Green tea polyphenols alleviate di-(2-ethylhexyl)phthalate-induced liver injury in mice

BACKGROUND Di(2-ethylhexyl)phthalate(DEHP)is a common plasticizer known to cause liver injury.Green tea is reported to exert therapeutic effects on heavy metal exposureinduced organ damage.However,limited studies have examined the therapeutic effects of green tea polyphenols(GTPs)on DEHP-induced liver damage.AIM To evaluate the molecular mechanism underlying the therapeutic effects of GTPs on DEHP-induced liver damage.METHODS C57BL/6J mice were divided into the following five groups:Control,model[DEHP(1500 mg/kg bodyweight)],treatment[DEHP(1500 mg/kg bodyweight)+GTP(70 mg/kg bodyweight),oil,and GTP(70 mg/kg bodyweight)]groups.After 8 wk,the liver function,blood lipid profile,and liver histopathology were examined.Differentially expressed micro RNAs(miRNAs)and mRNAs in the liver tissues were examined using high-throughput sequencing.Additionally,functional enrichment analysis and immune infiltration prediction were performed.The miRNA-mRNA regulatory axis was elucidated using the starBase database.Protein expression was evaluated using immunohistochemistry.RESULTS GTPs alleviated DHEP-induced liver dysfunction,blood lipid dysregulation,fatty liver disease,liver fibrosis,and mitochondrial and endoplasmic reticulum lesions in mice.The infiltration of macrophages,mast cells,and natural killer cells varied between the model and treatment groups.mmu-miR-141-3p(a differentially expressed miRNA),Zcchc24(a differentially expressed mRNA),and Zcchc24(a differentially expressed protein)constituted the miRNA-mRNA-protein regulatory axis involved in mediating the therapeutic effects of GTPs on DEHP-induced liver damage in mice.CONCLUSION This study demonstrated that GTPs mitigate DEHP-induced liver dysfunction,blood lipid dysregulation,fatty liver disease,and partial liver fibrosis,and regulate immune cell infiltration.Additionally,an important miRNAmRNA-protein molecular regulatory axis involved in mediating the therapeutic effects of GTPs on DEHP-induced liver damage was elucidated.

Green tea polyphenols ameliorate non-alcoholic fatty liver disease through upregulating AMPK activation in high fat fed Zucker fatty rats

AIM To investigate protective effects and molecular mechanisms of green tea polyphenols(GTP) on nonalcoholic fatty liver disease(NAFLD) in Zucker fatty(ZF) rats.METHODS Male ZF rats were fed a high-fat diet(HFD) for 2 wk then treated with GTP(200 mg/kg) or saline(5 m L/kg) for 8 wk, with Zucker lean rat as their control. At the end of experiment, serum and liver tissue were collected for measurement of metabolic parameters, alanine aminotransferase(ALT) and aspartate aminotransferase(AST), inflammatory cytokines and hepatic triglyceride and liver histology. Immunoblotting was used to detect phosphorylation of AMP-activated protein kinase(AMPK) acetyl-Co A carboxylase(ACC), and sterol regulatory element-binding protein 1c(SREBP1c). RESULTS Genetically obese ZF rats on a HFD presented with metabolic features of hepatic pathological changes comparable to human with NAFLD. GTP intervention decreased weight gain(10.1%, P = 0.052) and significantly lowered visceral fat(31.0%, P < 0.01). Compared with ZF-controls, GTP treatment significantly reduced fasting serum insulin, glucose and lipids levels. Reduction in serum ALT and AST levels(both P < 0.01) were observed in GTP-treated ZF rats. GTP treatment also attenuated the elevated TNFα and IL-6 in the circulation. The increased hepatic TG accumulation and cytoplasmic lipid droplet were attenuated by GTP treatment, associated with significantly increased expression of AMPK-Thr172(P < 0.05) and phosphorylated ACC and SREBP1c(both P < 0.05), indicating diminished hepatic lipogenesis and triglycerides out flux from liver in GTP treated rats. CONCLUSION The protective effects of GTP against HFD-induced NAFLD in genetically obese ZF rats are positively correlated to reduction in hepatic lipogenesis through upregulating the AMPK pathway.

Green tea polyphenols inhibit testosterone production in rat Leydig cells

This study investigated the acute effects of green tea extract （GTE） and its polyphenol constituents, （-）-epigallocatechin-3-gallate （EGCG） and （-）-epicatechin （EC）, on basal and stimulated testosterone production by rat Leydig cells in vitro. Leydig cells purified in a Percoll gradient were incubated for 3 h with GTE, EGCG or EC and the testosterone precursor androstenedione, in the presence or absence of either protein kinase A （PKA） or protein kinase C （PKC） activators. The reversibility of the effect was studied by pretreating cells for 15 min with GTE or EGCG, allowing them to recover for 1 h and challenging them for 2 h with human chorionic gonadotropin （hCG）, luteinizing hormone releasing hormone （LHRH）, 22（R）-hydroxycholesterol or androstenedione. GTE and EGCG, but not EC, inhibited both basal and kinase-stimulated testosterone production. Under the pretreatment conditions, the inhibitory effect of the higher concentration of GTE/EGCG on hCG/LHRH-stimulated or 22（R）- hydroxycholesterol-induced testosterone production was maintained, whereas androstenedione-supported testosterone production returned to control levels. At the lower concentration of GTE/EGCG, the inhibitory effect of these polyphenols on 22（R）-hydroxycholesterol-supported testosterone production was reversed. The inhibitory effects of GTE may be explained by the action of its principal component, EGCG, and the presence of a gallate group in its structure seems important for its high efficacy in inhibiting testosterone production. The mechanisms underlying the effects of GTE and EGCG involve the inhibition of the PKA/PKC signalling pathways, as well as the inhibition of P450 side-chain cleavage enzyme and 17β-hydroxysteroid dehydrogenase function.

Green Tea Polyphenols Alleviate Autophagy Inhibition Induced by High Glucose in Endothelial Cells

Bovine aortic endothelial cells（BAECs）were cultured with high glucose（33 mmol/L）,4 mg/L green tea polyphenols（GTPs）or 4 mg/L GTPs co-treatment with high glucose for 24 h in the presence or absence of Bafilomycin-A1（BAF）.We observed that high glucose increased the accumulation of LC3-II.Treatment with BAF did not further increase the accumulation of LC3-II.

Green tea polyphenols protect spinal cord neurons against hydrogen peroxide-induced oxidative stress

Green tea polyphenols are strong antioxidants and can reduce free radical damage. To investigate their neuroprotective potential, we induced oxidative damage in spinal cord neurons using hydrogen peroxide, and applied different concentrations （50-200μg,/mL） of green tea polyphenol to the cell medium for 24 hours. Measurements of superoxide dismutase activity, malondialdehyde content, and expression of apoptosis-related genes and proteins revealed that green tea polyphenol effectively alleviated oxidative stress. Our results indicate that green tea polyphenols play a protective role in spinal cord neurons under oxidative stress.

A novel long-chain acyl-derivative of epigallocatechin-3-O-gallate prepared and purified from green tea polyphenols

Lipophilic tea polyphenols (LTP) were prepared by catalytic esterification of green tea polyphenols (GTP) with hexadecanoyl chloride. A novel long chain acyl derivative of epigallocatechin 3 o gallate (EGCG) was first isolated from purification of LTP by high speed countercurrent chromatography (HSCCC) using a solvent system composed of n hexane ethyl acetate methanol water (1:1:1:1, v/v). The molecular structure of the acyl derivative, Epigallocatechin 3 O gallate 4′ O hexadecanate , was elucidated by means of elemental analysis, IR, 1H NMR and MS spectra.

Advances in Research of Green Tea Polyphenols in Drug Development

This paper elaborated the chemical components,biological metabolism,and progress in the field of drug development of green tea polyphenols,mainly in the prevention and treatment of cancer,neurodegenerative diseases,and diabetes.The potential anti-tumor activity of tea polyphenols can be achieved through intervening in various stages of tumor generation,development,and metastasis.However,the development of tea polyphenols as a therapeutic drug still faces many challenges,such as low bioavailability.Nanoparticle-based drug delivery systems have particular advantages over the simple tea polyphenols.Since there are emerging safety issues and potential local drug overdose effects,it is necessary to determine the actual dosage and pharmacological mechanism of the drug after encapsulating the nanoparticles.

Counteraction of Nogo-A and axonal growth inhibitors by green tea polyphenols and other natural products

Neuronal injuries such as stroke,traumatic brain injury,and spinal cord injury are leading causes of major disability and death.Chronic therapy for these neuronal injuries requires the promotion of axonal regeneration from the remaining neurons（Schwab and Strittmatter,2014）.

Allograft pretreatment for the repair of sciatic nerve defects: green tea polyphenols versus radiation

Pretreatment of nerve allografts by exposure to irradiation or green tea polyphenols can elimi- nate neuroimmunogenicity, inhibit early immunological rejection, encourage nerve regeneration and functional recovery, improve tissue preservation, and minimize postoperative infection. In the present study, we investigate which intervention achieves better results. We produced a 1.0 cm sciatic nerve defect in rats, and divided the rats into four treatment groups： autograft, fresh nerve allograft, green tea polyphenol-pretreated （1 mg/mL, 4~C） nerve allograft, and irradiation-pre- treated nerve allograft （26.39 Gy/min for 12 hours; total 19 kGy）. The animals were observed, and sciatic nerve electrophysiology, histology, and transmission electron microscopy were carried out at 6 and 12 weeks after grafting. The circumference and structure of the transplanted nerve in rats that received autografts or green tea polyphenol-pretreated nerve allografts were similar to those of the host sciatic nerve. Compared with the groups that received fresh or irradiation-pre- treated nerve allografts, motor nerve conduction velocity in the autograft and fresh nerve allograft groups was greater, more neurites grew into the aUografts, Schwann cell proliferation was evident, and a large number of new blood vessels was observed; in addition, massive myelinated nerve fibers formed, and abundant microfilaments and microtubules were present in the axoplasm. Our findings indicate that nerve allografts pretreated by green tea polyphenols are equivalent to trans- planting autologous nerves in the repair of sciatic nerve defects, and promote nerve regeneration. Pretreatment using green tea polyphenols is better than pretreatment with irradiation.

Influence of green tea polyphenols on mitochondrial permeability transition pore and Ca^2＋ transport

The authors investigated the influence of green tea polyphenols (GTPs) on the liver mitochondria permeability transition pore (PTP) opening through mitochondria swelling and change of mitochondria membrane potential. The data showed that GTPs had obvious protective effect on the Ca 2+-induced PTP opening in a dose-dependent manner detected by mitochondria swelling. The results were obtained by measuring the change of mitochondria membrane potential through Rh 123. Further experiments were conducted to examine the detailed influence of GTPs on Ca 2+import and export of mitochondria. The results showed that GTPs had remarkably inhibitory effect on the Ca 2+-induced Ca 2+ import in mitochondria; and that they could accelerate Ca 2+-release from mitochondria. Our data provide an alternate interpretation of the potent protective function of GTPs on cell against apoptosis.

Green Tea Polyphenols Prevent Early Vascular Aging Induced by High-Fat Diet via Promoting Autophagy in Young Adult Rats

Objective Epidemiology studies indicate that green tea polyphenols(GTP)perform a protective effect on cardiovascular diseases,but the underlying mechanisms are complex.The present study aimed to investigate the effect of GTP on high-fat diets(HFD)induced-early vascular aging.Methods Six-week young adult Wistar rats were fed with standard chow or HFD in the presence and absence of GTP(200 mg/kg body weight)for 18 weeks.In vitro experiment,human umbilical vascular endothelial cells(HUVECs)were treated with palmitic acid(PA)and GTP.Results The results showed that GTP alleviated the disorganized arterial wall and the increased intima-media thickness induced by HFD.In addition,the vascular oxidative injury was suppressed following GTP treatment.Furthermore,GTP elevated the ratio of LC3-II/LC3-I and suppressed expression of p62/SQSTM1,and restored SIRT3 expression in the aorta of HFD rats.Consistently,in cultured HUVECs,GTP inhibited cell senescence indicated by SA-β-gal and promoted endothelial autophagy compared with the PA treatment group.The activity of SIRT3 was specifically inhibited by 3-TYP,and the protective effect of GTP was consequently abolished.Conclusion The findings indicated that GTP protected against early vascular senescence in young HFD rats via ameliorating oxidative injury and promoting autophagy which was partially regulated by the SIRT3 pathway.

Quercetin and green tea polyphenols inhibit the mitochondrial damages and cytotoxicity induced by VO(acac)_2

Abstract： Vanadium compounds are promising therapeutic agents for the treatment of diabetes and cancer. However, vanadium toxicity has been a great concern. Many works suggested that vanadium-induced oxidative stress is a major reason of vanadium toxicity. Quercetin and green tea polyphenols （GTP） are well-known antioxidants that play important roles in the prevention of many oxidative stress-related diseases. In this study, we investigated the protective effects of quercetin and GTP against damages caused by VO（acac）2 on isolated mitochondria and whole cells. The experimental results demonstrated that quercetin and GTP could significantly inhibit mitochondrial dysfimctions induced by VO（acac）2, such as mitochondrial swelling, depolarization of the inner mitochondrial membrane potential （△ψm）, and increased release of reactive oxygen species （ROS）. Moreover, they also reduce cytotoxicity in Hep G2 cells. These results indicated that use of natural antioxidants to control the metal toxicity of vanadium compounds may be a promising strategy for developing metal-based therapeutic agents.

Promoting proliferation and differentiation of BMSCs by green tea polyphenols functionalized porous calcium phosphate

In this article,we proposed a facile protocol to functionalize porous calcium phosphate ceramics(PCPC)using dietary tea polyphenols(TP).TP molecules was attracted and anchored by Ca2t ions from the surface of CPC.These TP molecules modulated the nucleation and crystallization of calcium phosphate nanorods assemblies on the surface of PCPC.Our results prove that these calcium phosphate nanorods assemblies accompanies functional groups of TP make PCPC/TP effectively promote proliferation and differentiation of bone mesenchymal stem cells(BMSCs).We inferred that these calcium phosphate nanorods assemblies might change the surface microenvironment of PCPC,which is critical to promote the proliferation and differentiation of BMSCs.Compared with naked PCPC,PCPC/TP obviously increased BMP2,ErK/MAPK and JNK/MAPK level and mineralization capacity of cells(ALP level).

Green tea polyphenols induce cell death in breast cancer MCF-7 cells through induction of cell cycle arrest and mitochondrial-mediated apoptosis

In order to study the molecular mechanisms of green tea polyphenols（GTPs） in treatment or prevention of breast cancer, the cytotoxic effects of GTPs on five human cell lines（MCF-7, A549, Hela, PC3, and HepG2 cells） were determined and the antitumor mechanisms of GTPs in MCF-7 cells were analyzed. The results showed that GTPs exhibited a broad spectrum of inhibition against the detected cancer cell lines, particularly the MCF-7 cells. Studies on the mechanisms revealed that the main modes of cell death induced by GTPs were cell cycle arrest and mitochondrialmediated apoptosis. Flow cytometric analysis showed that GTPs mediated cell cycle arrest at both G1/M and G2/M transitions. GTP dose dependently led to apoptosis of MCF-7 cells via the mitochondrial pathways, as evidenced by induction of chromatin condensation, reduction of mitochondrial membrane potential（ΔΨ_m）, improvement in the generation of reactive oxygen species（ROS）, induction of DNA fragmentation, and activations of caspase-3 and caspase-9 in the present paper.

Green tea polyphenols supplementation alters immunometabolism and oxidative stress in dairy cows with hyperketonemia

Peripartal cows often experience negative energy balance,and are therefore prone to suffering from metabolic diseases such as hyperketonemia,which causes financial losses in dairy farms.This study aimed to investigate the effect of green tea polyphenol(GTP)supplementation during the periparturient period on production performance,oxidative stress and immunometabolism in dairy cows with hyperketonemia.One hundred Holstein cows were assigned to GTP(0.2 g/kg DM;n=50)or control(without GTP;n=50)group based on body weight,previous milk yield,and parity on d 15 before expected parturition.Subsequently,10 cows with hyperketonemia were selected from each group,according to bloodβ-hydroxybutyric acid(BHBA)concentration between 1.2 and 2.9 mmol/L from 2 to 3 d postpartum.All cows were fed a close-up diet and a lactation diet with or without GTP supply from 15 d prepartum until 30 d postpartum.Milk and blood samples were obtained from 20 cows selected with hyperketonemia on 10,20,and 30 d postpartum.Compared with control cows,greater milk yield and lower somatic cell count were observed in GTP cows.The GTP group had lower concentrations of BHBA,free fatty acids,cholesterol,triglyceride,reactive oxygen species,malondialdehyde,and hydrogen peroxide,greater concentrations of glucose,lower activities of aspartate aminotransferase,alanine aminotransferase,and glutamyl transpeptidase,alongside greater ac-tivities of superoxide dismutase,glutathione peroxidase,and total antioxidant capacity.Additionally,GTP supplementation up-regulated concentrations of interleukin-6 and interleukin-10,but down-regulated concentrations of tumor necrosis factor-α,interleukin-1β,interleukin-2,interleukin-8,and interferon-γin plasma.Greater concentrations of plasma immunoglobulin G were also detected in the GTP group.Overall,the data suggested that GTP supplementation from 15 d prepartum to 30 d postpartum improved the milk yield and health status in cows with hvoerketonemia during early lactation.

Scavenging Action of Zinc and Green Tea Polyphenol on Cisplatin and Nickel Induced Nitric Oxide Generation and Lipid Peroxidation in Rats

Objective Toxic metal ions have been implicated in the generation of reactive oxygen species (ROS) and nitric oxide (NO). Metallothionines (MT) and plant flavonoids have been reported in the intervention against oxidative damage. We investigated the effect of zinc induced MT and green tea polyphenol (GTP) in reducing the oxidative responses induced by nickel and platinum. Methods Zinc (10 mg/kg b. wt, sc) was administered to rats twice at a gap of 24hrs and GTP (10 mg/100 mL in drinking water) was fed ad libitum for 8 days. Nickel chloride (150 umol/kgb.wt, ip) and cisplatin (50 mmol/kg b.wt, sc) was administered to rats 24 h after Zn or GTP pre-treatment. Animals of all the groups were sacrificed 16 hrs after treatment and biochemical markers for toxicity were monitored. Results Zinc or GTP pre-treatment caused significant protection against nickel or cisplatin enhanced mortality in rats, and reduction in lipid peroxidation and NO. Conclusion It is proposed that inhibition of ROS and NO by GTP and zinc may prove useful as a selective pharmacological agent in the amelioration of metal toxicity.

COMPARATIVE STUDY OF GREEN TEA POLYPHENOL AND FLUORIDE ON STREPTOCOCCUS MUTANS

Objective To disclose the mechanism of green tea polyphenol in the prevention ol dental caries.ththods Using sodium fluoride (highly effective anticaries agent) as control and Streptococcus mutans(carigenous microbe) as target, green tea polyphenol (potential bacterial inhibitor) was used to testify its action onthe change of microbial morphology, extramicrobial sucrase, glucosyltranslerase (GTF), lactate hydrogenase (LDH),protein and pH values of the culture media. Results GTF activities were inhibited both by green tea polyphenoland sodium fluoride, the inhibitory ellcacy was stronger in green tea polyphenol. Morphologic changes consisted ofmembrane disroption in tea polyphenol treated microbes, and cytoplasmic vacuolization in fluoride treated bacteria.High protein level in fluoride treated culture media means cytoplasmic decomposition, intracellular protein leakageinto media. Conclusion The inhibition of GTF activity was stronger in green tea polyphenol treated microbes.The target of action was cell membrane disruption in green tea polyphenol treated cell and cytoplasmic in fluoridetreated microbes.

Isolation and Purification of a Novel Long-chain Acyl Catechin from Lipophilic Tea Polyphenols

Lipophilic tea polyphenols (LTP) was prepared by esterification of green tea polyphenols (GTP) with hexadecanoyl chloride. A novel long-chain acyl catechin was isolated and purified from LTP by high-speed countercurrent chromatography (HSCCC). Its molecular structure was elucidated as epigallocatechin-3-O-gallate-4'-O-hexadecanate by elemental analysis, IR, MS and H-1 NMR spectra.

Long Non-coding RNAs Expression Profile in HepG2 Cells Reveals the Potential Role of Long Non-coding RNAs in the Cholesterol Metabolism

Background：Green tea has been shown to improve cholesterol metabolism in animal studies,but the molecular mechanisms underlying this function have not been fully understood.Long non-coding RNAs （lncRNAs） have recently emerged as a major class of regulatory molecules involved in a broad range of biological processes and complex diseases.Our aim was to identify important lncRNAs that might play an important role in contributing to the benefits of epigallocatechin-3-gallate （EGCG） on cholesterol metabolism.Methods：Microarrays was used to reveal the lncRNA and mRNA profiles in green tea polyphenol（-）-epigallocatechin gallate in cultured human liver （HepG2） hepatocytes treated with EGCG and bioinformatic analyses of the predicted target genes were performed to identify lncRNA-mRNA targeting relationships.RNA interference was used to investigate the role of lncRNAs in cholesterol metabolism.Results：The expression levels of 15 genes related to cholesterol metabolism and 285 lncRNAs were changed by EGCG treatment.Bioinformatic analysis found five matched lncRNA-mRNA pairs for five differentially expressed lncRNAs and four differentially expressed mRNA.In particular,the lncRNA4 T102202 and its potential targets mRNA-3-hydroxy-3-methylglutaryl coenzyme A reductase （HMGCR） were identified.Using a real-time polymerase chain reaction technique,we confirmed that EGCG down-regulated mRNA expression level of the HMGCR and up-regulated expression ofAT102202.After AT102202 knockdown in HepG2,we observed that the level of HMGCR expression was significantly increased relative to the scrambled small interfering RNA control （P 〈 0.05）.Conclusions：Our results indicated that EGCG improved cholesterol metabolism and meanwhile changed the lncRNAs expression profile in HepG2 cells.LncRNAs may play an important role in the cholesterol metabolism.

ROS-responsive capsules engineered from EGCG-Zinc networks improve therapeutic angiogenesis in mouse limb ischemia

The successful treatment of limb ischemia requires that promote angiogenesis along with microenvironment improvement.Zinc ions have been reported to stimulate angiogenesis,but application was limited to the toxicity concerns.We hypothesized that zinc based metal-EGCG capsule(EGCG/Zn Ps)can achieve sustained release Zn2+resulting in reduced toxicity and improve angiogenesis as well as the improvement of microenvironment by ROS scavenging of EGCG.The surface morphology,zeta potential,infrared absorbance peaks and zinc ion release profile of the EGCG/Zn Ps were measured.In vitro,EGCG/Zn showed significantly antioxidant,antiinflammatory and induced cell migration effect.In addition,EGCG/Zn Ps enabled the sustained release of zinc ions,which reduced cytotoxicity and enhanced the secretion of vascular endothelial growth factor(VEGF)in vitro and in vivo.In mouse models of limb ischemia,EGCG/Zn Ps promoted angiogenesis and cell proliferation in ischemic tissues.Moreover,EGCG/Zn Ps group exhibited the most significant recovery of limb ischemic score,limb temperature and blood flow than other groups.In conclusion,EGCG/Zn Ps is a safe and promising approach to combine the merit of Zn2+and EGCG,thus enabling the direct application to limb ischemia.