Figure 2.

Comparison of the metabolization of the selected intermediates of the kynurenine, serotonin, and the indole pathway in malignant melanoma and in healthy control group. KP—kynurenine pathway, SP—serotonin pathway, IPP—indole pyruvate pathway; L-Trp—L-tryptophan, Kyn—kynurenine—intermediate in NAD⁺ biosynthesis but also neurotoxic intermediates 3-HK and QUIN, 3-HK—3-hydroxykynurenine, 3-HAA—3-hydroxyanthranilic acid, QUIN—quinolinic acid, NAD⁺—nicotinamide adenine dinucleotide, KYNA—kynurenic acid—product of KP branch, neuroprotective compound, AA—anthranilic acid, XA—xanthurenic acid, PIC—picolinic acid, 5-HT—serotonin, 5-HIAA—5-hydroxyindole-3-acetic acid—final product of SP, DHICA—5,6-dihydroxyindole-2-carboxylic acid—intermediate in melanin biosynthesis, IS—indoxyl sulfate—product of microbial degradation, uremic toxin, cardiotoxin.