Zhen-Gang Zhao

The antibiotic activity and mechanisms of sugarcane (Saccharum officinarum L.) bagasse extract against food-borne pathogens.

Sugarcane bagasse contains natural compositions that can significantly inhibit food-borne pathogens growth. In the present study, the phenolic content in sugarcane bagasse was detected as higher than 4 mg/g dry bagasse, with 470 mg quercetin/g polyphenol. The sugarcane bagasse extract showed bacteriostatic activity against the growth of Staphylococcus aureus, Listeria monocytogenes, Escherichia coli and Salomonella typhimurium. Additionally, the sugarcane bagasse extract can increase the electric conductivity of bacterial cell suspensions causing cellular leaking of electrolytes. Results of sodium dodecyl sulfate polyacrylamide gel electrophoresis suggested the antibacterial mechanism was probably due to the damaged cellular proteins by sugarcane bagasse extract. The results of scanning electron microscopy and transmission electron microscopy showed that the sugarcane bagasse extract might change cell morphology and internal structure.

Changes in the initial stages of a glucose-proline Maillard reaction model system influences dairy product quality during thermal processing

The Maillard reaction always occurs during the thermal processing of dairy products, which significantly influences their quality. In the present study, the initial stages of a glucose-proline model system were investigated in water and different types of buffer solutions. Results showed that phosphate buffer accelerated the reversible degradation of the initial stages of the reaction. The proposed catalysis mechanism was that hydrogenous and dihydric phosphate radical anions simultaneously accepted and donated protons for the conversion of the intermediates into N-glycosylamine. The catalysis mechanism was confirmed via testing and no reducing of hydrogenous and dihydric phosphate radical anions was observed during the reaction. Moreover, both N-(1-deoxy-D-fructos-1-yl)proline and its degradation compounds were analyzed. Results showed that degradation of N-(1-deoxy-D-fructos-1-yl)proline to form 5-hydroxymethyl-2-furaldehyde and formic acid was also accelerated by phosphate buffer. An interesting phenomenon was that citrate decreased 5-hydroxymethyl-2-furaldehyde formation, which might be because Strecker-type degradation occurred more easily than 1,2-enolization reaction in citrate buffer solution. However, this hypothesis has not been confirmed, and element label experiments should be carried out in the future.

Separation and determination of 4-methylimidazole, 2-methylimidazole and 5-hydroxymethylfurfural in beverages by amino trap column coupled with pulsed amperometric detection

A method for simultaneous determination of 4-methylimidazole (4-MeI), 2-methylimidazole (2-MeI) and 5-hydroxymethylfurfural (HMF) in beverages was developed using solid-phase extraction (SPE) and amino trap column coupled with pulsed amperometric detection (AMTC-PAD). A single amino trap column (P/N: 046122) was first applied to separate the targeted analytes in samples after SPE pretreatment. This method demonstrated low limit of quantification (0.030mg/L for methylimidazoles and 0.300mg/L for HMF) and excellent linearity with correlation of determination (R(2)=0.999 for 2-MeI, 0.997 for 4-MeI and 0.998 for HMF). Nearly no 2-MeI was found in all soft drinks. However, 4-MeI could be detected in cola drinks and soft drinks containing caramel colour (ranging from 0.13 to 0.34mg/L), whereas HMF were only found in cola drinks (ranging from 1.07 to 4.47mg/L). Thus, AMTC-PAD technique would be a valid and inexpensive alternative to analysis of 4-MeI, 2-MeI and HMF.

Simultaneous Analysis of 2- and 4-Methylimidazole in Caramel Color and Soft Drinks Using IC-PAD with Post-Column Addition of Hydroxide

High-performance cation exchange chromatography with pulsed integrated amperometric electrochemical detector (HPCEC-PAD) with post-column addition of hydroxide was first developed for simultaneous analysis of 4-methylimidazole (4-MeI) and 2-methylimidazole (2-MeI) in caramel color and soft drinks after solid-phase extraction (SPE). A CS12A cation exchange column was used to separate the targeted analytes with a perfect resolution (2.70). This method demonstrated low limit of quantification (0.05–10xa0mg/L) and excellent linearity with correlation of determination (R2u2009>u20090.999 for 2-MeI and 0.997 for 4-MeI). Low concentrations of 4-MeI were found in five soft drinks, whereas those in caramel color were generally high. Additionally, the suggested method showed higher resolution and sensitivity comparing with previous reported methods for 4-MeI and 2-MeI analyses.

Cytotoxicity and Apoptotic Effects of Polyphenols from Sugar Beet Molasses on Colon Carcinoma Cells in Vitro

Three polyphenols were isolated and purified from sugar beet molasses by ultrasonic-aid extraction and various chromatographic techniques, and their structures were elucidated by spectral analysis. Cytotoxicity and the molecular mechanism were measured by methyl thiazolyl tetrazolium (MTT) assay, flow cytometry, caspase-3 activity assay and Western blot assay. The results showed that gallic acid, cyanidin-3-O-glucoside chloride and epicatechin have cytotoxicity to the human colon, hepatocellular and breast cancer cells. Cyanidin-3-O-glucoside chloride showed its cytotoxicity against various tumor cell lines, particularly against colon cancer Caco-2 cells with half maximal inhibitory concentration (IC50) value of 23.21 ± 0.14 μg/mL in vitro. Cyanidin-3-O-glucoside chloride may be a potential candidate for the treatment of colon cancer. In the mechanism study, cyanidin-3-O-glucoside chloride increased the ratio of cell cycle at G0/G1 phase and reduced cyclin D1 expression on Caco-2 cells. Cyanidin-3-O-glucoside chloride decreased mutant p21 expression, and increased the ratio of Bax/Bcl-2 and the activation of caspase-3 to induce apoptosis.

Poly[[di-μ3-nicotinato-μ3-oxalato-samarium(III)silver(I)] dihydrate]

In the title three-dimensional heterometallic complex, {[AgSm(C6H4NO2)2(C2O4)]·2H2O}n, the SmIII ion is eight-coordinated by four O atoms from four different nicotinate ligands and four O atoms from two different oxalate ligands. The three-coordinate AgI ion is bonded to two N atoms from two different nicotinate anions and one O atom from an oxalate anion. These metal coordination units are connected by bridging nicotinate and oxalate ligands, generating a three-dimensional network. The uncoordinated water molecules link the carboxylate groups via O—H⋯O hydrogen bonding. The crystal structure is further stabilized by hydrogen bonds between the water molecules.

2-Hydr­oxy-1,6,7,8-tetra­meth­oxy-3-methyl­anthraquinone

The title compound, C19H18O7, also known as chrysoobtusin, was isolated from Cassia tora L. (Leguminosae). The anthraquinone ring system is almost planar, the dihedral angle between the two benzene rings being 4.27u2005(4)°. The structure is stabilized by intra- and intermolecular O—H⋯O and C—H⋯O hydrogen bonds, and by weak π–π stacking interactions along the b axis, with a centroid–centroid distance between related benzene rings of 3.800u2005(4)u2005Å.

Short communication: Amino trap column improves the separation of methylimidazoles, 5-hydroxymethyl-2-furaldehyde, and sugars in Maillard reaction.

A simultaneous analysis of methylimidazoles, reducing sugars, and 5-hydroxymethyl-2-furaldehyde in the Maillard reaction was improved by use of an amino trap column. Analysis was carried out by using high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) coupled with an amino trap column. The amino trap column was a useful tool to improve the separation of methylimidazoles, reducing sugars, and 5-hydroxymethyl-2-furaldehyde. This technique is useful for simultaneous analysis of methylimidazoles, reducing sugars, and 5-hydroxymethyl-2-furaldehyde in risk assessment for dairy products.

Poly[[di-μ3-nicotinato-μ3-oxalato-samarium(III)silver(I)] dihydrate]. Corrigendum

Corrigendum to Acta Cryst. (2009), E65, m1105.