Purification and Characterization of a Novel Galloyltransferase Involved in Catechin Galloylation in the Tea Plant

Abstract

Catechins (flavan-3-ols), the most important secondary metabolites in the tea plant, have positive effects on human health and are crucial in defense against pathogens of the tea plant. The aim of this study was to elucidate the biosynthetic pathway of galloylated catechins in the tea plant. The results suggested that galloylated catechins were biosynthesized via 1-O-glucose ester-dependent two-step reactions by acyltransferases, which involved two enzymes, UDP-glucose:galloyl-1-O-β-d-glucosyltransferase (UGGT) and a newly discovered enzyme, epicatechin:1-O-galloyl-β-d-glucose O-galloyltransferase (ECGT). In the first reaction, the galloylated acyl donor β-glucogallin was biosynthesized by UGGT from gallic acid and uridine diphosphate glucose. In the second reaction, galloylated catechins were produced by ECGT catalysis from β-glucogallin and 2,3-cis-flavan-3-ol. 2,3-cis-Flavan-3-ol and 1-O-galloyl-β-d-glucose were appropriate substrates of ECGT rather than 2,3-trans-flavan-3-ol and 1,2,3,4,6-pentagalloylglucose. Purification by more than 1641-fold to apparent homogeneity yielded ECGT with an estimated molecular mass of 241 to 121 kDa by gel filtration. Enzyme activity and SDS-PAGE analysis indicated that the native ECGT might be a dimer, trimer, or tetramer of 60- and/or 58-kDa monomers, and these monomers represent a heterodimer consisting of pairs of 36- or 34- of and 28-kDa subunits. MALDI-TOF-TOF MS showed that the protein SCPL1199 was identified. Epigallocatechin and epicatechin exhibited higher substrate affinities than β-glucogallin. ECGT had an optimum temperature of 30 °C and maximal reaction rates between pH 4.0 and 6.0. The enzyme reaction was inhibited dramatically by phenylmethylsulfonyl fluoride, HgCl2, and sodium deoxycholate.

Introduction

Flavonoids, a major class of secondary metabolites in plants, have a number of important physiological roles as endogenous auxin transport regulators, root development , seed germination, allelopathy , plant-bacterium interaction , UV-B protection , and plant defense against pathogens and environmental stress.

Flavonoids can be grouped into several subgroups including chalcone, flavone, flavonol, flavandiol, anthocyanin, proanthocyanidin (oligomer or polymer of flavan-3-ols and flavan-3,4-diol units) and other specialized forms. Flavan-3-ols (catechins), which comprise ∼70–80% of tea polyphenols, are rich in young leaves and shoots of the tea plant (Camellia sinensis (L.) O. Kuntze). Catechins, with a basic 2-phenylchromone structure, are characterized by the di- or tri-hydroxyl group substitution of the B ring, the 2,3-position isomer of the C ring, and presence of a galloyl group at the 3-postion of the C ring . On the basis of the classical definition proposed of galloyl group structural features, catechins are divided into galloylated and nongalloylated compounds. Galloylated catechins, including (−)-epigallocatechin gallate (EGCG)3 and (−)-epicatechin gallate (ECG), esterified often with gallic acid (GA) in the 3-hydroxyl group of the flavan-3-ol units are major catechin compounds that account for up to 76% of catechins in the tea plant .

Resource: http://www.ncbi.nlm.nih.gov
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Benefits of Green Tea

Abstract

The health benefits of green tea for a wide variety of ailments, including different types of cancer, heart disease, and liver disease, were reported. Many of these beneficial effects of green tea are related to its catechin, particularly (-)-epigallocatechin-3-gallate, content. There is evidence from in vitro and animal studies on the underlying mechanisms of green tea catechins and their biological actions. There are also human studies on using green tea catechins to treat metabolic syndrome, such as obesity, type II diabetes, and cardiovascular risk factors.

Long-term consumption of tea catechins could be beneficial against high-fat diet-induced obesity and type II diabetes and could reduce the risk of coronary disease. Further research that conforms to international standards should be performed to monitor the pharmacological and clinical effects of green tea and to elucidate its mechanisms of action.

Background

In recent years, the health benefits of consuming green tea, including the prevention of cancer and cardiovascular diseases, the anti-inflammatory, antiarthritic, antibacterial, antiangiogenic, antioxidative , antiviral, neuroprotective, and cholesterol-lowering effects of green tea and isolated green tea constituents are under investigation. However, adding green tea to the diet may cause other serious health concerns.

The health-promoting effects of green tea are mainly attributed to its polyphenol content, particularly flavanols and flavonols, which represent 30% of fresh leaf dry weight. Recently, many of the aforementioned beneficial effects of green tea were attributed to its most abundant catechin, (-)-epigallocatechin-3-gallate (EGCG). Green Tea Extract are more stable than pure epigallocatechin gallate, one of the major constituents of green tea, because of the presence of other antioxidant constituents in the extract. In general, herbal medicines are complex mixtures of different compounds that often act in a synergistic fashion to exert their full beneficial effect . However, relatively few herbal medicines have been well characterized and their efficacy demonstrated in systematic clinical trials as compared to Western drugs. This review article highlights the recent research on the efficacy, action mechanisms, and side effects of green tea and its catechins in in vitro, in vivo, and ex vivo systems .

The review on green tea and its catechins focused on language literature in English. The literature search was conducted in the following databases: Pubmed (1980-2009), EMBASE (1980-2009), Allied and complementary Medicine Database (AMED, 1985-2009) and China Journals Full Text Database (1975-2009). The keywords used were selected from the following terms: green tea, catechins, anticancer, diabetes, polyphenols, in vivo studies, general pharmacology and toxicology. The health benefits and adverse effects of green tea and its catechins were reviewed.

The authors read full articles and reached consensus after discussion. Articles included in the study covered the following effects of green tea:  the health benefits in humans and animals, absorption of metal ions and drug-metabolizing enzymes,  antioxidation and inhibition of oxidative stress,  carbohydrate metabolism and diabetes mellitus, and adverse effects. A total of 105 peer-reviewed papers in English were selected for this review.

Resource: http://www.ncbi.nlm.nih.gov
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Weight Loss Information in a Popular Diet Book: Is It Fact, Fiction, or Something in Between?

Abstract

BACKGROUND/OBJECTIVE

Diet books dominate the New York Times Advice Best Seller list and consumers cite such books as an important source of nutrition information. However, the scientific support for nutrition claims presented as fact (nutrition facts) in diet books is not known.

DESIGN/MEASUREMENTS

We assessed the quality of nutrition facts in the best-selling South Beach Diet using support in peer-reviewed literature as a measure of quality. We performed structured literature searches on nutrition facts located in the books' text, and then assigned each fact to 1 of 4 categories (1) fact supported, (2) fact not supported, (3) fact both supported and not supported, and (4) no related papers. A panel of expert reviewers adjudicated the findings.

RESULTS

Forty-two nutrition facts were included. Fourteen (33%) facts were supported, 7 (17%) were not supported, 18 (43%) were both supported and not supported, and 3 (7%) had no related papers, including the fact that the diet had been “scientifically studied and proven effective.”

CONCLUSIONS

Consumers obtain nutrition information from diet books. We found that over 67% of nutrition facts in a best-seller diet book may not be supported in the peer-reviewed literature. These findings have important implications for educating consumers about nutrition information sources.

Resource: http://www.ncbi.nlm.nih.gov/
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Effects of Hydrotherapy Treatment on Various Systems of the Body

Abstract

The use of water for various treatments (hydrotherapy) is probably as old as mankind. Hydrotherapy is one of the basic methods of treatment widely used in the system of natural medicine, which is also called as water therapy, aquatic therapy, pool therapy, and balneotherapy. Use of water in various forms and in various temperatures can produce different effects on different system of the body. Many studies/reviews reported the effects of hydrotherapy only on very few systems and there is lack of studies/reviews in reporting the evidence-based effects of hydrotherapy on various systems. We performed PubMed and PubMed central search to review relevant articles in English literature based on “effects of hydrotherapy/balneotherapy” on various systems of the body. Based on the available literature this review suggests that the hydrotherapy has a scientific evidence-based effect on various systems of the body.

Introduction

Hydrotherapy is the external or internal use of water in any of its forms (water, ice, steam) for health promotion or treatment of various diseases with various temperatures, pressure, duration, and site. It is one of the naturopathic treatment modality used widely in ancient cultures including India, Egypt, China, etc. Though many countries used water to produce different physiological/therapeutic effects on different part of the system for maintaining health, preventing, and treating the diseases, the scientific evidence-based effects are not well documented. There are many studies/reviews that reported either physiological or therapeutic or combination of both the effects of hydrotherapy on particular system but did not report in all the major systems of the body, which made us to do this review with the aim and objective to report scientific evidenced-based effects of hydrotherapy on various systems of the body. In order to provide a general overview, we performed PubMed and PubMed central search to review relevant articles in English literature based on “effects of hydrotherapy/balneotherapy” on various systems of the body. Articles published from 1986 to 2012 were included in this review.

Resource: http://www.ncbi.nlm.nih.gov
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In 18350- 1900 Healthy Skin Definition

Abstract

The concept of a healthy skin penetrated the lives of many people in late-nineteenth-century Britain. Popular writings on skin and soap advertisements are significant for pointing to the notions of the skin as a symbolic surface: a visual moral ideal. Popular health publications reveal how much contemporary understanding of skin defined and connected ideas of cleanliness and the visual ideals of the healthy body in Victorian Britain. Characterised as a ‘sanitary commissioner’ of the body, skin represented the organ of drainage for body and society. The importance of keeping the skin clean and purging it of waste materials such as sweat and dirt resonated in a Britain that embraced city sanitation developments, female beauty practices, racial identities and moral reform. By focusing on the popular work by British surgeon and dermatologist Erasmus Wilson (1809–84), this article offers a history of skin through the lens of the sanitary movement and developments in the struggle for control over healthy skin still in place today.

Resource: http://www.ncbi.nlm.nih.gov/
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Botanicals Uses in Skin Care

Abstract

Cosmeceuticals are the fastest growing sector of the cosmetic industry, and the future of antiaging cosmeceuticals in particular is very promising. Botanical extracts that support the health, texture, and integrity of the skin, hair, and nails are widely used in cosmetic formulations. They form the largest category of cosmeceutical additives found in the marketplace today due to the rising consumer interest and demand for natural products. Various plant extracts that formed the basis of medical treatments in ancient civilizations and many traditional cultures are still used today in cleansers, moisturizers, astringents, and many other skin care products. New botanical skin care treatments are emerging, presenting dermatologists and their patients the challenge of understanding the science behind these cosmeceuticals. Thus, dermatologists must have a working knowledge of these botanicals and keep up with how they evolve to provide optimal medical care and answer patient questions. The most popular botanicals commonly incorporated into skin care protocols are discussed.

The cosmeceutical market is one of constant fluctuation depending upon consumer demand. Skin care companies are continuously pressured to release new, innovative products that promise to transform the appearance of aging skin overnight. Over the past decade, there has been fervent interest in products found in nature because of their perceived safety. Skin care products are often developed from plants. Many believe that if a product can be safely ingested, it will also be safe for topical application. In general, plant-derived, botanical, cosmeceutical products tend to be antioxidant in action since these organisms must thrive in constant direct ultraviolet (UV) light, the Earth's most prolific manufacturer of free radicals. In this article, the authors review the most popular ingredients in this class and comment on their possible usefulness in skin care protocols.

Soy

Soy extract has positive research support for its antioxidant, antiproliferative, and anticarcinogenic activities. Topical application of soy has been used to reduce hyperpigmentation, enhance skin elasticity, control oil production, moisturize the skin, and delay hair regrowth. Soy also has the potential to decrease photoaging of the skin and prevent skin cancers through the estrogen-type and antioxidant effects of its metabolites.

The major components of soy are phospholipids, such as phosphatidylcholine and essential fatty acids. The minor components of soy include the most active compounds, such as isoflavones, saponins, essential amino acids, phytosterols, calcium, potassium, iron, and proteases soybean trypsin inhibitor (STI) and Bowman-Birk inhibitor (BBI). The various components of soy have a variety of beneficial effects making them useful additions to skin care products. The most potent isoflavones are the phytoestrogens known as genistein and daidzein. Genistein is a potent antioxidant that inhibits lipid peroxidation and chemical and ultraviolet light B (UVB)-induced carcinogenesis. Genistein was shown to significantly inhibit chemical, carcinogen-induced, reactive oxygen species; oxidative DNA damage; and proto-oncogene expression, as well as the initiation and promotion of skin carcinogenesis in mouse skin. Topical estrogens have been shown to promote collagen synthesis and increase skin thickness, which may be beneficial for postmenopausal women who develop a thinner dermis and decreased collagen. The small proteases STI and BBI appear to promote skin lightening and reduce unwanted facial and body hair in human clinical trials. Beyond the depigmenting activity, STI, BBI, and soy milk were also found to prevent UV-induced pigmentation both in vitro and in vivo. In addition, soy lipids, lecithins, and phytosterols are believed to restore barrier function and replenish moisture.

Beyond its moisturizing ability, soy appears to be a safe and effective treatment for postmenopausal women and for hyperpigmentation disorders (other than melasma, which is somewhat estrogen mediated). Although further research is necessary, the antioxidant and anticarcinogenic activities of soy and its isoflavones show a promising role for this botanical in the cosmeceutical industry. Soy has therefore become a popular addition to a wide variety of skin care products.

Resource: http://www.ncbi.nlm.nih.gov
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Atypical Occurrence of Two Biotin Protein Ligases in Francisella novicida

ABSTRACT

The physiological function of biotin requires biotin protein ligase activity in order to attach the coenzyme to its cognate proteins, which are enzymes involved in central metabolism. The model intracellular pathogen Francisella novicida is unusual in that it encodes two putative biotin protein ligases rather than the usual single enzyme. F. novicida BirA has a ligase domain as well as an N-terminal DNA-binding regulatory domain, similar to the prototypical BirA protein in E. coli. However, the second ligase, which we name BplA, lacks the N-terminal DNA binding motif. It has been unclear why a bacterium would encode these two disparate biotin protein ligases, since F. novicida contains only a single biotinylated protein. In vivo complementation and enzyme assays demonstrated that BirA and BplA are both functional biotin protein ligases, but BplA is a much more efficient enzyme. BirA, but not BplA, regulated transcription of the biotin synthetic operon. Expression of bplA (but not birA) increased significantly during F. novicida infection of macrophages. BplA (but not BirA) was required for bacterial replication within macrophages as well as in mice. These data demonstrate that F. novicida has evolved two distinct enzymes with specific roles; BplA possesses the major ligase activity, whereas BirA acts to regulate and thereby likely prevent wasteful synthesis of biotin. During infection BplA seems primarily employed to maximize the efficiency of biotin utilization without limiting the expression of biotin biosynthetic genes, representing a novel adaptation strategy that may also be used by other intracellular pathogens.

IMPORTANCE

Our findings show that Francisella novicida has evolved two functional biotin protein ligases, BplA and BirA. BplA is a much more efficient enzyme than BirA, and its expression is significantly induced upon infection of macrophages. Only BplA is required for F. novicida pathogenicity, whereas BirA prevents wasteful biotin synthesis. These data demonstrate that the atypical occurrence of two biotin protein ligases in F. novicida is linked to distinct roles in virulence and biotin metabolism.

Resource: http://www.ncbi.nlm.nih.gov
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