title: An in vitro evaluation of epigallocatechin gallate (eGCG) as a biocompatible inhibitor of ricin toxin.
abstract: The catechin, epigallocatechin gallate (eGCG), found in green tea, has inhibitory activity against a number of protein toxins and was investigated in relation to its impact upon ricin toxin (RT) in vitro. The IC(50) for RT was 0.08±0.004 ng/mL whereas the IC(50) for RT+100 μM eGCG was 3.02±0.572 ng/mL, indicating that eGCG mediated a significant (p<0.0001) reduction in ricin toxicity. This experiment was repeated in the human macrophage cell line THP-1 and IC(50) values were obtained for RT (0.54±0.024 ng/mL) and RT+100 μM eGCG (0.68±0.235 ng/mL) again using 100 μM eGCG and was significant (p=0.0013). The documented reduction in ricin toxicity mediated by eGCG was found to be eGCG concentration dependent, with 80 and 100 μg/mL (i.e. 178 and 223 μM respectively) of eGCG mediating a significant (p=0.0472 and 0.0232) reduction in ricin toxicity at 20 and 4 ng/ml of RT in Vero and THP-1 cells (respectively). When viability was measured in THP-1 cells by propidium iodide exclusion (as opposed to the MTT assays used previously) 10 ng/mL and 5 ng/mL of RT was used. The addition of 1000 μM and 100 μM eGCG mediated a significant (p=0.0015 and <0.0001 respectively) reduction in ricin toxicity relative to an identical concentration of ricin with 1 μg eGCG. Further, eGCG (100 μM) was found to reduce the binding of RT B chain to lactose-conjugated Sepharose as well as significantly (p=0.0039) reduce the uptake of RT B chain in Vero cells. This data suggests that eGCG may provide a starting point to refine biocompatible substances that can reduce the lethality of ricin.
authors.affiliation: Department of Life and Sports Science, University of Greenwich, Central Avenue, Chatham, Kent ME4 4TB, UK.
authors.forename: Paul D R
authors.initials: PD
authors.lastname: Dyer
authors.affiliation: Department of Life and Sports Science, University of Greenwich, Central Avenue, Chatham, Kent ME4 4TB, UK.
authors.forename: Arun K
authors.initials: AK
authors.lastname: Kotha
authors.affiliation: Department of Life and Sports Science, University of Greenwich, Central Avenue, Chatham, Kent ME4 4TB, UK.
authors.forename: Alex S
authors.initials: AS
authors.lastname: Gollings
authors.affiliation: Department of Life and Sports Science, University of Greenwich, Central Avenue, Chatham, Kent ME4 4TB, UK.
authors.forename: Susan A
authors.initials: SA
authors.lastname: Shorter
authors.affiliation: Department of Life and Sports Science, University of Greenwich, Central Avenue, Chatham, Kent ME4 4TB, UK.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Shepherd
authors.affiliation: Department of Life and Sports Science, University of Greenwich, Central Avenue, Chatham, Kent ME4 4TB, UK.
authors.forename: Marie W
authors.initials: MW
authors.lastname: Pettit
authors.affiliation: Department of Pharmaceutical, Chemical and Environmental Science, University of Greenwich, Central Avenue, Chatham, Kent ME4 4TB, UK.
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Alexander
authors.affiliation: Department of Life and Sports Science, University of Greenwich, Central Avenue, Chatham, Kent ME4 4TB, UK.
authors.forename: Giulia T M
authors.initials: GT
authors.lastname: Getti
authors.affiliation: Department of Life and Sports Science, University of Greenwich, Central Avenue, Chatham, Kent ME4 4TB, UK.
authors.forename: Samer
authors.initials: S
authors.lastname: El-Daher
authors.affiliation: School of Pharmacy and Pharmaceutical Sciences, Cardiff University, King Edward VII Avenue, Cardiff CF10 3AX, UK.
authors.forename: Les
authors.initials: L
authors.lastname: Baillie
authors.affiliation: Department of Life and Sports Science, University of Greenwich, Central Avenue, Chatham, Kent ME4 4TB, UK. Electronic address: S.C.W.Richardson@Greenwich.ac.uk.
authors.forename: Simon C W
authors.initials: SC
authors.lastname: Richardson
mesh_terms: D000818:Animals; D000931:Antidotes / Q000494:pharmacology*; D001692:Biological Transport; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D004305:Dose-Response Relationship, Drug; D006801:Humans; D020128:Inhibitory Concentration 50; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D011485:Protein Binding; D012276:Ricin / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D014709:Vero Cells
chemical_list: D000931:Antidotes; D002392:Catechin; D012276:Ricin; C045651:epigallocatechin gallate
keywords: Endocytosis; Epigallocatechin gallate; Polyphenol; Ricin toxin; Tea; eGCG