•The low absorption rate of tea polyphenols impedes their bioactivity in vivo.•Nanoparticle delivery system based on chitosan can enhance absorption of bioactive compounds.•The fabrication methods and potential benefits of chitosan nanoparticles in tea polyphenols delivery were described.•The challenges and future trends of chitosan nanoparticles as a carrier for oral delivery of tea polyphenols are discussed.Tea polyphenols find a wide range of applications in food, medical and pharmaceutical fields owing to their multi-health benefits including antioxidant and antibacterial activities, cancer prevention, anti-radiation and immune enhancement. However, the low absorption rate of tea polyphenols impedes their bioactivity in vivo. The low absorption and bioavailability have been attributed to their poor stability, passive diffusion, and active efflux in the gastrointestinal (GI) tract. Nanoparticle delivery system based on chitosan (CS), a natural biomaterial, has been widely applied in pharmaceutical field to enhance absorption of bioactive compounds. A few studies reported the enhanced absorption and bioavailability of tea polyphenols by the application of chitosan nanoparticles. This review describes the fabrication methods and potential benefits of chitosan nanoparticles as delivery systems for tea polyphenols for their enhanced absorption in the GI tract. In addition, challenges and future trends of chitosan nanoparticles as a carrier for oral delivery of tea polyphenols are also discussed.Chitosan nanoparticles enhance the intestinal absorption of tea polyphenols.Download high-res image (93KB)Download full-size image

Both enantiomers of (3Z,9Z)-cis-6,7-epoxy-3,9-octadecadiene, one of which is the major component of the sex pheromone of Ectropis oblique Prout, were synthesized in 23% overall yield for the (−)-(6S,7R)-enantiomer and 18% yield for the (+)-(6R,7S)-isomer. This protocol uses a sequential regioselective ring-opening strategy and provides a convenient and reliable access to other structurally related insect sex pheromones. Preliminary biological studies revealed that (−)-(6S,7R)-2a was roughly as active as the natural pheromone, while racemic (±)-2 was less bioactive and (+)-2b was much less bioactive.Download high-res image (80KB)Download full-size image

•EGCG-loaded nanocapsules suspension (NCs) was successfully prepared.•Antioxidant films based on chitosan hydrochloride and EGCG NCs were developed.•The NCs incorporated films exhibited higher DPPH scavenging activity than control.•The NCs incorporated films showed better mechanical properties than control.•The obtained films can be used to protect foodstuffs against photooxidative damage.Antioxidant edible films based on chitosan hydrochloride (CHC) and epigallocatechin gallate (EGCG)-loaded nanocapsules (NCs) were developed. The CHC films incorporated with NCs were prepared by a casting method in three different proportions. The obtained films were characterized using the techniques including scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. Meanwhile, the mechanical and color properties, optical transmittance, EGCG release profile and antioxidant activity were also determined. The addition of NCs to CHC films increased their tensile strength (TS) and the percent elongation at break (%E). Lightness was significantly decreased in the NCs embedded films compared to controls, which in turn led to high antioxidant activity and excellent barrier properties against visible light. EGCG was rapidly released into food simulant although the concentration fluctuates over time. Therefore, these films can prevent the oxidation of fatty food stuffs.

Based on the use of multi-walled carbon nanotubes (MWCNTs) in matrix solid-phase dispersion (MSPD) extraction, a novel, rapid and reliable method was developed for the analysis of 11 photoinitiators used in food packaging ink followed by quantitation by gas chromatography-tandem mass spectrometry. The use of MWCNTs was compared with that of the adsorbents C18 silica and diatomaceous earth (DE) in the MSPD procedure. The extracts obtained using MWCNTs were better than those obtained using C18 and DE. Using the newly developed method, recoveries ranged from 70.9% to 121.4%, the RSDs were between 0.1% and 3.5%, and the LOQs ranged from 0.002–0.008 mg kg−1. This method was used to test the degree of migration of the photoinitiators into food, showing that the migration into tea powder increased with increasing initial concentration of the pollutants, while this phenomenon was not found in milk powder. The ability of the photoinitiators to migrate into food matrices was shown to be closely related to their molecular weight and to their molecular conformation, as well as the particular characteristics of the food matrix.

•EGCG encapsulated CS NPs coated with zein was prepared.•EGCG release was relatively higher from zein/CS NPs in 95% ethanol fatty simulant.•EGCG encapsulated zein/CS NPs was higher DPPH scavenging activity than the control.•Zein/CS NPs could be as a promising encapsulation and delivery system for EGCG.The objective of this study was to prepare chitosan nanoparticles (CS NPs) coated with zein as a promising encapsulation and delivery system for epigallocatechin gallate (EGCG). The factors influencing the nanoparticle fabrication, including zein concentration, zein/chitosan weight ratio and EGCG encapsulation percentage, were systematically investigated. The physicochemical and structural analysis showed that the electrostatic interactions and hydrogen bonds were the major forces responsible for nanoparticles formation. The transmission electron microscopy study revealed the spherical nature with smooth surface of obtained nanoparticles. The release profile of EGCG showed a burst effect, followed by slow release. EGCG release was relatively higher from zein/chitosan nanoparticles (zein/CS NPs) with higher DPPH scavenging activity, than that of NPs without zein coating in 95% ethanol fatty simulant. These results indicated that controlled-release of EGCG from zein/CS NPs and its corresponding antioxidant activities in 95% ethanol fatty simulant may provide long-term protection against oxidation for fatty foods.

To explore the potential of theanine against cancer, we have studied the anticancer activities of theanine from tea and its semisynthesized derivative, (R)-2-(6,8-dibromo-2-oxo-2H-chromene-3-carboxamido)-5-(ethylamino)-5-oxopentanoic ethyl ester (DTBrC), in in vitro, ex vivo, and in vivo models of human hepatocellular carcinoma (HHC). Theanine and DTBrC displayed inhibitory effects on the growth and migration of HHC cells in vitro, ex vivo, and in vivo. Theanine and DTBrC significantly enhanced the repression of HHC cell growth in combination with anticancer drug pirarubicin. Theanine and DTBrC completely suppressed HGF- and EGF+HGF-induced migration with a reduction of p53 tumor suppressor level and enhanced the p53 protein expression in HHC cells. The Akt and NF-κB knockdown greatly reduced cancer cell migration with a decrease in CD44 expression. DTBrC and theanine significantly repressed the protein expressions in the Met/EGFR/VEGFR-Akt/NF-κB pathways, which might be the mechanism for their biologic effects.Keywords: DTBrC; human hepatocellular carcinoma; inhibition; signaling pathways; theanine;

Gallic acid, caffeine, catechins and amino acids in different grades of white teas and white teas under different storage times were determined in this study. The qualitative analysis was carried out on the main chemical components in white teas by ultra-performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry (UPLC-QQQ-MS/MS). A total of 29 compounds were detected in white teas. The results showed that contents of total catechins and caffeine decreased with grades reducing. The middle-grade of white tea, Gong Mei, contained the amino acids at the highest content of 53.606 mg g−1, while the low grade Shou Mei contained the lowest (14.848 mg g−1). It was observed that contents of catechins and amino acids showed a similar tendency to decrease with storage times, while gallic acid increased with storing time (from 0.770 to 1.420 mM). This study suggested that high- and low-grade white tea should not be distinguished solely based on a single characteristic component or by market price, as well as providing an important basis for changes in characteristic components in white tea of different storage times.

Tea (Camellia sinensis (L.) O. Kuntze) hyper-accumulates fluoride (F), mainly in the leaves. To understand how tea copes with the stress caused by F, we tracked photosynthesis, antioxidant defense, and cell ultrastructure under different F concentrations (0–50 mg L−1). High F (≥5 mg L−1) caused decreases in photosynthetic and chlorophyll fluorescence parameters. Activated oxygen metabolism was altered by F, as manifested in increasing lipid peroxidation, electrolyte leakage (EL), and accumulation of H2O2. The activities of ascorbate peroxidase (APX, EC 1.11.1.1) and catalase (CAT, EC 1.11.1.6) increased at 0–5 mg L−1 F, but sharply decreased less than 10–50 mg L−1 F. The activity of manganese superoxide dismutase (Mn-SOD, EC 1.15.1.1) decreased with increasing F concentration. Expression of genes encoding antioxidant enzymes were in accordance with their measured activities. The results suggest that the antioxidant enzymes in the tea plant can eliminate reactive oxygen species (ROS) at <5 mg L−1 F, but not at 20–50 mg L−1 F. High F increased the number of epidermal hairs on tea leaves and decreased the stomatal aperture, reducing water loss. The leaf cellular structure appeared normal under 1–50 mg L−1 F, although starch grains in chloroplast increased with increasing F. Proline and betaine play important roles in osmotic regulation in tea plant tolerating F stress. ROS scavenging and greater number of epidermal hairs are likely parts of the tea plant F-tolerance mechanism.

In this paper, a novel type of adsorbent was prepared by loading Al/Zr onto carboxymethyl starch sodium to generate CMS–Al, CMS–Zr or CMS–Al–Zr. The adsorbents were tested for removal of fluoride by batch adsorption experiments under various conditions. It was found that CMS–Al–Zr performed well over a considerably wide pH range of 4–10. The adsorption process could be described by a Langmuir isotherm model and Lagergren pseudo-second-order kinetic model. The maximum adsorption capacity for CMS–Al–Zr (60.61 mg g−1) was higher than CMS–Al (51.44 mg g−1) and CMS–Zr (40.23 mg g−1) due to synergistic interactions between Al and Zr. SEM, EDS, XRD, FTIR and XPS studies revealed the Al/Zr loading process and mechanism of fluoride adsorption. The results showed that the metal complex was coordinated to the –COO group of CMS through ion exchange of sodium during the loading process.

A novel and low-cost biosorbent of tea waste supported hydrous aluminium oxide (Tea–APAM–Al) was prepared with help of anionic polyacrylamide (APAM) for highly efficient defluoridation of drinking water. Batch adsorption studies were carried out by varying the adsorbent dosage, initial fluoride concentration, contact time, initial pH, and presence of co-existing ions to evaluate the efficiency of fluoride removal. It was found that Tea–APAM–Al performed well over a considerably wide pH range, from 4.0–9.0. With the exception of bicarbonate, other co-existing ions (nitrate, chloride and sulphate) did not have a significant effect on the defluoridation process. The adsorption process could be described by the Lagergren pseudo-second-order kinetic model. Adsorption data could be fitted by the Langmuir isotherm model and the maximum fluoride adsorption capacity for Tea–APAM–Al was 42.14 mg g−1. The results from SEM, EDS, XRD, FTIR and XPS studies showed that the fluoride adsorption mechanism likely involved hydroxyl and sulfate ion exchange with fluoride. Moreover, fluoride anion exchange with sulfate ions was the main mechanism for fluoride adsorption at low initial fluoride concentration.

In Southwest China, tea polyphenols are usually utilized by way of butter tea. Tea polyphenols inhibit the absorption and biosynthesis of fatty acids in vivo, but the effects of butter on the pharmacokinetics of tea polyphenols have drawn less concern. A rapid UHPLC-MS/MS method was used to quantitatively determine the catechins in the plasma, feces and bile of rats after the oral administration of tea polyphenol or its combination with butter. In comparison with the single tea polyphenol treatment, the maximum plasma concentrations (Cmax) of the free EGCG, EGC, EC, GCG, GC and ECG significantly decreased after the co-administration of butter. The mean residence times (MRT) of the free EGCG, EGC, EC, GC and ECG were also significantly prolonged. When the plasma samples were treated with β-glucuronidase and arylsulfatase, the pharmacokinetic parameters of the total catechins (free and conjugated forms) were not affected by the co-administration of butter. These results indicated that the total absorption of catechins was not affected by butter, but the metabolism of catechins had been changed. Furthermore, the fecal catechins were significantly increased by butter. The total fecal amount and excretion ratio of all catechins were increased highly. The biliary excretion of EGCG, EGC, EC, GCG and GC was significantly increased by the co-administration of butter. To sum up, the butter changed the metabolism of catechins in vivo by decreasing the plasma concentration of the free catechins but increasing the conjugated catechins.

A rapid, sensitive and selective ultra-high performance liquid chromatography tandem mass spectrometry method was developed and validated for the determination and pharmacokinetic investigation of seven catechins in rat plasma. The rat plasma was extracted with simple liquid–liquid extraction using ethyl acetate. Plasma sample was separated by UHPLC on a Hypersil GOLD C18 column (1.9 μm, 50 × 2.1 mm) using a mobile phase consisting of methanol–0.05% formic acid in water with gradient elution. The total run time was 10.5 min and seven catechins were efficiently separated. The detection was performed on a selected reaction monitoring using the respective transitions m/z 289.070 → 109.010 for (−)-epicatechin/(+)-catechin, 305.089 → 125.228 for (−)-epigallocatechin/(−)-gallocatechin and 441.150 → 169.325 for (−)-epicatechin gallate and 456.840 → 169.257 for (−)-epigallocatechin gallate/(−)-gallocatechin gallate. Mean recovery of seven catechins was in the range of 84.92–102.18%. The intra- and inter-day precisions (RSD) of these analytes were all less than 6.17% and 5.84%. This method was successfully applied in the pharmacokinetic study of seven catechins in the plasma of rats after oral administration of 700 mg kg−1 tea polyphenols.

An analytical method using gel permeation chromatography (GPC) coupled with gas chromatography-mass spectrometry (GC-MS) was established for the determination of 10 photo-initiators – benzophenone (BP), 2-methyl benzophenone (2-MBP), 1-hydroxycyclohexyl phenyl ketone (Irgacure 184), 3-methyl benzophenone (3-MBP), 4-methyl benzophenone (4-MBP), ethyl 4-dimethylaminobenzoate (EDB), 2,2-dimethoxy-2-phenylacetophenone (Irgacure 651), o-methyl-benzoyl benzoate (OMBB), 2-ethylhexyl-4-dimethylamino benzoate (EHA) and 2-isopropylthioxanthone (ITX) – in plastic food packaging. The plastic samples were treated with ultrasound in cyclohexane/ethyl acetate (1:1, v/v). The extract was cleaned up by gel permeation chromatography. The final solution was subjected to GC-MS using an external standard method for quantitation in selected ion monitoring mode. The 10 target photo-initiators showed linear recovery relationships over the concentrations of 0.005 to 0.2 mg L−1, with r2 > 0.999. The recoveries from spiked samples (0.07 × 10−3, 0.17 × 10−3 and 0.33 × 10−3 mg dm−2 of standard) for each of the 10 photo-initiators ranged from 77.0% to 120.6%, with relative standard deviations (RSDs) of 0.5–13.9%. The limits of detection (LOD) were from 0.03 × 10−3 mg dm−2 to 0.12 × 10−3 mg dm−2. The developed extraction method is simple and yields a sufficiently pure test sample, while the analytical method meets the sensitivity and precision requirements for photo-initiator detection. This method could be routinely used to determine the levels of photo-initiator residues in plastic food packaging.

A rapid UPLC-ESI (+)-MS/MS method was developed and validated for simultaneous determination of eight neonicotinoid insecticides (dinotefuran, nitenpyram, thiamethoxam, clothianidin, imidacloprid, acetamiprid, thiacloprid and imidaclothiz) in tea samples based on a refined QuEChERS extraction method. In order to eliminate the matrix effect and obtain satisfactory recoveries, an inexpensive and excellent absorbent material, polyvinylpolypyrrolidone (PVPP), was used to eliminate polyphenols from tea matrices. Further, combinations of PVPP and the commonly used sorbents PSA and GCB were investigated in this study. The optimized ‘quick, easy, cheap, effective, rugged and safe’ protocol is briefly described as follows. Tea samples were soaked in water and extracted with acetonitrile. Sample extracts were treated with 400 mg PVPP to remove polyphenols from tea matrices, and then cleaned up with a combination of PSA (25 mg), GCB (100 mg) and C18 (50 mg). Finally, the dried extract was dissolved in acetonitrile/water (15:85, v/v) and analyzed by UPLC-MS/MS. The recovery ratios from tea for eight neonicotinoid insecticides ranged from 60–109% at 0.01–0.5 mg kg−1 spiked levels. Relative standard deviations were <15.4% for all of the recovery tests. The limit of quantification was below 0.01 mg kg−1. The developed method was simple, effective, and sensitive. This method should prove to be highly useful for monitoring neonicotinoid insecticides in commercial tea products.

•Hydroponics and XPS were applied to study.•Chemical form of fluoride in abaxial and adaxial surfaces was identified.•AlF3 and trace amounts of MgF2 or CaF2 existed in the adaxial surface, only MgF2 for the abaxial surface.•Tea leaf surface changes under F treatment were analyzed.X-ray photoelectron spectroscopy (XPS) was applied to analyze the chemical form of fluoride and tea leaf surface changes. It was found that the leaf surface was mainly composed of C and O with some Si, N, and Al, besides a small amount of P and Ca in the adaxial surface. There was a tendency that Al was transferred from the abaxial surface to the adaxial surface with fluoride treatment. Under fluoride treatment, the content of C increased and O decreased in abaxial surface, while the opposite performance occurred in the adaxial surface. Meanwhile, the content of N of both the adaxial and abaxial surfaces decreased, suggesting a decreased nitrogen-fixation capacity. The results showed that fluoride treatment made cuticle thinner, and cutinized layer thicker and more active with a higher organic acid concentration for the adaxial surface, while both cuticle and cutinized layer got thicker and less active with a lower organic acid concentration for the abaxial surface. The content of protein decreased with fluoride treatment, causing tea leaf surface moisture loss. The ratio of O2/O1 was greater than 1 for untreated leaves, and the ratio dropped under treatment. AlF3 and trace amounts of MgF2 or CaF2 existed in the adaxial surface, however, only MgF2 for the abaxial surface.X-ray photoelectron spectroscopy (XPS) and hydroponic experiments were applied to analyze the chemical form of fluoride and tea leaf surface changes. And fluoride species present in tea leaves was identified.

Chinese dark tea (CDT) was investigated for chemical characteristics using liquid chromatography coupled with tandem mass spectrometry (LC-MS) metabolomics analysis. The LC-MSn method was used for detection of secondary metabolites in 10 CDT varieties. Pattern recognition methods, including principal component analysis (PCA) and orthogonal projection on latent structure-discriminant analysis (OPLS-DA), revealed clear differences and classified the CDT varieties into 2 categories. One category is fermented with Aspergillus niger while the other (fu teas) is fermented with Eurotium cristatum. Chemical analyses identified 25 marker compounds that contribute to the classification of the 2 CDT types. Flavonoid triglycosides and catechin derivatives were the distinctive compounds of fu teas, based on MS/MS fragmentation analysis. Although both fu teas and dark teas are commonly called CDTs, differences between these two CDT types are significant in the chemical classification.

Many researchers have reported that obesity is a major risk factor for diabetes, cardiovascular diseases, several forms of cancer (such as breast, colon and prostate), pulmonary, osteoarticular and metabolic diseases in the past decades. Recently, the hypolipidemic and anti-obesity effects of green tea in animals and humans have slowly become a hot topic in nutritional and food science research. This review will up-date the information of the anti-obesity effects of green tea in human intervention and animal studies. During recent years, an increasing number of clinical trials have confirmed the beneficial effects of green tea on obesity. However, the optimal dose has not yet been established owing to the very different results from studies with a similar design, which may be caused by differences in the extent of obesity, dietary intake, physical activity intensity, the strength of subjects’ compliance to test instruction, the genetic background of populations, body composition and dietary habits. Therefore, further investigations on a larger scale and with longer periods of observation and tighter controls are needed to define optimal doses in subjects with varying degrees of metabolic risk factors and to determine differences in beneficial effects among diverse populations. Moreover, data from laboratory studies have shown that green tea has important roles in fat metabolism by reducing food intake, interrupting lipid emulsification and absorption, suppressing adipogenesis and lipid synthesis and increasing energy expenditure via thermogenesis, fat oxidation and fecal lipid excretion. However, the exact molecular mechanisms remain elusive.

Sample preparation using an absorbent for removal of polyphenols and a solid-phase extraction (SPE) cartridge for cleanup followed by high-performance liquid chromatography (HPLC) has been investigated for the simultaneous determination of eight neonicotinoid insecticides (dinotefuran, nitenpyram, thiamethoxam, imidacloprid, clothianidin, imidaclothiz, acetamiprid, and thiacloprid). After tea samples were soaked with water and extracted with acetonitrile, sample extracts were treated with an appropriate amount of polyvinylpolypyrrolidone (PVPP) to effectively remove polyphenols. The treated extract was cleaned up with a Carb-PSA cartridge. Neonicotinoid insecticides were eluted with acetonitrile from the cartridge and dried. The extract was redissolved with methanol/water (1:9, v/v) and analyzed by conventional HPLC coupled with an ultraviolet detector. The recoveries of eight neonicotinoid insecticides in tea samples were 71.4–106.6% at 0.1–1.0 mg kg–1 spiked levels. Relative standard deviations were <10% for all of the recovery tests. The established method was simple, effective, and accurate and could be used for monitoring neonicotinoid insecticides in tea.

The current study investigated the effects of green tea polyphenols (GTPs) on lipid metabolism and its mechanisms using broiler chickens (Gallus gallus domesticus). A total of 36 male chickens (35 days old) had been subjected to an oral administration of GTPs at a dosage of 0, 50 (low), and 100 (high) mg/kg of body weight for 20 days. Our results showed that GTPs significantly decreased the abdominal and subcutaneous fat masses of broilers and reduced the serum triglyceride, total cholesterol, and low-density lipoprotein cholesterol levels compared to those of the control. Furthermore, the expression levels for lipid anabolism genes were significantly downregulated, while the expression levels of fat transportation and catabolism-related genes, carnitine palmitoyl transferase I (CPT-I), acyl-CoA oxidase 1 (ACOX1), and peroxisome proliferator-activated receptor-α (PPARα) in liver, adipose triglyceride lipase (ATGL) in abdominal fat, and lipoprotein lipase (LPL) in skeletal muscles, were notably upregulated. Our data have revealed that GTPs alleviate obesity and serum lipid levels in broiler chickens by suppressing fatty acid synthesis and stimulating lipolysis.

Metabolic profiles of broiler chickens were examined after the ingestion of green tea, tea polyphenols, and (−)-epigallocatechin-3-gallate (EGCG). Solid-phase extraction of serum and litters yielded free catechins and their metabolites, which were then identified and quantified by liquid chromatography–tandem mass spectrometry. In plasma samples, (−)-gallocatechin, (+)-catechin, and EGCG were detected in the green tea group; pyrogallol acid, (epi)catechin-O-sulfate, 4′-O-methyl-(epi)gallocatechin-O-glucuronide, and (epi)catechin-3′-O-glucuronide were detected in the tea polyphenols group; and EGCG, (−)-gallocatechin gallate (GCG), and 4′-O-methyl-(epi)gallocatechin-O-glucuronides were detected in the EGCG group. In litters, gallic acid, EGCG, GCG, and ECG were detected in the green tea and tea polyphenols groups; EGCG and ECG were detected in the EGCG group. The conjugated metabolites, 4′-O-methyl-(epi)gallocatechin-O-glucuronide, (epi)catechin-3′-glucuronide, and 4′-O-methyl-(epi)catechin-O-sulfate, were identified in the green tea group; 4′-O-methyl-(epi)catechin-O-sulfate and 4′-O-methyl-(epi)gallocatechin-O-sulfate were identified in the tea polyphenols group; only 4′-O-methyl-(epi)gallocatechin-O-sulfate was detected in the EGCG group. The excretion of tea catechins was 95.8, 87.7, and 97.7% for the green tea, tea polyphenols, and EGCG groups, respectively.

High-performance liquid chromatography (HPLC) has been used to quantify levels of free amino acids, catechins, and caffeine in Chinese green tea. Levels of free amino acids and catechins in green tea leaves show obvious variation from spring to summer, which is useful information to identify the production season of commercial green tea. Supervised pattern recognition methods such as the K-nearest neighbor (KNN) method and Bayesian discriminant method (a type of linear discriminant analysis (LDA)) were used to discriminate between the production seasons of Chinese green tea. The optimal accuracy of the KNN method was ≤97.61 and ≤94.80% as validated by resubstitution and cross-validation tests, respectively, and that of LDA was ≤95.22 and ≤93.54%, respectively. Compared with LDA, the KNN method did not require a Gaussian distribution and was more accurate than LDA. The KNN method in combination with chemical analysis is recommended for discrimination of the production seasons of Chinese green tea.

High levels of fluoride in tea plants pose a potential health risk to humans who drink tea. It has been demonstrated that tea plant fluoride is closely related to the available fluoride in soil. But approaches that could be used to regulate the availability of fluoride in soil have been rarely seen. This study aims to investigate how the addition of charcoal and bamboo charcoal affected soil fluoride availability and bioaccumulation of fluoride in tea plants. In a microcosm experiment, tea plants were grown in the tea garden soil mixed with different amounts of charcoal and bamboo charcoal [that is, 0.5, 1.0, 2.5, and 5.0 % (w/w)]. Soil-fluoride fractions and fluoride accumulated in tea plants were determined using the sequential extraction and ion selective electrode method. Obtained results showed that both charcoal and bamboo charcoal additions significantly enhanced the concentrations of Fe/Mn oxide-bound fluoride, but significantly reduced the concentrations of water-soluble and exchangeable fluoride (p < 0.05) in soil. Charcoal and bamboo charcoal additions also significantly decreased the amounts of fluoride in tea roots and tea leaves (p < 0.05). However, the additions of charcoal and bamboo charcoal had no impacts on the tea quality, as indexed by the concentrations of polysaccharides, polyphenols, amino acids, and caffeine in tea leaves. These results suggested that application of charcoal and bamboo charcoal may provide a useful method to reduce the availability of fluoride in soil and the subsequent fluoride uptake by tea plants.

Fuzhuan brick tea, a special microbial-fermented tea prepared from the leaves of Camellia sinensis var. sinensis, is a traditional beverage used in China throughout history. Phytochemical investigation of this material led to the identification of three new triterpenoids, 3β,6α,13β-trihydroxyolean-7-one (1), 3β-acetoxy-6α,13β-dihydroxyolean-7-one (2), and 3β-O-(8-hydroxyoctanoyl)-12-oleanene (3), together with 11 known compounds, friedelin (4), β-amyrone (5), β-amyrin (6), α-spinasterone (7), α-spinasterol (8), 22,23-dihydro-α-spinasterone (9), 22,23-dihydro-α-spinasterol (10), α-phytol (11), α-tocopherol (12), α-tocoquinone (13), and caffeine (14). The structures of 1−13 were determined by spectroscopic and chemical methods. Compounds 1 and 2 are the first two examples of triterpenoids possessing a 6-hydroxy-7-one function. All of the compounds, except 6, 8, 10, 11, and 14, were isolated from tea and Camellia spp. for the first time. The antibacterial activities of 1 were assessed against some enteric pathogenic microbes. Compound 1 showed no cytotoxic activity against A-549, Bel-7402, and HCT-8 cell lines.

The determination of theanine has been performed by micellar electrokinetic capillary chromatography (MECC) using 2,4-dinitrofluorobenzene (DNFB) as a derivative reagent. To achieve the separation, a fused-silica capillary column was used with a borax buffer at 0.03 mol/L pH 9.8 (containing Brij35 and isopropanol) at 17 °C with detection wave length at 360 nm. The factors affecting the efficiency of the sample separation were examined simultaneously. A 40-min reaction at 35 °C between l-glutamate and ethylamine (with Tris–HCl buffer, pH 7.5) was investigated using the theanine synthetase from budding tea seeds. A novel method for the analysis of theanine synthetase activity based on MECC was established. The method shows mean recovery ranged from 87.1 to 105.3% and linearity ranged from 0.2 to 5.0 mmol/L.

•Tea supplementation could suppress carbohydrates absorption.•Tea intervention could stimulate glucose metabolism.•Tea consumption also could alleviate the oxidative stress.A growing body of evidence showed that tea has anti-hyperglycemia and anti-diabetes effects during recent years. Tea may exert beneficial effects on decreasing blood glucose and ameliorating insulin resistance by first, suppressing carbohydrates absorption; second, stimulating glucose metabolism; and third, alleviating the oxidative stress. Furthermore, it was also reported that tea consumption could ameliorate the complications of diabetes mellitus. However, being a key factor in the occurrence and development of diabetes mellitus, oxidative stress should be paid more attention. The relationship between the anti-oxidative efficacy and anti-diabetes actions of tea, and the underlying molecular mechanisms of this relevance need further meticulous research. In order to understand the research trends of this field, this review highlights the latest advances in the anti-hyperglycemia and anti-diabetes actions of tea in animal studies since 2012.Download full-size image

•Four novel and inexpensive biosorbents were developed for defluoridation of water.•Common metal ions (Zr, Al, Fe and La) were loaded onto porous starch (PS).•Biosorbents retained metal ions during defluoridation.•PS-Zr showed superior adsorption capacity over a pH range of 3.0–9.0.•PS-Zr maximum adsorption capacity was 25.41 mg fluoride/g biosorbent.In this study, porous corn starch was loaded with Zr, Al, Fe or La to produce the composites PS-Zr, PS-Al, PS-Fe and PS-La. Fluoride adsorption from water was tested at different biosorbent dosages, contact times, solution pH values and initial fluoride concentrations. The biosorbents were characterized by microscopy and spectroscopy. PS-Zr was shown superior defluoridation capacity over a pH range of 3.0–9.0. The adsorption process could be described by the Langmuir isotherm model and the Lagergren pseudo-second-order kinetic model. The maximum fluoride adsorption capacity calculated to be for PS-Zr was 25.41 mg/g. Our results revealed that PS-Zr could be employed as an effective biosorbent for removal of fluoride from drinking water.

A rapid, sensitive and selective ultra-high performance liquid chromatography tandem mass spectrometry method was developed and validated for the determination and pharmacokinetic investigation of seven catechins in rat plasma. The rat plasma was extracted with simple liquid–liquid extraction using ethyl acetate. Plasma sample was separated by UHPLC on a Hypersil GOLD C18 column (1.9 μm, 50 × 2.1 mm) using a mobile phase consisting of methanol–0.05% formic acid in water with gradient elution. The total run time was 10.5 min and seven catechins were efficiently separated. The detection was performed on a selected reaction monitoring using the respective transitions m/z 289.070 → 109.010 for (−)-epicatechin/(+)-catechin, 305.089 → 125.228 for (−)-epigallocatechin/(−)-gallocatechin and 441.150 → 169.325 for (−)-epicatechin gallate and 456.840 → 169.257 for (−)-epigallocatechin gallate/(−)-gallocatechin gallate. Mean recovery of seven catechins was in the range of 84.92–102.18%. The intra- and inter-day precisions (RSD) of these analytes were all less than 6.17% and 5.84%. This method was successfully applied in the pharmacokinetic study of seven catechins in the plasma of rats after oral administration of 700 mg kg−1 tea polyphenols.

An analytical method using gel permeation chromatography (GPC) coupled with gas chromatography-mass spectrometry (GC-MS) was established for the determination of 10 photo-initiators – benzophenone (BP), 2-methyl benzophenone (2-MBP), 1-hydroxycyclohexyl phenyl ketone (Irgacure 184), 3-methyl benzophenone (3-MBP), 4-methyl benzophenone (4-MBP), ethyl 4-dimethylaminobenzoate (EDB), 2,2-dimethoxy-2-phenylacetophenone (Irgacure 651), o-methyl-benzoyl benzoate (OMBB), 2-ethylhexyl-4-dimethylamino benzoate (EHA) and 2-isopropylthioxanthone (ITX) – in plastic food packaging. The plastic samples were treated with ultrasound in cyclohexane/ethyl acetate (1:1, v/v). The extract was cleaned up by gel permeation chromatography. The final solution was subjected to GC-MS using an external standard method for quantitation in selected ion monitoring mode. The 10 target photo-initiators showed linear recovery relationships over the concentrations of 0.005 to 0.2 mg L−1, with r2 > 0.999. The recoveries from spiked samples (0.07 × 10−3, 0.17 × 10−3 and 0.33 × 10−3 mg dm−2 of standard) for each of the 10 photo-initiators ranged from 77.0% to 120.6%, with relative standard deviations (RSDs) of 0.5–13.9%. The limits of detection (LOD) were from 0.03 × 10−3 mg dm−2 to 0.12 × 10−3 mg dm−2. The developed extraction method is simple and yields a sufficiently pure test sample, while the analytical method meets the sensitivity and precision requirements for photo-initiator detection. This method could be routinely used to determine the levels of photo-initiator residues in plastic food packaging.

A rapid UPLC-ESI (+)-MS/MS method was developed and validated for simultaneous determination of eight neonicotinoid insecticides (dinotefuran, nitenpyram, thiamethoxam, clothianidin, imidacloprid, acetamiprid, thiacloprid and imidaclothiz) in tea samples based on a refined QuEChERS extraction method. In order to eliminate the matrix effect and obtain satisfactory recoveries, an inexpensive and excellent absorbent material, polyvinylpolypyrrolidone (PVPP), was used to eliminate polyphenols from tea matrices. Further, combinations of PVPP and the commonly used sorbents PSA and GCB were investigated in this study. The optimized ‘quick, easy, cheap, effective, rugged and safe’ protocol is briefly described as follows. Tea samples were soaked in water and extracted with acetonitrile. Sample extracts were treated with 400 mg PVPP to remove polyphenols from tea matrices, and then cleaned up with a combination of PSA (25 mg), GCB (100 mg) and C18 (50 mg). Finally, the dried extract was dissolved in acetonitrile/water (15:85, v/v) and analyzed by UPLC-MS/MS. The recovery ratios from tea for eight neonicotinoid insecticides ranged from 60–109% at 0.01–0.5 mg kg−1 spiked levels. Relative standard deviations were <15.4% for all of the recovery tests. The limit of quantification was below 0.01 mg kg−1. The developed method was simple, effective, and sensitive. This method should prove to be highly useful for monitoring neonicotinoid insecticides in commercial tea products.