Heterocyclic CompoundsAza CompoundsHeterocyclic Compounds, Bridged-RingNitrogen CompoundsCyclizationHeterocyclic Compounds, 2-RingIndolesPalladiumMolecular StructureHeterocyclic Compounds with 4 or More RingsHeterocyclic Compounds, 3-RingMagnetic Resonance SpectroscopyHeterocyclic Compounds, 1-RingIndole AlkaloidsAzathioprineAzacitidineSecologanin Tryptamine AlkaloidsSulfur CompoundsStructure-Activity RelationshipVolatile Organic CompoundsTryptophanCarbolinesSpiro CompoundsCatharanthusStereoisomerismPlant ExtractsSkatoleSmall Molecule LibrariesDrug Evaluation, PreclinicalInhibitory Concentration 50TryptophanasePhenolsChromatography, High Pressure LiquidDose-Response Relationship, Drug