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1392 KiB

Open AccessArticle

In Vitro Chemopreventive Properties of Green Tea, Rooibos and Honeybush Extracts in Skin Cells

by Tandeka U. Magcwebeba, Pieter Swart, Sonja Swanevelder, Elizabeth Joubert and Wentzel C. A. Gelderblom

Molecules 2016, 21(12), 1622; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules21121622 - 25 Nov 2016

Cited by 19 | Viewed by 6711

Abstract

The chemopreventive properties of the herbal teas rooibos (Aspalathus linearis) and honeybush (Cyclopia spp.) have been demonstrated on mouse skin in vivo but the underlying mechanisms are not clear. The aim of the current study was to determine the anti-proliferative [...] Read more.

The chemopreventive properties of the herbal teas rooibos (Aspalathus linearis) and honeybush (Cyclopia spp.) have been demonstrated on mouse skin in vivo but the underlying mechanisms are not clear. The aim of the current study was to determine the anti-proliferative and pro-apoptotic activity of methanol and aqueous extracts of rooibos and two Cyclopia species in different skin cells, using green tea (Camellia sinensis) as a benchmark. Extracts were also characterised for their major individual polyphenols by high performance liquid chromatography and spectroscopically for the total polyphenol (TP) groups. The methanol extract of rooibos, containing higher levels of polyphenols than its aqueous extract, displayed similar activity to green tea as it selectively targeted premalignant cells by inhibiting cell proliferation at lower concentrations whilst inducing apoptosis via membrane depolarisation at higher concentrations. Specific roles of the major rooibos dihydrochalcones and flavanol/proanthocyanidin-type (FLAVA) compounds are likely to be involved. The aqueous extracts of the Cyclopia species were more active against cell proliferation and at inducing apoptosis which was associated with a higher FLAVA content and a reduced TP/FLAVA ratio. In contrast, their methanol extracts exhibited a cytoprotective effect against apoptosis which was related to their monomeric xanthone and flavanone content. The underlying chemopreventive properties of green tea and the herbal teas appear to be associated with diverse and complex monomeric/polymeric polyphenolic cell interactions. Full article

(This article belongs to the Special Issue Catechins and Human Health: Current State of the Science)

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3120 KiB

Open AccessArticle

Gallic Acid Content in Taiwanese Teas at Different Degrees of Fermentation and Its Antioxidant Activity by Inhibiting PKCδ Activation: In Vitro and in Silico Studies

by Teeradate Kongpichitchoke, Ming-Tzu Chiu, Tzou-Chi Huang and Jue-Liang Hsu

Molecules 2016, 21(10), 1346; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules21101346 - 12 Oct 2016

Cited by 24 | Viewed by 6161

Abstract

Teas can be classified according to their degree of fermentation, which has been reported to affect both the bioactive components in the teas and their antioxidative activity. In this study, four kinds of commercial Taiwanese tea at different degrees of fermentation, which include [...] Read more.

Teas can be classified according to their degree of fermentation, which has been reported to affect both the bioactive components in the teas and their antioxidative activity. In this study, four kinds of commercial Taiwanese tea at different degrees of fermentation, which include green (non-fermented), oolong (semi-fermented), black (fully fermented), and Pu-erh (post-fermented) tea, were profiled for catechin levels by using high performance liquid chromatography (HPLC). The result indicated that the gallic acid content in tea was directly proportional to the degree of fermentation in which the lowest and highest gallic acid content were 1.67 and 21.98 mg/g from green and Pu-erh tea, respectively. The antioxidative mechanism of the gallic acid was further determined by in vitro and in silico analyses. In vitro assays included the use of phorbol ester-induced macrophage RAW264.7 cell model for determining the inhibition of reactive oxygen species (ROS) production, and PKCδ and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunit (p47) activations. The results showed that only at a concentration of 5.00 μM could gallic acid significantly (p < 0.05) reduce ROS levels in phorbol ester-activated macrophages. Moreover, protein immunoblotting expressed similar results in which activations of PKCδ and p47 were only significantly (p < 0.05) attenuated by 5.00 μM treatment. Lastly, in silico experiments further revealed that gallic acid could block PKCδ activation by occupying the phorbol ester binding sites of the protein. Full article

(This article belongs to the Special Issue Catechins and Human Health: Current State of the Science)

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1372 KiB

Open AccessArticle

Catechins Variously Affect Activities of Conjugation Enzymes in Proliferating and Differentiated Caco-2 Cells

by Kateřina Lněničková, Eliška Procházková, Lenka Skálová, Petra Matoušková, Hana Bártíková, Pavel Souček and Barbora Szotáková

Molecules 2016, 21(9), 1186; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules21091186 - 07 Sep 2016

Cited by 6 | Viewed by 5239

Abstract

The knowledge of processes in intestinal cells is essential, as most xenobiotics come into contact with the small intestine first. Caco-2 cells are human colorectal adenocarcinoma that once differentiated, exhibit enterocyte-like characteristics. Our study compares activities and expressions of important conjugation enzymes and [...] Read more.

The knowledge of processes in intestinal cells is essential, as most xenobiotics come into contact with the small intestine first. Caco-2 cells are human colorectal adenocarcinoma that once differentiated, exhibit enterocyte-like characteristics. Our study compares activities and expressions of important conjugation enzymes and their modulation by green tea extract (GTE) and epigallocatechin gallate (EGCG) using both proliferating (P) and differentiated (D) caco-2 cells. The mRNA levels of the main conjugation enzymes were significantly elevated after the differentiation of Caco-2 cells. However, no increase in conjugation enzymes’ activities in differentiated cells was detected in comparison to proliferating ones. GTE/EGCG treatment did not affect the mRNA levels of any of the conjugation enzymes tested in either type of cells. Concerning conjugation enzymes activities, GTE/EGCG treatment elevated glutathione S-transferase (GST) activity by approx. 30% and inhibited catechol-O-methyltransferase (COMT) activity by approx. 20% in differentiated cells. On the other hand, GTE as well as EGCG treatment did not significantly affect the activities of conjugation enzymes in proliferating cells. Administration of GTE/EGCG mediated only mild changes of GST and COMT activities in enterocyte-like cells, indicating a low risk of GTE/EGCG interactions with concomitantly administered drugs. However, a considerable chemo-protective effect of GTE via the pronounced induction of detoxifying enzymes cannot be expected as well. Full article

(This article belongs to the Special Issue Catechins and Human Health: Current State of the Science)

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Open AccessArticle

Location and Effects of an Antitumoral Catechin on the Structural Properties of Phosphatidylethanolamine Membranes

by Francisco Casado, José A. Teruel, Santiago Casado, Antonio Ortiz, José N. Rodríguez-López and Francisco J. Aranda

Molecules 2016, 21(7), 829; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules21070829 - 24 Jun 2016

Cited by 6 | Viewed by 5611

Abstract

Green tea catechins exhibit high diversity of biological effects including antioncogenic properties, and there is enormous interest in their potential use in the treatment of a number of pathologies. It is recognized that the mechanism underlying the activity of catechins relay in part [...] Read more.

Green tea catechins exhibit high diversity of biological effects including antioncogenic properties, and there is enormous interest in their potential use in the treatment of a number of pathologies. It is recognized that the mechanism underlying the activity of catechins relay in part in processes related to the membrane, and many studies revealed that the ability of catechins to interact with lipids plays a probably necessary role in their mechanism of action. We present in this work the characterization of the interaction between an antitumoral synthetically modified catechin (3-O-(3,4,5-trimethoxybenzoyl)-(−)-catechin, TMCG) and dimiristoylphosphatidyl-ethanolamine (DMPE) membranes using an array of biophysical techniques which include differential scanning calorimetry, X-ray diffraction, infrared spectroscopy, atomic force microscopy, and molecular dynamics simulations. We found that TMCG incorporate into DMPE bilayers perturbing the thermotropic transition from the gel to the fluid state forming enriched domains which separated into different gel phases. TMCG does not influence the overall bilayer assembly of phosphatidylethanolamine systems but it manages to influence the interfacial region of the membrane and slightly decrease the interlamellar repeat distance of the bilayer. TMCG seems to be located in the interior of the phosphatidylethanolamine bilayer with the methoxy groups being in the deepest position and some portion of the molecule interacting with the water interface. We believe that the reported interactions are significant not only from the point of view of the known antitumoral effect of TMCG, but also might contribute to understanding the basic molecular mechanism of the biological effects of the catechins found at the membrane level. Full article

(This article belongs to the Special Issue Catechins and Human Health: Current State of the Science)

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Review

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4122 KiB

Open AccessReview

Catechins and Their Therapeutic Benefits to Inflammatory Bowel Disease

by Fei-Yan Fan, Li-Xuan Sang and Min Jiang

Molecules 2017, 22(3), 484; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules22030484 - 19 Mar 2017

Cited by 209 | Viewed by 13224

Abstract

Catechins are natural polyphenolic phytochemicals that exist in food and medicinal plants, such as tea, legume and rubiaceae. An increasing number of studies have associated the intake of catechins-rich foods with the prevention and treatment of chronic diseases in humans, such as inflammatory [...] Read more.

Catechins are natural polyphenolic phytochemicals that exist in food and medicinal plants, such as tea, legume and rubiaceae. An increasing number of studies have associated the intake of catechins-rich foods with the prevention and treatment of chronic diseases in humans, such as inflammatory bowel disease (IBD). Some studies have demonstrated that catechins could significantly inhibit the excessive oxidative stress through direct or indirect antioxidant effects and promote the activation of the antioxidative substances such as glutathione peroxidases (GPO) and glutathione (GSH), reducing the oxidative damages to the colon. In addition, catechins can also regulate the infiltration and proliferation of immune related-cells, such as neutrophils, colonic epithelial cells, macrophages, and T lymphocytes, helping reduce the inflammatory relations and provide benefits to IBD. Perhaps catechins can further inhibit the deterioration of intestinal lesions through regulating the cell gap junctions. Furthermore, catechins can exert their significant anti-inflammatory properties by regulating the activation or deactivation of inflammation-related oxidative stress-related cell signaling pathways, such as nuclear factor-kappa B (NF-κB), mitogen activated protein kinases (MAPKs), transcription factor nuclear factor (erythroid-derived 2)-like 2 (Nrf2), signal transducer and the activator of transcription 1/3 (STAT1/3) pathways. Finally, catechins can also stabilize the structure of the gastrointestinal micro-ecological environment via promoting the proliferation of beneficial intestinal bacteria and regulating the balance of intestinal flora, so as to relieve the IBD. Furthermore, catechins may regulate the tight junctions (TJ) in the epithelium. This paper elaborates the currently known possible molecular mechanisms of catechins in favor of IBD. Full article

(This article belongs to the Special Issue Catechins and Human Health: Current State of the Science)

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476 KiB

Open AccessReview

Preventive Effects of Catechins on Cardiovascular Disease

by Xiao-Qiang Chen, Ting Hu, Yu Han, Wei Huang, Hai-Bo Yuan, Yun-Tian Zhang, Yu Du and Yong-Wen Jiang

Molecules 2016, 21(12), 1759; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules21121759 - 21 Dec 2016

Cited by 78 | Viewed by 7403

Abstract

Catechins are polyphenolic phytochemicals with many important physiological activities that play a multifaceted health care function in the human body, especially in the prevention of cardiovascular disease. In this paper, various experimental and clinical studies have revealed the role of catechins in the [...] Read more.

Catechins are polyphenolic phytochemicals with many important physiological activities that play a multifaceted health care function in the human body, especially in the prevention of cardiovascular disease. In this paper, various experimental and clinical studies have revealed the role of catechins in the prevention and treatment of cardiovascular disorders, and we review the preventive effects of catechins on cardiovascular disease from the following aspects: Regulating lipid metabolism, regulating blood lipid metabolism, vascular endothelial protection, and reducing blood pressure. Full article

(This article belongs to the Special Issue Catechins and Human Health: Current State of the Science)

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Open AccessReview

Molecular Mechanisms and Metabolomics of Natural Polyphenols Interfering with Breast Cancer Metastasis

by Yingqian Ci, Jinping Qiao and Mei Han

Molecules 2016, 21(12), 1634; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules21121634 - 17 Dec 2016

Cited by 47 | Viewed by 10175

Abstract

Metastatic cancers are the main cause of cancer-related death. In breast primary cancer, the five-year survival rate is close to 100%; however, for metastatic breast cancer, that rate drops to a mere 25%, due in part to the paucity of effective therapeutic options [...] Read more.

Metastatic cancers are the main cause of cancer-related death. In breast primary cancer, the five-year survival rate is close to 100%; however, for metastatic breast cancer, that rate drops to a mere 25%, due in part to the paucity of effective therapeutic options for treating metastases. Several in vitro and in vivo studies have indicated that consumption of natural polyphenols significantly reduces the risk of cancer metastasis. Therefore, this review summarizes the research findings involving the molecular mechanisms and metabolomics of natural polyphenols and how they may be blocking breast cancer metastasis. Most natural polyphenols are thought to impair breast cancer metastasis through downregulation of MMPs expression, interference with the VEGF signaling pathway, modulation of EMT regulator, inhibition of NF-κB and mTOR expression, and other related mechanisms. Intake of natural polyphenols has been shown to impact endogenous metabolites and complex biological metabolic pathways in vivo. Breast cancer metastasis is a complicated process in which each step is modulated by a complex network of signaling pathways. We hope that by detailing the reported interactions between breast cancer metastasis and natural polyphenols, more attention will be directed to these promising candidates as effective adjunct therapies against metastatic breast cancer in the clinic. Full article

(This article belongs to the Special Issue Catechins and Human Health: Current State of the Science)

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732 KiB

Open AccessReview

Cancer Preventive Activities of Tea Catechins

by Chung S. Yang and Hong Wang

Molecules 2016, 21(12), 1679; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules21121679 - 09 Dec 2016

Cited by 163 | Viewed by 11956

Abstract

Catechins are widely occurring in our diet and beverages. The cancer-preventive activities of catechins have been extensively studied. Of these, (−)-epigallocatechin-3-gallate (EGCG), the principal catechin in green tea, has received the most attention. The inhibitory activities of tea catechins against carcinogenesis and cancer [...] Read more.

Catechins are widely occurring in our diet and beverages. The cancer-preventive activities of catechins have been extensively studied. Of these, (−)-epigallocatechin-3-gallate (EGCG), the principal catechin in green tea, has received the most attention. The inhibitory activities of tea catechins against carcinogenesis and cancer cell growth have been demonstrated in a large number of laboratory studies. Many mechanisms for modulating cancer signaling and metabolic pathways have been proposed based on numerous studies in cell lines with EGCG, the most active tea catechin. Nevertheless, it is not known whether many of these mechanisms indeed contribute to the anti-cancer activities in animals and in humans. Human studies have provided some results for the cancer preventive activities of tea catechins; however, the activities are not strong. This article reviews the cancer preventive activities and mechanisms of action of tea catechins involving their redox activities, biochemical properties and binding to key enzymes or signal transduction proteins. These mechanisms lead to suppression of cell proliferation, increased apoptosis and inhibition of angiogenesis. The relevance of the proposed mechanisms for cancer prevention are assessed in the light of the situation in vivo. The potential and possible problems in the application of tea and tea-derived products for cancer prevention are discussed. Full article

(This article belongs to the Special Issue Catechins and Human Health: Current State of the Science)

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Open AccessReview

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

by Masami Suganuma, Atsushi Takahashi, Tatsuro Watanabe, Keisuke Iida, Takahisa Matsuzaki, Hiroshi Y. Yoshikawa and Hirota Fujiki

Molecules 2016, 21(11), 1566; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules21111566 - 18 Nov 2016

Cited by 42 | Viewed by 11654

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Catechins and Human Health: Current State of the Science)

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