L-Kynurenine ((S)-Kynurenine) is a key intermediate in the breakdown pathway of tryptophan. L-Kynurenine is a substrate of kynureninase, KMO, and KAT associated with the suppression of antitumor immune responses. It has been shown to inhibit allogeneic T-cell proliferation and to increase malignant U87 glioma cell invasion into a collagen matrix.

Cannflavin A, isolated from Cannabis sativa L., exhibits anti-cancer, neuroprotective, and anti-inflammatory activities by inhibiting Aβ1-42 aggregation and kynurenine-3-monooxygenase (KMO), as well as inducing apoptosis through caspase-3 cleavage [1] [2] [3] [4].

Quinolinic acid (QUIN) is an endogenous N-methyl-D-aspartate (NMDA) receptor agonist synthesized from L-tryptophan via the kynurenine pathway.