Research Progress on the Effect and Mechanism of Tea Products with Different Fermentation Degrees in Regulating Type 2 Diabetes Mellitus.

A popular non-alcoholic beverage worldwide, tea can regulate blood glucose levels, lipid levels, and blood pressure, and may even prevent type 2 diabetes mellitus (T2DM). Different tea fermentation levels impact these effects. Tea products with different fermentation degrees containing different functional ingredients can lower post-meal blood glucose levels and may prevent T2DM. There are seven critical factors that shed light on how teas with different fermentation levels affect blood glucose regulation in humans. These factors include the inhibition of digestive enzymes, enhancement of cellular glucose uptake, suppression of gluconeogenesis-related enzymes, reduction in the formation of advanced glycation end products (AGEs), inhibition of dipeptidyl peptidase-4 (DPP-4) activity, modulation of gut flora, and the alleviation of inflammation associated with oxidative stress. Fermented teas can be used to lower post-meal blood glucose levels and can help consumers make more informed tea selections.

Comparative Metabolomics Study of Four Kinds of Xihu Longjing Tea Based on Machine Fixing and Manual Fixing Methods.

China Xihu Longjing tea is famous for its good flavor and quality. However, information on its related metabolites, except for flavonoids, is largely deficient. Different processing methods for China Xihu Longjing tea fixing-by machines at both the first and second step (A1), first step by machine and second step by hand (A2), first step by hand and second step by machine (A3), and by hand at both the first and second step (A4)-were compared using a UHPLC-QE-MS-based metabolomics approach. Liquid chromatography-mass spectrometry was used to analyze the metabolic profiles of the processed samples. A total of 490 metabolites (3 alkaloids, 3 anthracenes, 15 benzene and substituted derivatives, 2 benzopyrans, 13 coumarins and derivatives, 128 flavonoids, 4 furanoid lignans, 16 glycosides and derivatives, 5 indoles and derivatives, 18 isocoumarins and derivatives, 4 chalcones and dihydrochalcones, 4 naphthopyrans, 3 nucleosides, 78 organic acids and derivatives, 55 organooxygen compounds, 5 phenols, 109 prenol lipids, 3 saccharolipids, 3 steroids and steroid derivatives, and 17 tannins) were identified. The different metabolic profiles were distinguished using PCA and OPLS-DA. There were differences in the types and contents of the metabolites, especially flavonoids, furanoid lignans, glycosides and derivatives, organic acids and derivatives, and organooxygen compounds. There was a positive correlation between flavonoid metabolism and amino acid metabolism. However, there was a negative correlation between flavonoid metabolism and amino acid metabolism, which had the same trend as prenol lipid metabolism and tannins. This study provides new valuable information regarding differences in the metabolite profile of China Xihu Longjing tea processed based on machine fixing and on manual fixing methods.

Separation and antioxidant activities of new acetylated EGCG compounds.

Acetylation could improve the bioavailability of (-)-Epigallocatechin-3-Gallate (EGCG), but the relationship of substitution degree and antioxidant capacity of acetylated EGCG was unclear. The acetylated EGCG products were separated by preparation high performance liquid chromatography (HPLC). Two mono substituted acetylated EGCG, three substituted acetylated EGCG (T-AcE), eight substituted acetylated EGCG (E-AcE) and (-)-Epigallocatechin gallate (EGCG) were isolated. The 7-acetyl-EGCG (S7-ACEGCG) and 7-acetyl-EGCG (T-AcE) were identified for the first time. The antioxidant capacity, superoxide anion radical scavenging capacities, and hydroxyl radical scavenging capacities of EGCG decreased significantly after acetylation modification. The more EGCG acetylation modification sites, the lower the total antioxidant capacity, superoxide anion radical scavenging capacities, and hydroxyl radical scavenging capacities. The antioxidant capacity, superoxide anion radical scavenging capacities, and hydroxyl radical scavenging capacities of 5-acetyl-EGCG (S5-ACE) were higher than 7-acetyl-EGCG (S7-AcE). Combining all the results in this and previous studies, acetylation modification is not conducive to the performance of EGCG antioxidant capacity.

Bitterness quantification and simulated taste mechanism of theasinensin A from tea.

Theasinensin A is an important quality chemical component in tea, but its taste characteristics and the related mechanism are still unclear. The bitterness quantification and simulated taste mechanism of theasinensin A were researched. The results showed that theasinensin A was significantly correlated with the bitterness of tea. The bitterness threshold of theasinensin A was identified as 65 µmol/L for the first time. The dose-over-threshold (DOT) value of theasinensin A was significantly higher than that of caffeine in black tea soup. The concentration-bitterness curve and time-intensity curve of theasinensin A were constructed. The bitterness contribution of theasinensin A in black tea was higher than in oolong and green tea. Theasinensin A had the highest affinity with bitterness receptor protein TAS2R16, which was compared to TAS2R13 and TAS2R14. Theasinensin A was mainly bound to a half-open cavity at the N-terminal of TAS2R13, TAS2R14, and TAS2R16. The different binding capacity, hydrogen bond, and hydrophobic accumulation effect of theasinensin A and bitterness receptor proteins might be the reason why theasinensin A presented different bitterness senses in human oral cavity.

Stability of glycosylated complexes loaded with Epigallocatechin 3-gallate (EGCG).

The application of Epigallocatechin-3-gallate (EGCG) in food industry was limited by its low stability in aqueous solutions and poor bioavailability in vivo. The novel EGCG glycosylated arachin nanoparticles (Ara-CMCS-EGCG) and EGCG glycosylated casein nanoparticles (Cas-CMCS-EGCG) were prepared to improve the stability and bioavailability of EGCG. The effect of different variables on the storage stability and the slow-release behavior of novel glycosylation complexes in nanoparticle background solution and artificial gastrointestinal fluid were investigated. The results showed that the DPPH scavenging activity of Ara-CMCS-EGCG and Cas-CMCS-EGCG were stable in temperature (25 âˆ¼ 70 °C). EGCG could enhance the crosslinking effect of molecular particles in glycosylation complexes solution. The glycosylated protein nanoparticles were stable to acid-base and enzymolysis in simulated gastrointestinal fluid. The release rate of EGCG in simulated intestinal fluid was higher than that in simulated gastric fluid. The glycosylated protein carrier can not only release EGCG slowly, but also significantly improve the stability and bioavailability of EGCG in simulated gastrointestinal fluid.

Preparation and characterization of high embedding efficiency epigallocatechin-3-gallate glycosylated nanocomposites.

Glycosylated protein nano encapsulation was an efficient encapsulation technology, but its embedding rate for EGCG was not high, and the research on the embedding mechanism was relatively weak. Based on this, this study compared the embedding effect of glycosylated peanut globulin and glycosylated casein on EGCG. The embedding mechanism of EGCG with glycosylated protein was discussed by ultraviolet, fluorescence, infrared and fluorescence microscopy. Results revealed that the highest encapsulation efficiency of EGCG was 93.89 ± 1.11%. The neutral pH value and 0.3 mg/mL EGCG addition amount were suitable for EGCG glycosylated nanocomposites. The hydrogen bond between EGCG hydroxyl group and tyrosine and tryptophan of glycosylated protein is mainly non covalent. The encapsulation effect of EGCG glycosylated nanocomposites could be quenched by changing the polar environment and spatial structure of the group. The fluorescence characteristic and dispersibility of EGCG glycosylated peanut globin were higher than EGCG glycosylated casein. This study might provide a theoretical basis for EGCG microencapsulation technology and EGCG application in tea beverage and liquid tea food systems.

Adsorption Equilibrium and Thermodynamics of Tea Theasinensins on HP20-A High-Efficiency Macroporous Adsorption Resin.

The separation and preparation of theasinensins have been hot spots in the field of tea chemistry in recent years. However, information about the mechanism of efficient adsorption of tea theasinensins by resin has been limited. In this study, the adsorption equilibrium and thermodynamics of tea theasinensins by a high-efficiency macroporous adsorption HP20 resin were evaluated. The adsorption of theasinensin A, theasinensin B, and theasinensin C on HP20 resin were spontaneous physical reaction processes. Adsorption processes were exothermic processes, and lowering the temperature was beneficial to the adsorption. The Freundlich model was more suitable to describe the adsorption of tea theasinensins. The adsorption equilibrium constant and maximum adsorption capacity of theasinensin A were significantly higher than theasinensin B and theasinensin C, which indicated that the adsorption affinity of theasinensin A was stronger than that of theasinensin B and theasinensin C. The phenolic hydroxyl groups and intramolecular hydrogen bonds of theasinensin A were more than those of theasinensin B and theasinensin C, which might be the key to the resin's higher adsorption capacity for theasinensin A. The HP20 resin was very suitable for efficient adsorption of theasinensin A.

Dual effects of ascorbic acid on the stability of EGCG by the oxidation product dehydroascorbic acid promoting the oxidation and inhibiting the hydrolysis pathway.

A series of incubation systems of pure (-)-Epigallocatechin gallate (EGCG), ascorbic acid (AA) and dehydroascorbic acid (DHAA) at 80 °C were performed to investigated the effect and mechanism of AA on the stability of EGCG. Results shows the dual function of AA, protect action at low concentration and promoting degradation at high concentration, and the critical concentration is about 10 mmol/L. The protective properties of AA due to the reversible reaction from AA to DHAA inhibiting oxidation pathway of EGCG to EGCG quinone or other activated intermediates, and both AA and DHAA can inhibit the hydrolysis of EGCG. The properties of promoting degradation is mainly due to the fact that DHAA, the oxidation product of AA, can react with EGCG to generate some ascorbyl adducts of EGCG. This result is helpful to control the stability of catechins and further clarify the complex interaction on healthy between EGCG and AA.

Knowledge, attitude and behavior on salt and health among primary school students in Jinan / 中国学校卫生

Objective@#To investigate the knowledge, attitude and practice(KAP) of salt and health among primary school students in Jinan, and to provide scientific evidence for targeted interventions.@*Methods@#1 293 primary school students of grade 4 in Jinan were randomly selected by cluster sampling method, and a self-designed questionnire on "salt and health" was applied among them.@*Results@#Among grade 4 students in Jinan, 35.73% were aware the diagnostic criteria of hypertension in adults, 67.67% were aware that eating less salt help lowering blood pressure. The proportion of students who knew the recommended daily intake of salt for adults, children aged 1-6 years and for children aged 7-13 years was 55.68%, 53.21% and 50.62%, respectively. The proportion of students who favor lower intake of salt(70.84%), actively choose low-salt food(65.89%), received publicity or education on low-salt diet(72.85%), pay attention to the salt/sodium content when purchasing packaged food(73.01%), believe that packaged food should be labelled with salt/sodium content(84.45%), and heard of low-sodium salt (alternative salt)(57.77%).The boys and girls were found no statistical significance in the differences of their attitude toward controlling salt, skills and behaviors(P<0.05),with 68.05% of boys and 73.91% of girls agreed, 13.76% of boys and 9.24% of girls reported no attention paid. There was no significant difference in other salt control attitudes, skills and behaviors between boys and girls(P>0.05).@*Conclusion@#A series of interventions taken by Shandong Ministry of Health Action on Salt Reduction and Hypertension (SMASH) within schools show positive effects. However, gaps in salt taste and salt intake among primary school students still exist, suggesting health education should be further strengthened in respect of daily salt intake recommendation, salt intake attitude and behaviors, especially for boys.

Functional Characteristics, Electrophysiological and Antennal Immunolocalization of General Odorant-Binding Protein 2 in Tea Geometrid, Ectropis obliqua.

As one of the main lepidopteran pests in Chinese tea plantations, Ectropisobliqua Warren (tea geometrids) can severely decrease yields of tea products. The olfactory system of the adult tea geometrid plays a significant role in seeking behaviors, influencing their search for food, mating partners, and even spawning grounds. In this study, a general odorant-binding protein (OBP) gene, EoblGOBP2, was identified in the antennae of E. obliqua using reverse transcription quantification PCR (RT-qPCR). Results showed that EoblGOBP2 was more highly expressed in the antennae of males than in females relative to other tissues. The recombinant EoblGOBP2 protein was prepared in Escherichia coli and then purified through affinity chromatography. Ligand-binding assays showed that EoblGOBP2 had a strong binding affinity for some carbonyl-containing tea leaf volatiles (e.g., (E)-2-hexenal, methyl salicylate, and acetophenone). Electrophysiological tests confirmed that the male moths were more sensitive to these candidate tea plant volatiles than the female moths. Immunolocalization results indicated that EoblGOBP2 was regionally confined to the sensilla trichoid type-II in the male antennae. These results indicate that EoblGOBP2 may be primarily involved in the olfactory activity of male E. obliqua moths, influencing their ability to sense tea leaf volatiles. This study provides a new perspective of insect GOBPs and implies that olfactory function can be used to prevent and control the tea geometrid.

Physicochemical Evidence on Sublethal Neonicotinoid Imidacloprid Interacting with an Odorant-Binding Protein from the Tea Geometrid Moth, Ectropis obliqua.

Nowadays the excessive usage of neonicotinoid insecticides always results in residues in Chinese tea fields. It is not clear whether the insecticide residue at the sublethal level influences the physiological processes of tea pests. Here, we provide evidence of interaction between the neonicotinoid imidacloprid and a general odorant-binding protein, EoblGOBP2, from the tea geometrid moth, Ectropis obliqua. The interacting process was demonstrated through multiple fluorescence spectra, UV absorption spectra, circular dichroism (CD) spectra, molecular docking, etc. The binding mode was determined to be static (from 300 to 310 K) and dynamic quenching (from 290 to 300 K). The binding distance was calculated to be 6.9 nm on the basis of FRET theory. According to the thermodynamic analysis, the process was mainly driven by enthalpy (ΔH < 0), and hydrogen bond and van der Waals interactions were the main driving forces in the static and dynamic binding cases, respectively. Moreover, synchronous fluorescence spectra and CD spectra analysis showed stretching of the EoblGOBP2 peptide chains with a decreasing α-helix when imidacloprid was added. Molecular docking was applied and predicted that two hydrogen bonds were formed between imidacloprid and Arg110 in the mature peptide of EoblGOBP2. Moreover, when the absolute amounts of EoblGOBP2 in the moth antennae were measured and calculated by using real-time PCR, it was estimated that imidacloprid at sublethal level (about 0.233 and 0.175 ng/male and female moth antennae, respectively) inhibited the binding of a tea volatile, E-2-hexenal, to EoblGOBP2 at about half. This study indicates that neonicotinoid insecticide at sublethal level may still affect the olfactory cognition of the tea geometrid moth to volatile compounds from tea leaves.