Different cytotoxic and clastogenic effects of epigallocatechin gallate in various cell-culture media due to variable rates of its oxidation in the culture medium.
Positive genotoxicity results are often observed using mammalian cells in culture with agents that are not in vivo genotoxins. We here illustrate one possible explanation: interaction of test chemicals with the cell-culture media used. We find that the toxicity and clastogenicity of epigallocatechin gallate (EGCG) to Chinese Hamster ovary (CHO) cells is affected by the culture medium used and appears largely or entirely due to variable rates of formation of hydrogen peroxide (H(2)O(2)) by chemical reactions of EGCG with the culture media. Catalase decreased EGCG toxicity substantially. Of seven different types of commonly used media evaluated, F-10 and F-12 nutrient mixtures were the least prone to produce this artefact. Although it generated H(2)O(2) in the culture media, ascorbate was not toxic to CHO cells because the H(2)O(2) levels achieved were insufficient to kill these cells. Thus, the culture medium, the cell type and the presence or absence of catalase (e.g. its variable amounts in S9 fractions) must be taken into account in in vitro genotoxicity testing.
Long
Lee Hua
LH
Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, MD7 Level 2 Singapore, Singapore.
Kirkland
David
D
Whitwell
James
J
Halliwell
Barry
B
D000818:Animals; D016466:CHO Cells; D002374:Catalase / Q000494:pharmacology; D002392:Catechin / Q000031:analogs & derivatives* / Q000633:toxicity; D002470:Cell Survival; D006224:Cricetinae; D003412:Cricetulus; D003470:Culture Media; D005260:Female; D006861:Hydrogen Peroxide / Q000378:metabolism*; D009153:Mutagens / Q000633:toxicity*; D010084:Oxidation-Reduction
D003470:Culture Media; D009153:Mutagens; D002392:Catechin; D006861:Hydrogen Peroxide; C045651:epigallocatechin gallate; D002374:Catalase