Mechanistic aspects of green tea as a cancer preventive: effect of components on human stomach cancer cell lines

Effect of dietary inclusion of tea residue and tea leaves on ruminal fermentation characteristics and methane production

The aim of this study was to compare the differences of dietary tea leaves (TL) and tea residue (TR) inclusion on rumen fermentation characteristics and to explore whether TR could be an alternative feedstuff of ruminants. For these purposes, seven treatments consisted of two inclusion types (TL vs. TR) and three inclusion levels (g/g of dry matter basis) of 10% (TL10/TR10), 20% (TL20/TR20), and 30% (TL30/TR30) in each inclusion type, plus control group with inclusion of 0% (CON) were designed, with four replicates in each group, to conduct an in vitro ruminal fermentation test. Results showed that the contents of crude protein, neutral detergent fiber, and acid detergent fiber were higher in TR than TL, while TL contained more ether extract and crude ash than TR. Interaction effects between inclusion type and inclusion level were observed in concentrations of isobutyrate and microbial crude protein (MCP), as well as in gas production and digestibility of organic matter. Fermentation characteristics were significantly influenced by TL and TR depending on the inclusion level, except for the concentration of total branched-chain volatile fatty acid. These significant differences of fermentation characteristics due to inclusion level mainly focused on CON and tea inclusion, with higher values in CON than TR or TL groups. The total gas production during the 48-h incubation showed no differences among CON, TL10, and TR10. The inclusion of TR and TL decreased the production of methane. The concentration of MCP in CON, TR10 and TR30 was lower than TR20 and all TL groups. In conclusion, dietary inclusion of TR and TL possessed equivalent effect on rumen fermentation characteristics and methane production, substituting diet with TR or TL for over 10% would inhibit rumen fermentation despite positive effects in TR20 and all TL groups regarding more MCP and less methane production. This study indicates that special attention should be paid to the inclusion level of TR and TL when considering them as alternative feedstuffs of ruminants. Further in vivo study is needed to evaluate the applicability of tea residue as a feedstuff for production of ruminants.

Extraction Methods, Properties, Functions, and Interactions with Other Nutrients of Lotus Procyanidins: A Review

Lotus procyanidins, natural polyphenolic compounds isolated from the lotus plant family, are widely recognized as potent antioxidants that scavenge free radicals in the human body and exhibit various pharmacological effects, such as anti-inflammatory, anticancer, antiobesity, and hypoglycemic. With promising applications in food and healthcare, lotus procyanidins have attracted extensive attention in recent years. This review provides a comprehensive summary of current research on lotus procyanidins, including extraction methods, properties, functions, and interactions with other nutrient components. Furthermore, this review offers an outlook on future research directions, providing ideas and references for the exploitation and utilization of lotus.

Green Tea Catechins: Nature’s Way of Preventing and Treating Cancer

Green tea’s (Camellia sinensis) anticancer and anti-inflammatory effects are well-known. Catechins are the most effective antioxidants among the physiologically active compounds found in Camellia sinesis. Recent research demonstrates that the number of hydroxyl groups and the presence of specific structural groups have a substantial impact on the antioxidant activity of catechins. Unfermented green tea is the finest source of these chemicals. Catechins have the ability to effectively neutralize reactive oxygen species. The catechin derivatives of green tea include epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECG) and epigallocatechin gallate (EGCG). EGCG has the greatest anti-inflammatory and anticancer potential. Notably, catechins in green tea have been explored for their ability to prevent a variety of cancers. Literature evidence, based on epidemiological and laboratory studies, indicates that green tea catechins have certain properties that can serve as the basis for their consideration as lead molecules in the synthesis of novel anticancer drugs and for further exploration of their role as pharmacologically active natural adjuvants to standard chemotherapeutics. The various sections of the article will focus on how catechins affect the survival, proliferation, invasion, angiogenesis, and metastasis of tumors by modulating cellular pathways.

Encapsulation of catechin into nano-cyclodextrin-metal-organic frameworks: Preparation, characterization, and evaluation of storage stability and bioavailability

This study, nanoscale α-, β-, γ-cyclodextrin (CD)-metal-organic frameworks (MOFs) were successfully prepared using solvothermal assisted ultrasound method. CD-MOFs were used as nanocarriers to encapsulate catechin (CA), and their encapsulation capacities were evaluated. Encapsulation capacities of CD-MOFs to incorporate CA followed the order: β-CD-MOFs > γ-CD-MOFs > α-CD-MOFs. CA/CD-MOFs were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). DSC and SEM results provided evidence for the formation of CA/CD-MOFs. XRD results indicated the new solid crystalline phases formed in CA/CD-MOFs complex. Results of FT-IR showed that CA was combined with CD-MOFs through hydrogen bonding and van der Waals forces. Current research demonstrated that encapsulation of CA within CD-MOFs provided it against light, oxygen and temperature. Moreover, encapsulation by CD-MOFs improved storage stability and bioavailability of CA. Thus, these CA/CD-MOFs have potential to be used as nutritional supplements and functional foods.

Natural Products for the Prevention and Treatment of Oral Mucositis-A Review

Cancer, a major world public health problem, is associated with chemotherapy treatments whose administration leads to secondary concerns, such as oral mucositis (OM). The OM disorder is characterized by the presence of ulcers in the oral mucosa that cause pain, bleeding, and difficulty in ingesting fluids and solids, or speaking. Bioactive compounds from natural sources have arisen as an effective approach for OM. This review aims to summarize the new potential application of different natural products in the prevention and treatment of OM in comparison to conventional ones, also providing a deep insight into the most recent clinical studies. Natural products, such as Aloe vera, Glycyrrhiza glabra, Camellia sinensis, Calendula officinalis, or honeybee crops, constitute examples of sources of bioactive compounds with pharmacological interest due to their well-reported activities (e.g., antimicrobial, antiviral, anti-inflammatory, analgesic, or wound healing). These activities are associated with the bioactive compounds present in their matrix (such as flavonoids), which are associated with in vivo biological activities and minimal or absent toxicity. Finally, encapsulation has arisen as a future opportunity to preserve the chemical stability and the drug bioa vailability of bioactive compounds and, most importantly, to improve the buccal retention period and the therapeutic effects.

The Influence of Biomolecule Composition on Colloidal Beer Structure

Recent studies have revealed an interest in the composition of beer biomolecules as a colloidal system and their influence on the formation of beer taste. The purpose of this research was to establish biochemical interactions between the biomolecules of plant-based raw materials of beer in order to understand the overall structure of beer as a complex system of bound biomolecules. Generally accepted methods of analytical research in the field of brewing, biochemistry and proteomics were used to solve the research objectives. The studies allowed us to establish the relationship between the grain and plant-based raw materials used, as well as the processing technologies and biomolecular profiles of beer. The qualitative profile of the distribution of protein compounds as a framework for the formation of a colloidal system and the role of carbohydrate dextrins and phenol compounds are given. This article provides information about the presence of biogenic compounds in the structure of beer that positively affect the functioning of the body. A critical assessment of the influence of some parameters on the completeness of beer taste by biomolecules is given. Conclusion: the conducted analytical studies allowed us to confirm the hypothesis about the nitrogen structure of beer and the relationship of other biomolecules with protein substances, and to identify the main factors affecting the distribution of biomolecules by fractions.

Development and characterization of catechin-in-cyclodextrin-in-phospholipid liposome to eradicate MRSA-mediated surgical site infection: Investigation of their anti-infective efficacy through in vitro and in vivo studies

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the prime pathogens responsible for surgical site infection (SSI). Treatment of SSI remains challenging because of resistant nature of MRSA, which is a major threat in recent years. Our previous work revealed the antibacterial potential of catechin isolated from cashewnut shell against MRSA. However, the application of catechin to treat MRSA-mediated SSI is hampered because of its poor solubility and low trans-dermal delivery. Hence, the present study focused on developing catechin-in-cyclodextrin-in-phospholipid liposome (CCPL) and evaluating its physicochemical characteristics and anti-infective efficacy through in vitro and in vivo models. Encapsulation of catechin with β-cyclodextrin and soybean lecithin was confirmed through UV-Vis spectroscopy, FTIR, and XRD techniques, while TEM imaging revealed the size of CCPL (206 nm). The CCPL displayed a higher level of water solubility (25.13%) and in vitro permeability (42.14%) compared to pure catechin. A higher level of encapsulation efficiency (98.9%) and antibacterial activity (19.8 mm of ZOI and 31.25 μg/mL of MIC) were noted in CCPL compared to the catechin/cyclodextrin complex. CCPL recorded significant and dose-dependent healing of the incision, significant reduction of bacterial count, improved epithelization, and effective prevention of inflammation in skin samples of SSI-induced Balb/c mice. Data of the present work suggest that the CCPL could be considered as a novel and potential candidate to mitigate MRSA-mediated SSI after clinical trials.

Green Tea Catechins Induce Inhibition of PTP1B Phosphatase in Breast Cancer Cells with Potent Anti-Cancer Properties: In Vitro Assay, Molecular Docking, and Dynamics Studies

The catechins derived from green tea possess antioxidant activity and may have a potentially anticancer effect. PTP1B is tyrosine phosphatase that is oxidative stress regulated and is involved with prooncogenic pathways leading to the formation of a.o. breast cancer. Here, we present the effect of selected green tea catechins on enzymatic activity of PTP1B phosphatase and viability of MCF-7 breast cancer cells. We showed also the computational analysis of the most effective catechin binding with a PTP1B molecule. We observed that epigallocatechin, epigallocatechin gallate, epicatechin, and epicatechin gallate may decrease enzymatic activity of PTP1B phosphatase and viability of MCF-7 cells. Conclusions: From the tested compounds, epigallocatechin and epigallocatechin gallate were the most effective inhibitors of the MCF-7 cell viability. Moreover, epigallocatechin was also the strongest inhibitor of PTP1B activity. Computational analysis allows us also to conclude that epigallocatechin is able to interact and bind to PTP1B. Our results suggest also the most predicted binding site to epigallocatechin binding to PTP1B.

Beneficial Properties of Green Tea Catechins

Green tea (Camellia sinesis) is widely known for its anticancer and anti-inflammatory properties. Among the biologically active compounds contained in Camellia sinesis, the main antioxidant agents are catechins. Recent scientific research indicates that the number of hydroxyl groups and the presence of characteristic structural groups have a major impact on the antioxidant activity of catechins. The best source of these compounds is unfermented green tea. Depending on the type and origin of green tea leaves, their antioxidant properties may be uneven. Catechins exhibit the strong property of neutralizing reactive oxygen and nitrogen species. The group of green tea catechin derivatives includes: epicatechin, epigallocatechin, epicatechin gallate and epigallocatechin gallate. The last of these presents the most potent anti-inflammatory and anticancer potential. Notably, green tea catechins are widely described to be efficient in the prevention of lung cancer, breast cancer, esophageal cancer, stomach cancer, liver cancer and prostate cancer. The current review aims to summarize the potential anticancer effects and molecular signaling pathways of major green tea catechins. It needs to be clearly emphasized that green tea as well as green tea catechols cannot replace the standard chemotherapy. Nonetheless, their beneficial effects may support the standard anticancer approach.

In Search of Panacea-Review of Recent Studies Concerning Nature-Derived Anticancer Agents

Cancers are one of the leading causes of deaths affecting millions of people around the world, therefore they are currently a major public health problem. The treatment of cancer is based on surgical resection, radiotherapy, chemotherapy or immunotherapy, much of which is often insufficient and cause serious, burdensome and undesirable side effects. For many years, assorted secondary metabolites derived from plants have been used as antitumor agents. Recently, researchers have discovered a large number of new natural substances which can effectively interfere with cancer cells’ metabolism. The most famous groups of these compounds are topoisomerase and mitotic inhibitors. The aim of the latest research is to characterize natural compounds found in many common foods, especially by means of their abilities to regulate cell cycle, growth and differentiation, as well as epigenetic modulation. In this paper, we focus on a review of recent discoveries regarding nature-derived anticancer agents.

Beyond the Antioxidant Activity of Dietary Polyphenols in Cancer: the Modulation of Estrogen Receptors (ERs) Signaling

The potential "health benefits" of dietary polyphenols have been ascribed to their direct antioxidant activity and their impact on the regulation of cell and tissue redox balance. However, because of the relative poor bioavailability of many of these compounds, their effects could not be easily explained by the antioxidant action, which may occur only at high circulating and tissue concentrations. Therefore, many efforts have been put forward to clarify the molecular mechanisms underlining the biological effect of polyphenols in physiological and pathological conditions. Polyphenols' bioavailability, metabolism, and their effects on enzyme, membrane, and/or nuclear receptors and intracellular transduction mechanisms may define the overall impact of these compounds on cancer risk and progression, which is still debated and not yet clarified. Polyphenols are able to bind to estrogen receptor α (ERα) and β (ERβ), and therefore induce biological effects in human cells through mimicking or inhibiting the action of endogenous estrogens, even at low concentrations. In this work, the role and effects of food-contained polyphenols in hormone-related cancers will be reviewed, mainly focusing on the different polyphenols' mechanisms of action with particular attention on their estrogen receptor-based effects, and on the consequences of such processes on tumor progression and development.

Cancer Prevention with Green Tea and Its Principal Constituent, EGCG: from Early Investigations to Current Focus on Human Cancer Stem Cells

Cancer preventive activities of green tea and its main constituent, (-)-epigallocatechin gallate (EGCG) have been extensively studied by scientists all over the world. Since 1983, we have studied the cancer chemopreventive effects of EGCG as well as green tea extract and underlying molecular mechanisms. The first part of this review summarizes ground-breaking topics with EGCG and green tea extract: 1) Delayed cancer onset as revealed by a 10-year prospective cohort study, 2) Prevention of colorectal adenoma recurrence by a double-blind randomized clinical phase II trial, 3) Inhibition of metastasis of B16 melanoma cells to the lungs of mice, 4) Increase in the average value of Young's moduli, i.e., cell stiffness, for human lung cancer cell lines and inhibition of cell motility and 5) Synergistic enhancement of anticancer activity against human cancer cell lines with the combination of EGCG and anticancer compounds. In the second part, we became interested in cancer stem cells (CSCs). 1) Cancer stem cells in mouse skin carcinogenesis by way of introduction, after which we discuss two subjects from our review on human CSCs reported by other investigators gathered from a search of PubMed, 2) Expression of stemness markers of human CSCs compared with their parental cells, and 3) EGCG decreases or increases the expression of mRNA and protein in human CSCs. On this point, EGCG inhibited self-renewal and expression of pluripotency-maintaining transcription factors in human CSCs. Human CSCs are thus a target for cancer prevention and treatment with EGCG and green tea catechins.

Polyphenols in Colorectal Cancer: Current State of Knowledge including Clinical Trials and Molecular Mechanism of Action

Polyphenols have been reported to have wide spectrum of biological activities including major impact on initiation, promotion, and progression of cancer by modulating different signalling pathways. Colorectal cancer is the second most major cause of mortality and morbidity among females and the third among males. The objective of this review is to describe the activity of a variety of polyphenols in colorectal cancer in clinical trials, preclinical studies, and primary research. The molecular mechanisms of major polyphenols related to their beneficial effects on colorectal cancer are also addressed. Synthetic modifications and other future directions towards exploiting of natural polyphenols against colorectal cancer are discussed in the last section.

Epigallocatechin Gallate Modulates Cytokine Production by Bone Marrow-Derived Dendritic Cells Stimulated with Lipopolysaccharide or Muramyldipeptide, or Infected with Legionella pneumophila

The primary polyphenol in green tea extract is the catechin epigallocatechin gallate (EGCG). Various studies have shown significant suppressive effects of catechin on mammalian cells, either tumor or normal cells, including lymphoid cells. Previous studies from this laboratory reported that EGCG has marked suppressive activity on murine macrophages infected with the intracellular bacterium Legionella pneumophila (Lp), an effect mediated by enhanced production of both tumor necrosis factor-α (TNF-α) and γ-interferon (IFN-γ). In the present study, primary murine bone marrow (BM)-derived dendritic cells (DCs), a phagocytic monocytic cell essential for innate immunity to intracellular microorganisms, such as Lp, were stimulated in vitro with the microbial stimulant lipopolysaccharide (LPS) from gram-negative bacteria, the cell wall component from gram-positive bacteria muramyldipeptide (MDP) or infected with Lp. Production of the T helper cell (Th1)-activating cytokine, interleukin-12 (IL-12) and the proinflammatory cytokine, tumor necrosis factor-α (TNF-α), produced mainly by phagocytic cells and important for antimicrobial immunity, was determined in cell culture supernatants by enzyme-linked immunosorbent assay (ELISA). Treatment of the cells with EGCG inhibited, in a dose-dependent manner, production of IL-12. In contrast, enhanced production of TNF-α occurred in a dose-dependent manner in the DC cultures stimulated with either soluble bacterial product or infected with Lp. Thus, the results of this study show that the EGCG catechin has a marked effect in modulating production of these immunoregulatory cytokines in stimulated DCs, which are important for antimicrobial immunity, especially innate immunity. Further studies are necessary to characterize the physiologic function of the effect of EGCG on TNF-α and IL-12 during Lp infection, and the mechanisms involved.

Biophysical Approach to Mechanisms of Cancer Prevention and Treatment with Green Tea Catechins

Green tea catechin and green tea extract are now recognized as non-toxic cancer preventives for humans. We first review our brief historical development of green tea cancer prevention. Based on exciting evidence that green tea catechin, (−)-epigallocatechin gallate (EGCG) in drinking water inhibited lung metastasis of B16 melanoma cells, we and other researchers have studied the inhibitory mechanisms of metastasis with green tea catechins using biomechanical tools, atomic force microscopy (AFM) and microfluidic optical stretcher. Specifically, determination of biophysical properties of cancer cells, low cell stiffness, and high deformability in relation to migration, along with biophysical effects, were studied by treatment with green tea catechins. The study with AFM revealed that low average values of Young’s moduli, indicating low cell stiffness, are closely associated with strong potential of cell migration and metastasis for various cancer cells. It is important to note that treatments with EGCG and green tea extract elevated the average values of Young’s moduli resulting in increased stiffness (large elasticity) of melanomas and various cancer cells. We discuss here the biophysical basis of multifunctions of green tea catechins and green tea extract leading to beneficial effects for cancer prevention and treatment.

Challenging the effectiveness of green tea in primary and tertiary cancer prevention

PURPOSE

Drinking green tea daily is part of Japanese culture, and various studies have revealed that green tea is a cancer preventive. We here review our progress in cancer prevention with green tea on 12 main topics, from basic to clinical level. TOPICS AND METHODS: Biochemical and biological studies of green tea catechins, a prospective cohort study, preclinical safety trials with tablets of green tea extract, double-blind randomized clinical phase II prevention trial for recurrence of colorectal adenomas, and synergistically enhanced inhibition by the combination of green tea catechins and anticancer drugs. All results were significant, including human studies with informed consent.

RESULTS

Drinking 10 Japanese-size cups of green tea per day delayed the cancer onset of humans 7 years for females. For tertiary cancer prevention, consuming 10 cups of green tea per day fortified by green tea tablets, 50 %, significantly prevented the recurrence of colorectal adenomas. A minimum effective amount of green tea catechins for cancer prevention was found in humans. In addition, the combination of green tea catechins and anticancer drugs engendered a new cancer therapeutic strategy.

CONCLUSION

The consumption of 10 Japanese-size cups of green tea per day is a significant factor in primary cancer prevention for the general population, and the preventive effect on recurrence of colorectal adenomas in patients is vital evidence in tertiary cancer prevention.

Reduction of oxidative stress in liver cancer patients by oral green tea polyphenol tablets during hepatic arterial infusion chemotherapy

Hepatic arterial infusion chemotherapy (HAI) using an implanted port system is the standard regimen for primary and metastatic liver cancers (MLCs). However, there have been few studies concerning HAI-induced oxidative stress and damage to the liver or other organs. The aim of the present study was to investigate the ability of green tea polyphenols (GTPs) to reduce the oxidative stress or increase the biological antioxidative potential in HAI-treated patients. A total of 19 patients with inoperable hepatocellular carcinoma (HCC) or MLC from colorectal malignancy were eligible for HAI with cisplatin (CDDP) and 5-fluorouracil (5FU). The study subjects were randomly assigned to either a 3 or a 6 oral GTP tablets per day group. Each tablet had a GTP content equivalent to 79 mg of epigallocatechin-3-gallate. The oxidative stress was assessed by measuring the levels of derivatives of reactive oxygen metabolites (d-ROMs) and the biological antioxidative potential (BAP) values in patient plasma using the Free Radical Analytical System 4 (FRAS4), and correlating the results with clinical laboratory data for the patients. The levels of d-ROMs were significantly reduced by the oral intake of 6 GTP tablets for 6–9 months (P=0.0463) but were not significantly reduced by the oral intake of 3 GTP tablets daily. BAP values remained constant in the 3 and 6 tablet groups for 6–9 months during the follow-up study. The total serum bilirubin (T-bil) levels increased significantly at 3 (P=0.028) and 9 (P=0.0151) months and the red blood cell (RBC) count decreased at 6 months (P=0.0458) after intake for the 6 GTP tablet group. Alkaline phosphatase (ALP) levels increased significantly at 9 months (P=0.0298). Cholinesterase (ChE) decreased significantly at 9 (P= 0.0127) and 12 (P= 0.0207) months after intake for the 3 GTP tablet group. The results indicate that the daily intake of 6 GTP tablets containing 474 mg polyphenols significantly reduces HAI-induced oxidative stress in HCC or MLC patients while the antioxidative potentials of the patients remain constant.

Health-promoting effects of green tea

Green tea is manufactured from the leaves of the plant Camellia sinensis Theaceae and has been regarded to possess anti-cancer, anti-obesity, anti-atherosclerotic, anti-diabetic, anti-bacterial, and anti-viral effects. Many of the beneficial effects of green tea are related to the activities of (-)-epigallocatechin gallate (EGCG), a major component of green tea catechins. For about 20 years, we have engaged in studies to reveal the biological activities and action mechanisms of green tea and EGCG. This review summarizes several lines of evidence to indicate the health-promoting properties of green tea mainly based on our own experimental findings.

Cancer chemoprevention with green tea catechins by targeting receptor tyrosine kinases

Recent studies indicate that receptor tyrosine kinases (RTKs), which play important roles in cell proliferation, are one of the possible targets of green tea catechins (GTCs) in cancer cell growth inhibition. (-)-Epigallocatechin-3-gallate (EGCG), the major catechin in green tea, inhibits cell proliferation and induces apoptosis in various types of cancer cells, including colorectal cancer and hepatocellular carcinoma cells, by blocking the activation of the epidermal growth factor receptor (EGFR) family of RTKs. EGCG inhibits the activation of insulin-like growth factor-1 receptor (IGF-1R) and VEGFR2, the other members of the RTK family, and this effect is also associated with the anticancer and chemopreventive properties of this agent. EGCG suppresses the activation of EGFR in part by altering membrane lipid organization and causing the subsequent inhibition of the dimerization and activation of this receptor. Preliminary trials have shown that GTCs successfully prevent the development and progression of precancerous lesions, such as colorectal adenomas, without causing severe adverse effects. The present report reviews evidence indicating that GTCs exert anticancer and chemopreventive effects by inhibiting the activation of specific RTKs, especially EGFR, IGF-1R, and VEGFR2, and concludes that targeting RTKs and their related signaling pathways by using tea catechins could be a promising strategy for the prevention of human cancers.

Epicatechin gallate and catechin gallate are superior to epigallocatechin gallate in growth suppression and anti-inflammatory activities in pancreatic tumor cells

Green tea catechins are considered as possible cancer preventive agents for several cancer types but little is known regarding their effects on pancreatic cancer cells. The best studied catechin and the major polyphenol present in green tea is epigallocatechin gallate (EGCG). In the present study, we investigated the in vitro anti-tumoral properties of EGCG on human pancreatic ductal adenocarcinoma (PDAC) cells PancTu-I, Panc1, Panc89 and BxPC3 in comparison with the effects of two minor components of green tea catechins, catechin gallate (CG) and epicatechin gallate (ECG). We found that all three catechins inhibited proliferation of PDAC cells in a dose- and time-dependent manner. Interestingly, CG and ECG exerted much stronger anti-proliferative effects than EGCG. Western blot analyses performed with PancTu-I cells revealed catechin-mediated modulation of cell cycle regulatory proteins (cyclins, cyclin-dependent kinases [CDK], CDK inhibitors). Again, these effects were clearly more pronounced in CG or ECG than in EGCG-treated cells. Importantly, catechins, in particular ECG, inhibited TNFα-induced activation of NF-κB and consequently secretion of pro-inflammatory and invasion promoting proteins like IL-8 and uPA. Overall, our data show that green tea catechins ECG and CG exhibit potent and much stronger anti-proliferative and anti-inflammatory activities on PDAC cells than the most studied catechin EGCG.

Multistage carcinogenesis process as molecular targets in cancer chemoprevention by epicatechin-3-gallate

The consumption of green tea has long been associated with a reduced risk of cancer development. (-)-Epicatechin-3-gallate (ECG) or (-)-epigallocatechin-3-gallate (EGCG) are the major antioxidative polyphenolic compounds of green tea. They have been shown to exert growth-inhibitory potential of various cancer cells in culture and antitumor activity in vivo models. ECG or EGCG could interact with various molecules like proteins, transcription factors, and enzymes, which block multiple stages of carcinogenesis via regulating intracellular signaling transduction pathways. Moreover, ECG and EGCG possess pharmacological and physiological properties including induction of phase II enzymes, mediation of anti-inflammation response, regulation of cell proliferation and apoptosis effects and prevention of tumor angiogenesis, invasion and metastasis. Numerous review articles have been focused on EGCG, however none have been focused on ECG despite many studies supporting the cancer preventive potential of ECG. To develop ECG as an anticarcinogenic agent, more clear understanding of the cell signaling pathways and the molecular targets responsible for chemopreventive and chemotherapeutic effects are needed. This review summarizes recent research on the ECG-induced cellular signal transduction events which implicate in cancer management.

Iranian black tea and cowslip extracts induce tumor necrosis factor-alpha secretion from mouse macrophage cell culture

Many species of tea (Camellia sinensis) and cowslip (Echium amoenum) are used in Iranian traditional medicine. The aim of this study was to conduct the survey on the ability of Iranian black tea and cowslip extracts on secretion of tumor necrosis factor-alpha (TNF-alpha) by non-infected and infected mouse macrophages. A macrophage infection model with Legionella pneumophila and enzyme linked immunosorbent assay (ELISA) technique was used in this study. Research showed that the concentrations of TNF-alpha in non-infected and infected macrophage culture supernatant treated with various concentrations of Iranian black tea and cowslip extracts was significantly higher than the control. Various concentrations of cowslip (0.5, 5 and 50 μg/mL) had significantly a great effect on the induction of TNF-alpha secretion in comparison with the Iranian black tea extract (P < 0.0001). In conclusion, we demonstrated the ability of Iranian black tea and cowslip on the induction of TNF-alpha, which can exert an anti-L. pneumophila activity on macrophages at a low dose. However, further studies to elucidate the mechanism(s) of the induction of macrophages by Iranian black tea and cowslip as well as their potential inhibitory effects on the growth of infected cells and their possible antitumor effects should be carried out in future works.

Induction of apoptosis by immature plum in human hepatocellular carcinoma

In the present study, the effect of an extract of immature Prunus salicina Lindl. cv. Soldam fruit on the viability and induction of apoptosis in human hepatocellular carcinoma HepG2 cells was investigated. The results showed that in comparison with other cancer cells, the growth inhibition exerted by immature plum extracts was greatest in HepG2. Apoptosis in HepG2 cells mediated by immature plums was associated with "death receptor signaling." Immature plum extracts significantly increased the activation of caspase-8, -10, and -3 and expression of the caspase-3 target proteins alpha-fodrin (induces membrane blebbing and cell shrinkage), poly(ADP-ribose) polymerase (a nuclear enzyme that is involved in DNA repair following DNA nicks), and DNA fragmentation factor (induces apoptotic DNA fragmentation). The total yield of identified polyphenols in immature plum extract was 10 g/kg dry weight. The major components, (-)-epicatechin and (-)-gallocatechin gallate, were 34.7% and 28.6% of total polyphenols, respectively. (+)-Catechin, (-)-epicatechin gallate, and (-)-catechin gallate were also found. On the basis of these results, the immature plum (P. salicina Lindl. cv. Soldam) and its active compound, (-)-epicatechin, are expected to be a natural resource for developing novel therapeutic agents for cancer prevention and treatment.

Effects of epigallocatechin gallate on tissue protection and functional recovery after contusive spinal cord injury in rats

Recent studies revealed the neuroprotective effects of epigallocatechin gallate (EGCG) on a variety of neural injury .The purpose of this study was to determine the effects of EGCG on the tissue protection and behavioral improvement after spinal cord injury (SCI). Rats were randomly divided into four groups of 18 rats each as follows: sham-operated group, trauma group, and EGCG treatment groups (50 mg/kg, i.p., immediately and 1 hour after SCI). Spinal cord samples were taken 24 hours after injury and studied for determination of malodialdehyde (MDA) levels, immunohistochemistry of Bax and Bcl-2, and TUNEL reaction. Behavioral testing was performed weekly up to 6 weeks post-injury. Then, the rats were euthanized for histopathological assessment. The results showed that MDA levels were significantly decreased in EGCG treatment groups. Greater Bcl-2 and attenuated Bax expression could be detected in the EGCG-treated rats. EGCG significantly reduced TUNEL-positive rate. Also, EGCG significantly reduced the percentage of lesion area and improved behavioral function than the trauma group. On the basis of these findings, we propose that EGCG may be effective in protecting rat spinal cord from secondary injury.

Inhibitory effect of immature plum on PMA-induced MMP-9 expression in human hepatocellular carcinoma

The goal of this study was to evaluate the anticancer effect of Prunus salicina Lindl. cv. Soldam at three maturity stages (immature, midmature and mature). In search for anticancer effects of immature plum extract (IPE), we have found its antimigrative property in (phorbol 12-myristate 13-acetate) PMA-induced HepG2 cells, and this effect is associated with inhibition of MMP-9 activity. IPE appeared to have a strong inhibitory effect on the PMA-induced MMP-9 secretion through suppression of the transcriptional activity of the MMP-9 gene independently of the TIMP gene in HepG2 cells. PMA induced the translocation of c-jun and p65 to the nucleus; however, IPE inhibited their nuclear translocations induced by PMA in HepG2 cells. These results clearly indicate that IPE suppresses both AP-1- and NF-kappaB-mediated MMP-9 gene transcriptional activity through inhibiting the nuclear translocations of AP-1 and NF-kappaB. These findings suggest that AP-1 and NF-kappaB activations through the ERK, p38 MAPK and JNK pathways appears to be required for the induction of MMP-9 expression by PMA in IPE, and IPE regulates PMA-stimulated MMP-9 expression by suppressing the p38 MAPK, JNK and ERK pathways. IPE leads to a decrease in the migration potential of HepG2 cells in vitro, and this suggests that the migration inhibition is correlated well with its inhibition of MMP-9 expression.

Chemoprevention of fibroid tumors by [-]-epigallocatechin-3-gallate in quail

Spontaneous leiomyomas of the oviduct are common tumors of the Japanese quail (Coturnix coturnix japonica), and fibroid tumors in the laying hen are similar to human fibroid tumors with respect to estrogen and progesterone receptors. This makes the quail a good animal model for screening potential agents for that aid in the prevention and treatment of human myoma uteri. We have previously reported a decreased incidence of leiomyomas in the oviduct of Japanese quail with antioxidant supplementation, for example, lycopene and soy isoflavones. Most of the health benefits associated with green tea consumption is attributed to EGCG, one of 4 major catechins found in green tea. This study investigated the effects of epigallocatechin-3-gallate supplementation on the development of leiomyomas in the oviduct of Japanese quail. We also measured serum and tissue levels of malondialdehyde and TNF-alpha. One hundred eighty quail (8 months old) were assigned to 3 treatment groups consisting of 6 replicates of 10 quail in each group. Animals were fed either a basal diet (control group) or the basal diet supplemented with 200 or 400 mg of EGCG/kg of diet. The animals were euthanized at the end of the 12-month study period, and the tumors were characterized. Epigallocatechin gallate supplementation significantly decreased the number of leiomyomas as compared with the controls (P = .001). The tumors in the EGCG fed birds were smaller than those found in the control birds (P = .001). Serum and liver malondialdehyde and TNF-alpha concentrations decreased (P = .001) with EGCG supplementation. The results indicate that dietary supplementation with EGCG reduces the incidence and size of spontaneously occurring leiomyoma of the oviduct in Japanese quail. Clinical trials should be conducted to investigate the efficacy of EGCG supplementation in the prevention and treatment of uterine leiomyoma in humans.

Green tea extracts for the prevention of metachronous colorectal adenomas: a pilot study

BACKGROUND

Experimental studies indicate the chemopreventive properties of green tea extract (GTE) on colorectal cancer. Epidemiologically, green tea consumption of > 10 cups daily reduced colorectal cancer risk in Japanese. Because colorectal adenomas are the precursors to most sporadic colorectal cancers, we conducted a randomized trial to determine the preventive effect of GTE supplements on metachronous colorectal adenomas by raising green tea consumption in the target population from an average of 6 cups (1.5 g GTE) daily to > or = 10 cups equivalent (2.5 g GTE) by supplemental GTE tablets.

METHODS

We recruited 136 patients, removed their colorectal adenomas by endoscopic polypectomy, and 1 year later confirmed the clean colon (i.e., no polyp) at the second colonoscopy. The patients were then randomized into two groups while maintaining their lifestyle on green tea drinking: 71 patients supplemented with 1.5 g GTE per day for 12 months and 65 control patients without supplementation. Follow-up colonoscopy was conducted 12 months later in 125 patients (65 in the control group and 60 in the GTE group).

RESULTS

The incidence of metachronous adenomas at the end-point colonoscopy was 31% (20 of 65) in the control group and 15% (9 of 60) in the GTE group (relative risk, 0.49; 95% confidence interval, 0.24-0.99; P < 0.05). The size of relapsed adenomas was also smaller in the GTE group than in the control group (P < 0.001). No serious adverse events occurred in the GTE group.

CONCLUSION

GTE is an effective supplement for the chemoprevention of metachronous colorectal adenomas.

Green tea polyphenols as a natural tumour cell proteasome inhibitor

The cancer-preventive effects of green tea and its main constituent (-)-epigallocatechin gallate [(-)-EGCG] are widely supported by results from epidemiological, cell culture, animal and clinical studies although the molecular target has not been well defined. We previously reported that ester bond-containing tea polyphenols, e. g. (-)-EGCG, and their synthetic analogs potently and specifically inhibited the proteasomal activity. Subsequently, we further demonstrated that methylation on green tea polyphenols under physiological conditions decreased their proteasome-inhibitory activity, contributing to decreased cancer-preventive effects of tea consumption. Since (-)-EGCG is unstable under physiological conditions, we also developed the peracetate-protected or prodrug form of (-)-EGCG, Pro-EGCG (1), and shown that Pro-EGCG (1) increases the bioavailability, stability, and proteasome-inhibitory and anticancer activities of (-)-EGCG in human breast cancer cells and xenografts, suggesting its potential use for cancer prevention and treatment.

Effects of green tea polyphenol on methylation status of RECK gene and cancer cell invasion in oral squamous cell carcinoma cells

RECK is a novel tumour suppressor gene that negatively regulates matrix metalloproteinases (MMPs) and inhibits tumour invasion, angiogenesis and metastasis. In the present study, we investigated the effects of epigallocatechin-3-gallate (EGCG), a major polyphenol in green tea, on the methylation status of the RECK gene and cancer invasion in oral squamous cell carcinoma cell lines. Our results showed that treatment of oral cancer cells with EGCG partially reversed the hypermethylation status of the RECK gene and significantly enhanced the expression level of RECK mRNA. Inhibition of MMP-2 and MMP-9 levels was also observed in these cells after treatment with EGCG. Interestingly, EGCG significantly suppressed cancer cell-invasive ability by decreasing the number of invasive foci (P<0.0001) as well as invasion depth (P<0.005) in three-dimensional collagen invasion model. Although further investigation is required to assess the extent of contribution of RECK on MMPs to the suppression of invasive behaviour, these results support the conclusion that EGCG plays a key role in suppressing cell invasion through multiple mechanisms, possibly by demethylation effect on MMP inhibitors such as RECK.

Differential growth suppression of human melanoma cells by tea (Camellia sinensis) epicatechins (ECG, EGC and EGCG)

We previously reported that catechins of green tea have different antiproliferative effects on cell lines derived from gender-dependent cancers; epicatechin 3-gallate (ECG) had the strongest inhibitory effect. In the present study, we examined the effects of epigallocatechin (EGC), epicatechin-gallate (ECG) and EGC 3-gallate (EGCG) on the viability, density, doubling time and cycle number of cell lines derived from melanoma metastasized to lymph nodes (MB-1133 and SE-0154) or distant organs (CH-0356, JK-0346, SA-1171, GE-0208, NS-1176 and LF-0023). These catechins have been documented to have no growth suppressive or apoptotic effects on normal melanocytes (Nihal et al., Int J Cancer 2005;114:513-21). EGCG (50 muM) showed greater inhibitory potency than EGC (50 muM) in SE-0154, NS-1176, GE-0208 and LF-0023 cell lines but the two catechins produced similar inhibitory effects in CH-0356, JK-0346 and SA-1171 cell lines. The IC(50) (50% inhibitory concentration) was lower for EGC than EGCG in MB-1133 and CH-0356 cells, higher for EGC than EGCG in GE-0208 cells and comparable (11-12 muM) for both the catechins in LF-0023 cells. When compared with EGC, the cytotoxic effect (% dead cell counts) and the suppression of the growth (change in cell number) of all melanoma cell lines tested were pronounced with EGCG. This investigation validates the hypothesis that anticancer action of the various catechins may vary with the type of malignancy and provides a model for tumor cell heterogeneity based on susceptibility and resistance of tumor cells to different green tea catechins. Therefore, this information is critical for undertaking chemopreventive or chemotherapeutic trials against melanoma and gender-based cancers.

Synergistic effects of multiple treatments, and both DNA and RNA direct bindings on, green tea catechins

This article reviews two main topics: (1) the synergistic effects of multiple treatments with green tea catechin and (2) the direct binding of (-)-epigallocatechin gallate (EGCG) to both DNA and RNA molecules. Japanese drink green tea throughout the day, so we studied whether multiple treatments of cells with EGCG would enhance the expression of apoptosis-related genes, such as growth arrest and DNA damage-inducible gene (GADD153) and cyclin-dependent kinase inhibitor gene (p21(waf1)): The results suggest that the synergistic enhancement of both GADD153 and p21(waf1) gene expressions by multiple treatments plays a significant role in human cancer prevention with green tea beverage. Our previous observation-that nucleic acids extracted from catechin-treated cells are colored-allowed us to speculate that catechins directly interact with nucleic acids. Surface plasmon resonance assay (Biacore) indicated that four catechins, EGCG, (-)-epicatechin gallate (ECG), (+)-gallocatechin gallate (GCG), and (+)-catechin gallate (CG), bound to DNA oligomers. Cold spray ionization mass spectrometry (CSI-MS) analysis showed that one to three EGCG molecules bound to single-stranded 18 mers of DNA and RNA. Moreover, one or two molecules of EGCG bound to double-stranded AG:CT oligomers of various nucleotide lengths. Double-stranded DNA (dsDNA) oligomers were detected only as EGCG-bound forms at high temperature, whereas at low temperature both the free and bound forms were detected, suggesting that EGCG protects double-stranded DNA oligomers from double-stranded melting into single-stranded DNA. We assume that catechins accumulate in both double-stranded DNA and RNA molecules through multiple administrations of green tea beverage in in vivo, and that the accumulated green tea catechins play a significant role for human cancer prevention.

Green tea extract inhibits paraquat-induced pulmonary fibrosis by suppression of oxidative stress and endothelin-l expression

Paraquat-induced pulmonary fibrosis involves two factors, direct injury by oxygen free radicals and indirect injury by inflammatory cells and fibroblasts. Endothelin-1 (ET-1) has been shown to act as a mediator of pulmonary fibrosis, and its formation increases during oxidative stress. We investigated whether green tea extract (GTE), which has antioxidant properties, inhibits paraquat-induced pulmonary fibrosis and whether ET-1 is involved in this process. Paraquat (0.3 mg/kg) was instilled into the right lungs of rats, following which the rats were either not further treated (Group P, n = 7), or they were administered 1% GTE mixed with feed (Group PG; n = 7) or the ET(A) receptor antagonist ZD2574 (10 mg/kg through gavage; Group PZ; n = 7) for two weeks. As control, we used rats instilled with saline (Group N; n = 6). Two weeks after paraquat instillation, we assayed the degree of pulmonary fibrosis by light microscopic morphometry and hydroxyproline content; lipid peroxidation as a marker of oxidative stresses by measurement of malondialdehyde (MDA); ET-1 by immunohistochemistry; and prepro-ET-1 mRNA expression by reverse transcription-polymerase chain reaction. Compared with Group N, significant pulmonary fibrosis was observed in Group P, accompanied by increases in MDA, ET-1, and prepro-ET-1 mRNA expression. Compared with Group P, Group PG showed significant decreases in pulmonary fibrosis, along with decreases in MDA, ET-1, and prepro-ET-1 mRNA expression. We also observed significant decreases in pulmonary fibrosis in Group PZ compared with Group P. These findings suggest that GTE inhibits paraquat-induced pulmonary fibrosis by suppression of oxidative stress and ET-1 expression.

Identification of two biologically crucial hydroxyl groups of (−)-epigallocatechin gallate in osteoclast culture

(-)-Epigallocatechin gallate (EGCG) induces cell death of osteoclasts in an Fe(2+)- and H(2)O(2)-dependent manner. In the present study, we further explore the cytotoxic mechanism of EGCG using four EGCG analogues. Molecules methylated at position 4' in the B ring (EGCG-4'-O-Me) or at position 4'' in the D-ring (EGCG-4''-O-Me) showed markedly decreased cytotoxicity to osteoclasts, indicating that hydroxyl groups at these two positions of EGCG are crucial for inducing cell death of osteoclasts. EGCG-4'-O-Me also showed the lowest Fe(3+)-reducing activity among five EGCGs. The Fe(3+)-reducing activity of EGCG was enhanced under conditions whereby protonated EGCG levels were increased, indicating that the protonated status of EGCG was involved in the Fe(3+)-reducing activity. The hydroxyl group at position 4'' in the D-ring was shown by quantum chemical calculation to be preferentially deprotonated among all of the hydroxyl groups in EGCGs. It was also shown that the highest occupied molecular orbital (HOMO) was localized to the B-ring of EGCGs, except for EGCG-4'-O-Me. We report here that the HOMO on the B-ring plays crucial roles in both the Fe(3+)-reducing activity of EGCG and the cytotoxicity of EGCG to osteoclasts, while deprotonation of the hydroxyl group at position 4'' in the D-ring plays a supplementary role.

The effects of (-)-epigallocatechin-3-gallate on the proliferation and differentiation of human megakaryocytic progenitor cells

Epigallocatechin-3-gallate (EGCg) has been widely recognized as a powerful antioxidant and free radical scavenger. The effects of EGCg on the proliferation and differentiation of X-irradiated megakaryocytic progenitor cells (colony-forming unit-megakaryocyte, CFU-Meg) using CD34+ cells prepared from human placental and umbilical cord blood have been shown. In the absence of exogenous thrombopoietin (TPO), no colonies are observed in cultures containing or lacking EGCg (1 nM-100 microM). In the presence of TPO, in contrast, EGCg significantly promotes CFU-Meg-derived colony formations within the 10-100-nM range. A 1.5-fold increase in the total number of CFU-Meg has been counted compared with the control. These favorable effects of EGCg are also observed in the culture of CD34+ cells before and after X irradiation with 2 Gy. Moreover, in order to investigate the function of EGCg promoting megakaryocytopoiesis and thrombopoiesis in ex vivo cultures, both non-irradiated and X-irradiated CD34+ cells are grown in liquid cultures supplemented with TPO. In both cultures, EGCg increases the total number of cells and megakaryocytes. It has been suggested that the favorable effects of EGCg reduce the risk factor from radiation damage in megakaryocytopoiesis.

Epicatechins Purified from Green Tea (Camellia sinensis) Differentially Suppress Growth of Gender-Dependent Human Cancer Cell Lines

The anticancer potential of catechins derived from green tea is not well understood, in part because catechin-related growth suppression and/or apoptosis appears to vary with the type and stage of malignancy as well as with the type of catechin. This in vitro study examined the biological effects of epicatechin (EC), epigallocatechin (EGC), EC 3-gallate (ECG) and EGC 3-gallate (EGCG) in cell lines from human gender-specific cancers. Cell lines developed from organ-confined (HH870) and metastatic (DU145) prostate cancer, and from moderately (HH450) and poorly differentiated (HH639) epithelial ovarian cancer were grown with or without EC, EGC, ECG or EGCG. When untreated cells reached confluency, viability and doubling time were measured for treated and untreated cells. Whereas EC treatment reduced proliferation of HH639 cells by 50%, EGCG suppressed proliferation of all cell lines by 50%. ECG was even more potent: it inhibited DU145, HH870, HH450 and HH639 cells at concentrations of 24, 27, 29 and 30 µM, whereas EGCG inhibited DU145, HH870, HH450 and HH639 cells at concentrations 89, 45, 62 and 42 µM. When compared with EGCG, ECG more effectively suppresses the growth of prostate cancer and epithelial ovarian cancer cell lines derived from tumors of patients with different stages of disease.

DNA and RNA as new binding targets of green tea catechins

The significance of catechins, the main constituent of green tea, is being increasingly recognized with regard to cancer prevention. Catechins have been studied for interactions with various proteins, but the mechanisms of the various catechins are not yet elucidated. Based on our previous observation that nucleic acids extracted from catechin-treated cells are colored, we studied whether catechins directly interact with nucleic acids using surface plasmon resonance assay (Biacore) and cold spray ionization-mass spectrometry. These two methods clearly showed that (-)-epigallocatechin gallate (EGCG) binds to both DNA and RNA molecules: the Biacore assay indicated that four catechins bound to DNA oligomers, and cold spray ionization-mass spectrometry analysis showed one to three EGCG molecules bound to single strand 18 mers of DNA and RNA. Moreover, one or two molecules of EGCG bound to double-stranded (AG-CT) oligomers of various nucleotide lengths. These results suggest that multiple binding sites of EGCG are present in DNA and RNA oligomers. Double-stranded DNA (dsDNA) oligomers were detected only as EGCG-bound forms at high temperature, whereas at low temperature both the free and bound forms were detected, suggesting that EGCG protects dsDNA oligomers from dsDNA melting to single-stranded DNA. Because both galloyl and catechol groups of EGCG are essential for DNA binding, both groups seem to hold strands of DNA via their branching structure. These findings reveal for the first time the link between catechins and polynucleotides and will intensify our understanding of the effects of catechins on DNA in terms of cancer prevention.