Substituted β-carboline

A substituted β-carboline is a chemical compound featuring a β-carboline moiety with one or more substitutions. β-Carbolines include more than one hundred alkaloids and synthetic compounds. The effects of these substances depend on their respective substituent. Natural β-carbolines primarily influence brain functions but can also exhibit antioxidant effects. Synthetically designed β-carboline derivatives have recently been shown to have neuroprotective, cognitive enhancing and anti-cancer properties.

β-Carbolines are indole alkaloids featuring a fused pyridine and indole ring structure similar to tryptamine, forming a three-ringed system with variable saturation in the third ring. β-Carboline alkaloids naturally occur widely in prokaryotes, plants, animals, certain marine tunicates, and foods like coffee and smoked meats, and are also responsible for the fluorescence of scorpion cuticles under ultraviolet light. β-Carbolines occurring naturally in Peganum harmala (Syrian rue) are known as harmala alkaloids.

Some β-carbolines, like harmaline, are hallucinogenic. According to Alexander Shulgin, harmaline is the only β-carboline that has been extensively studied and well-established as a hallucinogen. β-Carbolines are known to act as monoamine oxidase inhibitors (MAOIs), among possessing other activities. They are an essential component of ayahuasca, by inhibiting the metabolism of the psychedelic dimethyltryptamine (DMT).