•24-Epibrassinolide (EBR) reduced browning on the cut surface of lotus root slices.•EBR alleviated membrane lipid peroxidation and inhibited PAL and PPO activity.•EBR induced POD, CAT and APX activity and suppressed ascorbic acid loss.Fresh-cut lotus root slices were treated with 80 nM 24-epibrassinolide (EBR) and then stored at 4 °C for 8 days to investigate the effects on cut surface browning. The results showed that EBR treatment reduced cut surface browning in lotus root slices and alleviated membrane lipid peroxidation as reflected by low malondialdehyde content and lipoxygenase activity. EBR treatment inhibited the activity of phenylalanine ammonia lyase and polyphenol oxidase, and subsequently decreased phenolics accumulation and soluble quniones formation. The treatment also stimulated the activity of peroxidase, catalase and ascorbate peroxidase and delayed the loss of ascorbic acid, which would help prevent membrane lipid peroxidation, as a consequence, reducing decompartmentation of enzymes and substrates causing enzymatic browning. These results indicate that EBR treatment is a promising attempt to control browning at cut surface of fresh-cut lotus root slices.

•Physicochemical properties of A. cerana honey was reported for the first time;•cerana honey has good antioxidant activity in vitro;•cerana honey improved antioxidant capacity in serum;•Pretreatment with A. cerana honey could prevent acute alcohol-induced liver damage;•More importantly, administration of A. cerana honey remarkably inhibited the expression of TGF-β1.A. cerana honey, gathered from Apis cerana Fabricius (A. cerana), has not been fully studied. Samples of honey originating from six geographical regions (mainly in the Qinling Mountains of China) were investigated to determine their antioxidant and hepatoprotective effects against acute alcohol-induced liver damage. The results showed that A. cerana honeys from the Qinling Mountains had high total phenolic contents (345.1–502.1 mg GA kg− 1), ascorbic acid contents (153.8–368.4 mg kg− 1), and strong antioxidant activities in DPPH radical scavenging activity assays (87.5–136.2 IC50 mg mL− 1), ferric reducing antioxidant powers (191.8–317.4 mg Trolox kg− 1), and ferrous ion-chelating activities (27.5–35.5 mg Na2EDTA kg− 1). Pretreatment with A. cerana honey (Qinling Mountains) at 5, 10, or 20 g kg− 1 twice daily for 12 weeks significantly inhibited serum lipoprotein oxidation and increased serum radical absorbance capacity (ORAC) (P < 0.05). Moreover, A. cerana honey inhibited acute alcohol-induced increases in alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in serum (P < 0.05), reduced the production of hepatic malondialdehyde (MDA) (P < 0.05), and promoted superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities (P < 0.05). More importantly, it also remarkably inhibited the level of TGF-β1 in the serum and liver (P < 0.05). The results of this study indicate that administration of A. cerana honey prevents acute alcohol-induced liver damage likely because of its antioxidant properties and ability to prevent oxidative stress.Download high-res image (163KB)Download full-size image

The amino acid contents of five floral sources Chinese honeys (jujube, rape, chaste, acacia, and lungan) were measured using reversed phase high-performance liquid chromatography (RP-HPLC). The results showed that proline was the main amino acid in most of the analyzed samples. Phenylalanine presents at the highest content in chaste honey samples, and the total amino acid contents of chaste honeys were also significantly higher than those of other honey samples. Based on the amino acid contents, honey samples were classified using chemometric methods (cluster analysis (CA), principal component analysis (PCA), and discriminant analysis (DA)). According to the CA results, chaste honeys could be separated from other honeys, while the remaining samples were correctly grouped together when the chaste honey data were excluded. By using DA, the overall correct classification rate reached 100%. The results revealed that amino acid contents could potentially be used as indicators to identify the botanical origin of unifloral honeys.

In this study, the antioxidant activity and the protective effect against hydrogen peroxide-induced DNA damage were assessed for five honeys of different botanical origin. Seven phenolic acids were detected in the honey samples. Ferulic acid was the most abundant phenolic acid detected in longan honey, jujube honey and buckwheat honey. Ellagic acid, p-hydroxybenzoic acid and protocatechuic acid were the main phenolic acids detected in vitex honey. Of all honey samples tested, the highest total phenolic content and antioxidant activity were found in buckwheat honey, whereas the lowest total phenolic content and antioxidant activity were found in locust honey. Treatment with hydrogen peroxide induced a 62% increase in tail DNA in mice lymphocytes, and all studied honeys significantly inhibited this effect (P < 0.05). The buckwheat honey with higher antioxidant capability also exhibited super protective effect than others. Phenolic extracts of honey displayed greater protective effects than whole honey in comet assay. The hydrogen peroxide-generated increase in 8-hydroxy-2-deoxyguanosine (8-OHdG) was effectively inhibited by the honeys studied (P < 0.05). Moreover, a dose-effect relationship between honey concentration and its protective effect was clearly observed in this study. It can be deduced that phenolic acids of honey can penetrate into lymphocytes and protect DNA from oxidative damage by scavenging hydrogen peroxide and/or chelating ferrous ions.

•We analysed the potential floral markers of the selected honey samples.•We established the fingerprints of the monofloral honey samples.•The classification was performed using phenolic acids and common chromatography peaks.•We demonstrated the accuracy of the method by using 41 test specimens.A total of 77 jujube, longan and chaste honey samples were collected from 18 different areas of China. Thirteen types of phenolic acids in the honey samples were analysed using high-performance liquid chromatography with electrochemical detection (HPLC–ECD). Moreover, HPLC–ECD fingerprints of the monofloral honey samples were established. From the analysis of the HPLC–ECD fingerprints, common chromatography peak information was obtained, and principal component analysis and discriminant analysis were performed using selected common chromatography peak areas as variables. By comparing with phenolic acids as variables, using a chemometric analysis which is based on the use of common chromatography peaks as variables, 36 honey samples and 41 test samples could be correctly identified according to their floral origin.

Honey adulteration with sugar syrups is a widespread problem. Several types of syrups have been used in honey adulteration, and there is no available method that can simultaneously detect all of these adulterants. In this study, we generated a small-scale database containing the specific chromatographic and mass spectrometry information on sugar syrup markers and developed a simple, rapid, and effective ultrahigh-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UHPLC/Q-TOF-MS) method for the detection of adulterated honey. Corn syrup, high-fructose corn syrup, inverted syrup, and rice syrup were used as honey adulterants; polysaccharides, difructose anhydrides, and 2-acetylfuran-3-glucopyranoside were used as detection markers. The presence of 10% sugar syrup in honey could be easily detected in <30 min using the developed method. The results revealed that UHPLC/Q-TOF-MS was simple and rapid.

The identification of three light-coloured unifloral honeys was accomplished in this work. Chromatographic fingerprints were obtained through high performance liquid chromatography-electrochemical detection (HPLC-ECD). From the established chromatographic fingerprints, 17 common peaks with relatively high responses were selected as variables for classification. All 40 honey samples (including linden, Vicia villosa Roth and rape honeys) were correctly classified according to their botanical origin using a chemometric method. Additionally, several physicochemical parameters and the content of phenolic acids in the samples were determined. Using physicochemical parameters and phenolic profiles as variables, the overall correct classification rate reached 97.5% and 100%, respectively. The results indicated that the information obtained from the chromatographic ECD fingerprints was useful for the identification of the floral origin of the three light-coloured honeys.

•We studied the effects of honey processing on nitrofuran levels.•We described an environment-friendly method that can remove nitrofurans from honey.•LS-901 resin was selected as the optimal resin for removing nitrofurans from honey.•Resin-treated honey can be safely used as winter feed for honeybees.There is increasing concern that the presence of antibiotics such as nitrofurans in animal-derived food products is harmful to human. This study originally assessed the effects of different honey processing steps on the stabilities of four nitrofuran metabolites (3-amino-2-oxazolidone, 1-aminohydantonin, semicarbazide and 3-amino-5-morpholinomethyl-2-oxazolidone). Macroporous adsorption resins (MARs) were evaluated for the removal of these residues. Nitrofuran metabolites were analysed by LC–MS/MS after each processing step. The results revealed that honey processing reduced nitrofuran metabolites in honey and the total loss was from 56.6% to 90.4%. Furthermore, LS-901 was the optimum MAR with adsorption rates of 69.9–91.8% for four metabolites. After removing nitrofuran metabolites, the honey could be safely used as winter feed for honeybees.

In the present study, phenolic compounds are extracted from the date plum persimmon fruits using water, methanol and acetone as solvents. Antioxidant activities of the phenolic extracts are measured using four different tests, namely, DPPH, hydroxyl radical scavenging activities, chelating and reducing power assays. All the extracts show dose dependent DPPH radical scavenging activity, reducing and chelating powers and moreover, they are well correlated with the total phenolic and total flavonoid substances, suggesting direct contribution of phenolic compounds to these activities. In further, the extracts are identified and quantified by HPLC-ECD. Results show that gallic acid is the most abundant phenolic compound, with amounts ranging between 45.49and 287.47 μg/g dry sample. Myricetin is the dominant flavonoid in all extracts. Its level varied from 2.75 μg/g dry sample in acetone extract to 5.28 μg/g dry sample in water extract. On the basis of the results obtained, the date plum persimmon fruits phenolic extract is a potential source of natural antioxidants owing to its significant antioxidant activities.

The adulteration of honey is generally a concern of consumers and management departments of safety and quality. Adding low-price honey to high-price honey is often seen in the market. In this study, a reliable and simple method of liquid chromatography–electrochemical detection (LC-ECD) was presented to detect the adulteration of acacia honey which was added with rape honey at different levels (5–50 %, w/w). Chromatographic separation was carried out with a reversed phase column, and the mobile phase was methanol/2 % (v/v) aqueous acetic acid. Fingerprints of authentic honeys showed that the contents of chlorogenic acid were higher in acacia honey (1.738 mg kg−1), while those of ellagic acid were much lower (0.274 mg kg−1) in rape honey, so the chlorogenic acid and ellagic acid could be considered as possible markers of acacia and rape honeys, respectively. Samples were classified by cluster analysis and principal component analysis (PCA) according to the contents of phenolic acids. The results of PCA showed that chlorogenic acid and ellagic acid were the major variables, and no adulterated sample was identified as authentic honey. The results of cluster analysis (CA) indicated that the samples were appropriately divided into three main clusters, and adulterated samples were identified. Therefore, acacia honey adulteration with rape honey could be undoubtedly detected by LC-ECD combined with chemometric methods down to the level of 5 %.

A simple, accurate and inexpensive high performance liquid chromatography with electrochemical detection (HPLC-ECD) method for the simultaneous separation and determination of the three synthetic estrogens including diethylstilbestrol, dienestrol, and hexestrol in milk was established. For the sample treatment procedure, acetonitrile was added to the milk sample, the mixture was vortex mixed, centrifuged, concentrated by evaporation and determined by HPLC-ECD. The detection and quantification limits of the three estrogens obtained with ECD were lower than those obtained by diode array detection (DAD). Calibration curves, limit of detection and recoveries of diethylstilbestrol, dienestrol, and hexestrol with ECD ranged from 0.04 to 24 μg ml−1, 4.7 × 10−3 to 7.1 × 10−3 μg ml−1, and 83 to 103%, respectively. Meanwhile, the effect of thermal treatment on the stability of the estrogens was investigated, and the results showed that these compounds initially decreased by 26% for diethylstilbestrol, 32% for dienestrol, and 41% for hexestrol after five minutes of heat treatment, then remained stable with increasing duration of heat treatment. The method was applied to the determination of the three synthetic estrogens in authentic milk samples.

The chelation between luteolin and Cr(III) ion is studied using the theoretical methods. Many different potential complexes, formed with natural and deprotonated luteolin chelating bare and hydrated Cr(III) ion, respectively, are studied by using Density Functional Theory method. Both total and binding energies are calculated. The results from the studies indicate that Cr(III) ion is affine in forming a complex with luteolin at the 5-hydroxy-4-keto site and that deprotonated luteolin has stronger chelating power than natural luteolin. The reactivity differences between luteolin and luteolin–Cr(III) complexes are observed through comparison of their Conceptual DFT reactivity indices. Apart from the theoretical studies, the experiments are performed to modify the theoretical conclusions. Meanwhile, luteolin–Cr(III) complex has been synthesized, and the chelation site is analyzed using IR spectroscopy and UV/vis spectrum. The experimental results are found to have the same conclusions as those by theoretical studies.Highlights► Cr(III) ion is inclined to chelate at 5-hydroxy-4-keto site of luteolin. ► The reactive activity of luteolin–Cr(III) complex is higher than that of luteolin. ► Luteolin and luteolin–Cr(III) complex have different nucleophilic region.

A sensitive and accurate method for simultaneous separation and determination of four phenolic compounds, including caffeic acid, p-coumaric acid, ferulic acid, and hesperetin in Chinese citrus honey by high performance liquid chromatography using electrochemical detection (HPLC-ECD) has been established. Chromatographic separation was performed using a reversed phase column and methanol/4% (v/v) aqueous acetic acid as the mobile phase. The detection and quantification limits of the four compounds with ECD were 6–14 times greater than those obtained with diode-array detection (DAD). All calibration curves of the four phenolic compounds showed good linearity (r ⩾ 0.9994) within the test ranges, 1.10–66 μg/ml, 0.35–70 μg/ml, 0.16–16 μg/ml and 0.03–10 μg/ml, respectively. The recoveries ranged from 98.9% to 100.3%. The extraction process was very simple, because of the dissolution of honey only involving water. Taken together, the application of ECD in honey determination leads to a significant improvement in the quantification of phenolic compounds, whereby paying the way for the establishment of a better quality control of citrus honey.

Flavonoid–metal complex is reported to exhibit a higher antioxidant activity than parent flavonoid. In this paper, experimental and theoretical methods are applied to study the antioxidant properties of quercetin and quercetin–Cr(III) complex, to find out the antioxidant activity variation and the role of Cr(III) ion on the antioxidant activity of the complex. Bond dissociation energy (BDE) and ionization potential (IP) of quercetin and the complex are calculated at the B3LYP/6-311++G(2d,2p)//B3LYP/LANL2DZ level. The experimental results show that the complex has a higher DPPH radical scavenging activity than quercetin. The calculated results show that the complex displays lower BDE and IP than quercetin. The IP of the complex declines obviously, indicating that the Cr (III) ion has more impact on the electron donating ability than on the hydrogen atom transferring ability of the complex.

In order to locate the exact chelation site, the chelation between quercetin and Cr(III) ion is studied using the theoretical methods. Many different potential complexes, formed with natural and deprotonated quercetin chelating bare and hydrated Cr(III) ion, respectively, are studied by using Density Functional Theory method. Both total and binding energies are calculated. The results from the studies indicate that Cr(III) ion is affine in forming a complex with quercetin at the 5-hydroxy-4-keto site and that deprotonated quercetin has stronger chelating power than natural quercetin. Apart from the theoretical studies, the experiments are performed to modify the theoretical conclusions. Meanwhile, quercetin–Cr(III) complex has been synthesized, and the chelation site is analyzed using IR spectroscopy and UV/vis spectrum. The experimental results are found to have the same conclusions as those by theoretical studies.

A simple, accurate and inexpensive high performance liquid chromatography with electrochemical detection (HPLC-ECD) method for the simultaneous separation and determination of the three synthetic estrogens including diethylstilbestrol, dienestrol, and hexestrol in milk was established. For the sample treatment procedure, acetonitrile was added to the milk sample, the mixture was vortex mixed, centrifuged, concentrated by evaporation and determined by HPLC-ECD. The detection and quantification limits of the three estrogens obtained with ECD were lower than those obtained by diode array detection (DAD). Calibration curves, limit of detection and recoveries of diethylstilbestrol, dienestrol, and hexestrol with ECD ranged from 0.04 to 24 μg ml−1, 4.7 × 10−3 to 7.1 × 10−3 μg ml−1, and 83 to 103%, respectively. Meanwhile, the effect of thermal treatment on the stability of the estrogens was investigated, and the results showed that these compounds initially decreased by 26% for diethylstilbestrol, 32% for dienestrol, and 41% for hexestrol after five minutes of heat treatment, then remained stable with increasing duration of heat treatment. The method was applied to the determination of the three synthetic estrogens in authentic milk samples.

The identification of three light-coloured unifloral honeys was accomplished in this work. Chromatographic fingerprints were obtained through high performance liquid chromatography-electrochemical detection (HPLC-ECD). From the established chromatographic fingerprints, 17 common peaks with relatively high responses were selected as variables for classification. All 40 honey samples (including linden, Vicia villosa Roth and rape honeys) were correctly classified according to their botanical origin using a chemometric method. Additionally, several physicochemical parameters and the content of phenolic acids in the samples were determined. Using physicochemical parameters and phenolic profiles as variables, the overall correct classification rate reached 97.5% and 100%, respectively. The results indicated that the information obtained from the chromatographic ECD fingerprints was useful for the identification of the floral origin of the three light-coloured honeys.