Epigallocatechin-3-gallate regulates cell growth, cell cycle and phosphorylated nuclear factor-κB in human dermal fibroblasts

Research progress on the potential delaying skin aging effect and mechanism of tea for oral and external use

Skin aging is characterized by the gradual loss of elasticity, the formation of wrinkles and various color spots, the degradation of extracellular matrix proteins, and the structural changes of the dermis. With the increasingly prominent problems of environmental pollution, social pressure, ozone layer thinning and food safety, skin problems have become more and more complex. The skin can reflect the overall health of the body. Skincare products for external use alone cannot fundamentally solve skin problems; it needs to improve the overall health of the body. Based on the literature review in recent 20 years, this paper systematically reviewed the potential delaying effect of tea and its active ingredients on skin aging by oral and external use. Tea is the second-largest health drink after water. It is rich in tea polyphenols, l-theanine, tea pigments, caffeine, tea saponins, tea polysaccharides and other secondary metabolites. Tea and its active substances have whitening, nourishing, anti-wrinkle, removing spots and other skincare effects. Its mechanism of action is ultraviolet absorption, antioxidant, anti-inflammatory, inhibition of extracellular matrix aging, inhibiting the accumulation of melanin and toxic oxidation products, balancing intestinal and skin microorganisms, and improving mood and sleep, among other effects. At present, tea elements skincare products are deeply loved by consumers. This paper provides a scientific theoretical basis for tea-assisted beauty and the high-end application of tea in skincare products.

Targeted Pulmonary Delivery of the Green Tea Polyphenol Epigallocatechin Gallate Controls the Growth of Mycobacterium tuberculosis by Enhancing the Autophagy and Suppressing Bacterial Burden

Growing rates of tuberculosis (TB) superbugs are alarming, which has hampered the progress made to-date to control this infectious disease, and new drug candidates are few. Epigallocatechin gallate (EGCG), a major polyphenolic compound from green tea extract, shows powerful efficacy against TB bacteria in in vitro studies. However, the therapeutic efficacy of the molecule is limited due to poor pharmacokinetics and low bioavailability following oral administration. Aiming to improve the treatment outcomes of EGCG therapy, we investigated whether encapsulation and pulmonary delivery of the molecule would allow the direct targeting of the site of infection without compromising the activity. Microencapsulation of EGCG was realized by scalable spray-freeze-drying (SFD) technology, forming free-flowing micrometer-sized microspheres (epigallocatechin-3-gallate-loaded trehalose microspheres, EGCG-t-MS) of trehalose sugar. These porous microspheres exhibited appropriate aerodynamic parameters and high encapsulation efficiencies. In vitro studies demonstrated that EGCG-t-MS exhibited dose- and time-dependent killing of TB bacteria inside mouse macrophages by cellular mechanisms of lysosome acidification and autophagy induction. In a preclinical study on TB-infected Balb/c mice model (4 weeks of infection), we demonstrate that the microencapsulated EGCG, administered 5 days/week for 6 weeks by pulmonary delivery, showed exceptional efficacy compared to oral treatment of free drug. This treatment approach exhibited therapeutic outcomes by resolution of inflammation in the infected lungs and significant reduction (P < 0.05) in bacterial burden (up to ∼2.54 Log₁₀ CFU) compared to untreated control and orally treated mice groups. No pathological granulomas, lesions, and inflammation were observed in the histopathological investigation, compared to untreated controls. The encouraging results of the study may pave the avenues for future use of EGCG in TB therapeutics by targeted pulmonary delivery and lead to its translational success.

Surface engineering of titanium alloy using metal-polyphenol network coating with magnesium ions for improved osseointegration

Although titanium-based implants are widely used in orthopedic and dental clinics, improved osseointegration at the bone–implant interface is still required.

Safety Assessment of Camellia sinensis-Derived Ingredients As Used in Cosmetics

Cosmetic ingredients derived from Camellia sinensis (tea) plant parts function as antioxidants and skin conditioning agents-humectant and miscellaneous. The Cosmetic Ingredient Review (CIR) Expert Panel (Panel) reviewed relevant animal and human data related to these ingredients. The use of the leaf ingredients in beverages results in much larger systemic exposures than those possible from cosmetic use. Accordingly, concern over the systemic toxicity potential of leaf-derived ingredients is mitigated. Because product formulations may contain multiple botanical ingredients, each containing the same constituents of concern, formulators are advised to be aware of these constituents and to avoid reaching levels that may lead to sensitization or other toxic effects. The Panel concluded that the C sinensis leaf-derived ingredients are safe in the present practices of use and concentration described in this safety assessment when formulated to be nonsensitizing. However, the available data are insufficient to determine whether the non-leaf-derived ingredients are safe for use in cosmetics.

Epigallocatechin-3-Gallate Promotes the Growth of Mink Hair Follicles Through Sonic Hedgehog and Protein Kinase B Signaling Pathways

Background: Hair follicles play an essential role in the growth of hair. Epigallocatechin-3-gallate (EGCG), a catechin polyphenol in green tea, has various bioactivities. The present study aims to evaluate the effect of EGCG on the growth of mink hair follicles and investigate the possible molecular mechanisms.

Methods: The length of hair follicles was recorded up to 6 days in presence of 0.1–5 μM EGCG. Primary dermal papilla cells (DPCs) and outer root sheath cells (ORSCs) were treated with 0.25–4 μM EGCG, and their growth was evaluated by MTT assay and cell cycle detection. The levels of key molecules in sonic hedgehog (Shh) and protein kinase B (AKT) signaling pathways were further assessed by quantitative real-time PCR, western blot and immunofluorescence. To determine the involvement of Shh and AKT pathways in EGCG-mediated growth-promotion of ORSCs and DPCs, Shh pathway inhibitors cyclopamine and GANT61 or AKT pathway inhibitor LY294002 were employed, and then cell proliferation and cell cycle were analyzed.

Results: Data from ex vivo culture showed that, in presence of 0.5–2.5 μM EGCG, the growth of mink hair follicles was promoted. In vitro, the proliferation of DPCs and ORSCs was enhanced by 0.5–4 μM EGCG treatment. More cells entered S phase upon treatment of EGCG, accompanied with upregulation of cyclin D1 and cyclin E1. Furthermore, when exposed to EGCG, the Shh and AKT signaling pathways were activated in both hair follicles and primary DPCs and ORSCs. Inhibiting either of these two pathways partly reversed the effect of EGCG on proliferation and cell cycle of DPCs and ORSCs.

Conclusion: EGCG promotes the growth of mink hair follicles at concentrations of 0.5–2.5 μM. This growth-promoting effect of EGCG may be associated with the increased proliferation of DPCs and ORSCs through activating Shh and AKT signaling pathways.

Polyphenol Polymerization by an Alternative Oxidative Microbial Enzyme and Characterization of the Biological Activity of Oligomers

The recombinant catalase-peroxidase HPI from E. coli was used as an alternative enzyme in polymerization reactions for the production of (−) epicatechin oligomers and their biological activity was characterized. The enzyme was prepared in two forms: a purified and an immobilized form. Both were tested for their activity in oxidative polymerization reactions, and their stability and reusability were assessed. The polymerization reactions were followed by SEC-HPLC analyses, and the substrate was completely converted into one or more polymerization products depending on the reactions conditions. Results showed that the utilized conditions allowed for the isolation of some oligomers of different molecular weight: the oligomers containing 6 and 7 units of epicatechin substrate are the heaviest ones. Epicatechin was also used in reactions catalyzed by HRP in the same reaction conditions for comparison. In addition, one selected oligomer obtained by HPI enzyme catalysis was shown to act as in vitro inhibitor of tumor cell growth, like one oligomer deriving from epicatechin by HRP catalysis. These data confirm that epicatechin oligomeric form is more effective than its monomer in biological activity and suggest the use of HPI as an alternative enzyme in reactions for the production of epicatechin oligomers.

Effects of polyphenols on doxorubicin-induced oral keratinocyte cytotoxicity and anticancer potency against oral cancer cells

BACKGROUND

Normal human oral keratinocytes are highly sensitive to anticancer drugs including doxorubicin. Resveratrol, epigallocatechin gallate, and tannic acid are polyphenolic compounds that were reported to have cardioprotective effect when combined with doxorubicin. However, it is unknown whether these polyphenols could protect normal human oral keratinocytes against doxorubicin-induced cytotoxicity without weakening its cytotoxic potential against oral cancer cells. Here, we examined the effects of the 3 polyphenolic compounds on doxorubicin-induced cytotoxicity in normal human oral keratinocytes and also investigated their effects on doxorubicin potency in HSC-2 human oral squamous cell carcinoma cells.

METHODS

Cell viability was evaluated, followed by the analysis of apoptosis and necrosis. The changes in intracellular reactive oxygen species at the early stage after treatment were also examined.

RESULTS

The results revealed that resveratrol in combination with doxorubicin additively augmented doxorubicin cytotoxicity in both types of cells. However, epigallocatechin gallate and tannic acid at a certain concentration mitigated the doxorubicin-induced keratinocyte toxicity mainly due to reduced doxorubicin-induced necrosis in normal human oral keratinocytes without weaken doxorubicin anticancer efficacy. The exact mechanism is still unknown but intracellular reactive oxygen species might be not the sole factor.

CONCLUSIONS

This study for the first time reported the effects of resveratrol, epigallocatechin gallate, and tannic acid on doxorubicin-induced cytotoxicity in normal oral keratinocytes and oral cancer cells. The combined use of epigallocatechin gallate or tannic acid with doxorubicin at a certain concentration could mitigate doxorubicin-induced keratinocyte cytotoxicity without weakening doxorubicin anticancer efficacy.

Hyaluronic Acid/PLGA Core/Shell Fiber Matrices Loaded with EGCG Beneficial to Diabetic Wound Healing

During the last few decades, considerable research on diabetic wound healing strategies has been performed, but complete diabetic wound healing remains an unsolved problem, which constitutes an enormous biomedical burden. Herein, hyaluronic acid (HA)/poly(lactic-co-glycolic acid, PLGA) core/shell fiber matrices loaded with epigallocatechin-3-O-gallate (EGCG) (HA/PLGA-E) are fabricated by coaxial electrospinning. HA/PLGA-E core/shell fiber matrices are composed of randomly-oriented sub-micrometer fibers and have a 3D porous network structure. EGCG is uniformly dispersed in the shell and sustainedly released from the matrices in a stepwise manner by controlled diffusion and PLGA degradation over four weeks. EGCG does not adversely affect the thermomechanical properties of HA/PLGA-E matrices. The number of human dermal fibroblasts attached on HA/PLGA-E matrices is appreciably higher than that on HA/PLGA counterparts, while their proliferation is steadily retained on HA/PLGA-E matrices. The wound healing activity of HA/PLGA-E matrices is evaluated in streptozotocin-induced diabetic rats. After two weeks of surgical treatment, the wound areas are significantly reduced by the coverage with HA/PLGA-E matrices resulting from enhanced re-epithelialization/neovascularization and increased collagen deposition, compared with no treatment or HA/PLGA. In conclusion, the HA/PLGA-E matrices can be potentially exploited to craft strategies for the acceleration of diabetic wound healing and skin regeneration.

Functional testing of topical skin formulations using an optimised ex vivo skin organ culture model

A number of equivalent-skin models are available for investigation of the ex vivo effect of topical application of drugs and cosmaceuticals onto skin, however many have their drawbacks. With the March 2013 ban on animal models for cosmetic testing of products or ingredients for sale in the EU, their utility for testing toxicity and effect on skin becomes more relevant. The aim of this study was to demonstrate proof of principle that altered expression of key gene and protein markers could be quantified in an optimised whole tissue biopsy culture model. Topical formulations containing green tea catechins (GTC) were investigated in a skin biopsy culture model (n = 11). Punch biopsies were harvested at 3, 7 and 10 days, and analysed using qRT-PCR, histology and HPLC to determine gene and protein expression, and transdermal delivery of compounds of interest. Reduced gene expression of α-SMA, fibronectin, mast cell tryptase, mast cell chymase, TGF-β1, CTGF and PAI-1 was observed after 7 and 10 days compared with treated controls (p < 0.05). Histological analysis indicated a reduction in mast cell tryptase and chymase positive cell numbers in treated biopsies compared with untreated controls at day 7 and day 10 (p < 0.05). Determination of transdermal uptake indicated that GTCs were detected in the biopsies. This model could be adapted to study a range of different topical formulations in both normal and diseased skin, negating the requirement for animal models in this context, prior to study in a clinical trial environment.

Augmented anti-angiogenesis activity of polysulfated heparin-endostatin and polyethylene glycol-endostatin in alkali burn-induced corneal ulcers in rabbits

Endostatin (ES) is an endogenous angiogenesis inhibitor that has the ability to inhibit tumor growth and metastasis. However, its clinical application is limited by a number of disadvantages, such as poor stability, short half-life and the requirement of high doses to maintain its efficacy. The chemical modification on ES may offer a solution to these disadvantages. The aim of the present study was to evaluate the effects of ES, polysulfated heparin-endostatin (PSH-ES) and polyethylene glycol-endostatin (PEG-ES) on the endothelial cell proliferation and angiogenesis associated with corneal neovascularization (CNV) and to determine their mechanisms of action. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) was used to study the effects of ES and its derivatives on endothelial cell proliferation in vitro, and rabbits were used to evaluate the effects of ES and its derivatives on CNV in vivo. In the evaluation of CNV, the expression of vascular endothelial growth factor in the cornea was measured via immunohistochemistry and microvessels were counted. ES and its derivatives significantly inhibited endothelial cell proliferation in vitro (P<0.05) and suppressed CNV in vivo. Among the compounds examined, ES most effectively inhibited endothelial cell proliferation in vitro (P<0.05); however, PSH-ES and PEG-ES most effectively inhibited CNV in vivo (P<0.05). These results indicate that PSH-ES and PEG-ES are candidate anti-angiogenesis drugs.

Punicalagin inhibits inflammation in LPS-induced RAW264.7 macrophages via the suppression of TLR4-mediated MAPKs and NF-κB activation

Punicalagin (2,3,hexahydroxydiphenoyl-gallagyl-D-glucose and referred to as PUN) is a bioactive ellagitannin isolated from pomegranate, which is widely used for the treatment of inflammatory bowel disease (IBD), diarrhea, and ulcers in Chinese traditional medicine. In this study, we detected the anti-inflammation potentials of PUN in lipopolysaccharide (LPS)-induced macrophages and tried to uncover the underlying mechanism. Results demonstrated that PUN (25, 50, or 100 μM) treatment could significantly decrease the LPS-induced production of nitric oxide), prostaglandin E2 (PGE2), interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α in RAW264.7 cells. Molecular research showed that PUN inhibited the activation of upstream mediator nuclear factor-κB by suppressing the phosphorylation of IκBα and p65. Results also indicated that PUN could suppress the phosphorylation of mitogen-activated protein kinase including p38, c-Jun N-terminal kinase, and extracellular signal-regulated kinase. In conclusion, we observed that PUN could inhibit LPS-induced inflammation, and it may be a potential choice for the treatment of inflammation diseases.

The protective action of ketanserin against lipopolysaccharide-induced shock in mice is mediated by inhibiting inducible NO synthase expression via the MEK/ERK pathway

Nitric oxide (NO) plays an important role in the pathogenesis of endotoxic shock. This work tested the hypothesis that ketanserin could attenuate endotoxic shock by inhibiting the expression of inducible NO synthase (iNOS). The results demonstrated that ketanserin could inhibit iNOS expression in the heart, lungs, liver, and kidneys and nitrate production in the serum upon endotoxic shock in mice. In RAW264.7 cells, ketanserin significantly inhibited the expression of iNOS and decreased the production of NO, TNFα, IL-6, and reactive oxygen species upon lipopolysaccharide (LPS) challenge. Ketanserin also increased the level of ATP and mitochondrial membrane potential in RAW264.7 cells upon LPS exposure. LPS-induced iNOS expression was inhibited by the 5-HT2A receptor antagonist ritanserin and not the α1 receptor antagonist prazosin. Knockdown of 5-HT2A receptor by siRNA abolished the inhibitory effect of ketanserin on the expression of iNOS. These results indicated that the inhibitory effect of ketanserin on the expression of iNOS is mediated by blocking the 5-HT2A receptor. Furthermore, ketanserin significantly inhibited the activation of ERK1/2 and NF-κB signal. Pretreatment with PD184352, a specific inhibitor of ERK1/2, blocked the inhibitory effect of ketanserin on the expression of iNOS and NO production, indicating a critical role for the MEK/ERK1/2 signaling pathway. Collectively, our findings indicate that inhibition of the expression of iNOS via the MEK/ERK pathway mediates the protective effects of ketanserin against LPS-induced shock in mice.

Cellular targets for the beneficial actions of tea polyphenols

Green and black teas contain different biologically active polyphenolic compounds that might offer protection against a variety of human diseases. Although promising experimental and clinical data have shown protective effects, limited information is available on how these beneficial effects of tea polyphenols are mediated at the cellular level. Evidence is accumulating that catechins in green tea as well as theaflavins and thearubigins from black tea are the substances responsible for the physiologic effects of tea in vitro. The green tea catechin epigallocatechin-3-gallate (EGCG) is generally considered to be the biologically most active compound in vitro. The changes in the activities of various protein kinases, growth factors, and transcription factors represent a common mechanism involved in cellular effects of tea polyphenols. In addition to modification of intracellular signaling by activation of cellular receptors, it was shown that, at least for EGCG, tea polyphenols can enter the cells and directly interact with their molecular targets within cells. There, they frequently result in opposite effects in primary compared with tumor cells. Although tea polyphenols were long regarded as antioxidants, research in recent years has uncovered their prooxidant properties. The use of high nonphysiologic concentrations in many cell culture studies raises questions about the biological relevance of the observed effects for the in vivo situation. Efforts to attribute functional effects in vivo to specific molecular targets at the cellular level are still ongoing.

Preventive effects of epigallocatechin-3-O-gallate against replicative senescence associated with p53 acetylation in human dermal fibroblasts

Considering the various pharmacological activities of epigallocatechin-3-O-gallate (EGCG) including anticancer, and anti-inflammatory, antidiabetic, and so forth, relatively less attention has been paid to the antiaging effect of EGCG on primary cells. In this study, the preventive effects of EGCG against serial passage-induced senescence were investigated in primary cells including rat vascular smooth muscle cells (RVSMCs), human dermal fibroblasts (HDFs), and human articular chondrocytes (HACs). The involvement of Sirt1 and acetylated p53 was examined as an underlying mechanism for the senescence preventive activity of EGCG in HDFs. All cells were employed with the initial passage number (PN) between 3 and 7. For inducing senescence, the cells were serially passaged at the predetermined times and intervals in the absence or presence of EGCG (50 or 100 μM). Serial passage-induced senescence in RVSMCs and HACs was able to be significantly prevented at 50 μM EGCG, while in HDFs, 100 μM EGCG could significantly prevent senescence and recover their cell cycle progression close to the normal level. Furthermore, EGCG was found to prevent serial passage- and H(2)O(2)-induced senescence in HDFs by suppressing p53 acetylation, but the Sirt1 activity was unaffected. In addition, proliferating HDFs showed similar cellular uptake of FITC-conjugated EGCG into the cytoplasm with their senescent counterparts but different nuclear translocation of it from them, which would partly account for the differential responses to EGCG in proliferating versus senescent cells. Taking these results into consideration, it is suggested that EGCG may be exploited to craft strategies for the development of an antiaging or age-delaying agent.

Detailed analysis of apoptosis and delayed luminescence of human leukemia Jurkat T cells after proton irradiation and treatments with oxidant agents and flavonoids

Following previous work, we investigated in more detail the relationship between apoptosis and delayed luminescence (DL) in human leukemia Jurkat T cells under a wide variety of treatments. We used menadione and hydrogen peroxide to induce oxidative stress and two flavonoids, quercetin, and epigallocatechin gallate, applied alone or in combination with menadione or H₂O₂. 62 MeV proton beams were used to irradiate cells under a uniform dose of 2 or 10 Gy, respectively. We assessed apoptosis, cell cycle distributions, and DL. Menadione, H₂O₂ and quercetin were potent inducers of apoptosis and DL inhibitors. Quercetin decreased clonogenic survival and the NAD(P)H level in a dose-dependent manner. Proton irradiation with 2 Gy but not 10 Gy increased the apoptotic rate. However, both doses induced a substantial G₂/M arrest. Quercetin reduced apoptosis and prolonged the G₂/M arrest induced by radiation. DL spectroscopy indicated that proton irradiation disrupted the electron flow within Complex I of the mitochondrial respiratory chain, thus explaining the massive necrosis induced by 10 Gy of protons and also suggested an equivalent action of menadione and quercetin at the level of the Fe/S center N2, which may be mediated by their binding to a common site within Complex I, probably the rotenone-binding site.