5-Hydroxymethyl-2-furaldehyde (HMF), is a major product of sugar degradation found in food and solutions used in parenteral nutrition. Labeled [14C]HMF was synthesized by dehydration of [14C]fructose on ion-exchange resin and administered per os (po) and intravenously (iv) to rats. Metabolic balance of radioactivity demonstrated that HMF or its metabolites are rapidly eliminated in the urine with a recovery of 95-100% after 24 h. Literature reported, in some cases, 50% retention in the body. HMF was completely converted to two metabolites, which have been identified by nuclear magnetic resonance (NMR) and mass spectroscopy (MS) as 5-hydroxymethyl-2-furoic acid and N-(5-hydroxymethyl-2-furoyl)glycine. Administration of high doses of HMF showed a similar rapid elimination, but a proportional reduction of the amount of the glycine conjugate produced. Whole-animal-body autoradiography confirm that shortly after administration radioactive material was present in the liver but was mostly in the kidney and the bladder. The only significant difference between po and iv administration was the presence of a higher level of radioactive material in the brain of iv-treated rats.

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A simple and efficient method for the purification of mutagenic heterocyclic amines from heated meat products has been developed. In only two steps, namely extraction of raw material on Kieselgur followed by medium pressure liquid chromatography on Sephasorb HP, very clean fractions with high recovery rates of mutagenic compounds were obtained, thus allowing isolation and quantitation by high performance liquid chromatography (HPLC) with UV detection. The method was validated on both food grade and bacterial beef extracts as well as fried beef. In 1-5 g samples of beef extracts, levels up to 70 p.p.b. (ng/g) of 2-amino-3-methyl-imidazo[4,5-f]quinoline (IQ), 8-90 p.p.b. of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and up to 8 p.p.b. of 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx) were determined. In fried beef, 1 p.p.b. of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 1 p.p.b. of MeIQx were measured. The quantitative results of beef samples were in agreement with results from determinations using immunoaffinity chromatography/HPLC or liquid chromatography coupled with mass spectrometry. MeIQx could be quantified in fried beef down to 1 ng/g of fresh beef material. According to assays performed with reference standards of tryptophan and glutamic acid pyrolysis products, the method could also be extended to quantitate other heterocyclic amines.

(and ethylene) no other phototransformation of 14a takes place. With a half-life of ca. 12 min at 19°C the photoproduct 15a is thermally isomerized back to the diene diester 14a. Via a regiospecific addition of HCI, methanol and water to the tetracycles 15a and 15b (H2O) the epimeric products 18, 19 are isolated in a ratio of ca. 9: 1. Their structure is elucidated by oxidation of 18c to 21 and 'H-n.m.r. spectroscopic comparison with the isomeric compounds 20 and 22, resp., synthesized by a different route.Towards bishomodienophilic reagents like tetracyanoethylene and dimethyl acetylenedicarboxylate 15a shows the expected reactivity. The addition proceeds at the nonsubstituted edge of t h e bishomocyclobutadiene unit yielding 24 and 26.Bereits die ersten photochemischen Untersuchungen im Cyclohexa-1 ,CdienSystem 2 und den sich davon ableitenden 1,4-uberbruckten Homodienen 5 und 8 lieBen eine auffallende Divergenz im Reaktionsergebnis erkennen. In Derivaten des fast planaren Diens 2 konnte keine intramolekulare [2x + 2x1-Cycloaddition zu 1 erreicht werden; stattdessen lauft in der Regel eine Isomerisierung zu 3 ab2). Dem-