[Diagnostic value of identifying location and amount of free gas in the abdominal cavity by multidetector computed tomography in patients with acute gastrointestinal perforation]

Objective: To evaluate the relationships between the location and extent of diffusion of free intraperitoneal air by multi-slice spiral CT (MSCT) and between the location and size of acute gastrointestinal perforation. Methods: This was a descriptive case series. We examined abdominal CT images of 33 patients who were treated for intraoperatively confirmed gastrointestinal perforation (excluding appendiceal perforation) in the Department of General Surgery, Nanfang Hospital between January and September 2022. We identified five locations of intraperitoneal air: the subphrenic space, hepatic portal space, mid-abdominal wall, mesenteric space, and pelvic cavity. We allocated the 33 patients to an upper gastrointestinal perforation (n=23) and lower gastrointestinal perforation group (n=10) base on intraoperative findings and analyzed the relationships between the locations of free gas and of gastrointestinal perforation. Additionally, we established two models for analyzing the extent of diffusion of free gas in the abdominal cavity and constructed receiver operating characteristic (ROC) curves to analyze the relationships between the two models and the size of the gastrointestinal perforation. Results: In the upper gastrointestinal perforation group, free gas was located around the hepatic portal area in 91.3% (21/23) of patients: this is a significantly greater proportion than that found in the lower gastrointestinal perforation group (5/10) (P=0.016). In contrast, free gas was located in the mesenteric interspace in 8/10 patients in the lower gastrointestinal perforation group; this is a significantly greater proportion than was found in the upper gastrointestinal perforation group (8.7%, 2/23) (P<0.010). The sensitivity of diagnosis of upper gastrointestinal perforation base on the presence of hepatic portal free gas was 84.8% and the specificity 71.4%. Further, the sensitivity of diagnosis of lower gastrointestinal perforation base on the presence of mesenteric interspace free gas was 80.0% and the specificity 91.3%. The rates of presence of free gas in the subdiaphragmatic area, mid-abdominal wall, and pelvic cavity did not differ significantly between the two groups (all P>0.05). Receiver operating characteristic curves showed that when free gas was present in four or more of the studied locations in the abdominal cavity, the optimal cutoff for perforation diameter was 2 cm, the corresponding sensitivity 66.7%, and the specificity 100%, suggesting that abdominal free gas diffuses extensively when the diameter of the perforation is >2 cm. Another model revealed that when free gas is present in three or more of the studied locations, the optimal cutoff for perforation diameter is 1 cm, corresponding to a sensitivity of 91.7% and specificity of 76.2%; suggesting that free gas is relatively confined in the abdominal cavity when the diameter of the perforation is <1 cm. Conclusion: Identifying which of five locations in the abdominal cavity contains free intraperitoneal air by examining MSCT images can be used to assist in the diagnosis of the location and size of acute gastrointestinal perforations.

CsMYB67 participates in the flavonoid biosynthesis of summer tea leaves

Flavonoids are important compounds in tea leaves imparting bitter and astringent taste, which also play key roles in tea plants responding to environmental stress. Our previous study showed that the expression level of CsMYB67 was positively correlated with the accumulation of flavonoids in tea leaves as exposed to sunlight. Here, we newly reported the function of CsMYB67 in regulating flavonoid biosynthesis in tea leaves. CsMYB67 was localized in the nucleus and responded to temperature. The results of transient expression assays showed the co-transformation of CsMYB67 and CsTTG1 promoted the transcription of CsANS promoter in the tobacco system. CsTTG1 was bound to the promoter of CsANS based on the results of yeast one-hybrid (Y1H) and transient expression assays, while CsMYB67 enhanced the transcription of CsANS through protein interaction with CsTTG1 according to the results of yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC). Thus, CsMYB67-CsTTG1 module enhanced the anthocyanin biosynthesis through up-regulating the transcription of CsANS. Besides, CsMYB67 also enhanced the transcription of CsFLS and CsUFGT through forming transcription factor complexes. The function of CsMYB67 on flavonoid biosynthesis in tea leaves was validated by gene suppression assay. As CsMYB67 was suppressed, the transcriptional level of CsFLS was greatly reduced, leading to a significant increase in the contents of total catechins and total anthocyanidins. Hence, CsMYB67 plays an important role in regulating the downstream pathway of flavonoid biosynthesis in summer tea leaves.

The light-harvesting chlorophyll a/b-binding proteins of photosystem II family members are responsible for temperature sensitivity and leaf color phenotype in albino tea plant

INTRODUCTION

Light-harvesting chlorophyll a/b-binding (LHCB) protein complexes of photosystem II are integral to the formation of thylakoid structure and the photosynthetic process. They play an important role in photoprotection, a crucial process in leaf development under low-temperature stress. Nonetheless, potential key genes directly related to low-temperature response and albino phenotype have not been precisely identified in tea plant. Moreover, there are no studies simultaneously investigating multiple albino tea cultivars with different temperature sensitivity.

OBJECTIVES

The study aimed to clarify the basic characteristics of CsLHCB gene family members, and identify critical CsLHCB genes potentially influential in leaf color phenotypic variation and low-temperature stress response by contrasting green and albino tea cultivars. Concurrently, exploring the differential expression of the CsLHCB gene family across diverse temperature-sensitive albino tea cultivars.

METHODS

We identified 20 putative CsLHCB genes according to phylogenetic analysis. Evolutionary relationships, gene duplication, chromosomal localization, and structures were analyzed by TBtools; the physiological and biochemical characteristics were analyzed by protein analysis websites; the differences in coding sequences and protein accumulation in green and albino tea cultivars, gene expression with maturity were tested by molecular biology technology; and protein interaction was analyzed in the STRING database.

RESULTS

All genes were categorized into seven groups, mapping onto 7 chromosomes, including three tandem and one segmental duplications. They all own a conserved chlorophyll A/B binding protein domain. The expression of CsLHCB genes was tissue-specific, predominantly in leaves. CsLHCB5 may play a key role in the process of leaf maturation and senescence. In contrast to CsLHCB5, CsLHCB1.1, CsLHCB2, and CsLHCB3.2 were highly conserved in amino acid sequence between green and albino tea cultivars. In albino tea cultivars, unlike in green cultivars, the expression of CsLHCB1.1, CsLHCB1.2, and CsLHCB2 was down-regulated under low-temperature stress. The accumulation of CsLHCB1 and CsLHCB5 proteins was lower in albino tea cultivars. Greater accumulation of CsLHCB2 protein was detected in RX1 and RX2 compared to other albino cultivars.

CONCLUSIONS

CsLHCB1.1, CsLHCB1.2, and CsLHCB2 played a role in the response to low-temperature stress. The amino acid sequence site mutation of CsLHCB5 would distinguish the green and albino tea cultivars. The less accumulation of CsLHCB1 and CsLHCB5 had a potential influence on albino leaves. Albino cultivars more sensitive to temperature exhibited lower CsLHCB gene expression. CsLHCB2 may serve as an indicator of temperature sensitivity differences in albino tea cultivars. This study could provide a reference for further studies of the functions of the CsLHCB family and contribute to research on the mechanism of the albino in tea plant.

Anthocyanin metabolism and its differential regulation in purple tea (Camellia sinensis)

Tea plants (Camellia sinensis) typically contain high-flavonoid phytochemicals like catechins. Recently, new tea cultivars with unique purple-colored leaves have gained attention. These purple tea cultivars are enriched with anthocyanin, which provides an interesting perspective for studying the metabolic flux of the flavonoid pathway. An increasing number of studies are focusing on the leaf color formation of purple tea and this review aims to summarize the latest progress made on the composition and accumulation of anthocyanins in tea plants. In addition, the regulation mechanism in its synthesis will be discussed and a hypothetical regulation model for leaf color transformation during growth will be proposed. Some novel insights are presented to facilitate future in-depth studies of purple tea to provide a theoretical basis for targeted breeding programs in leaf color.

Shading-Dependent Greening Process of the Leaves in the Light-Sensitive Albino Tea Plant 'Huangjinya': Possible Involvement of the Light-Harvesting Complex II Subunit of Photosystem II in the Phenotypic Characteristic

The light-sensitive albino tea plant can produce pale-yellow shoots with high levels of amino acids which are suitable to process high-quality tea. In order to understand the mechanism of the albino phenotype formation, the changes in the physio-chemical characteristics, chloroplast ultrastructure, chlorophyll-binding proteins, and the relevant gene expression were comprehensively investigated in the leaves of the light-sensitive albino cultivar 'Huangjinya' ('HJY') during short-term shading treatment. In the content of photosynthetic pigments, the ultrastructure of the chloroplast, and parameters of the photosynthesis in the leaves of 'HJY' could be gradually normalized along with the extension of the shading time, resulting in the leaf color transformed from pale yellow to green. BN-PAGE and SDS-PAGE revealed that function restoration of the photosynthetic apparatus was attributed to the proper formation of the pigment-protein complexes on the thylakoid membrane that benefited from the increased levels of the LHCII subunits in the shaded leaves of 'HJY', indicating the low level of LHCII subunits, especially the lack of the Lhcb1 might be responsible for the albino phenotype of the 'HJY' under natural light condition. The deficiency of the Lhcb1 was mainly subject to the strongly suppressed expression of the Lhcb1.x which might be modulated by the chloroplast retrograde signaling pathway GUN1 (GENOMES UNCOUPLED 1)-PTM (PHD type transcription factor with transmembrane domains)-ABI4 (ABSCISIC ACID INSENSITIVE 4).

[Evaluation effect of COMPERA 2.0 risk assessment model on prognosis of Chinese patients with pulmonary arterial hypertension]

Objectives: To clarify the evaluation effect of COMPERA 2.0 risk assessment model on prognosis of pulmonary arterial hypertension (PAH) in China. Methods: Patients with newly diagnosed PAH admitted in Fuwai hospital between April 2019 and March 2022 were enrolled retrospectively and divided in low, intermediate-low, intermediate-high and high strata by scores of COMPERA 2.0 risk assessment model. All the patients were followed up by clinic or telephone. The primary endpoint was defined as a composite of all-cause mortality, exacerbated heart failure and aggravated symptoms. Kaplan-Meier analysis and log-rank trend test were used to determine the risk of endpoints among the 4 groups. Multivariate Cox proportional hazards regression were used to analyze the association between COMPERA 2.0 scores and prognosis in patients with PAH. Results: A total of 951 patients with PAH were enrolled in this study. The age [M (Q₁, Q₃)] of the patients was 35 (28, 47) years, of which 706 cases (74.2%) were females. A total of 328 cases (34.5%) were assigned in low strata, 264 cases (27.8%) in intermediate-low strata, 193 cases (20.3%) in intermediate-high strata, and 166 cases (17.5%) in high strata. During the duration [M (Q₁, Q₃)] of follow-up after discharge of 1.8 (1.0, 2.8) years, the primary endpoint was occurred in 12.8% (42/328), 21.2% (56/264), 28.5% (55/193) and 42.8% (71/166) of low, intermediate-low, intermediate-high and high strata, respectively. The rates of primary endpoint were significantly increased with strata rising (P<0.001). Multivariate Cox proportional hazards regression showed that COMPERA 2.0 risk scores were associated with the primary endpoints in PAH patients (HR=1.801, 95%CI: 1.254-2.588, P=0.001) after adjusting confounders. Conclusion: COMPERA 2.0 risk assessment model is a simple and effective tool for evaluating the prognosis of newly diagnosed PAH patients in China.

A comprehensive review of matcha: production, food application, potential health benefits, and gastrointestinal fate of main phenolics

Matcha, a powder processed from tea leaves, has a unique green tea flavor and appealing color, in addition to many other sought after functional properties for a wide range of formulated food applications (e.g., dairy products, bakery products, and beverage). The properties of matcha are influenced by cultivation method and processing post-harvest. The transition from drinking tea infusion to eating whole leaves provides a healthy option for the delivery of functional component and tea phenolics in various food matrix. The aim of this review is to describe the physico-chemical properties of matcha, the specific requirements for tea cultivation and industrial processing. The quality of matcha mainly depends on the quality of fresh tea leaves, which is affected by preharvest factors including tea cultivar, shading treatment, and fertilization. Shading is the key measure to increase greenness, reduce bitterness and astringency, and enhance umami taste of matcha. The potential health benefits of matcha and the gastrointestinal fate of main phenolics in matcha are covered. The chemical compositions and bioactivities of fiber-bound phenolics in matcha and other plant materials are discussed. The fiber-bound phenolics are considered promising components which endow matcha with boosted bioavailability of phenolics and health benefits through modulating gut microbiota.

Variation of Major Chemical Composition in Seed-Propagated Population of Wild Cocoa Tea Plant Camellia ptilophylla Chang

Excessive intake of high-caffeine tea will induce health-related risk. Therefore, breeding and cultivating tea cultivars with less caffeine is a feasible way to control daily caffeine intake. Cocoa tea (Camellia ptilophylla Chang) is a wild tea plant which grows leaves with little or no caffeine. However, the vegetative propagation of cocoa tea plants is difficult due to challenges with rooting. Whether natural seeds collected from wild cocoa tea plants can be used to produce less-caffeinated tea remains unknown, because research on the separation of traits among the seed progeny population is lacking. The present study was set to investigate the variation of caffeine and other chemical compositions in seed-propagated plant individuals using colorimetric and HPLC methods. It shows that there were great differences in chemical composition among the seed-propagated population of wild cocoa tea plants, among which some individuals possessed caffeine contents as high as those of normal cultivated tea cultivars (C. sinensis), suggesting that the naturally seed-propagated cocoa tea seedlings are not suitable for directly cultivating leaf materials to produce low-caffeine tea. Therefore, the cocoa tea plants used for harvesting seeds for growing low-caffeine tea plants should be isolated in order to prevent their hybridization with normal cultivated C. sinensis plants. Interestingly, the leaves of cocoa tea seedlings contained high levels of gallocatechin gallate (GCG) and would be a good source of leaf materials for extracting more stable antioxidant, because GCG is a more stable antioxidant than epigallocatechin gallate (EGCG), the dominant component of catechins in normal cultivated tea cultivars. Some plant individuals which contained low levels of caffeine along with high levels of amino acids and medium levels of catechins, are considered to be promising for further screening of less-caffeinated green tea cultivars.

Anticarcinogenic potentials of tea catechins

Catechins are a cluster of polyphenolic bioactive components in green tea. Anticarcinogenic effects of tea catechins have been reported since the 1980s, but it has been controversial. The present paper reviews the advances in studies on the anticarcinogenic activities of tea and catechins, including epidemiological evidence and anticarcinogenic mechanism. Tea catechins showed antagonistic effects on many cancers, such as gynecological cancers, digestive tract cancers, incident glioma, liver and gallbladder cancers, lung cancer, etc. The mechanism underlying the anticarcinogenic effects of catechins involves in inhibiting the proliferation and growth of cancer cells, scavenging free radicals, suppressing metastasis of cancer cells, improving immunity, interacting with other anticancer drugs, and regulating signaling pathways. The inconsistent results and their causes are also discussed in this paper.

High-Light-Induced Degradation of Photosystem II Subunits’ Involvement in the Albino Phenotype in Tea Plants

The light-sensitive (LS) albino tea plant grows albinic shoots lacking chlorophylls (Chls) under high-light (HL) conditions, and the albinic shoots re-green under low light (LL) conditions. The albinic shoots contain a high level of amino acids and are preferential materials for processing quality green tea. The young plants of the albino tea cultivars are difficult to be cultivated owing to lacking Chls. The mechanisms of the tea leaf bleaching and re-greening are unknown. We detected the activity and composition of photosystem II (PSII) subunits in LS albino tea cultivar “Huangjinya” (HJY), with a normal green-leaf cultivar “Jinxuan” (JX) as control so as to find the relationship of PSII impairment to the albino phenotype in tea. The PSII of HJY is more vulnerable to HL-stress than JX. HL-induced degradation of PSII subunits CP43, CP47, PsbP, PsbR. and light-harvest chlorophyll–protein complexes led to the exposure and degradation of D1 and D2, in which partial fragments of the degraded subunits were crosslinked to form larger aggregates. Two copies of subunits PsbO, psbN, and Lhcb1 were expressed in response to HL stress. The cDNA sequencing of CP43 shows that there is no difference in sequences of PsbC cDNA and putative amino acids of CP43 between HJY and JX. The de novo synthesis and/or repair of PSII subunits is considered to be involved in the impairment of PSII complexes, and the latter played a predominant role in the albino phenotype in the LS albino tea plant.

[Safety and effectiveness of esophagojejunostomy through extracorporeal versus intracorporeal methods after laparoscopic total gastrectomy]

Objective: To compare the safety and effectiveness of esophagojejunostomy (EJS) through extracorporeal and intracorporeal methods after laparoscopic total gastrectomy (LTG). Methods: A retrospective cohort study was carried out. Clinicopathological data of 261 gastric cancer patients who underwent LTG, D2 lymphadenectomy, and Roux-en-Y EJS with complete postoperative 6-month follow-up data at the General Surgery Department of Nanfang Hospital from October 2018 to June 2021 were collected. Among these 261 patients, 139 underwent EJS with a circular stapler via mini-laparotomy (extracorporeal group), while 122 underwent intracorporeal EJS (intracorporeal group), including 43 with OrVil(TM) anastomosis (OrVil(TM) subgroup) and 79 with Overlap anastomosis (Overlap subgroup). Compared with the extracorporeal group, the intracorporeal group had higher body mass index, smaller tumor size, earlier T stage and M stage (all P<0.05). Compared with the Overlap subgroup, the Orvil(TM) subgroup had higher proportions of upper gastrointestinal obstruction and esophagus involvement, and more advanced T stage (all P<0.05). No other significant differences in the baseline data were found (all P>0.05). The primary outcome was complications at postoperative 6-month. The secondary outcomes were operative status, intraoperative complication and postoperative recovery. Continuous variables with a skewed distribution are expressed as the median (interquartile range), and were compared using Mann-Whitney U test. Categorical variables are expressed as the number and percentage and were compared with the Pearson chi-square, continuity correction or Fisher's exact test. Results: Compared with the extracorporeal group, the intracorporeal group had smaller incision [5.0 (1.0) cm vs. 8.0 (1.0) cm, Z=-10.931, P=0.001], lower rate of combined organ resection [0.8% (1/122) vs. 7.9% (11/139), χ(2)=7.454, P=0.006] and higher rate of R0 resection [94.3% (115/122) vs. 84.9 (118/139), χ(2)=5.957, P=0.015]. The morbidity of intraoperative complication in the extracorporeal group and intracorporeal group was 2.9% (4/139) and 4.1% (5/122), respectively (χ(2)=0.040, P=0.842). In terms of postoperative recovery, the extracorporeal group had shorter time to liquid diet [(5.1±2.4) days vs. (5.9±3.6) days, t=-2.268, P=0.024] and soft diet [(7.3±3.7) days vs. (8.8±6.5) days, t=-2.227, P=0.027], and shorter postoperative hospital stay [(10.5±5.1) days vs. (12.2±7.7) days, t=-2.108, P=0.036]. The morbidity of postoperative complication within 6 months in the extracorporeal group and intracorporeal group was 25.9% (36/139) and 31.1%, (38/122) respectively (P=0.348). Furthermore, there was also no significant difference in the morbidity of postoperative EJS complications [extracorporeal group vs. intracorporeal group: 5.0% (7/139) vs. 82.% (10/122), P=0.302]. The severity of postoperative complications between the two groups was not statistically significant (P=0.289). In the intracorporeal group, the Orvil(TM) subgroup had more estimated blood loss [100.0 (100.0) ml vs.50.0 (50.0) ml, Z=-2.992, P=0.003] and larger incision [6.0 (1.0) cm vs. 5.0 (1.0) cm, Z=-3.428, P=0.001] than the Overlap subgroup, seemed to have higher morbidity of intraoperative complication [7.0% (3/43) vs. 2.5% (2/79),P=0.480] and postoperative complications [37.2% (16/43) vs. 27.8% (22/79), P=0.286], and more severe classification of complication (P=0.289). Conclusions: The intracorporeal EJS after LTG has similar safety to extracorporeal EJS. As for intracorporeal EJS, the Overlap method is safer and has more potential advantages than Orvil(TM) method, and is worthy of further exploration and optimization.

Sugar signal mediates flavonoid biosynthesis in tea leaves

Sugar metabolism and flavonoid biosynthesis vary with the development of tea leaves. In order to understand the regulatory mechanisms underlying the associations between them, a comprehensive transcriptomic analysis of naturally growing tea leaves at different stages of maturity was carried out. Based on weighted gene coexpression network analysis, the key gene modules (Modules 2 and 3) related to the varying relationship between sugar metabolism and flavonoid biosynthesis as well as the corresponding hub genes were obtained. KEGG (Kyoto Encyclopedia of Genes and Genomes) enrichment analysis showed that the transcription factors (TFs) in Modules 2 and 3 were mainly enriched in the pathway of plant hormone signal transduction. An in vitro study showed that the transcriptional levels of ERF1B-like TF for hexokinase inhibitor and sucrose treatments were upregulated, being respectively 28.1- and 30.2-fold higher than in the control, suggesting that ERF1B-like TFs participate in the sugar-induced regulation of flavonoid biosynthesis. The results of yeast one-hybrid and dual-luciferase assays demonstrated that CsF3'H, encoding flavonoid 3'-hydroxylase, was the target flavonoid biosynthetic gene for CsERF1B-like TF. Our study identified the potential key regulators participating in the metabolism of sugars and flavonoids, providing new insights into the crosstalk between sugar metabolism and flavonoid biosynthesis in tea plants.

Antiviral Effects of Green Tea EGCG and Its Potential Application against COVID-19

(–)-Epigallocatechin-3-O-gallate (EGCG), the most abundant component of catechins in tea (Camellia sinensis (L.) O. Kuntze), plays a role against viruses through inhibiting virus invasiveness, restraining gene expression and replication. In this paper, the antiviral effects of EGCG on various viruses, including DNA virus, RNA virus, coronavirus, enterovirus and arbovirus, were reviewed. Meanwhile, the antiviral effects of the EGCG epi-isomer counterpart (+)-gallocatechin-3-O-gallate (GCG) were also discussed.

Roasting process shaping the chemical profile of roasted green tea and the association with aroma features

Roasting process impacts the chemical profile and aroma of roasted tea. To compare the impacts of far-infrared irradiation and drum roasting treatments (light, medium and heavy degrees), the corresponding roasted teas were prepared from steamed green tea for chemical analyses and quantitative descriptive analysis on aroma, and correlations between volatiles and aroma attributes were studied. There were 8 catechins, 13 flavonol glycosides and 105 volatiles quantified. Under heavy roasting treatments, most catechins and flavonol glycosides decreased, and aldehydes, ketones, furans, pyrroles/pyrazines, and miscellaneous greatly increased, while far-infrared irradiated teas had distinct nutty aroma compared with the roasty and burnt odor of drum roasted teas. The weighted correlation network analysis result showed that 56 volatiles were closely correlated with the aroma attributes of roasted teas. This study reveals the differential chemical and sensory changes of roasted teas caused by different roasting processes, and provides a novel way for flavor chemistry study.

Theacrine From Camellia kucha and Its Health Beneficial Effects

Theacrine, i.e., 1,3,7,9-tetramethyluric acid, is one of the major purine alkaloids found in leaf of a wild tea plant species Camellia kucha Hung T. Chang. Theacrine has been attracted great attentions academically owing to its diverse health benefits. Present review examines the advances in the research on the health beneficial effects of theacrine, including antioxidant effect, anti-inflammatory effect, locomotor activation and reducing fatigue effects, improving cognitive effect, hypnotic effect, ameliorating lipid metabolism and inhibiting breast cancer cell metastasis effect. The inconsistent results in this research field and further expectations were also discussed.

The anti-allergic potential of tea: a review of its components, mechanisms and risks

Allergy is an immune-mediated disease with increasing prevalence worldwide. Regular treatment with glucocorticoids and antihistamine drugs for allergy patients is palliative rather than permanent. Daily use of dietary anti-allergic natural products is a superior way to prevent allergy and alleviate the threat. Tea, as a health-promoting beverage, has multiple compounds with immunomodulatory ability. Persuasive evidence has shown the anti-allergic ability of tea against asthma, food allergy, atopic dermatitis and anaphylaxis. Recent advances in potential anti-allergic ability of tea and anti-allergic compounds in tea have been reviewed in this paper. Tea exerts its anti-allergic effect mainly by reducing IgE and histamine levels, decreasing FcεRI expression, regulating the balance of Th1/Th2/Th17/Treg cells and inhibiting related transcription factors. Further research perspectives are also discussed.

Study on the Accumulation Mechanism of Amino Acids during Bruising and Withering Treatment of Oolong Tea

Amino acids are very important for oolong tea brisk-smooth mouthfeel which is mainly associated with bruising and withering treatment (BWT). In this study, metabolome and transcriptome analyses were performed to comprehensively investigate the changes in abundance of amino acids and the expression pattern of relevant genes during BWT of oolong tea manufacturing. Levels of most amino acids increased during BWT in the leaves harvested from 4 cultivars, while expression of the relevant function genes responsible for synthesis and transformation of amino acids up-regulated accordingly. Upstream hub genes including receptor-like protein kinase IKU2, serine/threonine-protein kinase PBL11, MYB transcription factor MYB2, ethylene-responsive transcription factor ERF114, WRKY transcription factor WRKY71, aspartate aminotransferase AATC, UDP-glycosyltransferase U91D1, and 4-hydroxy-4-methyl-2-oxoglutarate aldolase 2 RRAA2, were predicted to be involved in regulation of the function genes expression and the amino acids metabolism through weighted gene coexpression network analysis. A modulation mechanism for accumulation of amino acids during BWT was also proposed. These findings give a deep insight into the metabolic reprogramming mechanism of amino acids during BWT of oolong tea.

[Epidemiological characteristics of imported COVID-19 cases in Guangzhou]

Objective: To understand the epidemiological characteristics of imported COVID-19 cases in Guangzhou and provide scientific basis for the prevention and control of the disease. Methods: The data of imported COVID-19 in Guangzhou reported as of April 1, 2020 were collected from National Notifiable Disease Report System of China. The software Excel 2010 and SPSS 19.0 were applied for data cleaning and statistical analysis. Results: As of April 1, 2020, a total of 103 imported COVID-19 cases had been reported in Guangzhou, in which 92 were confirmed cases and 11 were asymptomatic infection cases. The number of the confirmed imported cases accounted for 11.4% (92/806) in of the total in China at the same time. The male to female ratio of the cases was 1.58∶1 (63∶40). The median age of the cases was 31 years (P(25)-P(75):22-40 years), range of age was 11-63 years. The main occupational distributions of the cases were business services (41/103, 39.8%) and students (36/103, 35.0%). The imported cases whose destinations were 19 provinces and municipalities rather than Guangdong after entering the country accounted for 43.7%. The main source countries of infections were the United Kingdom (27/103, 26.2%), the Philippines (13/103, 12.6%), the United States (13/103, 12.6%) and Nigeria (7/103, 6.8%). There were 34 inbound flights from which the imported COVID-19 cases were detected, in which 10 flights (10/34, 29.4%) were found to carry more than 3 cases, with an average voyage time of (11.14±0.53) hours. A total of 29 imported cases(28.2%) showed symptoms before entering the country, and 65 cases (63.1%) had been isolated before the onset of the disease. The mean free activity time of the isolated cases after the onset was (6.76±0.79) days. The average number of the imported cases' close contacts was 53. There were 13 clusters of COVID-19 caused by the imported cases, involving 36 cases (including 1 imported associated case). Conclusions: The sources of the imported COVID-19 cases in Guangzhou were widely distributed, and no cases had been found to be infected on the flights. In the early stage of the imported epidemic, there was high risk for the spread of the epidemic. Strengthened prevention and control of imported COVID-19 effectively reduced the of transmission risk of COVID-19 in communities.

Transcriptomic and Translatomic Analyses Reveal Insights into the Developmental Regulation of Secondary Metabolism in the Young Shoots of Tea Plants (Camellia sinensis L.)

Accumulation of secondary metabolites in the young shoots of tea plants is developmentally modulated, especially flavonoids. Here, we investigate the developmental regulation mechanism of secondary metabolism in the developing leaves of tea plants using an integrated multiomic approach. For the pair of Leaf2/Bud, the correlation coefficient of the fold change of mRNA and RPFs abundances involved in flavonoid biosynthesis was 0.9359, being higher than that of RPFs and protein (R² = 0.6941). These correlations were higher than the corresponding correlation coefficients for secondary metabolisms and genome-wide scale. Metabolomic analysis demonstrates that the developmental modulations of the structural genes for flavonoid biosynthesis-related pathways align with the concentration changes of catechin and flavonol glycoside groups. Relatively high translational efficiency (TE > 2) was observed in the four flavonoid structural genes (chalcone isomerase, dihydroflavonol 4-reductase, anthocyanidin synthase, and flavonol synthase). In addition, we originally provided the information on identified small open reading frames (small ORFs) and main ORFs in tea leaves and elaborated that the presence of upstream ORFs may have a repressive effect on the translation of downstream ORFs. Our data suggest that transcriptional regulation coordinates with translational regulation and may contribute to the elevation of translational efficiencies for the structural genes involved in the flavonoid biosynthesis pathways during tea leaf development.

Polyphenol oxidase dominates the conversions of flavonol glycosides in tea leaves

Flavonol glycosides are associated with astringency and bitterness of teas. To clarify the dominant enzymatic reaction of flavonol glycosides in tea leaves, the catalytic effects of polyphenol oxidase (PPO), peroxidase (POD) and β-glucosidase were studied, with the maintaining rates of total flavonol glycosides (TFG) being 73.0%, 99.8% and 94.3%. PPO was selected for further investigations, including the effects of pH value (3.5 ~ 6.5), temperature (25 °C ~ 55 °C) and dosage (39 ~ 72 U/mL PPO and 36 U/mL PPO, 3 ~ 36 U/mL POD). The oxidation of flavonol glycosides were intensified at pH 6.5, with 51.8% and 15.4% of TFG maintained after PPO and PPO + POD treatments, suggesting an enhancement from POD. The sensitivity ranking to PPO was: myricetin glycosides > quercetin glycosides > kaempferol glycosides. The inhibitor treatment testified the leading role of PPO in catalyzing flavonol glycosides in tea leaves. Sugar moiety enhanced the docking affinity of flavonol glycosides for PPO. PPO shows the potential of modifying flavonol glycoside composition.

Utilization of albumin fraction from defatted rice bran to stabilize and deliver (-)-epigallocatechin gallate

This work aims to use defatted rice bran albumin (RBA) for delivering epigallocatechin gallate (EGCg). The mode of RBA particle size shifted from 142 nm to 164 nm upon interaction with EGCg. Hydrophobic interaction is the major force between EGCg and RBA resulted in the formation of EGCg-RBA complex based on fluorescence quenching. Upon incorporation into RBA, the recovery of EGCg in pH 7.4 phosphate buffer was elevated by 2 folds. The recovery of EGCg in EGCg-RBA was 18.9% after 2 h intestinal digestion, being higher than 7.6% of native EGCg. The pretreatments of HT-29 cells with EGCg, RBA and EGCg-RBA significantly repressed the transcriptional activation of mitogen-activated protein kinase 14, nuclear transcription factor-κB, and activators of transcription 3 as stimulated with interleukin-1β afterwards, leading to attenuated expressions of corresponding downstream genes. Antioxidant ability importantly functioned in anti-inflammation. RBA is a promising vehicle with inherent anti-inflammatory property for stabilizing and delivering EGCg.

Involvement of Salicylic Acid in Anthracnose Infection in Tea Plants Revealed by Transcriptome Profiling

Anthracnose is a major leaf disease in tea plant induced by Colletotrichum, which has led to substantial losses in yield and quality of tea. The molecular mechanism with regards to responses or resistance to anthracnose in tea remains unclear. A de novo transcriptome assembly dataset was generated from healthy and anthracnose-infected leaves on tea cultivars “Longjing-43” (LJ43) and “Zhenong-139” (ZN139), with 381.52 million pair-end reads, encompassing 47.78 billion bases. The unigenes were annotated versus Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), National Center for Biotechnology Information (NCBI) non-redundant protein sequences (Nr), evolutionary genealogy of genes: Non-supervised Orthologous Groups (eggNOG) and Swiss-prot. The number of differential expression genes (DEGs) detected between healthy and infected leaves was 1621 in LJ43 and 3089 in ZN139. The GO and KEGG enrichment analysis revealed that the DEGs were highly enriched in catalytic activity, oxidation-reduction, cell-wall reinforcement, plant hormone signal transduction and plant-pathogen interaction. Further studies by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and high-performance liquid chromatography (HPLC) showed that expression of genes involved in endogenous salicylic acid biosynthesis and also accumulation of foliar salicylic acid are involved in the response of tea plant to anthracnose infection. This study firstly provided novel insight in salicylic acid acting as a key compound in the responses of tea plant to anthracnose disease. The transcriptome dataset in this study will facilitate to profile gene expression and metabolic networks associated with tea plant immunity against anthracnose.

Inhibitory Effects of (-)-Epigallocatechin-3-gallate on Esophageal Cancer

There is epidemiological evidence showing that drinking green tea can lower the risk of esophageal cancer (EC). The effect is mainly attributed to tea polyphenols and their most abundant component, (−)-epigallocatechin-3-gallate (EGCG). The possible mechanisms of tumorigenesis inhibition of EGCG include its suppressive effects on cancer cell proliferation, angiogenesis, DNA methylation, metastasis and oxidant stress. EGCG modulates multiple signal transduction and metabolic signaling pathways involving in EC. A synergistic effect was also observed when EGCG was used in combination with other treatment methods.

Dissection of Chemical Composition and Associated Gene Expression in the Pigment-Deficient Tea Cultivar 'Xiaoxueya' Reveals an Albino Phenotype and Metabolite Formation

The tea cultivar 'Xiaoxueya', a temperature-sensitive albino mutant, is a rare tea germplasm because of its highly enriched amino acid content and brisk flavour. In comparison with green leaf tissues of 'Xiaoxueya', albino leaves show significant deficiency in chlorophylls and carotenoids and severely disrupted chloroplasts. Furthermore, the accumulation of quality-related secondary metabolites is altered in 'Xiaoxueya' albino leaf, with significantly increased contents of total amino acids, theanine, and glutamic acid and significantly decreased contents of alkaloids, catechins, and polyphenols. To uncover the molecular mechanisms underlying albinism and quality-related constituent variation in 'Xiaoxueya' leaves, expression profiles of pivotal genes involved in the biosynthetic pathways of pigments, caffeine, theanine, and catechins were investigated by quantitative real-time PCR technology. The results revealed that suppressed expression of the chloroplast-localized 1-deoxy-D-xylulose-5-phosphate synthase genes DXS1 and DXS2 involved in the 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway and protochlorophyllide oxidoreductase genes POR1 and POR2 involved in the chlorophyll biosynthetic pathway is responsible for the pigment deficiency in 'Xiaoxueya' albino leaf. Additionally, the low expression of the tea caffeine synthase gene (TCS) involved in caffeine biosynthesis and the chalcone synthase genes CHS1, CHS2, and CHS3, the chalcone isomerase gene CHI, the flavonoid 3',5'-hydroxylase genes F3'5'H1 and F3'5'H2, and the anthocyanidin reductase genes ANR1 and ANR2 involved in the flavonoid pathway is related to the reduction in alkaloid and catechin levels in 'Xiaoxueya' albino leaves.

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.

Different Catabolism Pathways Triggered by Various Methylxanthines in Caffeine-Tolerant Bacterium Pseudomonas putida CT25 Isolated from Tea Garden Soil

The degradation efficiency and catabolism pathways of the different methylxanthines (MXs) in isolated caffeine-tolerant strain Pseudomonas putida CT25 were comprehensively studied. The results showed that the degradation efficiency of various MXs varied with the number and position of the methyl groups on the molecule (i.e., xanthine > 7-methylxanthine ≈ theobromine > caffeine > theophylline > 1-methylxanthine). Multiple MX catabolism pathways coexisted in strain CT25, and a different pathway would be triggered by various MXs. Demethylation dominated in the degradation of N-7-methylated MXs (such as 7-methylxanthine, theobromine, and caffeine), where C-8 oxidation was the major pathway in the catabolism of 1-methylxanthine, whereas demethylation and C-8 oxidation are likely both involved in the degradation of theophylline. Enzymes responsible for MX degradation were located inside the cell. Both cell culture and cell-free enzyme assays revealed that N-1 demethylation might be a rate-limiting step for the catabolism of the MXs. Surprisingly, accumulation of uric acid was observed in a cell-free reaction system, which might be attributed to the lack of activity of uricase, a cytochrome c-coupled membrane integral enzyme.

De novo transcriptome assembly of fluorine accumulator tea plant Camellia sinensis with fluoride treatments

Tea plant (Camellia sinensis) is a typical fluoride (F) hyperaccumulator enriching most F in old leaves. There is association between the risk of fluorosis and excessive consumption of teas prepared using the old leaves. It is meaningful to develop methods for controlling F levels in tea leaves. We generated a comprehensive RNA-seq dataset from tea plants grown at various F levels for different durations by hydroponics, aiming at providing information on mechanism of F metabolism in tea plant. Besides raw reads of the RNA-seq dataset, we present assembled unigenes and aligned unigenes with annotations versus the Gene Ontology (GO) databases, Kyoto Encyclopaedia of Genes and Genomes (KEGG) databases, and Nonredundant (Nr) protein databases with low e-values. 69,488 unigenes were obtained in total, in which 40,894 were given Nr annotations.

Bioavailability of Tea Catechins and Its Improvement

Many in vitro studies have shown that tea catechins had vevarious health beneficial effects. However, inconsistent results between in vitro and in vivo studies or between laboratory tests and epidemical studies are observed. Low bioavailability of tea catechins was an important factor leading to these inconsistencies. Research advances in bioavailability studies involving absorption and metabolic biotransformation of tea catechins were reviewed in the present paper. Related techniques for improving their bioavailability such as nanostructure-based drug delivery system, molecular modification, and co-administration of catechins with other bioactives were also discussed.

Suppressive Effects of EGCG on Cervical Cancer

Cervical cancer is the fourth most common gynecological cancer worldwide. Although prophylactic vaccination presents the most effective method for cervical cancer prevention, chemotherapy is still the primary invasive intervention. It is urgent to exploit low-toxic natural anticancer drugs on account of high cytotoxicity and side-effects of conventional agents. As a natural product, (-)-epigallocatechingallate (EGCG) has abilities in anti-proliferation, anti-metastasis and pro-apoptosis of cervical cancer cells. Moreover, EGCG also has pharmaceutical synergistic effects with conventional agents such as cisplatin (CDDP) and bleomycin (BLM). The underlying mechanisms of EGCG suppressive effects on cervical cancer are reviewed in this article. Further research directions and ambiguous results are also discussed.

Formation mechanism of the oolong tea characteristic aroma during bruising and withering treatment

To elucidate formation mechanism of oolong tea aroma, the released and remaining volatiles during bruising and withering treatment were analyzed using head space solid-phase microextraction/gas chromatography-mass spectrometry. An increase in proportion of the released terpenoid volatiles (TVs) along with a decrease in proportion of the released C₆ green leaf volatiles (GLVs) was observed in both cultivars 'Zhejiang139' and 'Foshou'. Proportion of remaining TVs also fluctuated reversely with GLVs although the level of these volatiles increased remarkably. High ratio of TVs to GLVs was the key chemical foundation of oolong tea characteristic aroma and could be regarded as a good indicator in screening cultivar for suitably producing high quality oolong tea. Combining with transcriptome analysis, increased TVs and GLVs during the treatment might be largely generated through de novo synthesis and modulated at transcript level through up-regulation of genes involved in terpenoids metabolism and enzymatic cleavage of long-chain fatty acids.

[Analysis of community colorectal cancer screening in 50-74 years old people in Guangzhou, 2015-2016]

Objective: To analyze the effect of colorectal cancer screening in the general population in Guangzhou, and provide evidence for the for development of colorectal cancer screening policy and strategy. Methods: The data of colorectal cancer screening in Guangzhou during 2015- 2016 were collected. The participation, the positive rate of fecal occult blood test, the detection rate of colonoscopy and screening effect of colonoscopy were evaluated. Results: A total of 220 834 residents aged 50-74 years received the screening, and the positive rate of the screening was 16.77% (37 040 cases). Colonoscopy was performed for 7 821 cases (21.12%). Colorectal lesions were found in 4 126 cases (52.76%), of which 614 (7.85%) and 73 (0.93%) and 230 (2.94%) were identified as advanced adenoma, severe dysplasia lesions and colorectal cancers, respectively. The detection rates of all colorectal lesions were higher in men than in women (all P<0.01). The diagnostic rate of early lesion was 87.24%, and 99 early cancer cases were found, accounting for 46.26% of the total cases. The overall screening detection rate of colorectal cancer was 104.15/100 000, higher than the incidence rate (81.18/100 000) in colorectal cancer surveillance (P<0.001), but age group <70 years had higher detection rate, age group ≥70 years had higher incidence rate. Conclusions: The colorectal cancer screening strategy in Guangzhou is effective in the detection of the population at high risk, increase the detection rate of colorectal lesions, early diagnosis rate of precancerous lesions and diagnosis rate of early colorectal cancer. The benefit in those aged ≤69 years was more obvious than that in those aged 70-74 years. It is necessary to improve the compliancy of colorectal cancer screening in population at high risk.

Neuroprotective Effects and Mechanisms of Tea Bioactive Components in Neurodegenerative Diseases

As the population ages, neurodegenerative diseases such as Parkinson's disease (PD) and Alzheimer's disease (AD) impose a heavy burden on society and families. The pathogeneses of PD and AD are complex. There are no radical cures for the diseases, and existing therapeutic agents for PD and AD have diverse side effects. Tea contains many bioactive components such as polyphenols, theanine, caffeine, and theaflavins. Some investigations of epidemiology have demonstrated that drinking tea can decrease the risk of PD and AD. Tea polyphenols can lower the morbidity of PD and AD by reducing oxidative stress and regulating signaling pathways and metal chelation. Theanine can inhibit the glutamate receptors and regulate the extracellular concentration of glutamine, presenting neuroprotective effects. Additionally, the neuroprotective mechanisms of caffeine and theaflavins may contribute to the ability to antagonize the adenosine receptor A2AR and the antioxidant properties, respectively. Thus, tea bioactive components might be useful for neuronal degeneration treatment in the future. In the present paper, the neuro protection and the mechanisms of tea and its bioactive components are reviewed. Moreover, the potential challenges and future work are also discussed.

Food-grade Encapsulation Systems for (-)-Epigallocatechin Gallate

(-)-Epigallocatechin gallate (EGCG) has attracted significant research interest due to its health-promoting effects such as antioxidation, anti-inflammation and anti-cancer activities. However, its instability and poor bioavailability have largely limited its efficacy and application. Food-grade materials such as proteins, carbohydrates and lipids show biodegradability, biocompatibility and biofunctionality properties. Food-grade encapsulation systems are usually used to improve the bioavailability of EGCG. In the present paper, we provide an overview of materials and techniques used in encapsulating EGCG, in which the adsorption mechanisms of food-grade systems during in vitro digestion are reviewed. Moreover, the potential challenges and future work using food-grade encapsulates for delivering EGCG are also discussed.

[Clinical analysis of 34 cases with sepsis and systemic capillary leak syndrome]

Objective: To study the clinical characteristics of sepsis with systemic capillary leak syndrome(SCLS) and to evaluate the therapeutic effect and clinical significance of fluid therapy adjusted timely in these patients. Methods: The clinical data of 34 patients with sepsis and SCLS in the Department of Hepatobiliary Surgery ICU of General Hospital of People's Liberation Army General Hospital from July 2014 to January 2016 were retrospectively analyzed.There were 21 males and 13 females, aged from 21 to 74 years, with an average age of 56.3 years.Primary disease as follows: 18 cases with severe acute pancreatitis, 7 postoperative cases of subtotal hepatectomy, 5 postoperative cases of pancreatoduodenectomy, 4 postoperative cases of cholelithiasis.These patients were divided into survival group and death group according to their 28-day survival status.The clinical data including C-reactive protein(CRP), platelets (PLT), brain natriuretic peptide (BNP), the level of arterial blood lactic acid(LAC), oxygenation index(PaO₂/FiO₂, OI), net fluid balance(NFB) and norepinephrine dosage(NE) were collected and compared between two groups at three different intervals(day 1-3, day 4-6, day 7-9). The measurement data and numeration data were statistically analyzed with t test and χ² test respectively to explore the inherent characteristics of the disease evolution and its clinical significance. Results: The survival group (n=23)and the death group(n=11)had no significant difference in the characteristics of basic clinical characters.The condition of the survival group and the death group were both in progress in 1-3 days period manifested as increased CRP(t=-0.473, P=0.640) and BNP levels(t=0.140, P=0.895), decreased PLT counts(t=-0.505, P=0.620) in the inflammatory response, decreased LAC(t=-1.008, P=0.320) and OI level (t=-2.379, P=0.020)in tissue perfusion index, and positive fluid balance(NFB: t=0.910, P=0.370), required NE(t=-0.853, P=0.400) to maintain effective perfusion pressure with systemic edema in both groups.There was no significant difference of all these clinical parameters between the two groups.The patients' condition of the survival group reached a plateau phase, whereas all relative indicators of the death group implied significant aggravation and deterioration of systemic infection(CRP: t=-3.438, P=0.000; PLT: t=1.649, P=0.110; BNP: t=-10.612, P=0.000), tissue perfusion (LAC: t=-11.305, P=0.000; OI: t=2.743, P=0.010)and tissue edema NFB(t=-4.257, P=0.000) and NE(t=-7.956, P=0.000) in 4-6 days period.In the last 7-9 days period the patients' condition of the survival group took a turn for improvement, yet the condition of the death group continued to deteriorate, refractory septic shock developed and multiple organ dysfunction syndrome followed afterwards inevitably(CRP: t=-10.036, P=0.000; PLT: t=6.061, P=0.000; BNP: t=-10.119, P=0.000; LAC: t=-24.466, P=0.000; OI: t=13.443, P=0.010; NFB: t=-8.345, P=0.000; NE: t=-7.121, P=0.000). Conclusions: The condition of patient with sepsis and SCLS would be improved markedly at the critical turning point around 7-9 days period since the effective systemic treatment began.If the infection does not be significantly constrolled and SCLS still remains in a sustained extravasation period in 7-9 days, the prognosis of these patients may be worse and the mortality may be higher than that of the patients mentioned before.

Binding of tea catechins to rice bran protein isolate: Interaction and protective effect during in vitro digestion

Rice bran protein isolate (RBPI) was prepared from defatted rice bran and used to deliver tea catechins. RBPI had the high adsorption selectivity for tea catechins over caffeine. The adsorption characteristics of tea catechins onto RBPI were determined over a range of time (0-300min), concentration (0.25-3.5gL^-1) and temperatures (5°C, 20°C and 35°C). The adsorption kinetic data of EGCg and total catechins (TC) onto RBPI showed excellent fitness with the pseudo-second-order model, indicating that chemisorption is the dominating process. Langmuir and Freundlich models adequately described the isothermal adsorption of tea catechins onto RBPI, and the maximum adsorption of EGCg and TC were achieved at 5°C. SDS-PAGE profiles indicated that globulin and albumin were the major soluble proteins in RBPI to bind tea catechins. Fourier transforms infrared spectroscopy analysis showed that the protein secondary structures of RBPI were altered upon interaction with catechins, with a great increase in random coil and β-antiparallel, a minor increase in α-helix and a reduction in large loop and turn. Binding tea catechins to RBPI respectively increased the recovery% of EGCg and TC from 10.5% and 17.7% to 29.5% and 31.6% after in vitro intestinal digestion. Thus, RBPI is a promising food matrix for delivering tea catechins to gastrointestinal tract.

Tea Polysaccharides and Their Bioactivities

Tea (Camellia sinensis) is a beverage beneficial to health and is also a source for extracting bioactive components such as theanine, tea polyphenols (TPP) and tea polysaccharides (TPS). TPS is a group of heteropolysaccharides bound with proteins. There is evidence showing that TPS not only improves immunity but also has various bioactivities, such as antioxidant, antitumor, antihyperglycemia, and anti-inflammation. However, inconsistent results concerning chemical composition and bioactivity of TPS have been published in recent years. The advances in chemical composition and bioactivities of TPS are reviewed in the present paper. The inconsistent and controversial results regarding composition and bioactivities of TPS are also discussed.

Suppressive Effects of Tea Catechins on Breast Cancer

Tea leaf (Camellia sinensis) is rich in catechins, which endow tea with various health benefits. There are more than ten catechin compounds in tea, among which epigallocatechingallate (EGCG) is the most abundant. Epidemiological studies on the association between tea consumption and the risk of breast cancer were summarized, and the inhibitory effects of tea catechins on breast cancer, with EGCG as a representative compound, were reviewed in the present paper. The controversial results regarding the role of tea in breast cancer and areas for further study were discussed.

Recent Advances in Volatiles of Teas

Volatile compounds are important components of tea aroma, a key attribute of sensory quality. The present review examines the formation of aromatic volatiles of various kinds of teas and factors influencing the formation of tea volatiles, including tea cultivar, growing environment and agronomic practices, processing method and storage of tea. The determination of tea volatiles and the relationship of active-aroma volatiles with the sensory qualities of tea are also discussed in the present paper.

Differential behaviors of tea catechins under thermal processing: Formation of non-enzymatic oligomers

Tea catechins as a member of flavan-3-ols subclass with the same skeleton may behave differentially. This study investigated the chemical conversions of 8 catechins under heat treatment with the involvement of epimerization, hydrolysis and oxidation/condensation reactions. Three reactions were enhanced as temperature increased from 30 °C to 90 °C. The epimerization of non-gallated catechins was favored by epi-configuration but hindered by pyrogallol moiety, and the hydrolysis reaction of gallated catechins was facilitated by pyrogallol moiety. Epicatechin and epigallocatechin had the lowest thermostabilities due to epimerization and oxidation/condensation reactions respectively. Sufficient O2 was not a precondition for the occurrence of chemical conversions of catechins under heat treatment. Non-enzymatic oligomerization occurred to epi type catechins and catechin under heat treatment, and dehydrodicatechins A were mainly responsible for the browning of epicatechin and catechin solutions. The evidence of generation of catechin oligomers provides a novel way to explain sensory change of tea and relevant products during thermal processing.

Studies on the mechanism of efficient extraction of tea components by aqueous ethanol

Effect of solvent on the extraction yield and its relevant mechanism have been studied in this paper. Compared with extraction by water, catechins and caffeine could be easily extracted from green tea by aqueous ethanol, but hardly at all by absolute ethanol. Results of the vacuum-assisted extraction, solubility determination of EGCG and caffeine, as well as swelling ratio analysis of the infused leaves, indicated that an excellent leaf-matrix-swelling effect and high solubility of tea components might be the key mechanisms for high extraction efficiency by the aqueous ethanol. These mechanisms were further confirmed by the pre-swelling extraction. This is a first report on the mechanism of efficient extraction by aqueous organic solvent. Application of pre-swelling extraction is also discussed.