Table 2.
Chromogenic reaction of selected amino acids with neurotoxic (1,2-DAB) and non-neurotoxic (1,3-DAB) isomers of diacetylbenzene. Values represent mean absorbance ± standard deviation of the purple/blue color read at 540 nm on a scanning spectrophotometer. In triplicate, 0.5 ml aliquots of amino acid solution (0.1M phosphate buffer, pH 7.4) were incubated with 0.5 ml of 1,2-DAB or 1,3-DAB (1 mM) at 37°C for 30 or 60 minutes. L-Lysine, glycine and γ-aminobutyric acid and ornithine, a non-protein amino acid and higher homologue of L-lysine, were the most reactive of 22 tested amino acids. L-Cysteine was among the least reactive of the amino acids tested. Modified from Kim et al.48
| Diketone | 1,2-Diacetylbenzene (1,2-DAB) | 1,3-DAB | |
|---|---|---|---|
| Amino Acid | 30 min | 60 min | 60 min |
| L-Lysine | 3.22 ± 0.02 | 3.51 ± 0.02 | 0.00 |
| Ornithine | 2.80 + 0.01 | 3.56 ± 0.01 | 0.00 |
| Glycine | 2.21 + 0.02 | 3.32 + 0.04 | 0.00 |
| GABA | 1.93 + 0.03 | 3.02 + 0.02 | 0.00 |
| L-Cysteine | 0.00 | 0.02 | 0.00 |