Wei Cao

Identification of monofloral honeys using HPLC–ECD and chemometrics

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.

Melatonin treatment reduces chilling injury in peach fruit through its regulation of membrane fatty acid contents and phenolic metabolism

Effects of 0.1u202fmM melatonin (MT) on chilling injury (CI), membrane fatty acid content and phenolic metabolism in peach fruit were studied during storage at 1°C for 28u202fdays. MT treatment delayed the development of CI in peach fruit, as was illustrated by MT-treated fruit showing lower CI incidence, CI index and firmness loss than the control. MT treatment prevented membrane lipid peroxidation and contributed to maintaining a higher ratio of unsaturated to saturated fatty acids in peach fruit. MT treatment also stimulated the activities of glucose-6-phosphate dehydrogenase, shikimate dehydrogenase and phenylalanine ammonia lyase, but inhibited the activities of polyphenol oxidase and peroxidase. This would help in activating the accumulation of total phenolic and endogenous salicylic acid that might have a direct function in alleviation of CI. These results indicate that MT treatment can be an effective technique to reduce postharvest CI during low temperature storage of peach fruit.

A modified FOX-1 method for Micro-determination of hydrogen peroxide in honey samples

Hydrogen peroxide (H2O2) is a major antibacterial activity-associated biomarker in honey. Measurement of endogenous H2O2 in honey is of great value in prediction of the H2O2-depended antibacterial activity and characterization or selection of honey samples for their use as an antibacterial agent or natural food preservative. Considering current methods for H2O2 determination are either time-consuming or complicated with their high-cost, a study was conducted to modify and validate the spectrophotometry-based ferrous oxidation-xylenol orange (FOX-1) method for micro-determination of H2O2 in honey samples. The result suggested that the proposed FOX-1 method is fast, sensitive, precise and repeatable. The method was successfully applied for the analysis of a total of 35 honey samples from 5 floral origins and 33 geographical origins. The proposed method is low-cost and easy-to-run, and it can be considered by researchers and industry for routine analysis.

Effects of 24-epibrassinolide on enzymatic browning and antioxidant activity of fresh-cut lotus root slices

Fresh-cut lotus root slices were treated with 80nM 24-epibrassinolide (EBR) and then stored at 4°C for 8days 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.

Identification of botanical origin of Chinese unifloral honeys by free amino acid profiles and chemometric methods

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.

The Protective Effect of Whole Honey and Phenolic Extract on Oxidative DNA Damage in Mice Lymphocytes Using Comet Assay

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 (Pxa0<xa00.05). 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 (Pxa0<xa00.05). 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.

Hepatoprotective standardized EtOH–water extract from the seeds of Fraxinus rhynchophylla Hance

Fraxinus rhynchophylla Hance (Oleaceae), its stem barks are known as Cortex fraxini (秦皮 qín pí) listed in Chinese Pharmacopoeia. Phytochemical study has indicated that methanol extracts from Qinpi has protective effect on acute liver injury. The present study investigates the hepatoprotective activity of EtOH–water extract from the seeds of F. rhynchophylla Hance against carbon tetrachloride-induced liver injury in mice. The EtOH–water extract significantly alleviated liver damage as indicated by the decreased levels of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST), the malondialdehyde (MDA) content, and increased the levels of superoxide dismutase (SOD), glutathione (GSH) and glutathione peroxidase (GSH-Px), and reduced the pathological tissue injury induced by CCl4. Quantitative analysis of seven major constituents (1–7) in EtOH–water extract (EWE) was developed by high performance liquid chromatography-diode-array detector (HPLC-DAD). The current research indicates that the EWE from the seeds of F. rhynchophylla Hance decreased liver index, inhibited the increase of serum aminotransferase induced by CCl4, and decreased hepatic MDA content, SOD and GSH-Px activities. These results suggested that the pretreatment with EWE protected mice against CCl4-induced liver injuries. Based on the results, the EtOH–water extract from the seeds of F. rhynchophylla Hance is efficacious for prevention and treatment of CCl4-induced hepatic injury in mice. Secoiridoid and tyrosol glucosides might be the active ingredients responsible for the biological and pharmacological activities of hepatoprotection.

Hepatoprotective Effects of the Honey of Apis cerana Fabricius on Bromobenzene-Induced Liver Damage in Mice: Hepatoprotective effects of A. cerana honey…

Apis cerana honey (honey of Apis cerana Fabricius), widely distributed in the mountain areas of East Asia, has not been studied fully. The hepatoprotective activity of A. cerana honey was evaluated against bromobenzene-induced liver damage in mice. In high dose, A. cerana honey can significantly alleviate liver injury, as is indicated by the depressed levels of serum alanine aminotransferase (ALT) (59.13%) and aspartate aminotransferase (AST) (79.71%), the inhibited malondialdehyde (MDA) content (63.30%), the elevated activities of superoxide dismutase (SOD) (73.12%) and glutathione-Px (57.24%), and the decreased expression of Transforming growth factor β1 (51.83%) induced by bromobenzene (P < 0.05). The quantitative analysis of twelve major constituents (1 to 12) of A. cerana honey was executed by high performance liquid chromatography-diode array detector. The results indicate that treatment with A. cerana honey can prevent bromobenzene-induced hepatic damage in mice. Polyphenols might be the bioactive substances attributed to its antioxidant properties and intervention of oxidative stress.

Determination and distribution of biogenic amines in bee pollen

The natural decomposition of proteins yields peptides and amino acids, which are susceptible to further decay, resulting in formation of biogenic amines (BAs) in proteinaceous foods such as bee pollen (BP). However, excessive consumption of BAs will bring side effects, so it is vital to study the presence of BAs in BP. In this study, a sensitive and reliable ultra-high-performance liquid chromatography–tandem mass spectrometric method was used for the determination of 12 BAs in BP. Large variations in the distribution and levels of BAs were observed with its total concentrations ranging from 6837.4 to 25444.2xa0μgxa0kg−1. In addition, the changes in the levels of BAs during storage and fermentation were preliminarily investigated. The results showed that fermentation significantly altered the quantities of BAs in rape BP, while changes during storage were modest. The results of this study could be applied for quality evaluation and risk assessment of BP in near future.

Novel electrochemical sensing platform for ultrasensitive detection of cardiac troponin I based on aptamer-MoS 2 nanoconjugates

Cardiac troponin I (cTnI) is a specific and sensitive biomarker for the early diagnosis of acute myocardial infarction and for the subsequent clinical treatments. In this work, novel electrochemical sensing platform for sensing of cTnI based on aptamer-MoS2 nanoconjugates was proposed. For comparison, core-shell Au@SiO2@Au nanoparticles were also used for sensing of cTnI. The sensing schemes and electrochemical responses of the proposed sensors were investigated by electrochemical impedance spectroscopy (EIS) in 5.0u202fmM K3[Fe(CN)6]/K4[Fe(CN)6] (1:1) solution containing 0.1u202fM KCl, respectively. Results showed that the aptamer-Au@SiO2@Au based aptasensor shows a linear rage of 10u202fpM-10.0u202fμM with the detection limits of 1.23u202fpM For the aptamer-MoS2 nanosheets based aptasensor, the linear range for cTnI detection was from 10u202fpM to 1.0u202fμM with a lower detection limit of 0.95u202fpM Meanwhile, both the sensors were successfully applied for detection of cTnI in human blood samples. The two kinds of aptsensors have been successfully used for detecting of cTnI in human blood serums. Moreover, no negligible signal changes could be observed in the presence of non-targets of CK-MB and Myo, suggesting the good potential for clinic diagnosis.