Isolation for 6-hydroxykynurenic acid from the tobacco leaf.
1. 6-Hydroxykynurenic acid (4,6-dihydroxyquinoline-2-carboxylic acid, 6-HKA) was isolated in crystalline form from both green and cured tobacco leaves. 2. A method for the determination of 6-HKA by paper chromatography and fluorimetry is described. 3. The content of 6-HKA in the flowers, stem and roots of the tobacco plant was much lower than that in the leaf. 4. The 6-HKA content increased throughout leaf development and senescence. 5. 6-HKA was detected in the leaves of plants representing 11 out of 27 families sampled. 6. 6-HKA was found to be devoid of antibacterial and antifungal activity, and was inactive in the Avena-coleoptile and cress-seed-germination tests. 7. The presence of 6-HKA is taken as evidence in plants of the tryptophan-catabolic pathway already known in mammals and micro-organisms.
D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D002854:Chromatography, Paper; D005470:Fluorometry; D007736:Kynurenic Acid / Q000032:analysis*; D010947:Plants, Toxic; D014026:Nicotiana / Q000032:analysis*; D014364:Tryptophan / Q000378:metabolism
D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D014364:Tryptophan; D007736:Kynurenic Acid