baicalein and epigallocatechin-gallate

Increasing antibiotic resistance and beneficial effects of host microbiota has motivated the search for anti-infective agents that attenuate bacterial virulence rather than growth. For example, we discovered that specific flavonoids such as baicalein and quercetin from traditional medicinal plant extracts could attenuate Salmonella enterica serovar Typhimurium type III protein secretion and invasion of host cells. Here, we show epigallocatechin-3-gallate from green tea extracts also inhibits the activity of S. Typhimurium type III protein effectors and significantly reduces bacterial invasion into host cells. These results reveal additional dietary plant metabolites that can attenuate bacterial virulence and infection of host cells.

Topics: Bacterial Proteins; Catechin; Dose-Response Relationship, Drug; Epithelial Cells; HeLa Cells; Humans; Microbial Sensitivity Tests; Molecular Structure; Plant Extracts; Salmonella typhimurium; Structure-Activity Relationship; Tea

Exploration for inhibitors against expression of IgE receptor (Fc epsilonRI) on human mast cell, a significant trigger to acute and chronic allergic symptoms, disclosed epigallocatechin gallate (EGCG), epicatechin gallate, and gallocatechin gallate as active principles. Additionally, the anthocyanidin, delphinidin, and the flavone, tricetinidin, possessing a pyrogallol function were also revealed to suppress expression of Fc epsilonRI. Structure-activity relationship analysis among catechins, anthocyanidins, and flavones revealed the pyrogallol moiety to be crucial for biological potency. Furthermore, EGCG was clarified to reduce generation of gamma-chain subunit to suppress expression of Fc epsilonRI on human mast cells.

Topics: Anthocyanins; Anti-Allergic Agents; Catechin; Cell Line; Flavones; Flavonoids; Gene Expression; Humans; Hypersensitivity; Mast Cells; Receptors, IgE