Whey proteins were modified by reaction with selected phenolic compounds (ferulic-, chlorogenic-, caffeic- and gallic acid) and related substances (quinic acid and p-quinone) as well as with extracts from coffee, tea, potato and pear at pH 9. The derivatives formed were characterized in terms of their physicochemical and digestion properties. The derivatization was accompanied by a reaction at the lysine and tryptophan side chains, whereby their content was decreased in comparison to that in the control whey proteins. Moreover, the solubility of the derivatives decreased over a broad pH range and the derivatization influenced the hydrophobe-hydrophile character of the whey proteins. The isoelectric points were shifted to lower pH values in the order of reactivity as follows: gallic acid > p-quinone > caffeic acid > chlorogenic acid. The other derivatives showed no or few changes compared to the control whey proteins. The formation of high molecular fractions was documented with SDS-PAGE. Especially the derivatives of chlorogenic-, caffeic-, gallic acid and p-quinone showed an increase in molecular weight of beta-lactoglobulin fraction from 18,300 to 20,000 Da. A dimer formation in molecular range 40,000 was also registered. MALDI-TOF-MS was applied to characterize the binding of the individual phenolic compounds or their oxidation products to the whey protein fractions, alpha-lactalbumin and beta-lactoglobulin. In vitro experiments showed that the digestion of the derivatized whey proteins with the enzymes of the gastrointestinal tract (trypsin, chymotrypsin, pepsin and pancreatin) was adversely effected. Similar results with regard to physicochemical characterization and digestion properties of the whey proteins treated with the applied extracts from plant beverages, fruit and vegetable were also documented. Coffee and tee were comparatively the most reactive extracts.

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Nine isolates of the fungus Ascochyta rabiei have been assayed for their ability to produce solanapyrone toxins. All isolates formed solanapyrone A, B and C which were secreted into the culture medium. Pronounced production of the toxins only occurred after onset of sporulation. The identification of the fungal products was achieved by cochromatography (TLC, HPLC), 1H‐NMR (solanapyrone A and B) and mass spectrometry (solanapyrone B). Work with A. rabiei isolate X showed that cultivation in chickpea seed extract medium in a surface culture provided best conditions for maximal toxin production. The accumulation of solanapyrones over the growth cycle was monitored. Germinating spores produced solanapyrones C and B whereas solanapyrone A was formed from the 6th day of the culture period on. Application of a mixture of solanapyrones A, B and C to leaflets of intact plants from an A. rabiei resistant cultivar (ILC 3279) and a susceptible cultivar (ILC 1929) led to characteristic changes in leaf morphology which had earlier been obsevad in susceptible plants following infection with spores of A. rabiei. Attempts to demonstrate the occurrence of toxins in the infected leaf were unsuccessful. Application of solanapyrones to solanapyrones to chickpea cell suspension cultures (derived from both cultivars) led to pronounced losses in viability and to plasmolysis of cells.

The pterocarpan phytoalexin conjugates medicarpin 3-O-glucoside-6'-O-malonate and maackiain 3-O-glucoside-6'-O-malonate were isolated from cell suspension cultures of chickpea (Cicer arietinum L.) cultivar ILC 3279 and structurally elucidated. Both pterocarpan conjugates are constitutive metabolites of the chickpea cell cultures. Upon application of an elicitor from yeast to the cell cultures a substantial increase in the level of the phytoalexin aglycones medicarpin and maackiain was observed although a delayed but significantly higher rise of the conjugates also occurred. The significance of the pterocarpan conjugates for phytoalexin production is discussed.