Lehrstuhl für Lebensmittelchemie
Am Hubland, 97074 Würzburg
Research foci (and basic equipment-based research projects):
Four research areas are treated, i.e. (i) heterocyclic aromatic amines (HAA); (ii) benzodiazepine receptor (bzd-r) ligands; (iii) fumonisin mycotoxins; and (iv) tryptophan glycoconjugates.
(i) HAA: By means of LC-MS/MS qualitative and quantitative analysis of the occurrence of HAA in food and process flavours is performed to obtain reliable data for subsequent risk evaluation.
(ii) bzd-r ligands: The actual interest is focused on studies of flavones with anxiolytic potential.
(iii) fumonisins: This area comprises studies of the structure, biosynthesis, metabolism and mode of action of fumonisins and other mycotoxins in food and feed.
(iv) tryptophan glycoconjugates: LC-MS/MS is used to study the occurrence and importance of technologically produced alkaloids in food.
(i) HAA: Meat-containing products showed the highest HAA contents (0.1-5.3 ng/g PhIP and 0.1-5.2 ng/g MeIQx) in comparison to other food. In process flavours HAA ranged from 0.1 to 12 ng/g. Considering the dosage of these products in food this result excludes an additional risk for their use in food.
(ii) bzd-r ligands: A number of plant extracts was screened for affinity towards the bzd-r. The sage constituent hispidulin was found to be a very efficient ligand; animal experiments indicated an anticonvulsive potential.
(iii) mycotoxins: By means of HPLC-ESI-MS/MS sensitive and highly selective methods for the detection of fumonisins and hydrolyzed fumonisins in food were developed. Of importance are also reaction products, e.g. N-carboxymethyl-fumonisins, which are formed during food manufacturing processes.During our studies on the mode of action of fumonisins, we showed for the first time that hydrolyzed fumonisins HFBx are not only inhibitors of the ceramide synthase but also substrates of the enzyme being converted to N-acyl-fumonisins in-vitro and in-vivo. The toxicity of the N-acyl-metabolites was evaluated using HT29 cells and the “brine-shrimp”-bioassay. The new metabolites were more toxic than FB1 or HFB1 and did not induce apoptosis.
(iv) Model studies carried out with tryptophan/tryptamin and aldoses/pentoses revealed a number of novel condensation products. For the first time, tryptophan glycoconjugates were found as water-soluble ligands of the ah receptor.
Rewards and prizes:
Dr. Hans-Ulrich Humpf
1998: Peter B. Czedik-Eysenberg Award of the Gesellschaft Österreichischer Chemiker
2002: Stockmeyer Research Award 2002
Dr. Markus Herderich
2000: Kurt-Täufel-Award (Award for the young scientist))
The instrumentation comprises among others HRGC, dynamic headspace-HRGC, HRGC-SCD, HRGC-MS, SPE-HRGC-MS, HRGC-IRMS, HPLC, HPLC-DAD, HPLC-ELSD, as well as HPLC-MS/MS and HPLC-NMR. For configurational studies MDGC, MDGC-MS and CD spectroscopy are well established. Quantifications are performed routinely by HRGC-MS and HPLC-MS/MS using preferably isotope dilution analysis