Query: Antibacterial mechanism of tea polyphenols

title: Research on the antibacterial mechanism of tea polyphenols on Escherichia coli
abstract: Tea polyphenols is an active material with broad spectrum antibacterial action. In this paper,Oxford cup experiment was performed to study the minimal inhibitory concentration of TP on E. coli. Crystal violet assay,electrical conductivity test and ion leakage measurement were also performed to determine the effect of TP on cell membrane of E. coli. Agarose gel electrophoresis was carried out to analyze the effect of TP on E. coli DNA. The results was the minimal inhibitory concentration of TP was 40 mg m L. The value of OD590 increased with the increase of TP concentration. And the value of conductivity and ion leakage increased with the increase of time,which shown that TP could change cell membrane permeability. DNA of E. coli treated with TP was extracted and compared with blank control group,the band of DNA of experiment group emerged dimmed and trailing,and this result indicated that TP can act on DNA of E. coli.

title: In vitro antibacterial effect of tea polyphenols combined with common antibiotics on multidrug resistant Klebsiella pneumoniae.
abstract: To investigate the bactericidal effect of tea polyphenols on multi drug resistant Klebsiella pneumoniae and its antibacterial efficacy in combination with common antibiotics, and to explore its mechanism.  The VITEK 2 Compact automatic microbial identification system was used to identify 20 strains of Klebsiella pneumoniae isolated from clinical isolates. The KB method was used to detect sensitivity of common drugs such as imipenem, piperacillin, piperacillin/tazobactam and cefepime, cefotaxime and ceftazidime; agar dilution method was used for detection of minimum inhibitory concentration (MIC) of tea polyphenols; the variation of the diameter of the antibacterial ring after different concentrations (0.25 MIC, 0.5 MIC) of tea polyphenols in combination with commonly used antibacterial drugs was detected to judge the feasibility of the inhibition of the multidrug resistant Klebsiella pneumoniae by the combination of tea polyphenols and commonly used antibacterial drugs. Congo red and crystal violent staining was used to detect the impact on bacterial biofilm formation and extracellular mucus like substance (slime) RESULTS The K B values of 20 strains of Klebsiella pneumoniae against common antibiotics were 6 14 mm; the MIC of tea polyphenols against 20 strains of multi drug resistant Klebsiella pneumoniae was 1024 ug ml; 0.5 MIC tea polyphenols can increase the diameter of the bacteriostatic ring of imipenem, piperacillin, piperacillin/tazobactam, cefepime, cefotaxime and ceftazidime by 3 28 mm. Tea polyphenols at sub inhibitory concentrations significantly inhibited the production of Klebsiella pneumoniae biofilm and extracellular mucus (slime)  Tea polyphenols could be used in combination with commonly used antibiotics (imipenem, piperacillin, piperacillin/tazobactam, cefepime, cefotaxime and ceftazidime) against multidrug resistant Klebsiella pneumoniae. It has a synergistic bactericidal effect and affects the formation of bacterial outer membrane and the production of extracellular slime like substances (slime)

title: Improvement of Stability of Tea Polyphenols: A Review.
abstract: Tea polyphenols have received much attention from the pharmaceutical and food industries owing to their extraordinary antioxidant and antibacterial characteristics. However, tea polyphenols are very unstable in processing and storage, since they are sensitive to the environmental factors like temperature, light and pH. Therefore, the effective application of tea polyphenols requires a protective mechanism to maintain its activity. The utilization of compounded tea polyphenols, instead of raw materials, can potentially help to improve their stability. This review focuses on the summarization of the compounding technologies for tea polyphenols, including physical technologies, chemical interfacial technologies and nano scale compounding technologies. Of which, the emerging nano cellulose bio carrier, as a promising technology, is particularly proposed.

title: Antimicrobial action mechanism of tea polyphenols to P.aeruginosa
abstract: In this study,investigated is the antimicrobial effect of tea polyphenols(TP) against P.aeruginosa and examined is the related mechanism.The minimal inhibitory concentration is determined by antibacterial activity assay.The antimicrobial kinetics against P.aeruginosa is also established.Furthermore,the enzyme(alkaline phosphate and adenosine triphosphatase) alkaline and the protein(bacterial soluble total protein and soluble membrane protein) are analysised.The results show that the activity of the enzyme is decreased and the soluble membrane protein is impressed,which would cause metabolic disorder and destroy structure of cell,so as to play the role of antibacterial activity.

title: Research progress in preservative mechanism and application of tea polyphenols in aquatic product
abstract: There are proteins,unsaturated fatty acids and large amounts of water in aquatic products. Aquatic products are easy to corrupt,degenerate,so the aquatic products preservation technology has been become a hot research,especially bio preservation. Tea polyphenols are phenolic compounds in general. It has a good antioxidant,antibacterial and antitumor etc. In this paper,constitute,antioxidative and antibacterial mechanism of tea polyphenols were introduced. Its application of tea polyphenols in aquatic products was summarized, and the application prospect of tea polyphenols was also predicted.

title: Development of novel monoclonal antibodies directed against catechins for investigation of antibacterial mechanism of catechins.
abstract: Catechins are major polyphenolic compounds of green tea. To investigate mechanism for antibacterial action of catechins, 11 monoclonal antibodies (MAbs) were raised against a 3 succinyl epicatechin (EC) keyhole limpet hemocyanin (KLH) conjugate. Amino acid sequences of variable regions determined for MAbs b 1058, b 1565, and b 2106 confirmed their innovative character. MAb b 1058 strongly interacted with its target substances in the following order of magnitude: theaflavin 3,3' di O gallate (TFDG)>theaflavin 3 O gallate (TF3G)=theaflavin 3' O gallate (TF3'G)>gallocatechin gallate (GCg)>penta O galloyl b d glucose (PGG)>epigallocatechin gallate (EGCg) as determined using surface plasmon resonance (SPR) on MAb immobilized sensor chips. The affinity profiles of MAbs b 1058 and b 2106 to the various polyphenols tested suggested that flavan skeletons with both carbonyl oxygen and hydroxyl groups are important for this interaction to take place. S. aureus cells treated with EGCg showed green fluorescence around the cells after incubation with FITC labeled MAb b 1058. The fluorescence intensity increased with increasing concentrations of EGCg. These MAbs are effective to investigate antibacterial mechanism of catechins and theaflavins.

title: The antibacterial activity of tea infusions and their effect against the hospital pathogen clostridium difficile
abstract: Clostridium difficile is one of the UK's most common hospital acquired infections and there is anecdotal evidence to suggest that the bacteria are sensitive to the antibacterial properties of tea. Surprisingly, little research has been undertaken to characterise the inhibitory activity of aqueous tea infusions that are representative of traditional drinking habits. The antibacterial properties of tea are thought to be due to a group of polyphenols called catechins. However, their contribution to the inhibitory activity of tea infusions and their mechanism of action is still subject to debate. An antimicrobial assay, developed using Staphylococcus aureus as a model organism, was used to determine the antibacterial activity of a range of tea infusions against 75 clinical isolates of C. difficile that represented all the major strain ribotypes over 11 years. Green teas demonstrated more potent antibacterial activity than black teas and their activity was positively correlated with antioxidant power, hydrogen peroxide production, and catechin content. Furthermore, the country of origin of the tea affected the catechin content and subsequent antimicrobial activity of the infusion. Detailed chemical analysis using high performance liquid chromatography and counter current chromatography suggests that the antibacterial activity of tea is probably the result of synergistic interactions between a number of catechins rather than the activity of an individual compound. With regards to the mode of action by which tea inhibits C. difficile, electron microscopy studies of the bacterium treated with green tea revealed distinct changes to the outer cell structures of the bacteria. These changes were indicative of cell membrane blebbing, thus supporting the theory that tea compounds interact with the bacterial membrane and/or cell wall. Overall, this investigation concluded that tea infusions have inhibitory activity against C. difficile in vitro and may be useful in the treatment or prevention of C. difficile infections in vivo.

title: Antiseptic mechanism of tea polyphenol and its applied prospect
abstract: Plant polyphenols are the most characteristic secondary metabolites and has many potential medicinal value and biological activity,of which the antibacterial activity is one of the hot spots.An overview of the recent study on tea polyphenol bacteriostasis progress and prospects for the inhibitory mechanism of tea polyphenol and applications can provide a theoretical information platform of further research.

title: Difference in the antibacterial action of epigallocatechin gallate and theaflavin 3,3' di O gallate on Bacillus coagulans
abstract: To study the mechanism of the antibacterial action of tea polyphenols such as catechins and theaflavins against Bacillus coagulans, and the interaction of epigallocatechin gallate (EGCg) or theaflavin 3,3' di O gallate (TFDG) with the surface of B. coagulans cells was investigated.

title: Antibacterial activity of polyphenolic fraction of Kombucha against Vibrio cholerae: targeting cell membrane
abstract: The present study was undertaken to determine the mechanism of antibacterial activity of a polyphenolic fraction, composed of mainly catechin and isorhamnetin, previously isolated from Kombucha, a 14 day fermented beverage of sugared black tea, against the enteropathogen Vibrio cholerae N16961. Bacterial growth was found to be seriously impaired by the polyphenolic fraction in a dose dependent manner. Scanning Electron Microscopy demonstrated morphological alterations in bacterial cells when exposed to the polyphenolic fraction in a concentration dependent manner. Permeabilization assays confirmed that the fraction disrupted bacterial membrane integrity in both time and dose dependent manners, which were proportional to the production of intracellular reactive oxygen species (ROS) Furthermore, each of the polyphenols catechin and isorhamnetin showed the ability to permeate bacterial cell membranes by generating oxidative stress, thereby suggesting their role in the antibacterial potential of Kombucha. Thus, the basic mechanism of antibacterial activity of the Kombucha polyphenolic fraction against V. cholerae involved bacterial membrane permeabilization and morphological changes, which might be due to the generation of intracellular ROS. To the best of our knowledge, this is the first report on the investigation of antibacterial mechanism of Kombucha, which is mostly attributed to its polyphenolic content.