β-Carboline

9-Me-BC is a β-carboline — the same tryptophan-derived ring system found in cooked meat, coffee and tobacco smoke, and in human blood and brain. Most members of that family damage dopaminergic neurons, which is why they have been investigated as causes of Parkinson's disease; 9-Me-BC does the opposite in cell culture and in one rat study, raising tyrosine hydroxylase, inducing neurotrophic factors and restoring dopamine after a neurotoxin. Ten days of treatment also improved maze learning in rats and thickened dendrites in the dentate gyrus. No human has been studied at any dose.