Green Tea Catechins Quench The Fluorescence of Bacteria-Conjugated Alexa Fluor Dyes.

Green Tea Catechins Quench The Fluorescence of Bacteria-Conjugated Alexa Fluor Dyes. Inflamm Allergy Drug Targets. 2013 Sep 3; Authors: Zhao L, Li W, Zhu S, Tsai S, Li J, Tracey KJ, Wang P, Fan S, Sama AE, Wang H Abstract Accumulating evidence suggest that Green tea polyphenolic catechins, especially the (-)-epigallocatechin gallate (EGCG), can be cross-linked to many proteins, and confer a wide range of anti-bacterial activities possibly by damaging microbial cytoplasmic lipids and proteins. At the doses that conferred protection against lethal polymicrobial infection (induced by cecal ligation and puncture), EGCG significantly reduced bacterial loads particularly in the liver and lung. To elucidate its bactericidal mechanisms, we determined whether EGCG affected the fluorescence intensities of bacteria-conjugated Alexa Fluor 488 or 594 dyes. When mixed with unconjugated Alexa Fluor 488 or 594 dyes, EGCG or analogs did not affect the fluorescence intensity of these dyes. In a sharp contrast, EGCG and some analogs (e.g., Catechin Gallate, CG), markedly reduced the fluorescence intensity of Gram-positive Staphylococcus aureus-conjugated Alexa 594 and Gram-negative Escherichia coli-conjugated Alexa 488. Interestingly, co-treatment with ethanol impaired the EGCG-mediated fluorescence quenching of the G+ S. aureus, but not of the G- E. coli-conjugated Alexa Flour dyes. In light of the notion that Alexa Fluor dyes can be quenched by aromatic amino ...
Source: Inflammation and Allergy Drug Targets - Category: Allergy & Immunology Authors: Tags: Inflamm Allergy Drug Targets Source Type: research