Figure 5: NAD+ synthesis from quinolinic acid and via the salvage pathway. Adapted from Figure 1 in ref [6] (A. A.-B. Badawy. Kynurenine pathway of tryptophan metabolism: regulatory and functional aspects. Int J Tryptophan Res. 10, 1-20, 2017 doi: 10.1177/1178646917691938.