Pinacidil ameliorates cardiac microvascular ischemia-reperfusion injury by inhibiting chaperone-mediated autophagy of calreticulin.

Calcium overload is the key trigger in cardiac microvascular ischemia-reperfusion (I/R) injury, and calreticulin (CRT) is a calcium buffering protein located in the endoplasmic reticulum (ER). Additionally, the role of pinacidil, an antihypertensive drug, in protecting cardiac microcirculation against I/R injury has not been investigated. Hence, this study aimed to explore the benefits of pinacidil on cardiac microvascular I/R injury with a focus on endothelial calcium homeostasis and CRT signaling. Cardiac vascular perfusion and no-reflow area were assessed using FITC-lectin perfusion assay and Thioflavin-S staining. Endothelial calcium homeostasis, CRT-IP3Rs-MCU signaling expression, and apoptosis were assessed by real-time calcium signal reporter GCaMP8, western blotting, and fluorescence staining. Drug affinity-responsive target stability (DARTS) assay was adopted to detect proteins that directly bind to pinacidil. The present study found pinacidil treatment improved capillary density and perfusion, reduced no-reflow and infraction areas, and improved cardiac function and hemodynamics after I/R injury. These benefits were attributed to the ability of pinacidil to alleviate calcium overload and mitochondria-dependent apoptosis in cardiac microvascular endothelial cells (CMECs). Moreover, the DARTS assay showed that pinacidil directly binds to HSP90, through which it inhibits chaperone-mediated autophagy (CMA) degradation of CRT. CRT overexpression inhibited IP3Rs and MCU expression, reduced mitochondrial calcium inflow and mitochondrial injury, and suppressed endothelial apoptosis. Importantly, endothelial-specific overexpression of CRT shared similar benefits with pinacidil on cardiovascular protection against I/R injury. In conclusion, our data indicate that pinacidil attenuated microvascular I/R injury potentially through improving CRT degradation and endothelial calcium overload.

MAP4K4 exacerbates cardiac microvascular injury in diabetes by facilitating S-nitrosylation modification of Drp1.

Dynamin-related protein 1 (Drp1) is a crucial regulator of mitochondrial dynamics, the overactivation of which can lead to cardiovascular disease. Multiple distinct posttranscriptional modifications of Drp1 have been reported, among which S-nitrosylation was recently introduced. However, the detailed regulatory mechanism of S-nitrosylation of Drp1 (SNO-Drp1) in cardiac microvascular dysfunction in diabetes remains elusive. The present study revealed that mitogen-activated protein kinase kinase kinase kinase 4 (MAP4K4) was consistently upregulated in diabetic cardiomyopathy (DCM) and promoted SNO-Drp1 in cardiac microvascular endothelial cells (CMECs), which in turn led to mitochondrial dysfunction and cardiac microvascular disorder. Further studies confirmed that MAP4K4 promoted SNO-Drp1 at human C644 (mouse C650) by inhibiting glutathione peroxidase 4 (GPX4) expression, through which MAP4K4 stimulated endothelial ferroptosis in diabetes. In contrast, inhibition of MAP4K4 via DMX-5804 significantly reduced endothelial ferroptosis, alleviated cardiac microvascular dysfunction and improved cardiac dysfunction in db/db mice by reducing SNO-Drp1. In parallel, the C650A mutation in mice abolished SNO-Drp1 and the role of Drp1 in promoting cardiac microvascular disorder and cardiac dysfunction. In conclusion, our findings demonstrate that MAP4K4 plays an important role in endothelial dysfunction in DCM and reveal that SNO-Drp1 and ferroptosis activation may act as downstream targets, representing potential therapeutic targets for DCM.

Nicorandil alleviates cardiac microvascular ferroptosis in diabetic cardiomyopathy: Role of the mitochondria-localized AMPK-Parkin-ACSL4 signaling pathway.

Mitochondria-associated ferroptosis exacerbates cardiac microvascular dysfunction in diabetic cardiomyopathy (DCM). Nicorandil, an ATP-sensitive K+ channel opener, protects against endothelial dysfunction, mitochondrial dysfunction, and DCM; however, its effects on ferroptosis and mitophagy remain unexplored. The present study aimed to assess the beneficial effects of nicorandil against endothelial ferroptosis in DCM and the underlying mechanisms. Cardiac microvascular perfusion was assessed using a lectin perfusion assay, while mitophagy was assessed via mt-Keima transfection and transmission electron microscopy. Ferroptosis was examined using mRNA sequencing, fluorescence staining, and western blotting. The mitochondrial localization of Parkin, ACSL4, and AMPK was determined via immunofluorescence staining. Following long-term diabetes, nicorandil treatment improved cardiac function and remodeling by alleviating cardiac microvascular injuries, as evidenced by the improved microvascular perfusion and structural integrity. mRNA-sequencing and biochemical analyses showed that ferroptosis occurred and Pink1/Parkin-dependent mitophagy was suppressed in cardiac microvascular endothelial cells after diabetes. Nicorandil treatment suppressed mitochondria-associated ferroptosis by promoting the Pink1/Parkin-dependent mitophagy. Moreover, nicorandil treatment increased the phosphorylation level of AMPKα1 and promoted its mitochondrial translocation, which further inhibited the mitochondrial translocation of ACSL4 via mitophagy and ultimately suppressed mitochondria-associated ferroptosis. Importantly, overexpression of mitochondria-localized AMPKα1 (mitoAα1) shared similar benefits with nicorandil on mitophagy, ferroptosis and cardiovascular protection against diabetic injury. In conclusion, the present study demonstrated the therapeutic effects of nicorandil against cardiac microvascular ferroptosis in DCM and revealed that the mitochondria-localized AMPK-Parkin-ACSL4 signaling pathway mediates mitochondria-associated ferroptosis and the development of cardiac microvascular dysfunction.

Cucurbitacin B protects against myocardial ischemia-reperfusion injury through activating JAK2/STAT3 signaling pathway.

Cucurbitacin B, a tetracyclic triterpenoid compound extracted from various plants, has been proven to exert a vital role in various diseases. However, the effect of cucurbitacin B on myocardial infarction (MI) and ischemia-reperfusion (I/R) injury is still relatively unclear. The main purpose of the present study was to investigate the effect of cucurbitacin B on cell apoptosis and oxidative damage after myocardial I/R injury in vitro and in vivo and elucidate the molecular mechanisms underlying its role. The 56-day-old adult mice and 1-day-old neonatal mice cardiomyocytes were used to construct I/R or oxygen-glucose deprivation/reoxygenation (OGD/R) injury models. The oxidative injury, western blot and TUNEL assay were performed to evaluate cardiomyocyte damage in the present study. In vitro， we confirmed that cucurbitacin B could attenuate LDH release, oxidative stress and cell apoptosis in cardiomyocytes exposed to OGD/R. Besides, we confirmed in an adult I/R mouse model that cucurbitacin B can improve cardiac repair and block cell apoptosis in the acute phase (24 h) post-myocardial I/R injury, as well as promote long-term cardiac function and fiber scar area after 28 days of I/R. Mechanically, we clarify that cucurbitacin B exerts cardiomyocyte protective effects through activating the JAK2/STAT3 signaling pathway. In conclusion, our study elucidates for the first time the protective role of cucurbitacin B in cardiac I/R injury, which provides a novel perspective for better prevention of I/R injury through the JAK2/STAT3 signaling pathway.

Plasma anti-myosin autoantibodies in the diagnosis of necrotizing enterocolitis.

We aimed to assess whether autoantibodies can be used as biomarkers for necrotizing enterocolitis (NEC) and applied for its early diagnosis. A prospective observational study was conducted in neonates with suspected NEC abdominal distension (the developmental study), which consisted of 50 neonates finally divided into NEC (n = 24) and non-NEC (n = 26) cohorts based on follow-up results. Serum samples were collected within 48 h of illness onset and used for screening NEC-associated plasma autoantibodies by autoantigen microarray. Additionally, we validated anti-myosin autoantibodies by enzyme-linked immunosorbent assay (ELISA) in an independent validation study, for which we selected plasma samples within 48 h of onset of NEC (n = 38) and samples of gestational age- and weight-matched controls (n = 13). Autoantigen microarray revealed that both IgG and IgM anti-myosin autoantibodies in plasma from neonates with NEC were significantly higher than those in neonates with other diagnoses. ELISA showed that plasma anti-myosin autoantibodies increased in the NEC cohort, with 1.5-fold higher levels than in the non-NEC cohort. Anti-myosin autoantibodies were able to distinguish NEC from non-NEC, achieving an area under the curve (AUC) of 0.8856 (95% confidence interval (CI): 0.7918-0.9795), with sensitivity of 81.58% and specificity of 76.93%. Plasma anti-myosin autoantibodies were significantly higher in all three subtypes of NEC (P < 0.0001 for NEC I; P = 0.0018 for NEC II; P = 0.0011 for NEC III), especially in NEC stage I than that in the non-NEC controls. CONCLUSION: Anti-myosin autoantibodies may be applied as a promising diagnostic marker for NEC, especially for NEC stage I. WHAT IS KNOWN: • Intestinal damage and self-antigen exposure may lead to increased autoantibodies, and they are widely used as biomarkers for diagnosing inflammatory bowel disease. • Necrotizing enterocolitis (NEC) is a devastating disease with overwhelming inflammation and immune dysregulation. WHAT IS NEW: • Increased autoantibodies were present in patients with NEC, even before typical X-ray manifestations. • Anti-myosin autoantibodies may be applied as a promising diagnostic marker for NEC.

The New Insight into the Effects of Different Fixing Technology on Flavor and Bioactivities of Orange Dark Tea.

Peach leaf orange dark tea (ODT) is a fruity tea made by removing the pulp from peach leaf orange and placing dry Qingzhuan tea into the husk, followed by fixing them together and drying. Since the quality of traditional outdoor sunlight fixing (SL) is affected by weather instability, this study explored the feasibility of two new fixing methods, including hot air fixing (HA) and steam fixing (ST). Results showed that fixing method had a great impact on ODT shape, aroma, and taste. Compared with SL and ST, HA endowed ODT with higher fruit aroma, mellow taste, better coordination, and higher sensory evaluation score. Physical-chemical composition analysis showed that SL-fixed orange peel was higher than HA- or ST-fixed peel in the content of polyphenols, flavonoids, soluble protein, hesperidin and limonin, while HA has a higher content of volatile substances and contains more alcohols, aldehydes and ketones, and acid and esters than ST and SL. Activity analysis showed that HA was superior to ST or SL in comprehensive antioxidant activity and inhibitory activity against α-glucosidase. Comprehensive results demonstrated that HA has better performance in improving ODT quality and can replace the traditional SL method in production.

Protective effect of HINT2 on mitochondrial function via repressing MCU complex activation attenuates cardiac microvascular ischemia-reperfusion injury.

Current evidence indicates that coronary microcirculation is a key target for protecting against cardiac ischemia-reperfusion (I/R) injury. Mitochondrial calcium uniporter (MCU) complex activation and mitochondrial calcium ([Ca2+]m) overload are underlying mechanisms involved in cardiovascular disease. Histidine triad nucleotide-binding 2 (HINT2) has been reported to modulate [Ca2+]m via the MCU complex, and our previous work demonstrated that HINT2 improved cardiomyocyte survival and preserved heart function in mice with cardiac ischemia. This study aimed to explore the benefits of HINT2 on cardiac microcirculation in I/R injury with a focus on mitochondria, the MCU complex, and [Ca2+]m overload in endothelial cells. The present work demonstrated that HINT2 overexpression significantly reduced the no-reflow area and improved microvascular perfusion in I/R-injured mouse hearts, potentially by promoting endothelial nitric oxide synthase (eNOS) expression and phosphorylation. Microvascular barrier function was compromised by reperfusion injury, but was repaired by HINT2 overexpression via inhibiting VE-Cadherin phosphorylation at Tyr731 and enhancing the VE-Cadherin/ß-Catenin interaction. In addition, HINT2 overexpression inhibited the inflammatory response by suppressing vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1). Mitochondrial fission occurred in cardiac microvascular endothelial cells (CMECs) subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) injury and resulted in mitochondrial dysfunction and mitochondrion-dependent apoptosis, the effects of which were largely relieved by HINT2 overexpression. Additional experiments confirmed that [Ca2+]m overload was an initiating factor for mitochondrial fission and that HINT2 suppressed [Ca2+]m overload via modulation of the MCU complex through directly interacting with MCU in CMECs. Regaining [Ca2+]m overload by spermine, an MCU agonist, abolished all the protective effects of HINT2 on OGD/R-injured CMECs and I/R-injured cardiac microcirculation. In conclusion, the present report demonstrated that HINT2 overexpression inhibited MCU complex-mitochondrial calcium overload-mitochondrial fission and apoptosis pathway, and thereby attenuated cardiac microvascular ischemia-reperfusion injury.

Discrimination and Identification of Aroma Profiles and Characterized Odorants in Citrus Blend Black Tea with Different Citrus Species.

Citrus blend black teas are popular worldwide, due to its unique flavor and remarkable health benefits. However, the aroma characteristics, aroma profiles and key odorants of it remain to be distinguished and cognized. In this study, the aroma profiles of 12 representative samples with three different cultivars including citrus (Citrus reticulata), bergamot (Citrus bergamia), and lemon (Citrus limon) were determined by a novel approach combined head space-solid phase microextraction (HS-SPME) with comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-TOFMS). A total of 348 volatile compounds, among which comprised esters (60), alkenes (55), aldehydes (45), ketones (45), alcohols (37), aromatic hydrocarbons (20), and some others were ultimately identified. The further partial least squares discrimination analysis (PLS-DA) certified obvious differences existed among the three groups with a screening result of 30 significant differential key volatile compounds. A total of 61 aroma-active compounds that mostly presented green, fresh, fruity, and sweet odors were determined in three groups with gas chromatography-olfactometry/mass spectrometry (GC-O/MS) assisted analysis. Heptanal, limonene, linalool, and trans-ß-ionone were considered the fundamental odorants associated with the flavors of these teas. Comprehensive analysis showed that limonene, ethyl octanoate, copaene, ethyl butyrate (citrus), benzyl acetate, nerol (bergamot) and furfural (lemon) were determined as the characterized odorants for each type.

Effect of Stereochemical Configuration on the Transport and Metabolism of Catechins from Green Tea across Caco-2 Monolayers.

The transcellular transport and metabolism of eight green tea catechins (GTCs) were studied in Caco-2 monolayers, with the aim of investigating the effect of cis⁻trans isomerism on the membrane permeability and biotransformation of GTCs. The results showed that the catechin stereochemistry significantly affects the efflux transport rather than the absorption transport in the Caco-2 monolayers. The trans catechins showed a better transcellular permeability than their corresponding cis (epi) catechins in the efflux transport, as the efflux amount of trans catechins were all significantly higher than that of the cis (epi) catechins at each concentration and each time point tested. Moreover, the relative contents of the (+)-catechin (C)-O-sulfate, (+)-gallocatechin (GC)-O-sulfate, (-)-catechin gallate (CG)-O-sulfate, and (-)-gallocatechin gallate (GCG)-O-sulfate in the efflux transport were 2.67, 16.08, 50.48, and 31.54 times higher than that of the (-)-epicatechin (EC)-O-sulfate, (-)-epigallocatechin (EGC)-O-sulfate, (-)-epicatechin gallate (ECG)-O-sulfate, and (-)-epigallocatechin gallate (EGCG)-O-sulfate, respectively. It indicated that more metabolites were observed after the transcellular efflux of trans catechins. Furthermore, after two hours of incubation, the GTCs could significantly increase the expression of multidrug resistance-associated protein 2 (MRP2) and breast cancer-resistance protein (BCRP), and decrease the expression of P-glycoprotein in the Caco-2 cells. The regulation of GTCs on P-glycoprotein, MRP2, and BCRP could also be significantly influenced by the chemical and dimensional structure. In a conclusion, catechin stereochemistry significantly affects the transport and metabolism of GTCs when refluxed in the Caco-2 monolayers.

Impact of light irradiation on black tea quality during withering.

Black tea manufacture usually involves the processes of withering, cutting, fermentation and drying. The aim of present study was to evaluate the effect of the relationship between the quality and withering with different light sources (ultraviolet, yellow, blue, purple, orange, red, cyan, green and white) an quality attribute of tea. The results indicated that the yellow, orange and red light withering significantly improved the aroma and taste, imparting the tea a sweet flavor and a fresh and mellow taste. Tea treated with yellow light was scored highest the sensory scores and showed the highest content in catechins, theaflavins, amino acids and aroma components, followed by the orange and red light treatments. The black tea withered with ultraviolet light showed a strong astringency, probably resulting from low contents of theaflavins, amino acids and soluble sugar. The green light irradiation remarkably damaged the aroma and taste of the tea, leading to a strong greenish flavor and an astringent taste, probably owing to the lowest contents of chemical compositions. No significant cumulative effect was found in the hybrid light withering treatments. Therefore, monochromatic yellow, orange and red lights were suggested for withering the black tea to improve its overall quality.

In vitro α-glucosidase inhibitory activity of isolated fractions from water extract of Qingzhuan dark tea.

BACKGROUND: Natural products have being used as potential inhibitors against carbohydrate-hydrolyzing enzymes to treat diabetes mellitus. Chinese dark tea has various interesting bioactivities. In this study, the active compounds from Qingzhuan dark tea were separated and their anti-diabetic activity was examined using an in vitro enzymatic model. METHODS: The chloroform, ethyl acetate, n-butanol, sediment and residual aqua fractions of a Chinese dark tea (Qingzhuan tea) were prepared by successively isolating the water extract with different solvents and their in vitro inhibitory activities against α-glucosidase were assessed. The fraction with the highest inhibitory activity was further characterized to obtain the main active components of Qingzhuan tea. RESULTS: The ethyl acetate fraction had the greatest inhibitory effect on α-glucosidase, followed by n-butanol, sediment and residual aqua fractions (with the IC50 values of 0.26 mg/mL, 2.94 mg/mL, 3.02 mg/mL, and 5.24 mg/mL, respectively), mainly due to the high content of polyphenols. Among the eight subfractions (QEF1-8) isolated from the ethyl acetate fraction, QEF8 fraction showed the highest α-glucosidase inhibitory potential in a competitive inhibitory manner (the K i value of 77.10 µg/mL). HPLC-MS analysis revealed that (-)-epigallocatechin gallate (EGCG) and (-)-epicatechin gallate (ECG) were the predominant active components in QEF8. CONCLUSION: These results indicated that Qingzhuan tea extracts exerted potent inhibitory effects against α-glucosidase, EGCG and ECG were likely responsible for the inhibitory activity in Qingzhuan tea. Qingzhuan tea may be recommended as an oral antidiabetic diet.

In vitro antioxidant and pancreatic α-amylase inhibitory activity of isolated fractions from water extract of Qingzhuan tea.

In the present work, Qingzhuan tea, a unique dark tea produced by post-fermentation technology, was selected to investigate its antioxidant and pancreatic α-amylase inhibiting activities. Water extract of Qingzhuan tea was successively isolated by solvent partitioning procedures to obtain chloroform, ethyl acetate, n-butanol, sediment and residual aqua fractions. Of different fractions, the ethyl acetate fraction (QEF) had the highest total polyphenols and catechins contents, demonstrated the strongest DPPH radical scavenging activity and exhibited the greatest inhibitory effect on porcine pancreatic α-amylase activity in vitro. Further separation of QEF by a Sephadex LH-20 column generated eight subfractions (QEF1-QEF8), with QEF8 being the most active subfraction based on the assays above mentioned. The major active components in QEF8 were identified as catechins EGCG and ECG by LC-MS analysis, with contents of 22.29 % and 11.11 % respectively. Inhibitory effects of catechin standards EGCG and ECG on porcine pancreatic α-amylase activity were also observed. In conclusion, Qingzhuan tea or its water extract could be potentially used as complementary therapy ingredients for diabetes treatment through lowering postprandial blood glucose, and catechins EGCG and ECG may be the most efficient components in the water extract.

Metal tolerance protein CsMTP4 has dual functions in maintaining zinc homeostasis in tea plant.

Plants have evolved a series of zinc (Zn) homeostasis mechanisms to cope with the fluctuating Zn in the environment. How Zn is taken up, translocated and tolerate by tea plant remains unknown. In this study, on the basis of RNA-Sequencing, we isolated a plasma membrane-localized Metal Tolerance Protein (MTP) family member CsMTP4 from Zn-deficient tea plant roots and investigated its role in regulation of Zn homeostasis in tea plant. Heterologous expression of CsMTP4 specifically enhanced the tolerance of transgenic yeast to Zn excess. Moreover, overexpression of CsMTP4 in tea plant hairy roots stimulated Zn uptake under Zn deficiency. In addition, CsMTP4 promoted the growth of transgenic Arabidopsis plants by translocating Zn from roots to shoots under Zn deficiency and conferred the tolerance to Zn excess by enhancing the efflux of Zn from root cells. Transcriptome analysis of the CsMTP4 transgenic Arabidopsis found that the expression of Zn metabolism-related genes were differentially regulated compared with wild-type plants when exposed to Zn deficiency and excess conditions. This study provides a mechanistic understanding of Zn uptake and translocation in plants and a new strategy to improve phytoremediation efficiency.

The key aroma components of steamed green tea decoded by sensomics and their changes under different withering degree.

Steamed green tea has a long history and unique aroma, but little is known about its key aroma components. In this study, 173 volatiles in steamed green tea were identified using solvent-assisted flavor evaporation and headspace-solid phase microextraction plus two chromatographic columns of different polarities. Aroma extract dilution analysis revealed 48 highly aroma-active compounds with flavor dilution factors 64-1024. Internal standards were used to calculate odorant active value (OAV), and 11 OAV > 1 key aroma compounds were determined. Omission test identified eight substances, including dimethyl sulfide, (E)-ß-ionone, cis-jasmone, linalool, nonanal, heptanal, isovaleraldehyde and (Z)-3-hexenol, as the key aroma active compounds of steamed green tea. With the increase of withering degree, the content of these substances increased first and then decreased except for heptanal and cis-jasmone. Moreover, the water content of 62 % was suggested to be an appropriate withering degree during the processing of steamed green tea.

Non-Targeted Metabolomics Reveals the Effects of Different Rolling Methods on Black Tea Quality.

A non-targeted metabolomics approach and sensory evaluation, coupled with multivariate statistical analysis, systematically uncover the impact of the rolling time on the quality parameters of black tea. GC-MS analysis reveals that a moderate extension of rolling time favorably contributes to the accumulation of characteristic aroma components in black tea. The volatile components reach their highest concentration in black tea samples processed during an 80-min rolling period. UHPLC-Q-TOF/MS analysis demonstrates a substantial decrease in the contents of catechins and flavonoids with an increase in rolling time. Simultaneously, the production of theaflavins, coupled with the degradation of green bitterness volatiles (GBVs), significantly contributes to the formation of endogenous aroma components in black tea. These findings underscore the close relationship between rolling time control and black tea quality, emphasizing that a moderate extension of the rolling time fosters the development of improved black tea flavor quality. The comprehensive quality evaluation indicates that the optimal duration is 80 min. However, the initial 0 to 20 min of rolling is a crucial phase for the genesis and transformation of black tea quality. This study offers valuable insights into the influence of rolling time on black tea quality, potentially enhancing future studies of rolling technology. It provides theoretical guidelines for optimizing the processing of Gongfu black tea.

Study on color, aroma, and taste formation mechanism of large-leaf yellow tea during an innovative manufacturing process.

This study used samples processed with an innovative manufacturing process to explore the dynamic changes of large-leaf yellow tea (LYT) in color, aroma, and taste substances, and the quality components were most significantly affected in the stages of first pile-yellowing (FP) and over-fired drying (TD). In this process, the moisture and temperature conditions caused chlorophyll degradation, Maillard reactions, caramelization reactions, and isomerization of phenolic substances, forming the quality of LYT. Specifically, chlorophyll degradation favored the formation of color quality; the taste quality was determined by the content of soluble sugars, amino acids, catechins, etc.; the aroma quality was dependent on the content changes of alcohols and aldehydes, as well as the increase of sweet and roasting aroma substances in the third drying stage. Additionally, twelve key aroma components, including linalool, (E)-ß-ionone, 2,3-diethyl-5-methyl-pyrazine, etc., were identified as contributors to revealing LYT rice crust-like and sweet aroma formation mechanism.

Mechanism of aroma enhancement methods in accelerating Congou black tea acidification subjected to room temperature storage.

Acidification of aroma-enhanced black tea during storage was studied. UPLC-Q-TOF/MS (Ultra Performance Liquid Chromatography and Quadrupole-Time of Flight Mass Spectrometer) and HPLC (High-Performance Liquid Chromatography) analysis of non-volatile substances and organic acids revealed a decrease of soluble sugars and amino acids in aroma-enhanced black tea, while an increase in organic acids such as oxalic acid, malic acid and quinic acid. Further in vitro experiments indicated that the acidification of aroma-enhanced tea during storage can be attributed to decomposition of sugars and amino acids by heating, oxidation of aromatic aldehydes. Meanwhile, the amino acids, catechins, soluble sugars and flavonoids that constitute the taste of black tea are further reduced, changing the taste composition of tea infusion and further increasing its acidity. This study revealed the reasons for black tea acidification during aroma enhancement and storage and provided a theoretical basis for improving black tea quality.

Role of NLRP3 inflammasome in central nervous system diseases.

The central nervous system (CNS) is the most delicate system in human body, with the most complex structure and function. It is vulnerable to trauma, infection, neurodegeneration and autoimmune diseases, and activates the immune system. An appropriate inflammatory response contributes to defence against invading microbes, whereas an excessive inflammatory response can aggravate tissue damage. The NLRP3 inflammasome was the first one studied in the brain. Once primed and activated, it completes the assembly of inflammasome (sensor NLRP3, adaptor ASC, and effector caspase-1), leading to caspase-1 activation and increased release of downstream inflammatory cytokines, as well as to pyroptosis. Cumulative studies have confirmed that NLRP3 plays an important role in regulating innate immunity and autoimmune diseases, and its inhibitors have shown good efficacy in animal models of various inflammatory diseases. In this review, we will briefly discuss the biological characteristics of NLRP3 inflammasome, summarize the recent advances and clinical impact of the NLRP3 inflammasome in infectious, inflammatory, immune, degenerative, genetic, and vascular diseases of CNS, and discuss the potential and challenges of NLRP3 as a therapeutic target for CNS diseases.

Study on the Variation Law of the Main Mechanical Properties in the Processing of Longjing Tea.

Fresh tea leaves, both single bud and one leaf with a bud, were used as the test materials in this study. The variation in the main mechanical properties, such as texture and tensile properties, during the processing of Longjing tea was examined by using texture profile analysis (TPA) and stress-strain tensile tests. The plasticity showed a trend of first increasing and then decreasing during the processing, whereas the elasticity displayed the opposite tendency. The flexibility reached a maximum during the fixing stage and then slowly declined with a relatively small change. Initially, the maximum force dropped down and then gradually elevated later.Both the tensile strength and the fracture strain indicated an upward movement at the beginning and then a downfall afterward. The elastic modulus changed little before the final panning stage, then raised significantly. The correlation analysis revealed that the flexibility of tea leaves was highly positively correlated with water content. At water content of 30% and 50%, the plasticity and flexibility of tea leaves reached a clear peak and the maximum force was at a low level, which is suitable for the shaping of Longjing tea. The results also demonstrated that the main mechanical properties of different tender materials change differently during the processing. The research findings can provide parameters for optimizing the mechanical design and processing technology of Longjing tea.

Effect and Mechanism of Theaflavins on Fluoride Transport and Absorption in Caco-2 Cells.

This paper investigated the effect and mechanism of theaflavins (TFs) on fluoride (F-) uptake and transport in the Caco-2 cell model through structural chemistry and transcriptome analysis. The results showed that the four major TFs (TF, TF3G, TF3'G and TFDG) at a 150 µg/mL concentration could all significantly decrease F- transport in Caco-2 cells after 2 h of treatment and, at 2 µg/mL F- concentration, the F- transport was more inclined to efflux. During transport, the F- retention in Caco-2 cells was significantly increased by TF3G while it was clearly decreased by TF. The interaction between TFs and F- was analyzed by Raman spectroscopy and isothermal titration calorimetry, and F- was shown to affect the π bond vibration on the benzene ring of TFs, thus influencing their stability. Additionally, F- showed weak binding to TF3G, TF3'G and TFDG, which may inhibit F- transport and absorption in the Caco-2 cell line. Transcriptome and RT-PCR analysis identified three key differentially expressed genes related to cell permeability, and TFs can be assumed to mediate F- transport by regulating the expression of permeability-related genes to change cell monolayer permeability and enhance cell barrier function; however, this needs to be further elucidated in future studies.