Amphiphilic Janus Graphene Oxide Acts as a Corrosion Inhibitor to Mitigate the Corrosion Caused by a 1 M HCl Solution on Mild Steel.

Great aqueous dispersibility, a large specific surface area, and high impermeability make graphene oxide (GO) the ideal candidate for a high-performance corrosion inhibitor. Numerous symmetrical modification methods have been reported to enhance the adsorption of GO on metal surfaces in various corrosive media. This work aims to investigate the enhancement and mechanism of unilateral hydrophobic modification on the corrosion inhibition performance of GO. In this study, amphiphilic Janus GO (JGO) was prepared by grafting hydrophobic alkyl chains on one side of GO, and its anticorrosion performance was evaluated via weight loss experiments and electrochemical tests. The results revealed that the corrosion inhibition efficiency for Q235 mild steel (MS) in a 1 M HCl aqueous solution of 25 ppm JGO (81.08%) was much higher than that of GO at the same concentration (22.12%). Furthermore, the Langmuir adsorption isotherm and computational study demonstrated that the synergistic effect of physical adsorption and chemical adsorption promoted the hydrophilic side of JGO close to the surface of the metal, and the dense protective layer was formed by the hydrophobic chains toward the corrosive medium, which effectively hindered the corrosion of MS by the acidic liquid. This study emphasizes the significant role of asymmetrically modified hydrophobic alkyl chains in improving the corrosion prevention performance of GO and provides a perspective for the structural design of GO-based corrosion inhibitors.

Low appendicular skeletal muscle index increases the risk of carotid artery plaque in postmenopausal women with and without hypertension/hyperglycemia: a retrospective study.

BACKGROUND: This study aimed to evaluate whether the low appendicular skeletal muscle index (ASMI) is closely associated with the risk of carotid artery plaque (CAP) in postmenopausal women with and without hypertension/hyperglycemia stratified by body mass index (BMI) categories. METHODS: A total of 2048 Chinese postmenopausal women aged 40-88 years were eventually enrolled in this retrospective study. Skeletal muscle mass was estimated by using segmental multifrequency bioelectrical impedance analysis. ASMI was defined as follows: appendicular skeletal muscle mass(kg)/[height(m)]2. CAP was assessed by B-mode ultrasound. We explored the association between ASMI quartiles or low skeletal muscle mass and the risk of CAP by using multivariate-adjusted logistic regression models. A potential nonlinear relationship was also tested using restricted cubic spline regression. RESULTS: CAP was observed in 289/1074 (26.9%) normal-weight and 319/974 (32.8%) overweight/obese postmenopausal women. Individuals with CAP had significantly lower ASMI values than those without (P < 0.001). The ASMI value also showed a linear relationship with the CAP risk in postmenopausal women stratified by BMI category (Pfor non-linearity > 0.05). In comparison with the highest ASMI quartile, the lowest ASMI quartile was significantly associated with a high risk of CAP development in non-hypertensive individuals with normal weight (odds ratio [OR] = 2.43; 95% confidence interval [CI]: 1.44 ~ 4.12) or overweight/obesity (OR = 4.82, 95% CI: 2.79 ~ 8.33), hypertensive individuals with normal weight (OR = 5.90, 95% CI: 1.46 ~ 11.49) or overweight/obesity (OR = 7.63, 95% CI: 1.62 ~ 35.86), non-hyperglycemic individuals with normal weight (OR = 2.61, 95% CI: 1.54 ~ 4.43) or overweight/obesity (OR = 2.94, 95% CI: 1.84 ~ 4.70), and hyperglycemic individuals with normal weight (OR = 6.66, 95% CI: 1.08 ~ 41.10) or overweight/obesity (OR = 8.11, 95% CI: 2.69 ~ 24.49). Moreover, low skeletal muscle was independently associated with the risk of CAP in postmenopausal women, regardless of the BMI category. CONCLUSION: ASMI was inversely associated with the risk of CAP development in postmenopausal women, especially in patients with high blood sugar and/or hypertension, indicating that skeletal muscle mass maintenance may contribute to prevention of CAP in postmenopausal women.

Prophylactic Penehyclidine Inhalation for Prevention of Postoperative Pulmonary Complications in High-risk Patients: A Double-blind Randomized Trial.

BACKGROUND: Postoperative pulmonary complications are common. Aging and respiratory disease provoke airway hyperresponsiveness, high-risk surgery induces diaphragmatic dysfunction, and general anesthesia contributes to atelectasis and peripheral airway injury. This study therefore tested the hypothesis that inhalation of penehyclidine, a long-acting muscarinic antagonist, reduces the incidence of pulmonary complications in high-risk patients over the initial 30 postoperative days. METHODS: This single-center double-blind trial enrolled 864 patients age over 50 yr who were scheduled for major upper-abdominal or noncardiac thoracic surgery lasting 2 h or more and who had an Assess Respiratory Risk in Surgical Patients in Catalonia score of 45 or higher. The patients were randomly assigned to placebo or prophylactic penehyclidine inhalation from the night before surgery through postoperative day 2 at 12-h intervals. The primary outcome was the incidence of a composite of pulmonary complications within 30 postoperative days, including respiratory infection, respiratory failure, pleural effusion, atelectasis, pneumothorax, bronchospasm, and aspiration pneumonitis. RESULTS: A total of 826 patients (mean age, 64 yr; 63% male) were included in the intention-to-treat analysis. A composite of pulmonary complications was less common in patients assigned to penehyclidine (18.9% [79 of 417]) than those receiving the placebo (26.4% [108 of 409]; relative risk, 0.72; 95% CI, 0.56 to 0.93; P = 0.010; number needed to treat, 13). Bronchospasm was less common in penehyclidine than placebo patients: 1.4% (6 of 417) versus 4.4% (18 of 409; relative risk, 0.327; 95% CI, 0.131 to 0.82; P = 0.011). None of the other individual pulmonary complications differed significantly. Peak airway pressures greater than 40 cm H2O were also less common in patients given penehyclidine: 1.9% (8 of 432) versus 4.9% (21 of 432; relative risk, 0.381; 95% CI, 0.171 to 0.85; P = 0.014). The incidence of other adverse events, including dry mouth and delirium, that were potentially related to penehyclidine inhalation did not differ between the groups. CONCLUSIONS: In high-risk patients having major upper-abdominal or noncardiac thoracic surgery, prophylactic penehyclidine inhalation reduced the incidence of pulmonary complications without provoking complications.

Light control of catechin accumulation is mediated by photosynthetic capacity in tea plant (Camellia sinensis).

BACKGROUND: Catechins are crucial in determining the flavour and health benefits of tea, but it remains unclear that how the light intensity regulates catechins biosynthesis. Therefore, we cultivated tea plants in a phytotron to elucidate the response mechanism of catechins biosynthesis to light intensity changes. RESULTS: In the 250 µmol·m- 2·s- 1 treatment, the contents of epigallocatechin, epigallocatechin gallate and total catechins were increased by 98.94, 14.5 and 13.0% respectively, compared with those in the 550 µmol·m- 2·s- 1 treatment. Meanwhile, the photosynthetic capacity was enhanced in the 250 µmol·m- 2·s- 1 treatment, including the electron transport rate, net photosynthetic rate, transpiration rate and expression of related genes (such as CspsbA, CspsbB, CspsbC, CspsbD, CsPsbR and CsGLK1). In contrast, the extremely low or high light intensity decreased the catechins accumulation and photosynthetic capacity of the tea plants. The comprehensive analysis revealed that the response of catechins biosynthesis to the light intensity was mediated by the photosynthetic capacity of the tea plants. Appropriately high light upregulated the expression of genes related to photosynthetic capacity to improve the net photosynthetic rate (Pn), transpiration rate (Tr), and electron transfer rate (ETR), which enhanced the contents of substrates for non-esterified catechins biosynthesis (such as EGC). Meanwhile, these photosynthetic capacity-related genes and gallic acid (GA) biosynthesis-related genes (CsaroB, CsaroDE1, CsaroDE2 and CsaroDE3) co-regulated the response of GA accumulation to light intensity. Eventually, the epigallocatechin gallate content was enhanced by the increased contents of its precursors (EGC and GA) and the upregulation of the CsSCPL gene. CONCLUSIONS: In this study, the catechin content and photosynthetic capacity of tea plants increased under appropriately high light intensities (250 µmol·m- 2·s- 1 and 350 µmol·m- 2·s- 1) but decreased under extremely low or high light intensities (150 µmol·m- 2·s- 1 or 550 µmol·m- 2·s- 1). We found that the control of catechin accumulation by light intensity in tea plants is mediated by the plant photosynthetic capacity. The research provided useful information for improving catechins content and its light-intensity regulation mechanism in tea plant.

The Physiochemical Properties and Adsorption Characteristics of Processed Pomelo Peel as a Carrier for Epigallocatechin-3-Gallate.

The NaOH-HCl- and ethanol-pretreated pomelo peel samples were prepared to apply to the batch adsorption for epigallocatechin-3-gallate (EGCG). The characteristics of peel samples were determined by Fourier transform infrared spectroscopy, scanning electron microscopy and a laser particle analyzer. The results of the physiochemical properties of the peel samples demonstrate that these peel samples have a promising adsorption capacity for EGCG, because of the increased potential binding sites on the surface compared with those of untreated peel samples. These two peel samples showed enhanced adsorption capacities of EGCG compared with that of unmodified peel in terms of the isothermal adsorption process, which could be described by both Langmuir and Freundlich models, with the theoretical maximum adsorption capacity of 77.52 and 94.34 mg g-1 for the NaOH-HCl and ethanol-treated peel samples, respectively. The adsorption kinetics demonstrated an excellent fitness to pseudo-second-order, showing that chemisorption was the rate-limiting step. The thermodynamics analysis revealed that the adsorption reaction was a spontaneous and endothermic process. This work highlights that the processed pomelo peels have outstanding adsorption capacities for EGCG, which could be promising candidates for EGCG delivering in functional food application.

Complementary iTRAQ Proteomic and Transcriptomic Analyses of Leaves in Tea Plant ( Camellia sinensis L.) with Different Maturity and Regulatory Network of Flavonoid Biosynthesis.

The quality of tea is highly related with the maturity of the fresh tea leaves at harvest. The present study investigated the proteomic and transcriptomic profiles of tea leaves with different maturity, using iTRAQ and RNA-seq technologies. A total of 4455 proteins and 27 930 unigenes were identified, with functional enrichment analyses of GO categorization and KEGG annotation. The compositions of flavonoids (catechins and flavonols) in tea leaves were determined. The total content of flavonoids decreased with leaf maturity, in accordance with the protein regulation patterns of shikimate, phenylpropanoid, and flavonoid pathways. The abundance of ANR had a positive correlation with epi-catechin content, while LAR abundance was positively related with catechin content ( P < 0.05). The biosynthetic network of flavonoid biosynthesis was discussed in combination with photosynthesis, primary metabolism, and transcription factors. Bud had the lowest activities of photosynthesis and carbon fixation but the highest flavonoid biosynthesis ability in opposite to mature leaf. SUS-INV switch might be an important joint for carbon flow shifting into the follow-up biochemical syntheses. This work provided a comprehensive overview on the functional protein profile changes of tea leaves at different growing stages and also proposed a research direction regarding the correlations between primary metabolism and flavonoid biosynthesis.

Numerical Study of Bubble Breakup in Fractal Tree-Shaped Microchannels.

Hydrodynamic behaviors of bubble stream flow in fractal tree-shaped microchannels is investigated numerically based on a two-dimensional volume of fluid (VOF) method. Bubble breakup is examined in each level of bifurcation and the transition of breakup regimes is discussed in particular. The pressure variations at the center of different levels of bifurcations are analyzed in an effort to gain further insight into the underlying mechanism of bubble breakup affected by multi-levels of bifurcations in tree-shaped microchannel. The results indicate that due to the structure of the fractal tree-shaped microchannel, both lengths of bubbles and local capillary numbers decrease along the microchannel under a constant inlet capillary number. Hence the transition from the obstructed breakup and obstructed-tunnel combined breakup to coalescence breakup is observed when the bubbles are flowing into a higher level of bifurcations. Compared with the breakup of the bubbles in the higher level of bifurcations, the behaviors of bubbles show stronger periodicity in the lower level of bifurcations. Perturbations grow and magnify along the flow direction and the flow field becomes more chaotic at higher level of bifurcations. Besides, the feedback from the unequal downstream pressure to the upstream lower level of bifurcations affects the bubble breakup and enhances the upstream asymmetrical behaviors.

Molecular Dynamics Simulation of Distribution and Diffusion Behaviour of Oil⁻Water Interfaces.

The distribution and diffusion behaviors of microscopic particles at fluorobenzene-water and pentanol-water interfaces are investigated using molecular dynamics simulation. The influences of Na+/Cl- ions and the steric effects of organic molecules are examined. The concentration distributions of different species, the orientations of oil molecules at the interface, and oil-water interface morphology as well as the diffusion behaviors of water molecules are explored and analyzed. The results indicate that a few fluorobenzene molecules move into the water phase influenced by Na+/Cl- ions, while the pentanol molecules at the interface prefer orientating their hydrophilic groups toward the water phase due to their large size. The water molecules more easily burst into the pentanol phase with larger molecular spaces. As the concentration of ions in the water phase increases, more water molecules enter into the pentanol molecules, leading to larger interface roughness and interface thickness. In addition, a lower diffusion coefficient for water molecules at the fluorobenzene-water interface are observed when introducing Na+/Cl- ions in the water phase, while for the pentanol-water system, the mobility of interfacial water molecules are enhanced with less ions and inhibited with more ions.

The application of pomelo peel as a carrier for adsorption of epigallocatechin-3-gallate.

BACKGROUND: Pomelo (Citrus grandis) is the largest citrus fruit, the peel of which is a well-known agricultural wastes. Disposal of pomelo peel after consumption is a serious environment problem. As a natural, versatile bio-absorbent, pomelo peel has shown excellent adsorption capacity for several pollutants, attributed to its micro-pores; however, there is no relevant report on its adsorption capacity for natural products or food ingredients. The ability of pomelo peel to adsorb epigallocatechin-3-gallate (EGCG) was examined in this study. The physicochemical characterizations of pomelo peel were determined by Fourier transform infrared spectroscopy, scanning electron microscopy and high-performance liquid chromatography. The adsorption process of EGCG onto pomelo peel from aqueous solution was carried out at a range of concentrations (50-800 mg L-1 ) and temperatures (25, 40 and 55 °C). RESULTS: The main components of pomelo peel are composed of dietary fiber, which provide sufficient adsorption sites during the adsorption process. The adsorption of EGCG onto pomelo peel showed excellent fitness with a pseudo-second-order model. Both Langmuir and Freundlich models were able to describe the isothermal adsorption of EGCG onto pomelo peel. The results of thermodynamic analysis suggested that adsorption is spontaneous and endothermic in nature, and that the process is likely to be dominated by a physisorption mechanism. CONCLUSION: The results of this study indicate that pomelo peel has potential adsorption capacity for EGCG, which can be used as an effective, low-cost carrier for delivery of natural products in functional food and dietary supplement applications. © 2018 Society of Chemical Industry.

FLZ attenuates learning and memory deficits via suppressing neuroinflammation induced by LPS in mice.

Alzheimer's disease (AD) is the most common neurodegenerative disorder in which neuroinflammation plays an important role. FLZ is a novel synthetic derivative of natural squamosamide. Previous studies demonstrated that FLZ had neuroprotective effects on AD models and showed strong anti-inflammatory property in Parkinson's disease models. However, whether the neuroprotective effects of FLZ on AD are associated with its anti-inflammatory property is still not fully elucidated. In this study, we aimed to investigate the ability of FLZ in modulating inflammation. The results showed that FLZ significantly improved memory deficits and alleviated neuronal damage as well as neuronal loss in the hippocampus of mice intracerebroventricular injected with lipopolysaccharide (LPS). Mechanistic studies revealed that the neuroprotective effects of FLZ were due to the suppression of neuroinflammation induced by LPS, as indicated by inactivation of astrocytes and microglia, reduced production of tumor necrosis factor-α, interleukin-1ß, and nitric oxide, as well as decreased expression of cyclooxygenase-2 and inducible nitric oxide synthase. The beneficial effects of FLZ on AD were further supported by the finding that FLZ attenuated ß-amyloid production through inhibiting ß-amyloid precursor protein cleaving enzyme 1 expression. These results suggested that anti-inflammatory agent could be useful for the treatment of AD.

Scavenger receptor on astrocytes and its relationship with neuroinflammation.

Neuroinflammation in central nervous system, featured by glial cells activation, can always be found during the development of neurodegenerative diseases. Astrocytes, the most abundant glial cells in the brain, can release both pro-inflammatory and anti-inflammatory factors, thus playing a crucial role in the neuroinflammation. A variety of pattern-recognition receptors on astrocytes are involve d in the inflammatory response, particularly the scavenger receptor. Scavenger receptor is a cell surface glycoprotein and can identify diverse ligands. With a variety of biological functions, it may activate many signal pathways related to neuroinflammation, regulate the host defense and the development of neuroinflammation, and eventually regulate the process of neuroinflammation. Thus, it play a key role in the development of neurodegenerative diseases and many other conditions. This review summarizes the scavenger receptor expressed on astrocytes and how it regulates signal transduction pathways associated with neuroinflammation and thus participates in regulating neuroinflammation.

Unveiling characteristic metabolic accumulation over enzymatic-catalyzed process of Tieguanyin oolong tea manufacturing by DESI-MSI and multiple-omics.

To achieve an integrative understanding of the spatial distribution and chronological flavoring compounds accumulation, desorption-electrospray-ionization coupled mass-spectrometry-imaging (DESI-MSI) and multi-omics techniques were performed on the leaf samples collected from the enzymatic-catalyzed-process (ECP) stage of Tieguanyin oolong tea manufacturing. The result of DESI-MSI visualization indicated transform or re-distribution of catechins, flavonols and amino acids were on-going attributing to the multi-stress over ECP stage. Out of identified 2621 non-volatiles and 45,771 transcripts, 43 non-volatiles and 12 co-expressed pathways were screened out as biomarkers and key cascades in response to adverse conditions. The targeted metabolic analysis on the characteristic flavoring compounds showed that the accumulations of free amino acids were enhanced, while catechins, flavonol glycosides, and alkaloids exhibited dynamic changes. This result suggests withering and turning-over process are compatible and collectively regulate the metabolic accumulation and development of flavoring metabolites, facilitating to the development of characteristic quality of Tieguanyin tea.

Study on the dynamic change of volatile components of white tea in the pile-up processing based on sensory evaluation and ATD-GC-MS Technology.

The pile-up processing has a great impact on the flavor of white tea. To investigate the effects of the volatile accumulation of white tea with different piling thickness treatments, tea leaves from different thickness treatments were subjected to sensory quantitative description analysis and ATD-GC-MS detection in this study. As a result, 122 volatile components were identified from white tea with different treatments. A total of 8 key compounds, including isovaleraldehyde, isobutyraldehyde, 2-methyl-butanal, 1-octene-3-ol, linalool, pentanoic acid, hexanal and 1-hexanol were screened out using multivariate statistical analysis, which were characteristic components of grassy, floral-fruity, pekoe aroma and sweet flavors. The results of the selected key characteristic volatile compounds were consistent with the sensory quantitative description. The aroma of mid-pile dried tea (MD) was exhibited a harmonious and pleasant overall flavor. This study provides a novel insight into the accumulation of volatile during the withering step of white tea production.

Gender difference in association between low muscle mass and risk of non-alcoholic fatty liver disease among Chinese adults with visceral obesity.

Background and aims: Although the association between low muscle mass and the risk of non-alcoholic fatty liver disease is well-known, it has not been explored in viscerally obese populations by gender. Besides, whether low muscle mass still increases the NAFLD risk in subjects with visceral obesity, independent of obesity, is still unknown. The aim of this study was to explore the gender-specific association between low muscle mass and the risk of non-alcoholic fatty liver disease (NAFLD) in subjects with visceral obesity. Methods: Overall, 1,114 participants aged 19-89 years were recruited in this retrospective study. Liver disease was diagnosed by hepatic ultrasound. Skeletal muscle mass was estimated by bioimpedance analysis and defined by the appendicular skeletal muscle index (ASMI). Gender-specific differences in the ASMI value were compared between NAFLD and control groups. Restricted cubic spline and multivariate logistic regression were performed to analyze the association (stratified by gender and age) between the ASMI and the risk of NAFLD, respectively. Results: Middle-aged females (40-60 years) and males (of any age) with NAFLD had a significantly lower ASMI compared with controls (P-value < 0.05). An inverse linear association was found between the ASMI and risk of NAFLD (all P fornon-linearity > 0.05). Lower quartiles of the ASMI conferred independent risk of NAFLD compared to higher quartiles (all P for trend < 0.001). Low muscle mass conferred a higher risk of NAFLD in middle-aged females (adjusted odds ratio = 2.43, 95% confidence interval: 1.19-4.95) and males [18-39 years: 3.76 (1.79-7.91); 40-60 years: 4.50 (2.16-9.39); and >60 years: 4.10 (1.13-14.84)]. Besides, Low muscle mass and low muscle mass with obesity increase the risk of developing NAFLD, independent of obesity. Conclusion: Among those with visceral obesity, low muscle mass increased the risk of NAFLD in males of any age, and middle-aged females, this may be explained by the postmenopausal decline in estrogen.

An integrated metabolomic and transcriptomic analysis reveals the dynamic changes of key metabolites and flavor formation over Tieguanyin oolong tea production.

To interpret the formation characteristic flavor during oolong tea manufacturing process, the dynamic changes of key flavor components in samples from various processing steps of Tieguanyin oolong tea production were investigated using widely-targeted metabolomic and the transcriptomic approaches. As a result, a total of 1078 metabolites were determined, of which 62 compounds were identified as biomarkers significantly changed over the manufacturing process. Quantitative determination of the total 50,343 transcripts showed 7480 of them were co-expressed different genes. Glutamic acid served as a critical metabolism hub and a signaling molecule for diverse stress responses. Additionally, the targeted quantification results showed that the contents of catechins and xanthine alkaloids in dried tea were dramatically decreased by 20.19% and 7.15% respectively than those in fresh leaves, which potentially contributed to the alleviation of astringent or bitter palates, promoting the characteristic mellow and rich flavor of Tieguanyin oolong tea.

Integrative analyses of transcriptome and metabolome reveal comprehensive mechanisms of Epigallocatechin-3-gallate (EGCG) biosynthesis in response to ecological factors in tea plant (Camellia sinensis).

Epigallocatechin-3-gallate (EGCG), a flavoured and healthy compounds in tea, is affected by the ecological factors. However, the biosynthetic mechanisms of EGCG in response to the ecological factors remian unclear. In this study, a response surface method with a Box-Behnken design was used to investigate the relationship between EGCG accumulation and ecological factors; further, integrative transcriptome and metabolome analyses were performed to explore the mechanism underlying EGCG biosynthesis in response to environmental factors. The optimal environmental conditions obtained for EGCG biosynthesis were as follows: 28℃, 70 % relative humidity of the substrate, and 280 µmol·m-2·s-1 light intensity; the EGCG content was increased by 86.83 % compared to the control (CK1). Meanwhile, the order of EGCG content in response to the interaction of ecological factors was as follows: interaction of temperature and light intensity > interaction of temperature and relative humidity of the substrate > interaction of light intensity and relative humidity of the substrate, indicating that temperature was the dominant ecological factors. EGCG biosynthesis in tea plants was found to be comprehensively regulated by a series of structural genes (CsANS, CsF3H, CsCHI, CsCHS, and CsaroDE), miRNAs (miR164, miR396d, miR5264, miR166a, miR171d, miR529, miR396a, miR169, miR7814, miR3444b, and miR5240), and transcription factors (MYB93, NAC2, NAC6, NAC43, WRK24, bHLH30, and WRK70); further, the metabolic flux was regulated and converted from phenolic acid to the flavonoid biosynthesis pathway based on accelerated consumption of phosphoenolpyruvic acid, d-erythrose-4-phosphate, and l-phenylalanine in response to ambient changes in temperature and light intensity. Overall, the results of this study reveal the effect of ecological factors on EGCG biosynthesis in tea plants, providing novel insights for improving tea quality.

Optimizing Processing Techniques of Oolong Tea Balancing between High Retention of Catechins and Sensory Quality.

Catechins are the major flavor substances in teas, which have a variety of health effects; however, high catechin and high sensory quality are a pair of contradictions that are difficult to coordinate. To explore the processing procedure with high catechins and high sensory quality, a single-factor processing experiment was carried out over the processing production of oolong tea. Combined with orthogonal partial least square discriminant analysis (OPLS-DA), correlation analysis, and principal component analysis (PCA), the optimal production procedure for oolong tea is as follows: red light withering for 8 h, leaf rotating for 10 min with a total standing time for 8 h, drum roasting for 5 min at 290 °C, low-temperature rolling (flattening at 4 °C for 5 min, without pressure for 1 min and under pressure for 5 min), microwave drying (800 W for 7.5 min). This study demonstrates a significant increase in the retention of catechins, which contributes to the mellow and brisk tastes of oolong tea, addressing the challenge of catechin content and sensory quality. Our study provides a novel insight into the relationship between the oolong tea processing and flavor formation.

The biosynthesis of EGCG, theanine and caffeine in response to temperature is mediated by hormone signal transduction factors in tea plant (Camellia sinensis L.).

As the main flavor components of tea, the contents of epigallocatechin-3-gallate (EGCG), theanine and caffeine are regulated by ambient temperature. However, whether the biosynthesis of EGCG, theanine and caffeine in response to temperature is regulated by endogenous hormones and its mechanism is still unclear. In this study, tea cuttings cultivated in the phytotron which treated at different temperatures 15℃, 20℃, 25℃ and 30℃, respectively. The UPLC and ESI-HPLC-MS/MS were used to determine the contents of EGCG, theanine, caffeine and the contents of phytohormones in one leaf and a bud. The results showed that indoleacetic acid (IAA), gibberellin 1(GA1) and gibberellin 3 (GA3) were significantly correlated with the content of EGCG; Jasmonic acid (JA), jasmonate-isoleucine (JA-Ile) and methyl jasmonate (MeJA) were strongly correlated with theanine content; IAA, GA1 and gibberellin 4 (GA4) were significantly correlated with caffeine content at different temperatures. In order to explore the internal intricate relationships between the biosynthesis of these three main taste components, endogenous hormones, and structural genes in tea plants, we used multi-omics and multidimensional correlation analysis to speculate the regulatory mechanisms: IAA, GA1 and GA3 up-regulated the expressions of chalcone synthase (CsCHS) and trans-cinnamate 4-monooxygenase (CsC4H) mediated by the signal transduction factors auxin-responsive protein IAA (CsIAA) and DELLA protein (CsDELLA), respectively, which promoted the biosynthesis of EGCG; IAA, GA3 and GA1 up-regulated the expression of CsCHS and anthocyanidin synthase (CsANS) mediated by CsIAA and CsDELLA, respectively, via the transcription factor WRKY DNA-binding protein (CsWRKY), and promoted the biosynthesis of EGCG; JA, JA-Ile and MeJA jointly up-regulated the expression of carbonic anhydrase (CsCA) and down-regulated the expression of glutamate decarboxylase (CsgadB) mediated by the signal transduction factors jasmonate ZIM domain-containing protein (CsJAZ), and promoted the biosynthesis of theanine; JA, JA-Ile and MeJA also jointly inhibited the expression of CsgadB mediated by CsJAZ via the transcription factor CsWRKY and AP2 family protein (CsAP2), which promoted the biosynthesis of theanine; IAA inhibited the expression of adenylosuccinate synthase (CspurA) mediated by CsIAA via the transcription factor CsWRKY; GA1 and gibberellin 4 (GA4) inhibited the expression of CspurA mediated by CsDELLA through the transcription factor CsWRKY, which promoted the biosynthesis of caffeine. In conclusion, we revealed the underlying mechanism of the biosynthesis of the main taste components in tea plant in response to temperature was mediated by hormone signal transduction factors, which provided novel insights into improving the quality of tea.

The stress-induced metabolites changes in the flavor formation of oolong tea during enzymatic-catalyzed process: A case study of Zhangping Shuixian tea.

To interpret the environmental stresses induced dynamic changes of volatile and non-volatile constitutes in oolong tea leaves during enzymatic-catalyzed processes (ECP), metabolomic and proteomic studies were carried out using the processed leaf samples collected at the different stages of ECP for Zhangping Shuixian tea manufacture. Non-processed leaves were applied as control. Out of identified 980 non-volatiles and 157 volatiles, 40 non-volatiles and 8 volatiles were screened out as biomarkers, respectively. The integrated analysis on metabolites-proteins showed that phenylpropanoid biosynthesis, flavonoid biosynthesis, and phenylalanine metabolism were significantly enriched and highly correlated to the dynamic changes of key metabolites during ECP stage. A biological pathway network was constructed to illuminate the enzymatic-catalyzed production of critical flavoring compounds, including carbohydrates, amino acids, flavonoids, and volatile phenylpropanoids/benzenoids. The electronic-sensory analyses indicated leaf dehydration and mechanical wounding occurred over the sun-withering and turning-over steps are indispensable to form characteristic flavor of Shuixian tea.

Oolonghomobisflavans exert neuroprotective activities in cultured neuronal cells and anti-aging effects in Caenorhabditis elegans.

Potential health benefits of tea has attracted significant scientific and public attention worldwide. Tea polyphenols are considered as natural promising complementary therapeutical agents for neurodegenerative diseases. However, the anti-neurodegeneration or anti-aging activities of oolong tea polyphenols have not been investigated. The current study aims to document beneficial effects of oolong tea polyphenols [dimers of epigallocatechin gallate (EGCG), oolonghomobisflavan A (OFA), and oolonghomobisflavan B (OFB)] with neuroprotective and neuritogenesis properties in cultured neuronal (Neuro-2a and HT22) cells and Caenorhabditis elegans models. In vitro, we found that the compounds (EGCG, OFA, and OFB) protect against glutamate-induced neurotoxicity via scavenging radical activity, suppression intracellular ROS and up-regulation of antioxidant enzymes. Moreover, the compounds induce neurite outgrowth via up-regulate Ten-4 gene expression. Interestingly, OFA and OFB exert stronger neuroprotective and neurite outgrowth properties than EGCG known as an excellent antioxidant agent in tea. In vivo, we found that the compounds protect against C. elegans Aß-induced paralysis, chemotaxis deficiency and α-synuclein aggregation. Moreover, the compounds are capable of extending the lifespan of C. elegans. OFA and OFB possess both anti-neurodegeneration and anti-aging activities, supporting its therapeutic potential for the treatment of age-related neurodegenerative diseases which need to be studied in more detail in intervention studies.