Tea catechins as a potential alternative anti-infectious agent

Green Tea Extract (Theaceae; Camellia sinensis L.): A Promising Antimicrobial, Anti-Quorum Sensing and Antibiofilm Candidate Against Multidrug-Resistant Campylobacter Species

BACKGROUND

Thermophilic Campylobacter species are among the main culprits behind bacterial gastroenteritis globally and have grown progressively resistant to clinically important antimicrobials. Many studies have been carried out to explore innovative and alternative strategies to control antibiotic-resistant campylobacters in animal reservoirs and human hosts; however, limited studies have been performed to develop efficient control schemes against Campylobacter biofilms.

METHODS

This study investigated the antimicrobial and antibiofilm activities of some herbal extracts against multidrug-resistant (MDR) Campylobacter species recovered from different sources using phenotypic and molecular techniques.

RESULTS

The overall Campylobacter species prevalence was 21.5%, representing 15.25% and 6.25% for C. jejuni and C. coli, respectively. Regarding C. jejuni, the highest resistance rate was observed for amoxicillin-clavulanic acid and colistin (85.25% each), followed by cefotaxime (83.61%) and tetracycline (81.97%), whereas C. coli isolates showed absolute resistance to cefotaxime followed by erythromycin (92%) and colistin (88%). Remarkably, all Campylobacter isolates were MDR with elevated multiple antimicrobial resistance (MAR) indices (0.54-1). The antimicrobial potentials of green tea (Camellia sinensis), rosemary (Rosmarinus officinalis) and ginger (Zingiber officinale) extracts against MDR Campylobacter isolates were assessed by the disk diffusion assay and broth microdilution technique. Green tea extract showed a marked inhibitory effect against tested isolates, exhibiting growth inhibition zone diameters of 8 to 38 mm and a minimum inhibitory concentration (MIC) range of 1.56-3.12 mg/mL, unlike the rosemary and ginger extracts. Our findings reveal a respectable antibiofilm activity (>50% biofilm formation inhibition) of green tea against the preformed biofilms of Campylobacter isolates. Furthermore, real-time quantitative polymerase chain reaction (RT-qPCR) results showed a significant decrease (p < 0.05) in the expression levels of biofilm biosynthesis gene and its regulator (FlaA and LuxS, respectively) in Campylobacter isolates treated with the green tea extract in comparison with untreated ones.

CONCLUSION

This is the first in vitro approach that has documented the inhibitory activity of green tea extract against MDR-biofilm-producing Campylobacter species isolated from different sources. Further in vivo studies in animals' models should be performed to provide evidence of concept for the implementation of this alternative candidate for the mitigation of MDR Campylobacter infections in the future.

The effect of a poly-herbal plant extract on the adhesion of Streptococcus mutans to tooth enamel

BACKGROUND

Dental caries, also known as tooth decay or cavity formation, is one of the world's most widespread dental conditions. It is a plaque-related infection caused mainly by Streptococcus mutans. People have relied on several plant species to treat oral infections; Heteropyxis natalensis, for example, has been used to treat toothache and gum infections.

METHODS

In this study, the antimicrobial and anti-adherence properties of H. natalensis and Camellia sinensis, as well as tea tree and peppermint essential oils were investigated on tooth enamel.

RESULTS

The bacterial load of S. mutans was reduced by approximately two orders of a magnitude after 48 h, with a lesser extent on the commensal bacteria, Lactobacillus paracasei. Scanning electron micrographs of enamel blocks showed a reduction in the attachment and chain formation of S. mutans and degraded cell morphology. Lastly, the combination and each component individually, showed low to no cellular toxicity when tested on human macrophages.

CONCLUSIONS

This is the first report of this polyherbal regarding its selectivity and potential prevention of dental caries.

Enhancing catechins, antioxidant and sirtuin 1 enzyme stimulation activities in green tea extract through pulse electric field-assisted water extraction: Optimization by response surface methodology approach

Green tea is an economic resource in Thailand because it is derived from smallholder agriculture and has expanded into food production. The purpose of this study is to optimize the parameters of pulsed electric field (PEF) assisted green tea extraction to produce a natural health product. A central composite design was involved to determine the effect of independent variables, including the intensity of electric field (I; 3-5 kV/cm), number of pulses (Np; 1000 to 3000 pulses) and green tea-to-water ratio (GT/W; 0.05-0.15 g/mL) on catechin (C), epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC) and epigallocatechin gallate (EGCG), total phenolic compound, antioxidant and sirtuin 1 enzyme stimulating activities. The results indicated that the Np had the most significant impact (p < 0.05) on the content of catechin and its derivatives and sirtuin 1 enzyme stimulating activity. The observations revealed that the I had a greater impact on antioxidant activities compared to the Np. The optimal conditions for PEF using the response surface method were determined to be I of 5 kV/cm, Np of 3000 pulses, GT/W of 0.14 g/mL and specific energy of 27 kJ/kg. Under the optimized conditions, the content of C, EC, ECG, EGC and EGCG were 7.34 ± 0.33, 11.26 ± 0.25, 3.75 ± 0.13, 7.53 ± 0.77 and 37.78 ± 0.58 mg/g extract, respectively. Furthermore, it was observed that green tea extract exhibited the ability to modulate the deacetylation activity of the sirtuin 1 enzyme, with a value of 22.63 ± 0.17 FIR. The results emphasized that the PEF led to achieving better responses compared to without pre-treatment using the PEF. Therefore, innovative technologies as PEF can be utilized for green tea extraction to produce natural ingredients, which can contribute to improved accessibility to healthcare. Additionally, the implementation of innovation techniques, such as PEF, in the extraction industry can enhance productivity growth and economic development.

Bioactive components and mechanisms of Pu-erh tea in improving levodopa metabolism in rats through COMT inhibition

Catechol-O-methyltransferase (COMT) plays a central role in the metabolic inactivation of endogenous neurotransmitters and xenobiotic drugs and hormones having catecholic structures. Its inhibitors are used in clinical practice to treat Parkinson's disease. In this study, a fluorescence-based visualization inhibitor screening method was developed to assess the inhibition activity on COMT both in vitro and in living cells. Following the screening of 94 natural products, Pu-erh tea extract exhibited the most potent inhibitory effect on COMT with an IC50 value of 0.34 μg mL-1. In vivo experiments revealed that Pu-erh tea extract substantially hindered COMT-mediated levodopa metabolism in rats, resulting in a significant increase in levodopa levels and a notable decrease in 3-O-methyldopa in plasma. Subsequently, the chemical components of Pu-erh tea were analyzed using UHPLC-Q-Exactive Orbitrap HRMS, identifying 24 major components. Among them, epigallocatechin gallate, gallocatechin gallate, epicatechin gallate, and catechin gallate exhibited potent inhibition of COMT activity with IC50 values from 93.7 nM to 125.8 nM and were the main bioactive constituents in Pu-erh tea responsible for its COMT inhibition effect. Inhibition kinetics analyses and docking simulations revealed that these compounds competitively inhibit COMT-mediated O-methylation at the catechol site. Overall, this study not only explained how Pu-erh tea catechins inhibit COMT, suggesting Pu-erh tea as a potential dietary intervention for Parkinson's disease, but also introduced a new strategy for discovering COMT inhibitors more effectively.

Medicinal Plants against Viral Infections: A Review of Metabolomics Evidence for the Antiviral Properties and Potentials in Plant Sources

Most plants have developed unique mechanisms to cope with harsh environmental conditions to compensate for their lack of mobility. A key part of their coping mechanisms is the synthesis of secondary metabolites. In addition to their role in plants' defense against pathogens, they also possess therapeutic properties against diseases, and their use by humans predates written history. Viruses are a unique class of submicroscopic agents, incapable of independent existence outside a living host. Pathogenic viruses continue to pose a significant threat to global health, leading to innumerable fatalities on a yearly basis. The use of medicinal plants as a natural source of antiviral agents has been widely reported in literature in the past decades. Metabolomics is a powerful research tool for the identification of plant metabolites with antiviral potentials. It can be used to isolate compounds with antiviral capacities in plants and study the biosynthetic pathways involved in viral disease progression. This review discusses the use of medicinal plants as antiviral agents, with a special focus on the metabolomics evidence supporting their efficacy. Suggestions are made for the optimization of various metabolomics methods of characterizing the bioactive compounds in plants and subsequently understanding the mechanisms of their operation.

Green Tea (Camellia sinensis) Products as Alternatives to Antibiotics in Poultry Nutrition: A Review

The overuse and misuse of antibiotics in poultry feeds increase the total cost of production and compromise the quality of poultry products, which poses a serious threat to human health. Globally, health-conscious poultry consumers have long called for the alternate use of natural additives to mitigate the development and spread of multidrug resistant pathogens. Phytogenic plants, such as green tea (Camellia sinensis) products, contain putative nutraceuticals with antibiotic properties that can be used as alternatives to therapeutic, metaphylactic, prophylactic, and growth-promoting antibiotics. However, there are limited studies in the literature that have evaluated the potential of green tea (GT) products when used as replacements to in-feed antibiotics, with most studies focusing on their potential as sources of dietary nutrients in poultry feeds. Thus, this review paper discusses the potential of GT products to replace various antibiotics in poultry diets while presenting GT bioactive substances that can improve the growth performance, carcass and meat quality traits, and health status of the birds. We postulate that the utilisation of GT products in place of antibiotics could deliver sustainable, organic poultry production systems that would contribute significantly to global food and nutrition security.

Antibiotic Combination Therapy: A Strategy to Overcome Bacterial Resistance to Aminoglycoside Antibiotics

After the first aminoglycoside antibiotic streptomycin being applied in clinical practice in the mid-1940s, aminoglycoside antibiotics (AGAs) are widely used to treat clinical bacterial infections and bacterial resistance to AGAs is increasing. The bacterial resistance to AGAs is owed to aminoglycoside modifying enzyme modification, active efflux pump gene overexpression and 16S rRNA ribosomal subunit methylation, leading to modification of AGAs' structures and decreased concentration of drugs within bacteria. As AGAs's side effects and bacterial resistance, the development of AGAs is time-consuming and difficult. Because bacterial resistance may occur in a short time after application in clinical practice, it was found that the antibacterial effect of the combination was not only better than that of AGAs alone but also reduce the dosage of antibiotics, thereby reducing the occurrence of side effects. This article reviews the clinical use of AGAs, the antibacterial mechanisms, the molecular mechanisms of bacterial resistance, and especially focuses a recent development of the combination of AGAs with other drugs to exert a synergistic antibacterial effect to provide a new strategy to overcome bacterial resistance to AGAs.

Anti-inflammatory properties of ethanolic extract from Vatairea macrocarpa leaves

ETHNOPHARMACOLOGICAL RELEVANCE

In Brazilian traditional folk medicine, the leaves and heartwood from Vatairea macrocarpa (Benth) Ducke (Angelim-of-Cerrado) (Fabaceae family) are used as remedy after cold maceration for the treatment of the condition popularly known as rheumatism, as well as for the general inflammatory aspects such as pains, injury and swelling. The rheumatological and rheumatic diseases affect 0.3-1.0% of the world population and all long-term treatment with conventional medications lead to adverse effects.

AIM OF THE STUDY

To investigate the chemical composition and the anti-inflammatory properties and of the ethanolic extract from V. macrocarpa leaves (EEVM) in experimental models.

MATERIAL AND METHODS

EEVM was chemically analyzed by spectrophotometry and the compounds characterization was performed by nuclear magnetic resonance and mass spectrometry. EEVM was evaluated in methylthiazolyldiphenyl-tetrazolium bromide (MTT) (3, 10, 30, and 90 μg/ml) and neutrophils phagocytic activity (1, 3, and 10 μg/ml) tests. For in vivo models, the EEVM (10, 30, 100, and 300 mg/kg) was orally administered (p.o.) for inflammatory evaluation in carrageenan-induced pleurisy in Swiss mice. The EEVM (30 and 100 mg/kg, p.o.) was tested against the Complete Freund Adjuvant (CFA)-induced paw persistent inflammation and Mycobacterium bovis (bacillus Calmette-Guerin - BCG)-induced pleurisy in C57bL6 mice.

RESULTS

The chemical composition of EEVM showed 157.06 mg (GAE)/g in relation to phenolic compounds, 82.13 mg (RUE)/g in relation to flavonoids and 48.99 mg (TAE)/g in relation to tannins. The flavonoid compounds identified were catechin, epicatechin and kaempferol-3-O-a-l-rhamnopyranoside. EEVM did not present cytotoxicity in MTT assay, however EEVM reduced phagocytic neutrophils activity at all tested concentration. EEVM significantly inhibited leukocytes migration/proteins exudation in carrageenan-induced pleurisy model. The daily administration of EEVM inhibited the inflammatory parameters in BCG and CFA models.

CONCLUSIONS

The present study showed anti-inflammatory features of EEVM (V. macrocarpa) as a natural agent against inflammatory diseases.

Multifaceted antiviral therapeutic potential of dietary flavonoids: Emerging trends and future perspectives

Phytochemicals are the natural biomolecules produced by plants via primary or secondary metabolism, which have been known to have many potential health benefits to human beings. Flavonoids or phytoestrogens constitute a major group of such phytochemicals widely available in variety of vegetables, fruits, herbs, tea, and so forth, implicated in a variety of bio-pharmacological and biochemical activities against diseases including bacterial, viral, cancer, inflammatory, and autoimmune disorders. More recently, these natural biomolecules have been shown to have effective antiviral properties via therapeutically active ingredients within them, acting at different stages of infection. Current review emphasizes upon the role of these flavonoids in physiological functions, prevention and treatment of viral diseases. More so the review focuses specifically upon the antiviral effects exhibited by these natural biomolecules against RNA viruses including coronaviruses. Furthermore, the article would certainly provide a lead to the scientific community for the effective therapeutic antiviral use of flavonoids using potential cost-effective tools for improvement of the pharmacokinetics, bioavailability, and biodistribution of such compounds for the concrete action along with the promotion of human health.

New insights into the role of the Nrf2 signaling pathway in green tea catechin applications

Nuclear factor-erythroid 2-related factor 2 (Nrf2) is a transcriptional signaling pathway that plays a crucial role in numerous clinical complications. Pivotal roles of Nrf2 have been proved in cancer, autoimmune diseases, neurodegeneration, cardiovascular diseases, diabetes mellitus, renal injuries, respiratory conditions, gastrointestinal disturbances, and general disorders related to oxidative stress, inflammation, apoptosis, gelatinolysis, autophagy, and fibrogenesis processes. Green tea catechins as a rich source of phenolic compounds can deal with various clinical problems and manifestations. In this review, we attempted to focus on intervention between green tea catechins and Nrf2. Green tea catechins especially epigallocatechin gallate (EGCG) elucidated the protective role of Nrf2 and its downstream molecules in various disorders through Keap-1, HO-1, NQO-1, GPx, GCLc, GCLm, NF-kB cross-link, kinases, and apoptotic proteins. Subsequently, we compiled an updated expansions of the Nrf2 role as a gate to manage and protect different disorders and feasible indications of green tea catechins through this signaling pathway. The present review highlighted recent evidence-based data in silico, in vitro, and in vivo studies on an outline for future clinical trials.

Epigallocatechin Gallate with Potent Anti-Helicobacter pylori Activity Binds Efficiently to Its Histone-like DNA Binding Protein

Helicobacter pylori (H. pylori)-a human gastric pathogen-forms a major risk factor for the development of various gastric pathologies such as chronic inflammatory gastritis, peptic ulcer, lymphomas of mucosa-associated lymphoid tissues, and gastric carcinoma. The complete eradication of infection is the primary objective of treating any H. pylori-associated gastric condition. However, declining eradication efficiencies, off-target effects, and patient noncompliance to prolong and broad-spectrum antibiotic treatments has spurred the clinical interest to search for alternative effective and safer therapeutic options. As natural compounds are safe and privileged with high levels of antibacterial-activity, previous studies have tested and reported a plethora of such compounds with potential in vitro/in vivo anti-H. pylori activity. However, the mode of action of majority of these natural compounds is unclear. The present study has been envisaged to compile the information of various such natural compounds and to evaluate their binding with histone-like DNA-binding proteins of H. pylori (referred here as Hup) using in silico molecular docking-based virtual screening experiments. Hup-being a major nucleoid-associated protein expressed by H. pylori-plays a strategic role in its survival and persistent colonization under hostile stress conditions. The ligand with highest binding energy with Hup-that is, epigallocatechin-(-)gallate (EGCG)-was rationally selected for further computational and experimental testing. The best docking poses of EGCG with Hup were first evaluated for their solution stability using long run molecular dynamics simulations and then using fluorescence and nuclear magnetic resonance titration experiments which demonstrated that the binding of EGCG with Hup is fairly strong (the resultant apparent dissociation constant (k _D) values were equal to 2.61 and 3.29 ± 0.42 μM, respectively).

Antibacterial activities of green tea crude extracts and synergistic effects of epigallocatechingallate (EGCG) with gentamicin against MDR pathogens

Plant extracts and their purified compounds were examined for synergistic antimicrobial activity using selected multi-drug resistant (MDR) pathogens. The study aims to investigate the antibacterial activity of green tea (Camellia sinensis) and its purified compound epigallocatechingallate (EGCG). The synergistic relation of the compound with antibiotic was detected against selected potential Gram positive and Gram negative pathogens. Staphylococcus aureus and Escherichia coli were used as test pathogens which were resistant to different groups of antibiotics. After collection of fresh green tea leaves, samples were washed and air dried. EGCG is one of the bioactive compounds and was separated from tea plant. Antibacterial activity of EGCG and crude extracts of green tea were done by microdilution method (minimum inhibitory concentration and minimum bactericidal concentration). The synergistic effect of EGCG and gentamicin was determined. MIC value of green tea extract was found at 125 μg/mL in case of MDR E. coli, MDR S. aureus and their reference strains and MBC at 500 μg/mL against S. aureus. No MBC value was found against E. coli. EGCG showed better activity on Gram positive pathogen compared to that of Gram negative. MBC value of this compound was 1250 μg/mL for E. coli where 625 μg/mL for S. aureus. Strong synergistic relation (FICI 0.325) was found against pathogens in the combination of EGCG with gentamycin. The purified EGCG compound of green tea has great synergistic effect against MDR pathogens. More investigation is needed to know the inhibitory effect of these plant extracts and their components.

Biological Activities of Heteropyxis natalensis Against Micro-Organisms Involved in Oral Infections

The use of complementary and alternative medicine from plants in South Africa, as in the rest of the world, continues to increase. Heteropyxis natalensis, known as the Lavender tree, is indigenous to South Africa and is traditionally used for oral care. The ethanolic extract, of the leaves and twigs, of H. natalensis was investigated for antimicrobial activity against selected oral microorganisms. Actinomyces israelii was found to be the most sensitive oral microorganism to the extract, with a minimum inhibitory concentration (MIC) of 0.88 mg/ml and an MIC of 2.6 mg/ml against Streptococcus mutans. Five known compounds were identified from the ethanolic extract of H. natalensis. The compounds were identified as aurentiacin A (1), cardamomin (2), 5-hydroxy-7-methoxy-6-methylflavanone (3), quercetin (4) and 3,5,7-trihydroxyflavan (5). The MICs of the compounds 1 and 4 were found to be 0.06 mg/ml and 1 mg/ml, respectively, against A. israelii. The cytotoxicity, acute and sub-acute toxicity in pre-clinical studies were also determined for H. natalensis. The extract showed moderate cytotoxicity (35.56 ± 0.16 μg/ml) on human monocyte cells. The acute and sub-acute toxicity analysis of H. natalensis indicated the NOEL (no-observed-effect level) at 200 mg/kg. Interleukin-8 (IL-8) is a chemokine that stimulates the recruitment of leukocytes. A significant reduction of IL-8 production by macrophage cells was observed when exposed to the extract of H. natalensis. It is possible that H. natalensis can prevent excessive tissue damage in periodontal diseases through its reduction of inflammation. Enzymatic bioanalysis of lactic and acetic acid production from Streptococcus mutans and Lactobacillus paracasei was done. A reduction in the acid production from each bacterium was observed on exposure to the extract of H. natalensis. Consequently, this increased the pH, which could possibly reduce the demineralization of enamel which may help prevent the formation of dental caries. In addition the extract may be considered for preventing periodontal diseases.

Flavonoids: promising natural compounds against viral infections

Flavonoids are widely distributed as secondary metabolites produced by plants and play important roles in plant physiology, having a variety of potential biological benefits such as antioxidant, anti-inflammatory, anticancer, antibacterial, antifungal and antiviral activity. Different flavonoids have been investigated for their potential antiviral activities and several of them exhibited significant antiviral properties in in vitro and even in vivo studies. This review summarizes the evidence for antiviral activity of different flavonoids, highlighting, where investigated, the cellular and molecular mechanisms of action on viruses. We also present future perspectives on therapeutic applications of flavonoids against viral infections.

Synthesis of Effective Food Constituents toward the Development of Chemical Biology Investigations

This article describes the development of various probes and immunogens for chemical-biological investigations of food flavonoids. We accomplished a large (gram)-scale asymmetric synthesis of a key intermediate, 5-aminopentyl deoxy epigallocatechin-3-gallate (APDOEGCg; 3), an analogue of green tea polyphenol EGCg, in which the key step was cationic cyclization utilizing neighboring group participation of the gallate carbonyl group. The synthetic APDOEGCg (3) was efficiently converted to a fluorescent probe 18 and an immunogen 19 by utilizing the high reactivity of the amine functional group. We confirmed the usefulness of these probes for imaging studies and the generation of antibodies, respectively. We also describe the efficient synthesis of a positron emission tomography (PET) probe [¹¹C]20 by incorporation of ¹¹C into EGCg (1), for which synthetic 4″-Me-EGCg (20) was utilized as an authentic sample. Our synthetic strategy was also applied for the practical synthesis of nobiletin (21), a polymethoxylated flavone from citrus. Synthetic nobiletin was readily converted to various probes by selective demethylation and incorporation of fluorescein, biotin or ¹¹C. These probes should be useful for a range of biological applications. Detailed examination of the mechanisms and further applications are in progress.

Honey and green/black tea consumption may reduce the risk of Helicobacter pylori infection

The aim of the study was to evaluate the influence of dietary and demographic factors and some habits on the prevalence of Helicobacter pylori infection in 150 dyspeptic patients examined endoscopically and by the urea breath test. Positivity rate was lower (50.6%) in patients consuming honey ≥1 day weekly compared with the remainder (70.8%) and in those consuming green/black tea ≥1 day weekly (45.2%) compared with the other patients (64.8%). Logistic regression confirmed that the factors associated with significantly lower H. pylori positivity rate were the consumption of honey (odds ratio [OR], 0.38; 95% confidence interval [CI], 0.19-0.78) and green/black tea (OR, 0.45; 95% CI, 0.21-0.95). In conclusion, honey and green/black tea intake is associated with reduced prevalence of H. pylori infection.

Effects of green tea on Escherichia coli as a uropathogen

Escherichia coli is the most common cause of urinary tract infections. The development of antibiotic resistance in E. coli is an important problem. Finding alternative antimicrobial agents from plant extracts has received growing interest. Camellia sinensis is a safe, nontoxic, cheap beverage that has been reported to have antimicrobial effects against various pathogenic bacteria including E. coli. Polyphenolic components of green tea ( lǜ chá) have antibacterial activity. Catechins also have synergistic effect with antibiotics such as chloramphenicol, amoxicillin, sulfamethoxazole, azithromycin, levofloxacin, gentamycin, methicillin, naldixic acid, and, especially ciprofloxacin. In this review, all experimental studies that evaluated the effect of green tea on E. coli were collected. Data from in vitro studies on the antimicrobial effects of green tea are promising, but human data are currently lacking. In vivo studies on antibacterial effects of green tea and evaluating the efficacy of its catechins in the treatment of urinary tract infection are needed.

3-O-galloylated procyanidins from Rumex acetosa L. inhibit the attachment of influenza A virus

Infections by influenza A viruses (IAV) are a major health burden to mankind. The current antiviral arsenal against IAV is limited and novel drugs are urgently required. Medicinal plants are known as an abundant source for bioactive compounds, including antiviral agents. The aim of the present study was to characterize the anti-IAV potential of a proanthocyanidin-enriched extract derived from the aerial parts of Rumex acetosa (RA), and to identify active compounds of RA, their mode of action, and structural features conferring anti-IAV activity. In a modified MTT (MTTIAV) assay, RA was shown to inhibit growth of the IAV strain PR8 (H1N1) and a clinical isolate of IAV(H1N1)pdm09 with a half-maximal inhibitory concentration (IC50) of 2.5 µg/mL and 2.2 µg/mL, and a selectivity index (SI) (half-maximal cytotoxic concentration (CC50)/IC50)) of 32 and 36, respectively. At RA concentrations>1 µg/mL plaque formation of IAV(H1N1)pdm09 was abrogated. RA was also active against an oseltamivir-resistant isolate of IAV(H1N1)pdm09. TNF-α and EGF-induced signal transduction in A549 cells was not affected by RA. The dimeric proanthocyanidin epicatechin-3-O-gallate-(4β→8)-epicatechin-3'-O-gallate (procyanidin B2-di-gallate) was identified as the main active principle of RA (IC50 approx. 15 µM, SI≥13). RA and procyanidin B2-di-gallate blocked attachment of IAV and interfered with viral penetration at higher concentrations. Galloylation of the procyanidin core structure was shown to be a prerequisite for anti-IAV activity; o-trihydroxylation in the B-ring increased the anti-IAV activity. In silico docking studies indicated that procyanidin B2-di-gallate is able to interact with the receptor binding site of IAV(H1N1)pdm09 hemagglutinin (HA). In conclusion, the proanthocyanidin-enriched extract RA and its main active constituent procyanidin B2-di-gallate protect cells from IAV infection by inhibiting viral entry into the host cell. RA and procyanidin B2-di-gallate appear to be a promising expansion of the currently available anti-influenza agents.

Nontraditional therapies to treat Helicobacter pylori infection

The Gram-negative pathogen Helicobacter pylori is increasingly more resistant to the three major antibiotics (metronidazole, clarithromycin and amoxicillin) that are most commonly used to treat infection. As a result, there is an increased rate of treatment failure; this translates into an overall higher cost of treatment due to the need for increased length of treatment and/or the requirement for combination or sequential therapy. Given the rise in antibiotic resistance, the complicated treatment regime, and issues related to patient compliance that stem from the duration and complexity of treatment, there is clearly a pressing need for the development of novel therapeutic strategies to combat H. pylori infection. As such, researchers are actively investigating the utility of antimicrobial peptides, small molecule inhibitors and naturopathic therapies. Herein we review and discuss each of these novel approaches as a means to target this important gastric pathogen.

Antibiofilm and quorum sensing inhibitory activity of Achyranthes aspera on cariogenic Streptococcus mutans: an in vitro and in silico study

CONTEXT

Traditionally, many cultures use chewing sticks for oral hygiene maintenance. When properly used, these chewing sticks are found to be efficient due to the combined effect of mechanical cleaning, enhanced salivation and the antimicrobial action of leached out plant compounds.

OBJECTIVE

Achyranthes aspera L. (Amaranthaceae), an ethanomedicinal herb was evaluated for its potential to inhibit growth and biofilm formation by cariogenic isolate Streptococcus mutans as an alternative means of caries management by quorum quenching (QQ).

MATERIALS AND METHODS

Biofilm forming cariogenic isolates were isolated and their susceptibility to the petroleum ether, benzene, methanol, aqueous extracts of A. aspera was evaluated. Gas chromatography-mass spectrometry (GC-MS), phytochemical analyses and structure-based virtual screening for their quorum sensing (QS) inhibitory activities, drug-likeness and bioavailability were also carried out.

RESULTS

The biofilm inhibition percentage obtained for methanol, benzene, petroleum ether and aqueous extracts (125 µg/mL) were ≤94%, ≤74%, ≤62% ≤42%, respectively. GC-MS analyses indicated 61 compounds, of which betulin recorded efficient interaction exhibiting comparable binding energy of -8.72 with S. mutans glycosyltransferase (GTF-SI) whereas 3,12-oleandione exhibited binding energy -5.92 with OmpR subfamily QS regulatory DNA-binding response regulator. Computer-assisted molecular descriptor and Lipinski's rule violation calculation uncovered the presence of more drug-like compounds.

DISCUSSION AND CONCLUSION

Anticaries bioactive compounds of A. aspera with higher QS response regulator binding energy, low toxicity and optimal pharmacokinetic properties were revealed. These compounds with possible QQ ability hold the potential for use as anticaries drug leads and antibiofilm preventative medicine.

Evaluation of the antiviral activity of a green tea solution as a hand-wash disinfectant

Based on the broad-spectrum antiviral effect of green tea catechins, we established an experimental skin contact model for influenza virus transmission and evaluated the use of a green tea solution as a first-hand disinfectant. The infectivity of the virus on the skin cell layer became obsolete when washed with the green tea solution. The skin contact model could be applied to develop non-pharmaceutical intervention measures for reducing human transmission of the influenza virus.

Alternative therapies for Helicobacter pylori: probiotics and phytomedicine

Helicobacter pylori is a common human pathogen infecting about 30% of children and 60% of adults worldwide and is responsible for diseases such as gastritis, peptic ulcer and gastric cancer. Treatment against H. pylori is based on the use of antibiotics, but therapy failure can be higher than 20% and is essentially due to an increase in the prevalence of antibiotic-resistant bacteria, which has led to the search for alternative therapies. In this review, we discuss alternative therapies for H. pylori, mainly phytotherapy and probiotics. Probiotics are live organisms or produced substances that are orally administrated, usually in addition to conventional antibiotic therapy. They may modulate the human microbiota and promote health, prevent antibiotic side effects, stimulate the immune response and directly compete with pathogenic bacteria. Phytomedicine consists of the use of plant extracts as medicines or health-promoting agents, but in most cases the molecular mode of action of the active ingredients of these herbal extracts is unknown. Possible mechanisms include inhibition of H. pylori urease enzyme, disruption of bacterial cell membrane, and modulation of the host immune system. Other alternative therapies are also reviewed.

Removal of caffeine from green tea by microwave-enhanced vacuum ice water extraction

In order to selectively remove caffeine from green tea, a microwave-enhanced vacuum ice water extraction (MVIE) method was proposed. The effects of MVIE variables including extraction time, microwave power, and solvent to solid radio on the removal yield of caffeine and the loss of total phenolics (TP) from green tea were investigated. The optimized conditions were as follows: solvent (mL) to solid (g) ratio was 10:1, microwave extraction time was 6 min, microwave power was 350 W and 2.5 h of vacuum ice water extraction. The removal yield of caffeine by MVIE was 87.6%, which was significantly higher than that by hot water extraction, indicating a significant improvement of removal efficiency. Moreover, the loss of TP of green tea in the proposed method was much lower than that in the hot water extraction. After decaffeination by MVIE, the removal yield of TP tea was 36.2%, and the content of TP in green tea was still higher than 170 mg g(-1). Therefore, the proposed microwave-enhanced vacuum ice water extraction was selective, more efficient for the removal of caffeine. The main phenolic compounds of green tea were also determined, and the results indicated that the contents of several catechins were almost not changed in MVIE. This study suggests that MVIE is a new and good alternative for the removal of caffeine from green tea, with a great potential for industrial application.

Concise synthesis of catechin probes enabling analysis and imaging of EGCg

A concise synthesis of APDOEGCg (3) was accomplished. Due to the reactivity of its amine group, the compound could be easily converted to the fluorescein probe 21 and immunogen probe 22 efficiently. We then demonstrated the usefulness of the probes for imaging studies and the generation of antibodies.

Viral membranes: an emerging antiviral target for enveloped viruses?

Evaluation of: Wolf MC, Freiberg AN, Zhang T et al. A broad-spectrum antiviral targeting entry of enveloped viruses. Proc. Natl Acad. Sci. USA 107, 3157-3162 (2010). The emergence and re-emergence of viruses and the widespread antiviral resistance calls for the development of a broad-spectrum strategy for viral infection. The article under review describes an approach to achieve this goal by developing an antiviral rhodanine derivative effective against enveloped viruses targeting the viral lipid membrane. By intercalating into the viral membrane, the compound irreversibly inactivates the virions with virucidal effects. Potential toxic effects on hosts could be minimized by continuous regeneration of cellular membranes. The present strategy exploits the therapeutic window that exists between static viral membranes and biogenic cellular membranes and provides a useful guideline for future research endeavors towards broad-spectrum antiviral approaches for enveloped viruses. Developing a formulation that ensures efficient delivery and pharmacokinetic properties while minimizing systemic toxicity on cell membranes remains a challenge. The advantages and disadvantages of a viral membrane-targeting approach for the control of emerging and re-emerging viruses will be discussed.

Immune-modulating efficacy of a polyphenol-rich beverage on symptoms associated with the common cold: a double-blind, randomised, placebo-controlled, multi-centric clinical study

In the present study, the immune-modulating efficacy of a polyphenol-rich beverage on symptoms associated with the common cold was evaluated. For this purpose, ninety-eight patients reporting common cold symptoms that began no longer than 24 h before the study intervention were randomly assigned to consume either the test beverage or placebo twice per d for 10 d. The severity of the disease was expressed as the total score of the five cold symptoms 'general feeling of sickness', 'headache and/or joint aches', 'sore throat and/or difficulty swallowing', 'hoarseness and/or cough' and 'stuffy nose/sniffle'. Consequently, the decrease from 10.2 (sd 3.1) points at the beginning to 2.1 (sd 2.7) points by the end of the study in the verum group demonstrated a clear improvement, whereas in the placebo group only a reduction from 10.5 (sd 3.0) to 6.3 (sd 3.8) points could be observed. The mean difference between the groups (primary efficacy criterion) of 3.9 points was highly significant (P < 0.01). At the end of the study there were highly significantly (P < 0.01) more patients in the verum group complaint free than in the placebo group (secondary efficacy criterion). In addition to these self-reported values, several local findings of the physical examination were also significantly improved in the verum group.

Antiviral activity of proanthocyanidin against feline calicivirus used as a surrogate for noroviruses, and coxsackievirus used as a representative enteric virus

Proanthocyanidin, which consists of (+) catechin, (-) epicatechin and their gallates (15%), (-) epicatechin gallate-dimers, -trimers, and -tetramers (80%), and (-) epicatechin gallate-pentamers, -hexamers, and -heptamers (5%), was evaluated for its antiviral activity against feline calicivirus F9 strain (FCV/F9), which is thought to be a surrogate for noroviruses, and coxsackievirus A7 strain (Cox.A7), which was selected as a representative enteric virus. To achieve a viral inactivation rate of 99% or greater after contact for 10 sec., at least 1 mg/ml and 10 mg/ml of proanthocyanidin were required against FCV/F9 and Cox.A7, respectively. Although the antiviral mechanism of proanthocyanidin is not clear at present, proanthocyanidin may be an effective disinfectant against enteroviruses such as noroviruses.

Green tea and death from pneumonia in Japan: the Ohsaki cohort study

BACKGROUND

Experimental and animal studies have shown the activities of catechins, the main constituents of green tea, against infectious agents. No data are available on the association between green tea consumption and the risk of pneumonia in humans.

OBJECTIVE

We examined the association between green tea consumption and death from pneumonia in humans.

DESIGN

We conducted a population-based cohort study, with follow-up from 1995 to 2006. The participants were National Health Insurance beneficiaries in Japan (19,079 men and 21,493 women aged 40-79 y). We excluded participants for whom data on green tea consumption frequency were missing or who had reported a history of cancer, myocardial infarction, stroke, and extreme daily energy intake at baseline. We used Cox proportional hazards regression analysis to calculate hazard ratios (HRs) and their 95% CIs for death from pneumonia according to green tea consumption.

RESULTS

Over 12 y of follow-up, we documented 406 deaths from pneumonia. In women, the multivariate HRs of death from pneumonia that were associated with different frequencies of green tea consumption were 1.00 (reference) for <1 cup/d, 0.59 (95% CI: 0.36, 0.98) for 1-2 cups/d, 0.55 (95% CI: 0.33, 0.91) for 3-4 cups/d, and 0.53 (95% CI: 0.33, 0.83) for > or =5 cups/d, respectively (P for trend: 0.008). In men, no significant association was observed.

CONCLUSION

Green tea consumption was associated with a lower risk of death from pneumonia in Japanese women.

Thermal destruction of Escherichia coli O157:H7 in sous-vide cooked ground beef as affected by tea leaf and apple skin powders

We investigated the heat resistance of a four-strain mixture of Escherichia coli O157:H7 in raw ground beef in both the absence and presence of white and green tea powders and an apple skin extract. Inoculated meat was cooked using the sous-vide technique, i.e., the meat was packaged in sterile bags and completely immersed in a circulating water bath at low temperature for a period of time. The bags were cooked for 1 h to an internal temperature of 55, 58, 60, or 62.5 degrees C, and then held from 240 min at 55 degrees C to 10 min at 62.5 degrees C. The surviving bacteria were enumerated by spiral plating onto tryptic soy agar overlaid with sorbitol-MacConkey agar. Inactivation kinetics of the pathogens deviated from first-order kinetics. D-values (time, in minutes, required for the bacteria to decrease by 90%) in the control beef ranged from 67.79 min at 55 degrees C to 2.01 min at 62.5 degrees C. D-values determined by a logistic model ranged from 36.22 (D1, the D-value of a major population of surviving cells) and 112.79 (D2, the D-value of a minor subpopulation) at 55 degrees C to 1.39 (D1) and 3.00 (D2) at 62.5 degrees C. A significant increase (P < 0.05) in the sensitivity of the bacteria to heat was observed with the addition of 3% added antimicrobials. D-value reductions of 62 to 74% were observed with apple powder and 18 to 58% with tea powders. Thermal death times from this study will assist the retail food industry to design cooking regimes that ensure the safety of beef contaminated with E. coli O157:H7.

Green tea polyphenols block the anticancer effects of bortezomib and other boronic acid-based proteasome inhibitors

The anticancer potency of green tea and its individual components is being intensely investigated, and some cancer patients already self-medicate with this "miracle herb" in hopes of augmenting the anticancer outcome of their chemotherapy. Bortezomib (BZM) is a proteasome inhibitor in clinical use for multiple myeloma. Here, we investigated whether the combination of these compounds would yield increased antitumor efficacy in multiple myeloma and glioblastoma cell lines in vitro and in vivo. Unexpectedly, we discovered that various green tea constituents, in particular (-)-epigallocatechin gallate (EGCG) and other polyphenols with 1,2-benzenediol moieties, effectively prevented tumor cell death induced by BZM in vitro and in vivo. This pronounced antagonistic function of EGCG was evident only with boronic acid-based proteasome inhibitors (BZM, MG-262, PS-IX), but not with several non-boronic acid proteasome inhibitors (MG-132, PS-I, nelfinavir). EGCG directly reacted with BZM and blocked its proteasome inhibitory function; as a consequence, BZM could not trigger endoplasmic reticulum stress or caspase-7 activation, and did not induce tumor cell death. Taken together, our results indicate that green tea polyphenols may have the potential to negate the therapeutic efficacy of BZM and suggest that consumption of green tea products may be contraindicated during cancer therapy with BZM.

Phytoceuticals: mighty but ignored weapons against Helicobacter pylori infection

Helicobacter pylori (H. pylori) infection causes peptic ulcer disease, mucosa-associated lymphoid tissue (MALT) lymphomas and gastric adenocarcinomas, for which the pathogenesis of chronic gastric inflammation prevails and provides the pathogenic basis. Since the role of H. pylori infection is promoting carcinogenesis rather than acting as a direct carcinogen, as several publications show, eradication alone cannot be the right answer for preventing H. pylori-associated gastric cancer. Therefore, a non-antimicrobial approach has been suggested to attain microbe-associated cancer prevention through controlling H. pylori-related chronic inflammatory processes and mediators responsible for carcinogenesis. Phytoceutical is a term for plant products that are active on biological systems. Phytoceuticals such as Korean red ginseng, green tea, red wine, flavonoids, broccoli sprouts, garlic, probiotics and flavonoids are known to inhibit H. pylori colonization, decrease gastric inflammation by inhibiting cytokine and chemokine release, and repress precancerous changes by inhibiting nuclear factor-kappa B DNA binding, inducing profuse levels of apoptosis and inhibiting mutagenesis. Even though further unsolved issues are awaited before phytoceuticals are accepted as a standard treatment for H. pylori infection, phytoceuticals can be a mighty weapon for either suppressing or modulating the disease-associated footprints of H. pylori infection.

The polyphenol (-)-epicatechin gallate disrupts the secretion of virulence-related proteins by Staphylococcus aureus

AIM

(-)-epicatechin gallate (ECg) modifies the morphology, cell wall architecture and beta-lactam antibiotic susceptibility of Staphylococcus aureus. As these effects result primarily from intercalation into the bacterial cytoplasmic membrane, the capacity of ECg to modulate the secretion of two key staphylococcal virulence factors, coagulase and alpha-toxin, was examined.

METHODS AND RESULTS

Bioassays were used to determine coagulase and haemolysin activity in culture supernatants of a number of S. aureus isolates grown in the presence and absence of ECg; alpha-toxin secretion was also evaluated by immunoblotting. Growth in ECg reduced the levels of activity of both proteins in culture supernatants; the effects could only be partly explained by ECg-mediated inhibition of bioactivity and by induction of secreted proteases.

CONCLUSION

ECg suppresses the secretion of coagulase and alpha-toxin by clinical isolates of S. aureus.

SIGNIFICANCE AND IMPACT OF THE STUDY

The observation that secretion of key components of staphylococcal virulence can be compromised by a naturally occurring polyphenol supports the notion that ECg and related compounds may have therapeutic utility for the control of infections that are currently difficult to treat due to the propensity of methicillin-resistant S. aureus to accumulate antibiotic resistance genes.

Biological evaluation of anti-influenza viral activity of semi-synthetic catechin derivatives

Catechin derivatives with different alkyl chain length and aromatic ring substitutions at the 3-hydroxyl group were synthesized from epigallocatechin (EGC) and (+)-catechin (C) and their anti-influenza viral activity were evaluated in vitro and in ovo. Pronounced antiviral activity was observed for derivatives carrying moderate chain length (7-9 carbons) as compared to those with aromatic rings, whereas the 5'-hydroxyl group of the trihydroxy benzyl moiety did not significantly contribute to antiviral activity. The derivatives exerted inhibitory effects for all six influenza subtypes tested including three major types of currently circulating human influenza viruses (A/H1N1, A/H3N2 and B type), H2N2 and H9N2 avian influenza virus. The compounds strongly inhibited adsorption of the viruses on red blood cell (RBC). They also restricted the growth of avian influenza virus in ovo with minimum inhibition concentration (MIC) of 5-10 microM far exceeding the neuraminidase (NA) inhibitor oseltamivir or M2 proton channel inhibitor amantadine. The antiviral activity appears to be mediated by interaction with hemagglutinin (HA)/viral membrane rendering HA less fusogenic at the initial stage of infection. The broad spectrum activity against various subtypes of influenza viruses may complement the limitations of current antivirals and contribute for managing potentially emerging influenza pandemic. The structure-activity data of catechin derivatives may usefully guideline future research endeavors for applying green tea catechins as alternative anti-viral agents.