2-Oxo-LSD

2-Oxo-LSD is formed directly from LSD in the body and is also possibly an intermediate in the generation of LSD's major metabolite 2-oxo-3-hydroxy-LSD (O-H-LSD), which is present in urine at concentrations 4 to 40 times those of LSD in humans.^{[7][3][8][9][10]} However, O-H-LSD may also form from other metabolites, such as 3-hydroxy-LSD.^[3][10][7] The specific enzymes responsible for the generation of individual LSD metabolites like 2-oxo-LSD are largely unknown.^[8][9][3][6] However, several cytochrome P450 enzymes were investigated and implicated in the formation of O-H-LSD in 2019.^[11]

2-Oxo-LSD showed absence of various pharmacological effects in animals.^[12][13] In contrast to LSD and certain other metabolites like 13-hydroxy-LSD, 2-oxo-LSD failed to produce LSD-like electroencephalogram (EEG) changes in rabbits.^[5] 2-Oxo-LSD at a dose of 300 μg orally produced no psychoactive effects in a human subject who had previously responded to 30 μg LSD.^{[4][12][14][13]} It was concluded that 2-oxo-LSD shows no LSD-like activity in the central nervous system and hence is inactive.^{[13][12][2][15]} 2-Oxo-LSD's derivative O-H-LSD showed profound loss of activity at the serotonin 5-HT₂ receptors compared to LSD in vitro.^[11] 2-Oxo-LSD is said to readily enter the brain.^[15]

2-Oxo-LSD contains most of the clinically used dopamine D₂-like receptor agonist and antiparkinsonian agent ropinirole within its chemical structure.^[16]

2-Oxo-LSD was first described in the scientific literature by Julius Axelrod and colleagues in 1957.^{[1][13][17][18]}

• Substituted lysergamide
• 2-Oxo-3-hydroxy-LSD
• 2,3-Dihydro-LSD
• Nor-LSD
• Lysergic acid ethyl-2-hydroxyethylamide (LEO)
• Lysergic acid ethylamide (LAE)
• 13-Hydroxy-LSD
• 14-Hydroxy-LSD
• 2-Bromo-LSD
• 2-Iodo-LSD