabilization assay, alkaline phosphatase (ALP) and glucose-6-phosphate dehydrogenase (G6PDH) assay, and SDS-PAGE assay techniques were used to investigate the interactions between COS/KA and bacterial membranes. The antibacterial activity of COS/KA was higher than those of unmodified COS. The electric conductivity of bacteria suspensions increased, followed by increasing of the units of average release for ALP and G6PDH. COS/KA can also rapidly increase the 1-N-phenylanphthylamine (NPN) uptake and the release of β-galactosidase via increasing the permeability of OM and IM in Escherichia coli. SDS-PAGE indicated the content of cellular soluble proteins decreased significantly in COS/KA-treated bacteria. Hence, COS/KA has potential in food industry and biomedical sciences.

Chitosan oligosaccharide-N-chlorokojic acid mannich base polymer as a potential antibacterial material

Here, a nontoxic antibacterial material based on Chitosan Oligosaccharide-N-Chlorokojic acid Mannich base (COS-N-MB) that was synthesized by using the selective partial alkylation reaction displaying excellent activity against bacterial infection. The proposed mechanism of the action of COS-N-MB is that this antibacterial material with positive charge and synergistic antibacterial effects can promote its adsorption to bacterial cell wall through electrostatic interaction and chelating metal cations. It changed the permeability of the membrane, caused cellular leakage, and destroyed the membrane integrity, leading to complete membrane disruption and eventually death of the bacteria. Besides, COS-N-MB can interact with membrane proteins, causing deformation in the structure and functionality. The good biocompatibility, noncytotoxic, and low hemolysis made this novel material a promising and effective compound for antibacterial applications.

Protective effects of lipid extract from brains of silver carp against oxidative damage in HEK-293 cells

Previous studies verified the protective effects of fish lipids against diseases caused by oxidative damage. Fish brains are rich in lipids. However, the actions and mechanisms of fish brain lipids on potent antioxidant activities remain unclear. In this study, total lipids (TLs) extracted from silver-carp brain were separated into neutral lipids (NLs) and polar lipids (PLs), and the protective roles of lipid fractions (LFs) against H2O2-induced oxidative damage were examined in a human embryonic kidney 293 (HEK-293) cell line. LFs effectively resisted H2O2-induced oxidative injury in HEK-293 cells by reducing cellular reactive oxygen species levels, protecting cellular antioxidant enzyme systems, inhibiting cell apoptosis and necrosis, and diminishing loss of mitochondrial-membrane potential. Among the TLs, PLs surpassed NLs in conferring antioxidant activities. The present study may help to explain the protective role of fish lipids against diseases caused by oxidative damage and promote fish-brain-derived lipids as potential preventive and therapeutic agents for human health.

Lipid Extracts from the Brains of Silver Carp (Hypophthalmichthys molitrix) Induce Apoptosis in MCF-7 Cells through the Generation of Reactive Oxygen Species and the Mitochondrial Pathway

ABSTRACT Previous studies have verified the protective role of n3 polyunsaturated fatty acids (PUFAs) in cancer. Fish brain lipids are rich in n3 PUFAs. However, the action and mechanism of their potent anticancer activities remain unclear. In this study, polar lipids (PLs) and neutral lipids (NLs) were isolated from the total lipids (TLs) of the silver carp brain, and the anticancer effects of the lipid fractions (LFs) were examined in a human breast cancer cell line (MCF-7). The LFs effectively inhibited the cell proliferation of MCF-7 cells in a time- and concentration-dependent manner by cell cycle arrest at the S stage and induction of apoptosis. Further analyses showed that the apoptotic effect of the LFs on MCF-7 cells was associated with the accumulation of elevated levels of reactive oxygen species and the loss of mitochondrial membrane potential. Among the TLs, PLs were more effective at causing breast cancer cell death than NLs. Our study showed that the LFs from silver carp brains may aid the prevention and treatment of human breast cancer.