Dual mechanisms of green tea extract (EGCG)-induced cell survival in human epidermal keratinocytes

Roles of anti- and pro-oxidant potential of cinnamic acid and phenylpropanoid derivatives in modulating growth of cultured cells

Cinnamic acid (CiA) and phenylpropanoid derivatives are widely distributed in plant foods. In this study, anti- and pro-oxidant properties of the derivatives and their roles in modulating cell growth were investigated. Ferulic acid, sinapinic acid, caffeic acid (CaA), and 3,4-dihydroxyhydrocinnamic acid (DHC) showed strong radical scavenging activities. They, except DHC, also performed considerable inhibitory effects on lipid peroxidation and reduced levels of intracellular reactive oxygen species (ROS). CaA and DHC, however, produced substantial amount of H₂O₂ with oxidative degradation in culture conditions. CaA and DHC (> 400 μM) showed potent cytotoxic effects which were abolished by superoxide dismutase/catalase; they significantly enhanced cell growth ROS-dependently at low levels (~ 100 μM). CiA derivatives without bearing hydroxyl group did not show any appreciable antioxidant activities. The results indicate that CiA derivatives with ortho-dihydroxyl group had strong anti- and pro-oxidant properties, which also play an important role in modulating cell growth.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-022-01042-x.

Potential role of green tea extract and epigallocatechin gallate in preventing bisphenol A-induced metabolic disorders in rats: Biochemical and molecular evidence

BACKGROUND

Bisphenol A (BPA) is an artificial chemical widely used in the production of polycarbonate plastics and epoxy resins. Accumulating evidence indicates that BPA exposure is associated with metabolic disorders. The beneficial effects of green tea and epigallocatechin gallate (EGCG), major catechin present in green tea, on alleviating BPA-induced metabolic disorders have been shown in various studies.

PURPOSE

Protective effects of green tea extract and EGCG on BPA-induced metabolic disorders and possible underlying mechanisms were investigated.

METHODS

Rats were randomly divided into control, green tea extract (50 and 100 mg/kg, IP), EGCG (20 and 40 mg/kg, IP), BPA (10 mg/kg, gavage), BPA plus green tea extract (25, 50, and 100 mg/kg, IP), BPA plus EGCG (10, 20, and 40 mg/kg, IP), and BPA plus vitamin E (200 IU/kg, IP). After two months, body weight, blood pressure, biochemical blood tests, hepatic malondialdehyde (MDA), and glutathione (GSH) were assessed. By enzyme-linked immunosorbent assay, serum levels of insulin, leptin, adiponectin, TNFα, and IL-6, and by western blotting, hepatic insulin signaling (IRS-1, PI3K, Akt) were measured.

RESULTS

BPA increased body weight, blood pressure, and MDA, decreased GSH, elevated serum levels of low-density lipoprotein cholesterol, total cholesterol, triglyceride, glucose, insulin, leptin, TNFα, IL-6, and liver enzymes including alanine aminotransferase and alkaline phosphatase, and lowered high-density lipoprotein cholesterol and adiponectin levels. In western blot, decreased phosphorylation of IRS-1, PI3K, and Akt was obtained. Administration of green tea extract, EGCG, or vitamin E with BPA reduced the detrimental effects of BPA.

CONCLUSION

These findings indicate that green tea extract and EGCG can be effective in preventing or reducing metabolic disorders induced by BPA linked to their antioxidant and anti-inflammatory activity, regulating the metabolism of lipids, and improving insulin signaling pathways.

Does Green Tea Induce Hormesis?

Green tea, and its principal constituent (-)-epigallocatechin-3-gallate (EGCG), are commonly shown to induce biphasic concentration/dose responses in a broad range of cell types, including non-tumor cells, and tumor cell lines. The most active area of research dealt with an assessment of neural cells with application to neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease cell models, often using preconditioning experimental protocols. The general findings demonstrate EGCG-induced hormetic effects resulting in an enhanced acquired resilience within an adaptive and temporally dependent homeodynamic framework. The biphasic dose responses displayed the typical quantitative features of the hormetic dose response with respect to the amplitude and width of the stimulatory response. These findings provide further evidence for the general occurrence of hormetic dose responses with such responses being independent of the biological model, end point, inducing agent, and mechanism. The biphasic nature of these responses has important implications since it suggests optimal dose ranges for end points of public health and therapeutic applications. These findings indicate the need to assess the entire dose-response continuum in order to better define the nature of the dose response, especially in the low-dose zone where such exposures are common in human populations.

Dose-dependent green tea effect on decrease of inflammation in human oral gingival epithelial keratinocytes: in vitro study

Objectives

This in vitro study aimed to analyze the anti-inflammatory and wound healing potential of green tea extract (GTE) in human gingival epithelial keratinocytes (HGEK) treated with lipopolysaccharides (LPS).

Materials and methods

A cell viability assay was conducted using MTT to determine nontoxic levels of GTE on immortalized HGEK. Cells were concomitantly treated with LPS (1 μg/ml) and GTE (1 mg/ml, 2.5 mg/ml, 5 mg/ml, and 10 mg/ml) to assess inflammation. Gene expression levels of inflammatory markers IL-β1, IL-6, and TNFα were measured by RT-PCR and their protein production was assessed by ELISA. The scratch wound healing assay was used to investigate the effects of different concentrations of GTE on cell migration. We also explored the effect of GTE on the induction of the Nrf2/HO-1 pathway in the cells with or without LPS.

Results

GTE at concentrations of 2.5 mg/ml, 5 mg/ml, and 10 mg/ml significantly enhanced cell viability (p < 0.05). And IL-β1, IL-6, and TNFα gene expression presented up to 10-fold decrease compared with LPS-treated cells, which was also similarly found on the protein levels. At the same concentrations, cell migration increased.

Conclusions

The mechanism results showed that GTE produced the anti-inflammatory response by activating the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway and increasing the level of anti-oxidant protein heme oxygenase-1 (HO-1).

Clinical relevance

GTE may be potentially used as oral rinse anti-inflammatory drug for treatment and prevention of oral inflammatory diseases, which is shown here by the ability to reduce the inflammation and increase in cell migration in a dose-dependent manner.

EGCG improves recombinant protein productivity in Chinese hamster ovary cell cultures via cell proliferation control

Chinese hamster ovary cell lines are good manufacturing practice-certified host cells and are widely used in the field of biotechnology to produce therapeutic antibodies. Recombinant protein productivity in cells is strongly associated with cell growth. To control cell proliferation, many approaches have previously been tested including: genetic engineering, chemical additives such as cell cycle inhibitors, and temperature shift of the culture. To be widely adopted in the biopharmaceutical industry, the culture methods should be simple, uniform and safe. To this end, we examined the use a natural compound to improve the production capacity. In this study, we focused on the antioxidants, catechin polyphenols, which are found in green tea, for cell proliferation control strategies. (-)-Epigallocatechin-3-gallate (EGCG), the major catechin that induces G0/G1 cell cycle arrest, was investigated for its effect on recombinant protein production. Adding EGCG to the cell culture media resulted in slower cellular growth and longer cell longevity, which improved the specific productivity and total yield of recombinant IgG1 in batch cultures by almost 50% for an extra 2 or 3 days of culture. A lower L-glutamine consumption rate was observed in cells cultured in EGCG-containing media, which may be suggesting that there was less stress in the culture environment. Additionally, EGCG did not affect the N-glycan quality of IgG1. Our results indicated that adding EGCG only on the first day of the culture enhanced the specific productivity and total amount of recombinant protein production in batch cultures. This approach may prove to be useful for biopharmaceutical production.

Agro-Industrial By-Products and Their Bioactive Compounds—An Ally against Oxidative Stress and Skin Aging

The increased consumer awareness towards hazards related with sun exposure has given a boost in the cosmetics industry and particularly the sun care market. Human skin is continually being threatened by the UV irradiation present in sunlight and acute UV exposure leads to skin photoaging. Cosmetic and/or dermatological applications include several bioactive compounds that contribute to the regulation of epidermal homeostasis by providing protection against solar radiation and improving the antioxidant activity of epidermis. Plant extracts are sources of active ingredients with intense therapeutic properties, and the topical application or oral intake of these compounds could ameliorate skin condition. Nowadays, there is a growing demand for the application of the bioactive agents contained in agro-industrial byproducts in sun care products, since many of them have shown promising properties as skin photoprotectants. However, well-conducted clinical studies are required to prove their safety and efficacy before they could be regularly used. Environmentally friendly extraction and sustainable techniques are therefore under examination for recovering such compounds from agro-industrial byproducts and converting them into innovative high-value natural ingredients used in cosmetic formulations.

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.

Neuroprotection in Glaucoma: Old and New Promising Treatments

Glaucoma is a major global cause of blindness, but the molecular mechanisms responsible for the neurodegenerative damage are not clear. Undoubtedly, the high intraocular pressure (IOP) and the secondary ischemic and mechanical damage of the optic nerve have a crucial role in retinal ganglion cell (RGC) death. Several studies specifically analyzed the events that lead to nerve fiber layer thinning, showing the importance of both intra- and extracellular factors. In parallel, many neuroprotective substances have been tested for their efficacy and safety in hindering the negative effects that lead to RGC death. New formulations of these compounds, also suitable for chronic oral administration, are likely to be used in clinical practice in the future along with conventional therapies, in order to control the progression of the visual impairment due to primary open-angle glaucoma (POAG). This review illustrates some of these old and new promising agents for the adjuvant treatment of POAG, with particular emphasis on forskolin and melatonin.

Effect of Catechins, Green tea Extract and Methylxanthines in Combination with Gentamicin Against Staphylococcus aureus and Pseudomonas aeruginosa: - Combination therapy against resistant bacteria

Objectives:

Bacterial resistant infections have become a global health challenge and threaten the society’s health. Thus, an urgent need exists to find ways to combat resistant pathogens. One promising approach to overcoming bacterial resistance is the use of herbal products. Green tea catechins, the major green tea polyphenols, show antimicrobial activity against resistant pathogens. The present study aimed to investigate the effect of catechins, green tea extract, and methylxanthines in combination with gentamicin against standard and clinical isolates of Staphylococcus aureus (S. aureus) and the standard strain of Pseudomonas aeruginosa (P. aeruginosa).

Methods:

The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) values of different agents against bacterial strains were determined. The interactions of green tea extract, epigallate catechin, epigallocatechin gallate, two types of methylxanthine, caffeine, and theophylline with gentamicin were studied in vitro by using a checkerboard method and calculating the fraction inhibitory concentration index (FICI).

Results:

The MICs of gentamicin against bacterial strains were in the range of 0.312 - 320 μg/mL. The MIC values of both types of catechins were 62.5 - 250 μg/ mL. Green tea extract showed insufficient antibacterial activity when used alone. Methylxanthines had no intrinsic inhibitory activity against any of the bacterial strains tested. When green tea extract and catechins were combined with gentamicin, the MIC values of gentamicin against the standard strains and a clinical isolate were reduced, and synergistic activities were observed (FICI < 1). A combination of caffeine with gentamicin did not alter the MIC values of gentamicin.

Conclusion:

The results of the present study revealed that green tea extract and catechins potentiated the antimicrobial action of gentamicin against some clinical isolates of S. aureus and standard P. aeruginosa strains. Therefore, combinations of gentamicin with these natural compounds might be a promising approach to combat microbial resistance.

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.

Epigallocatechin Gallate-Mediated Alteration of the MicroRNA Expression Profile in 5α-Dihydrotestosterone-Treated Human Dermal Papilla Cells

BACKGROUND

Dihydrotestosterone (DHT) induces androgenic alopecia by shortening the hair follicle growth phase, resulting in hair loss. We previously demonstrated how changes in the microRNA (miRNA) expression profile influenced DHT-mediated cell death, cell cycle arrest, cell viability, the generation of reactive oxygen species (ROS), and senescence. Protective effects against DHT have not, however, been elucidated at the genome level.

OBJECTIVE

We showed that epigallocatechin gallate (EGCG), a major component of green tea, protects DHT-induced cell death by regulating the cellular miRNA expression profile.

METHODS

We used a miRNA microarray to identify miRNA expression levels in human dermal papilla cells (DPCs). We investigated whether the miRNA expression influenced the protective effects of EGCG against DHT-induced cell death, growth arrest, intracellular ROS levels, and senescence.

RESULTS

EGCG protected against the effects of DHT by altering the miRNA expression profile in human DPCs. In addition, EGCG attenuated DHT-mediated cell death and growth arrest and decreased intracellular ROS levels and senescence. A bioinformatics analysis elucidated the relationship between the altered miRNA expression and EGCG-mediated protective effects against DHT.

CONCLUSION

Overall, our results suggest that EGCG ameliorates the negative effects of DHT by altering the miRNA expression profile in human DPCs.

Green tea compound epigallo-catechin-3-gallate (EGCG) increases neuronal survival in adult hippocampal neurogenesis in vivo and in vitro

Epigallo-catechin-3-gallate (EGCG), found in the leaves of Camellia sinensis (green tea), has antioxidant- and scavenger-functions and acts neuroprotectively. It has been publicized as anti-aging remedy but data on potential cellular mechanisms are scarce. Recent studies claimed that EGCG specifically promotes neural precursor cell proliferation in the dentate gyrus of C57Bl/6 mice, without changes at the level of immature and mature new neurons. We here analyzed the effects of EGCG on adult hippocampal neurogenesis in male Balb/C mice and saw a different pattern. Two weeks of treatment with EGCG (0, 0.625, 1.25, 2.5, 5 and 10mg/kg) showed a dose-response curve that peaked at 2.5mg/kg of EGCG with significantly increased cell survival without affecting cell proliferation but decreasing apoptotic cells. Also, EGCG increased the population of doublecortin-(DCX)-expressing cells that comprises the late intermediate progenitor cells (type-2b and -3) as well as immature neurons. After EGCG treatment, the young DCX-positive neurons showed more elaborated dendritic trees. EGCG also significantly increased net neurogenesis in the adult hippocampus and increased the hippocampal levels of phospho-Akt. Ex vivo, EGCG exerted a direct effect on survival and neuronal differentiation of adult hippocampal precursor cells, which was absent, when PI3K, a protein upstream of Akt, was blocked. Our results thus support a pro-survival and a pro-neurogenic role of EGCG. In the context of the conflicting published results, however, potential genetic modifiers must be assumed. These might help to explain the overall variability of study results with EGCG. Our data do indicate, however, that natural compounds such as EGCG can in principle modulate brain plasticity.

Transdermal solid delivery of epigallocatechin-3-gallate using self-double-emulsifying drug delivery system as vehicle: Formulation, evaluation and vesicle-skin interaction

The present study investigated a self-double-emulsifying drug delivery system loaded with epigallocatechin-3-gallate to improve epigallocatechin-3-gallate skin retention. The long chain solid lipids (cetostearyl alcohol) and macadamia oil were utilized as a carrier to deliver the bioactive ingredient. Response surface methodology was used to optimize the formulation, and the solid lipid to total lipid weight ratio, concentration of epigallocatechin-3-gallate and hydrophilic surfactant on skin retention were found to be the principal factors. The optimum formulation with high encapsulation efficiency (95.75%), self-double-emulsification performance (99.58%) and skin retention (87.24%) were derived from the fitted models and experimentally examined, demonstrating a reasonable agreement between experimental and predicted values. Epigallocatechin-3-gallate-self-double-emulsifying drug delivery system was found to be stable for 3 months. Transdermal studies could explain a higher skin diffusion of epigallocatechin-3-gallate from the self-double-emulsifying drug delivery system compared with EGCG aqueous solution. In vitro cytotoxicity showed that epigallocatechin-3-gallate-self-double-emulsifying drug delivery system did not exert hazardous effect on L929 cells up to 1:10.

Application of Green Tea Catechin for Inducing the Osteogenic Differentiation of Human Dedifferentiated Fat Cells in Vitro

Despite advances in stem cell biology, there are few effective techniques to promote the osteogenic differentiation of human primary dedifferentiated fat (DFAT) cells. We attempted to investigate whether epigallocatechin-3-gallate (EGCG), the main component of green tea catechin, facilitates early osteogenic differentiation and mineralization on DFAT cells in vitro. DFAT cells were treated with EGCG (1.25-10 μM) in osteogenic medium (OM) with or without 100 nM dexamethasone (Dex) for 12 days (hereafter two osteogenic media were designated as OM(Dex) and OM). Supplementation of 1.25 μM EGCG to both the media effectively increased the mRNA expression of collagen 1 (COL1A1) and runt-related transcription factor 2 (RUNX2) and also increased proliferation and mineralization. Compared to OM(Dex) with EGCG, OM with EGCG induced earlier expression for COL1A1 and RUNX2 at day 1 and higher mineralization level at day 12. OM(Dex) with 10 μM EGCG remarkably hampered the proliferation of the DFAT cells. These results suggest that OM(without Dex) with EGCG might be a preferable medium to promote proliferation and to induce osteoblast differentiation of DFAT cells. Our findings provide an insight for the combinatory use of EGCG and DFAT cells for bone regeneration and stem cell-based therapy.

An update on cutaneous aging treatment using herbs

Skin aging is caused by several factors. Ultraviolet (UV) exposure as well as oxidative stress elevates inflammatory mediators causing degradation of the extracellular matrix, which is regarded as the major cause of skin wrinkles, one of the signs of aging. Topical applications of active ingredients protect against dermal photodamage and scavenge radicals that can delay skin aging. Matrix metalloproteinase inhibitors against degradation of collagen, elastin, and hyaluronan are the key strategy to combat cutaneous aging. In addition, active ingredients with the efficacy to enhance extracellular matrix production, including those with UV protection efficacy, play an important role in protecting the skin from aging. Naturally derived compounds for combating skin wrinkles are gaining more interest among the consumers as they are perceived to be milder, safer, and healthier. This article, therefore, briefly addresses the causes of skin aging and extensively summarizes on herbs appraisal for skin wrinkles treatment. Therefore, delaying aging of skin using the functional herbs would maintain the individual's appearance with high esthetic and psychosocial impacts.

Novel naphthochalcone derivative accelerate dermal wound healing through induction of epithelial-mesenchymal transition of keratinocyte

Background

Wound healing is an intricate process whereby the skin repairs itself after injury. The epithelial-mesenchymal transition (EMT) is associated with wound healing and tissue regeneration. Naphthochalcone derivatives have various pharmaceutical properties. We investigated the effect of a novel naphthochalcone derivative, 2-(5-(2,4,6-trimethoxyphenyl)-4,5-dihydro-1H-pyrazol-3-yl)naphthalen-1-ol (TDPN), on dermal wound healing in vivo and the migration of keratinocytes in vitro.

Result

We investigated the effect of TDPN on signaling pathway and epithelial-mesenchymal transition through protein and transcriptional expression. The TDPN treatment accelerated dermal closure about 3 days and remodeling of dermis. We found that treatment with TDPN induced the migration of keratinocytes but not cytotoxicity. TDPN induced the phosphorylation of ERK and AKT. TDPN-treated cells showed loss of adherence protein and showed induction of the transcriptional factor Slug, mesenchymal marker, and fibronectin. Moreover, TDPN treatment induced the expression of matrix metalloproteinase-1 (MMP-1), which degrades specific components of the extracellular matrix, thereby providing new substrates that facilitate migration and invasion. MMP expression is considered to be one of the major attributes acquired by cells after EMT.

Conclusion

We propose that a novel naphthochalcone derivative TDPN is capable of promoting keratinocyte migration via the induction of EMT resulting acceleration of wound closure and matrix remodeling.

Electronic supplementary material

The online version of this article (doi:10.1186/s12929-015-0141-3) contains supplementary material, which is available to authorized users.

Non-Nutrient, Naturally Occurring Phenolic Compounds with Antioxidant Activity for the Prevention and Treatment of Periodontal Diseases

One of the main factors able to explain the pathophysiological mechanism of inflammatory conditions that occur in periodontal disease is oxidative stress. Given the emerging understanding of this relationship, host-modulatory therapies using antioxidants could be interesting to prevent or slow the breakdown of soft and hard periodontal tissues. In this context, non-nutrient phenolic compounds of various foods and plants have received considerable attention in the last decade. Here, studies focusing on the relationship between different compounds of this type with periodontal disease have been collected. Among them, thymoquinone, coenzyme Q (CoQ), mangiferin, resveratrol, verbascoside and some flavonoids have shown to prevent or ameliorate periodontal tissues damage in animal models. However evidence regarding this effect in humans is poor and only limited to topical treatments with CoQ and catechins. Along with animal experiments, in vitro studies indicate that possible mechanisms by which these compounds might exert their protective effects include antioxidative properties, oxygen and nitrogen scavenging abilities, and also inhibitory effects on cell signaling cascades related to inflammatory processes which have an effect on RNS or ROS production as well as on antioxidant defense systems.

Local Controlled Release of Polyphenol Conjugated with Gelatin Facilitates Bone Formation

Catechins are extensively used in health care treatments. Nevertheless, there is scarce information about the feasibility of local administration with polyphenols for bone regeneration therapy, possibly due to lack of effective delivery systems. Here we demonstrated that the epigallocatechin-3-gallate-conjugated gelatin (EGCG/Gel) prepared by an aqueous chemical synthesis using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-morpholinium chloride (DMT-MM) gradually disintegrated with time and facilitated bone formation in a critical size defect of a mouse calvaria. Conjugation of EGCG with the Gel generated cross-linking between the two molecules, thereby leading to a retardation of the degradation of the EGCG/Gel and to a delayed release of EGCG. The prepared EGCG/Gels represented significant osteogenic capability compared with that of the uncross-linked Gel and the cross-linked Gel with uncombined-EGCG. In vitro experiments disclosed that the EGCG/Gel induced osteoblastogenesis of a mouse mesenchymal stem cell line (D1 cells) within 14 days. Using fluorescently-labeled EGCG/Gel, we found that the fraction of EGCG/Gel adsorbed onto the cell membrane of the D1 cells possibly via a Gel-cell interaction. The interaction might confer the long-term effects of EGCG on the cells, resulting in a potent osteogenic capability of the EGCG/Gel in vivo. These results should provide insight into local controlled release of polyphenols for bone therapy.

Fucoidan promotes the reconstruction of skin equivalents

In this study we investigated the effects of fucoidan on the proliferation of fibroblasts and the reconstruction of a skin equivalent (SE). Fucoidan significantly stimulated the proliferation of CCD-25Sk human fibroblasts and Western blot analysis demonstrated that fucoidan markedly increased the expression of cyclin D1 and decreased the expression of p27. Fucoidan was used to reconstruct SE. Immunohistochemical staining showed that the addition of fucoidan to dermal equivalents increased expression of proliferating cell nuclear antigen (PCNA) and p63. In addition, expression of α6-integrin was significantly increased by fucoidan, whereas expression of β1-integrin, type 1 collagen, elastin, fibronectin did not markedly change. These results suggest that fucoidan has positive effects on epidermal reconstruction and will therefore be beneficial in the reconstruction of SE.

Active ingredients against human epidermal aging

The decisive role of the epidermis in maintaining body homeostasis prompted studies to evaluate the changes in epidermal structure and functionality over the lifetime. This development, along with the identification of molecular mechanisms of epidermal signaling, maintenance, and differentiation, points to a need for new therapeutic alternatives to treat and prevent skin aging. In addition to recovering age- and sun-compromised functions, proper treatment of the epidermis has important esthetic implications. This study reviews active ingredients capable of counteracting symptoms of epidermal aging, organized according to the regulation of specific age-affected epidermal functions: (1) several compounds, other than retinoids and derivatives, act on the proliferation and differentiation of keratinocytes, supporting the protective barrier against mechanical and chemical insults; (2) natural lipidic compounds, as well as glycerol and urea, are described as agents for maintaining water-ion balance; (3) regulation of immunological pathogen defense can be reinforced by natural extracts and compounds, such as resveratrol; and (4) antioxidant exogenous sources enriched with flavonoids and vitamin C, for example, improve solar radiation protection and epidermal antioxidant activity. The main objective is to provide a functional classification of active ingredients as regulatory elements of epidermal homeostasis, with potential cosmetic and/or dermatological applications.

Epigallocatechin-3-O-(3-O-methyl)-gallate-induced differentiation of human keratinocytes involves klotho-mediated regulation of protein kinase-cAMP responsive element-binding protein signaling

(−)-Epigallocatechin-3-O-gallate (EGCG) has long been known as a potent inducer of keratinocyte differentiation. Although its molecular mechanisms have been extensively studied, its actions on human skin remain to be elucidated. In this study, we demonstrated that methylated EGCG and EGCG increase the expression of klotho, and that klotho functions as a downstream target of EGCG and methylated EGCG in keratinocyte differentiation. We demonstrated that methylated EGCG3 and EGCG induce morphological changes in normal human epidermal keratinocytes (NHEKs) that are related to up-regulation of klotho expression. We also demonstrated that a klotho-induced keratinocyte differentiation marker in NHEKs is inhibited by H-89, a protein kinase (PKA) inhibitor. These results suggest that methylated EGCG and EGCG may function as inducers of keratinocyte differentiation via transcriptional regulation of the klotho protein.

Chemopreventive and hepatoprotective effects of Epigallocatechin-gallate against hepatocellular carcinoma: role of heparan sulfate proteoglycans pathway

Objective

Epigallocatechin-gallate (EGCG) claims a plethora of health benefits including protection against neoplastic diseases. Meanwhile, heparan-sulfate proteoglycans (HSPGs) have defensive role against tumour cell invasion. Therefore, the chemopreventive and hepatoprotective effects of EGCG were studied in hepatocellular carcinoma (HCC) in vivo and in vitro and compared with strong water soluble antioxidant, sodium ascorbate.

Methods

HCC was induced in SD rats by thioacetamide (200 mg/Kg). Some rats were treated with EGCG (20 mg/Kg) or sodium ascorbate (100 mg/Kg). Liver impairment was assessed by measuring serum α-fetoprotein and investigating liver sections stained with H/E. Hepatic HSPGs, syndecan-1 and matrix metalloproteinase-9 (MMP-9) were measured by ELISA. Gene expression of fibroblast growth factor (FGF)-2 was measured. Cell death was assessed by caspase-3 activity. In addition, all markers were measured in human hepatocellular carcinoma cell line (HepG2).

Key findings

EGCG increased the animal survival and decreased both α-fetoprotein and HepG2 viability. In addition, EGCG ameliorated fibrosis and massive hepatic tissue breakdown. EGCG restored HSPGs and reduced expression of MMP-9, syndecan-1 and FGF-2 in-vivo and in-vitro. Sodium ascorbate showed significantly lower results than EGCG.

Conclusions

Besides antioxidant activity, other mechanisms are involved in the chemopreventive and hepatoprotective effects of EGCG including restoration of HSPGs receptors and inhibition of vascular invasion.

Antimicrobial activity of green tea extract against isolates of methicillin-resistant Staphylococcus aureus and multi-drug resistant Pseudomonas aeruginosa

OBJECTIVE

To evaluate antibacterial activity of the Indonesian water soluble green tea extract, Camellia sinensis, against clinical isolates of methicillin-resistant Staphylococcus aureus (S. aureus) (MRSA) and multi-drug resistant Pseudomonas aeruginosa (MDR-P. aeruginosa).

METHODS

Antimicrobial activity of green tea extract was determined by the disc diffusion method and the minimum inhibitory concentration (MIC) was determined by the twofold serial broth dilutions method. The tested bacteria using in this study were the standard strains and multi-drug resistant clinical isolates of S. aureus and P. aeruginosa, obtained from Laboratory of Clinical Microbiology, Faculty of Medicine, University of Indonesia.

RESULTS

The results showed that the inhibition zone diameter of green tea extracts for S. aureus ATCC 25923 and MRSA were (18.970 ± 0.287) mm, and (19.130 ± 0.250) mm respectively. While the inhibition zone diameter for P. aeruginosa ATCC 27853 and MDR-P. aeruginosa were (17.550 ± 0.393) mm and (17.670 ± 0.398) mm respectively. The MIC of green tea extracts against S. aureus ATCC 25923 and MRSA were 400 µg/mL and 400 µg/mL, respectively, whereas the MIC for P. aeruginosa ATCC 27853 and MDR-P. aeruginosa were 800 µg/mL, and 800 µg/mL, respectively.

CONCLUSIONS

Camellia sinensis leaves extract could be useful in combating emerging drug-resistance caused by MRSA and P. aeruginosa.

A histochemical study of ultraviolet B irradiation and Origanum hypericifolium oil applied to the skin of mice

Ultraviolet (UV) rays cause skin damage. Chronic exposure to UV irradiation causes decreased collagen synthesis, degenerative changes in collagen bundles, accumulation of elastotic material and increased epidermal thickness. Origanum hypericifolium, an endemic Turkish plant, belongs to Lamiaceae family. The main constituents of its oil are monoterpenes including cymene, carvacrol, thymol and γ-terpinene. The effects of undiluted O. hypericifolium oil on UVB irradiated skin of mice were investigated histochemically. Four groups of female BALB/c mice, whose dorsal hair was shaved, were allocated as follows: non-UVB irradiated (Group 1), UVB-irradiated (Group 2), O. hypericifolium oil treated (Group 3), and O. hypericifolium oil treated and UVB irradiated (Group 4). Sections of dorsal skin samples were stained with Mallory's phosphotungstic acid hematoxylin for collagen fibers and Taenzer-Unna orcein for elastic fibers. Sections also were stained with hematoxylin and eosin to measure epidermal thickness. We observed intense staining of collagen and homogeneous, scattered thin elastic fibers in Group 1; scattered and weakly stained collagen and curled, amorphous, accumulate elastic fibers in Group 2; and intense staining of collagen in Groups 3 and 4. Accumulation of elastic fibers in the dermis was unremarkable in Groups 3 and 4. In Groups 3 and 4, O. hypericifolium oil treatment thickened the epidermis. Epidermal thickness was greatest in Group 4. We suggest that O. hypericifolium oil may block UVB induced alterations of collagen and elastic fibers, and increase epidermal thickness.

Potential therapeutic effects of natural heme oxygenase-1 inducers in cardiovascular diseases

SIGNIFICANCE

Many physiological effects of natural antioxidants, their extracts or their major active components, have been reported in recent decades. Most of these compounds are characterized by a phenolic structure, similar to that of α-tocopherol, and present antioxidant properties that have been demonstrated both in vitro and in vivo. Polyphenols may increase the capacity of endogenous antioxidant defenses and modulate the cellular redox state. Such effects may have wide-ranging consequences for cellular growth and differentiation.

CRITICAL ISSUES

The majority of in vitro and in vivo studies conducted so far have attributed the protective effect of bioactive polyphenols to their chemical reactivity toward free radicals and their capacity to prevent the oxidation of important intracellular components. One possible protective molecular mechanism of polyphenols is nuclear factor erythroid 2-related factor (Nrf2) activation, which in turn regulates a number of detoxification enzymes.

RECENT ADVANCES

Among the latter, the heme oxygenase-1 (HO-1) pathway is likely to contribute to the established and powerful antioxidant/anti-inflammatory properties of polyphenols. In this context, it is interesting to note that induction of HO-1 expression by means of natural compounds contributes to prevention of cardiovascular diseases in various experimental models.

FUTURE DIRECTIONS

The focus of this review is on the role of natural HO-1 inducers as a potential therapeutic strategy to protect the cardiovascular system against various stressors in several pathological conditions.

Silibinin is a potent sensitizer of UVA radiation-induced oxidative stress and apoptosis in human keratinocyte HaCaT cells

UVA radiation (315-400 nm), which constitutes ca 95% of the UV irradiation in natural sunlight reaching earth surface, is a major environmental risk factor associated with human skin cancer pathogenesis. UVA is an oxidizing agent that causes significant damage to cellular components through the release of reactive oxygen species (ROS) and leads to photoaging and photocarcinogenesis. Here we investigate the effect of silibinin, the flavonolignan from Silybum marianum, on UVA-induced ROS and cell death in human keratinocyte cell line HaCaT. In addition, the effect of silibinin on UVA-induced intracellular ROS-mediated endoplasmic reticulum (ER) stress was also analyzed. UVA irradiation resulted in ROS production and apoptosis in HaCaT cells in a dose-dependent manner, and the ROS levels and apoptotic index were found to be elevated significantly when the cells were treated with 75 μmsilibinin for 2 h before UVA exposure. When the cells were pretreated with 10 mmN-acetyl cysteine, the enhancement of UVA-induced apoptosis by silibinin was compromised. Furthermore, we found that silibinin enhances ER stress-mediated apoptosis in HaCaT cells by increasing the expression of CHOP protein. These results suggest that silibinin may be beneficial in the removal of UVA-damaged cells and the prevention of skin cancer.

Epigallocatechin-3-gallate suppresses IGF-I-induced lipogenesis and cytokine expression in SZ95 sebocytes

Acne vulgaris is the most common disease of the pilosebaceous unit. The pathogenesis of this inflammatory disease is complex, involving increased sebum production and perifollicular inflammation. To identify effective agents for factors that induce acne vulgaris, we explored the pharmacological potential of epigallocatechin-3-gallate (EGCG), which has been widely investigated as an anti-proliferative and anti-inflammatory agent. In this study, we demonstrated that topical application of EGCG to rabbit auricles reduced the size of the sebaceous glands. When applied to cultured human SZ95 sebocytes, EGCG strongly suppressed cell proliferation and lipogenesis. These actions of EGCG were reproduced in IGF-I-differentiated SZ95 sebocytes. To investigate the anti-inflammatory potential of EGCG, we evaluated pro-inflammatory cytokine synthesis in IGF-I-differentiated SZ95 sebocytes and found that expression of IL-1, IL-6, and IL-8 was decreased. These results provide early evidence that EGCG is an effective candidate for acne therapy whose mechanisms of action in IGF-I-differentiated SZ95 sebocytes include the inhibition of lipogenesis and inflammation.

Green tea extract: possible mechanism and antibacterial activity on skin pathogens

Camellia sinensis (tea) is known for its therapeutic properties (anti-inflammatory, anti-microbial, anti-tumour, anti-oxidative and anti-ageing). Although, anti-microbial properties of green tea have been studied, its role against bacterial strains related to skin infections and mechanism of action is not well understood. We focussed on exploring anti-microbial activity and the basic mechanism of aqueous green tea leaf extract on selected bacterial strains. Staphylococcus epidermidis, Micrococcus luteus, Brevibacterium linens, Pseudomonas fluorescens and Bacillus subtilis were found to be sensitive to green tea extract via disc diffusion assay (zone of inhibition ≥7 mm). Minimal inhibitory concentration (MIC) was determined via nitro blue tetrazolium (NBT) assay (0.156-0.313 mg/ml). Moreover, the aqueous extract was found to be not toxic to the Vero cell-line up to a concentration of 500 μg/ml. The effect of aqueous extract on adhesion of different bacteria to Vero cells indicated that it inhibits the adhesion at its MIC value.

Nutrition and human health from a sex-gender perspective

Nutrition exerts a life-long impact on human health, and the interaction between nutrition and health has been known for centuries. The recent literature has suggested that nutrition could differently influence the health of male and female individuals. Until the last decade of the 20th century, research on women has been neglected, and the results obtained in men have been directly translated to women in both the medicine and nutrition fields. Consequently, most modern guidelines are based on studies predominantly conducted on men. However, there are many sex-gender differences that are the result of multifactorial inputs, including gene repertoires, sex steroid hormones, and environmental factors (e.g., food components). The effects of these different inputs in male and female physiology will be different in different periods of ontogenetic development as well as during pregnancy and the ovarian cycle in females, which are also age dependent. As a result, different strategies have evolved to maintain male and female body homeostasis, which, in turn, implies that there are important differences in the bioavailability, metabolism, distribution, and elimination of foods and beverages in males and females. This article will review some of these differences underlying the impact of food components on the risk of developing diseases from a sex-gender perspective.

Nutrition and nonmelanoma skin cancers

The incidence of nonmelanoma skin cancer is increasing every year. Basal cell carcinoma and squamous cell carcinoma are the two major types of nonmelanoma skin cancer. Among other factors, understanding the potential role of nutrients in the development, progression, and treatment of nonmelanoma skin cancer is critical. This contribution provides a review of the nutrients that have been more extensively investigated in the literature with regard to nonmelanoma skin cancer, including dietary fats, retinol, carotenoids, vitamin C, vitamin D, vitamin E, selenium, copper, iron, zinc, green tea, and black tea.

A novel dietary supplement containing multiple phytochemicals and vitamins elevates hepatorenal and cardiac antioxidant enzymes in the absence of significant serum chemistry and genomic changes

A novel dietary supplement composed of three well-known phytochemicals, namely, Salvia officinalis (sage) extract, Camellia sinensis (oolong tea) extract, and Paullinia cupana (guarana) extract, and two prominent vitamins (thiamine and niacin) was designed to provide nutritional support by enhancing metabolism and maintaining healthy weight and energy. The present study evaluated the safety of this dietary supplement (STG; S=sage; T=tea; G=guarana) and assessed changes in target organ antioxidant enzymes (liver, kidneys and heart), serum chemistry profiles and organ histopathology in Fisher 344 rats. Adult male and female Fisher 344 rats were fed control (no STG) or STG containing (1X and 7X, 1X=daily human dose) diets and sacrificed after 2 and 4 months. Serum chemistry analysis and histopathological examination of three vital target organs disclosed no adverse influence on protein, lipid and carbohydrate profiles, genomic integrity of the liver and/or the tissue architecture. However, analysis of the most important antioxidant components in the liver, kidney and heart homogenates revealed a dramatic increase in total glutathione concentrations, glutathione peroxidase and superoxide dismutase enzyme activities. Concomitantly, oxidative stress levels (malondialdehyde accumulation) in these three organs were less than control. Organ specific serum markers (ALT/AST for the liver; CPK/AST for the heart; BUN/creatinine for kidneys) and the genomic integrity disclosed no STG-induced alteration. Some of the serum components (lipid and protein) showed insignificant changes. Overall, STG-exposed rats were more active, and the results suggest that STG exposure produces normal serum chemistry coupled with elevated antioxidant capacity in rats fed up to seven times the normal human dose and does not adversely influence any of the vital target organs. Additionally, this study reiterates the potential benefits of exposure to a pharmacologically relevant combination of phytochemicals compared to a single phytochemical entity.

Novel chemotherapeutic and renal protective effects for the green tea (EGCG): role of oxidative stress and inflammatory-cytokine signaling

BACKGROUND

The green tea catechin, epigallocatechin-gallate (EGCG) is a superb nature's medicine candidate. We evaluated the chemotherapeutic/chemoenhancing effects of EGCG in mice bearing the solid Ehrlich ascites carcinoma (EAC) tumor, and jointly monitored levels of serum C-reactive protein (CRP), lipid peroxidation (as malondialdehyde: MDA) and leukocytosis (LC). Besides, we verified whether; and how then, EGCG would protect against a devastating CP-induced nephrotoxicity in rats. In particular, renal proinflammatory (TNF-α) and oxidant stress signals have been investigated.

RESULTS

(EAC)-bearing mice displayed elevated serum-LC (2-fold), -CRP (11-fold) and -MDA levels (2.7-fold). EGCG (20, 40 mg/kg) significantly shrank tumors (by 48% and 92%, respectively), and reduced LC, CRP and MDA levels. Such responses for CP were less prominent than those of EGCG (40 mg/kg). Further, EGCG (20 mg/kg) markedly augmented such functional and biochemical responses to CP. Correlation studies showed positive association between tumor size and each of CRP (r=0.97) and LC (r=0.83). Additionally; in rats, CP (10 mg/kg) caused a prominent nephrotoxicity that was manifested as deteriorated glomerular filtration rate (GFR, 2-5-fold rise in serum creatinine/urea levels) after 4 days, and unanimous animal fatalities after 7 days. Kidney homogenates from CP-treated rats showed significantly higher MDA- and TNF-α-, and -depleted GSH levels. Rats treated with EGCG (50 mg/kg, but not 25 mg/kg) devoid the nephrotoxic effects of CP and their consequences; while their homogenates had appreciably lower MDA and TNF-α, and higher GSH levels. Notable correlation was detected between serum creatinine level and each of MDA (r=0.85), TNF-α (r=0.85) and GSH (r=-0.81).

CONCLUSION

This study shows remarkable cytotoxic/chemoenhancing effects for EGCG and introduces CRP as a predictor of both tumor's progression and responsiveness to chemotherapy. Further, this study is the first to reveal that EGCG can obliterate the lethal CP-induced nephrotoxicity. Mechanistically, EGCG acts by suppressing leukocytosis, systemic inflammation, oxidative stress, and their sequelae.

EGCG functions through estrogen receptor-mediated activation of ADAM10 in the promotion of non-amyloidogenic processing of APP

Estrogen depletion following menopause has been correlated with an increased risk of developing Alzheimer's disease (AD). We previously explored the beneficial effect of (-)-epigallocatechin-3-gallate (EGCG) on AD mice and found increased non-amyloidogenic processing of amyloid precursor protein (APP) through the α-secretase a disintegrin and metallopeptidase domain 10 (ADAM10). Our results in this study suggest that EGCG-mediated enhancement of non-amyloidogenic processing of APP is mediated by the maturation of ADAM10 via an estrogen receptor-α (ERα)/phosphoinositide 3-kinase/Ak-transforming dependent mechanism, independent of furin-mediated ADAM10 activation. These data support prior assertions that central selective ER modulation could be a therapeutic target for AD and support the use of EGCG as a well-tolerated alternative to estrogen therapy in the prophylaxis and treatment of this disease.

(-)-Epigallocatechin-3-gallate increases cell proliferation and neuroblasts in the subgranular zone of the dentate gyrus in adult mice

Neurogenesis is regulated by several factors such as age, stress and pharmacological agents. We observed the effects of (-)-epigallocatechin-3-gallate (EGCG), a major catechin of green tea, on neurogenesis in mice. The animals were orally administered EGCG for 4 weeks. Brain sections were stained using a marker for cell proliferation (Ki67 and BrdU) and neuroblasts (doublecortin, DCX). In all groups, Ki67, BrdU and DCX immunoreaction were observed in the subgranular zone of the dentate gyrus. Oral administration of EGCG significantly increased the number of Ki67-, BrdU- and DCX-immunoreactive cells as well as BrdU/DCX-colabled cells in the subgranular zone when compared to those in the vehicle-treated group. These results indicate that oral administration of EGCG can enhance cell proliferation and increase the number of neuroblasts in mice hippocampal dentate gyrus.

Anti-inflammatory and antimicrobial effects of nanocatechin in a chronic bacterial prostatitis rat model

Chronic bacterial prostatitis (CBP) is one of the most common relapsing urinary tract infection (UTI) in males. Catechin, an extract of green tea, is known to have anti-inflammatory and antimicrobial effects against various bacteria. However, catechin can be easily degenerated during digestion, and this may result in decreased absorption into the body. Nanocatechin is catechin coated with hydroxypropyl methyl cellulose by nanotechnology. It reduces degeneration during digestion and enhances absorption of catechin into the body. We evaluated the anti-inflammatory and antimicrobial effect of nanocatechin on CBP and also analyzed plasma concentration of catechins to evaluate absorptivity in an animal model. Forty rats demonstrating CBP were randomly divided into four groups: control, ciprofloxacin, catechin, and nanocatechin. After treatment, the results of microbiological culture of prostate and urine samples as well as histological findings of the prostate in each group were analyzed. Plasma concentration of catechins in catechin and nanocatechin groups was compared. The use of ciprofloxacin, catechin, and nanocatechin showed statistically significant decrease in bacterial growth and improvement in prostatic inflammation compared with the control group. The nanocatechin group showed statistically significant decrease in bacterial growth and improvement in prostatic inflammation compared with the catechin group. Plasma concentrations of epicatechin, gallocatechin gallate, and epigallocatechin gallate were significantly higher in the nanocatechin group than those in the catechin group. These results suggest that nanocatechin has better antimicrobial and anti-inflammatory effects on rat CBP than catechin due to higher absorption into the body.

Biological and Biomechanical Evaluations of Osteochondral Allografts Preserved in Cold Storage Solution Containing Epigallocatechin Gallate

The beneficial effects of (-)-epigallocatechin-3- O-gallate (EGCG) on the nonfrozen preservation of mammalian cells and tissues are generally not well understood. A storage solution containing EGCG was employed to test the hypothesis that EGCG is capable of extending the storage duration for the cold preservation of articular cartilages. Human articular cartilages were preserved in a storage solution composed of serum-free RPMI-1640 medium with 1% antibiotic-antimycotic solution and 1 mM EGCG at 4°C for 1, 2, and 4 weeks. The chondrocyte viability (CCK-8 assay), biochemical and immunohistochemical composition [glycosaminoglycans (GAG) and (type II) collagen], and biomechanical property (compressive elastic modulus) were assessed. The chondrocyte viability of the cartilages preserved with EGCG was significantly well maintained for at least 2 weeks with high content of GAG and total collagen. These beneficial effects of EGCG were confirmed by the immunohistochemical observations of well-preserved cartilaginous structures and delayed denaturation of the extracellular matrix in preserved cartilages. There was no significant difference in the compressive elastic modulus (MPa) between the cartilages preserved with and without EGCG. These results suggest that EGCG may play an effective role in preserving osteochondral allografts, which can be exploited in devising strategies for the long-term preservation of other tissues under cold storage conditions.

Effects of epigallocatechin-3-gallate on rat retinal ganglion cells after optic nerve axotomy

The purpose of this study was to investigate the effects of epigallocatechin-3-gallate (EGCG) in axotomized eyes and the pathways related to its action. Wistar rats received intracranial optic nerve (ON) axotomy 2 mm behind the globe in left eyes, whereas right eyes received sham operations. EGCG was administrated via intraperitoneal injection 30 min before and 4 days after axotomy. The density of retinal ganglion cell (RGC) was examined by a retrograde labeling technique. Western blot analysis was used to assess the expression of neuronal nitric oxide synthase (nNOS), Bax, Bcl-2, ERK and Akt. Optic nerve axotomy caused 54% RGC loss 7 days following surgery, and EGCG treatment reduced RGC loss by 12% (P = 0.017). The expression of the nNOS and pro-apoptotic Bax proteins were increased 5 days after axotomy, while EGCG treatment significantly blunted the up-regulation of the above two proteins (P = 0.04 and 0.02, respectively). Axotomy-induced p-ERK 1/2 and p-Akt proteins expression 5 days and 3 days following injury, respectively. Treatment with EGCG further enhanced p-ERK 1/2 and p-Akt expressions after axotomy. Inhibition of ERK and Akt pathways attenuated the protection of EGCG on RGC against axotomy damage. Thus, we demonstrated that administration of EGCG prior to axotomy promotes RGC survival. The neuroprotective capacity of EGCG appears to act through mediating nitric oxide, anti-apoptotic, and cell survival signaling pathways.