Antibacterial Activity of Tea Polyphenols against Phytopathogenic Bacteria.

Guo

Journal of Applied Microbiology

et al. 2010

Aims: To investigate the effect of tea polyphenol (TP) and Candida ernobii alone or in combination against postharvest disease (Diplodia natalensis) in citrus fruit and to evaluate the possible mechanisms involved. Methods and Results: TP at concentrations of 0·1%, 0·5% and 1·0% alone, or in combination with C. ernobii (1 × 106 CFU ml−1), showed a lower infection rate of stem‐end rot. TP at the concentration of 0·5% or above significantly inhibited the spore germination of D. natalensis. TP at the concentration of 1·0% showed inhibitary ability on mycelium growth of D. natalensis. The addition of TP did not affect the growth of C. ernobii in vitro and significantly increased the population of C. ernobii in vivo. Conclusions: TP exhibited an inhibitory effect against D. natalensis and improved the biocontrol efficacy of C. ernobii. It was direct because of the inhibitory effects of TP on spore germination and mycelial growth of D. natalensis in vitro and indirect because of the increased populations of C. ernobii in vivo. Significance and Impact of the Study: The results suggested that TP alone or in combination with biocontrol agents has great potential in commercial management of postharvest diseases in fruits.

Section: Discussionsupporting

confidence: 69%

Section: Introductionmentioning

confidence: 99%

Inhibitory activity of tea polyphenol and Candida ernobii against Diplodia natalensis infections

Guo

Journal of Applied Microbiology

et al. 2010

Molecular Nutrition Food Res

“…Phytopathogenic bacteria such as strains of Agrobacterium, Clavibacter, Pseudomonas, Erwinia, and Xanthomonas contaminate produce (eggplants, grapes, cabbage, lettuce, onions, potatoes, tomatoes). ECG and ECGC as well as theaflavins inhibited the growth of these bacteria in culture at MIC values of~100 ppm [79]. Related studies showed that EGCG, ECG, and theaflavins bound to and inactivated tobacco and cucumber mosaic viruses that cause lesions in plant leaves [80,81].…”

Section: Phytopathogensmentioning

confidence: 99%

Overview of antibacterial, antitoxin, antiviral, and antifungal activities of tea flavonoids and teas

Friedman¹

2006

567

373

Tea leaves produce organic compounds that may be involved in the defense of the plants against invading pathogens including insects, bacteria, fungi, and viruses. These metabolites include polyphenolic compounds, the six so-called catechins, and the methyl-xanthine alkaloids caffeine, theobromine, and theophylline. Postharvest inactivation of phenol oxidases in green tea leaves prevents oxidation of the catechins, whereas postharvest enzyme-catalyzed oxidation (fermentation) of catechins in tea leaves results in the formation of four theaflavins as well as polymeric thearubigins. These substances impart the black color to black teas. Black and partly fermented oolong teas contain both classes of phenolic compounds. A need exists to develop a better understanding of the roles of polyphenolic tea compounds in food and medical microbiology. This overview surveys and interprets our present knowledge of activities of tea flavonoids and teas against foodborne and other pathogenic bacteria, virulent protein toxins produced by some of the bacteria, virulent bacteriophages, pathogenic viruses and fungi. Also covered are synergistic, mechanistic, and bioavailability aspects of the antimicrobial effects. Further research is suggested for each of these categories. The herein described findings are not only of fundamental interest, but also have practical implications for nutrition, food safety, and animal and human health.

“…It is known that green tea exerts antimicrobial activity owing to specific flavonoid compounds named catechins [6,7], primarily represented by epigallocatechin gallate (EGCG). Moreover, this substance has recently attracted considerable interest because of its anticancer properties [15] by blocking the formation of new blood vessels.…”

Section: Discussionmentioning

confidence: 99%

“…Many scientists have searched for alternatives and a number of studies have concentrated on the bactericidal and bacteriostatic properties of various plants and plant extracts [3][4][5]. It is known that green tea extracts exert antimicrobial activity owing to specific flavonoid named catechins [6,7], primarily represented by epigallocatechin gallate (EGCG). Feeding supplementation with green tea has been used in fish [8], broiler chicks [9,10], calves [11] and also pigs [12].…”

Section: Introductionmentioning

confidence: 99%

EGCG, a major component of green tea, inhibits VEGF production by swine granulosa cells

Basini¹,

Bianco²,

Grasselli³

2005

BioFactors

Vascular Endothelial Growth Factor (VEGF) plays a pivotal role in the physiological ovarian angiogenic process: its production appears to be stimulated by the hypoxic environment which takes place during follicle development. Recently, epigallocatechin-3-gallate (EGCG) from green tea has been used in livestock nutrition as an alternative to antibiotics. However, despite many potential benefits of EGCG consumption, it is also important to get an insight on the possible reproductive-related consequences of feeding supplementation: in fact this substance has been found to inhibit angiogenesis, a process fundamental for follicle development. Therefore, we evaluated the effect of EGCG (5 and 50 microg/ml) on the production of the main angiogenetic factor, VEGF, by swine granulosa cells cultured in normoxia (19% O2), partial (5% O2) or total hypoxia (1% O2). In addition, we studied the effect of the catechin on cell proliferation. Our data demonstrate that both partial and total hypoxia stimulated VEGF production. EGCG reduced VEGF production independently of the O2 condition: 50 microM was the most effective doses. Granulosa cell proliferation was inhibited by EGCG even if only by the highest concentration. This effect might possibly be due to the decrease induced in VEGF production. Therefore feeding supplementation with EGCG should be carefully considered.