Isolation and characterization of new mutagens from fried ground beef

Abstract

Frying of ground beef at 250 degrees C results in the formation of a series of mutagenic heterocyclic amines, possibly as many as 10 distinct compounds. In this study, the mutagens are separated by aqueous/acid extraction from the beef, XAD adsorption, acid/neutral/base-liquid/liquid extraction, preparative reverse phase h.p.l.c., normal phase h.p.l.c., and analytical reverse phase h.p.l.c. Identification is by low and high resolution mass spectrometry, u.v. absorption spectroscopy and nitrite sensitivity assays. More than 30% of the mutagenic material is identified as 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx). The previously described beef mutagen, 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) contributes less than 12% of the total mutagenicity at high temperatures (300 degrees C) and less than 4% at lower temperatures. In addition to MeIQx major mutagens are seen with molecular ions at m/z 227 (C12H13N5), 209 (C13H11N3), and 176 (C9H12N4). Two very polar and two non-polar peaks making a relatively minor contribution to the total mutagenicity (less than 16% total) have not yet been identified. Estimates of the mass of these mutagens in the original cooked beef were made from the mass spectral analysis and the mutagenic recoveries. From one kilogram of cooked ground beef, 1.0 micrograms MeIQx, 0.02 micrograms of IQ, and up to 1.5 micrograms of additional mutagens are formed.

Ability of lactic acid bacteria isolated from Japanese fermented plant products to bind heterocyclic amines.

“…Our normal daily life is exposed to various mutagens produced in meat or fish cooked at high temperatures. [1][2][3][4][5] These mutagens are reported to be carcinogenic. [6][7][8][9] However, the damage to human health is less than might be predicted from the presence of these mutagens, suggesting the existence of antimutagens in the daily food too.…”

“…[1][2][3][4][5] Heterocyclic amines are well-known mutagenic compounds (carcinogens), [6][7][8][9][10][11][12] and we are exposed to such risky compounds every day. The effects of various antimutagenic materials, including chlorophyllin, 13) dietary fiber, 14,15) and bacterial cells, [16][17][18][19][20][21] have been reported to help us from the risk of such food-borne mutagens.…”

Human exposure to heterocyclic amine food mutagens/carcinogens: Relevance to breast cancer

“…Additional major mutagens were 4,8-DiMeIQx (0.5 g/kg) and PhIP (15 g/kg). Several other mutagens were present, including IQ (0.02 g/kg), MeIQ (at Ͻ0.01 g/kg), and TMIP (0.5 g/kg) [Felton et al, 1984]. More recently, analytical methods were further improved with the development of GC/MS techniques and solid-phase extraction with HPLC analysis [Gross and Grüter, 1992;Knize et al, 1992].…”

Analysis of Mutagens from Cooked Foods by Directly Combined Liquid Chromatography-Mass Spectrometry

“…Nishimura has recently reviewed the methods used for analysis of mutagens in cooked foods (2). Mass spectometry, often used in conjunction with off-line chromatography (3)(4)(5)(6) or directly combined with gas chromatography (2), has been of particular importance because of its relatively high sensitivity, and its selectivity toward some structural features, such as mo-*Department of Medicinal Chemistry, University of Utah, Salt Lake City, Ut 84112. tBiology Division, National Cancer Center Research Institute, Tsukiji 5-1-1, Chuo-ku, Tokyo 104, Japan.…”