Sugar-amine fluorescence, reaction

Polyamide microcrystalline powders form measurable polymer-bound fluorescent reaction products with malonaldehyde from oxidizing lipids and with reducing sugars. The compounds form on the terminal amine groups which appear to exist in zwitterionic fields with carboxylate anions, as revealed by titration with acid, alkali, or benzoquinones. 

The reaction of amino acids with sugars to form Schiff s base-type compounds has been often suggested to be a feasible process in the formation of coloured condensed material in seawater, particular in the presence of clay minerals (Hedges, 1978). It is also worthy to note that natural free sugars and amino acids when heated in seawater form fluorescent compounds whose excitation and emission maxima correspond with those formed on reaction of amines with aldehydes (Honda et al., 1974). These experiments were performed at high temperatures (G. Liebezeit, R. Dawson and K. Mopper, unpublished results) and there is some suggestion that the apparent disappearance of amino acids on standing in seawater at room temperature, may be connected in part to this abiotic process. 

The compound class reaction for total DFAA actually measures primary amine content and thus includes contributions of, e.g., amino sugars, oUgopeptides and ammonia to varying extents. The method is based on the reaction of primary amines with o-phthalaldehyde-mer-captoethanol (Roth, 1971) yielding highly fluorescent isoindole derivatives (Fig. 26-1). 

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