A substituted tetrahydroisoquinoline is a tetrahydroisoquinoline with one or more chemical substituents. [1] [2] Many simple tetrahydroisoquinoline alkaloids related to mescaline are known and occur naturally in cactus species such as peyote (Lophophora williamsii) and Pachycereus pringlei among many others. [1] [2] [3] [4] Simple tetrahydroisoquinolines may be thought of as cyclized phenethylamines. [1] [2] As an example, anhalinine may be thought of as a cyclized analogue of mescaline. [1] [2] The simple tetrahydroisoquinolines are analogous in concept to the β-carbolines and harmala alkaloids, which can be considered cyclized analogues of tryptamines. [5]
Some of the simple tetrahydroisoquinolines, for instance pellotine, are known to be pharmacologically active, although none are known to have hallucinogenic activity. [1] [2] [4] Known activities of simple tetrahydroisoquinolines include sedative and hypnotic effects, monoamine oxidase inhibition, and convulsant effects, among various others. [4] [2] In the 2020s, various simple tetrahydroisoquinolines, like pellotine, were identified as serotonin 5-HT1D receptor ligands, serotonin 5-HT6 receptor partial agonists, and/or serotonin 5-HT7 receptor inverse agonists. [6] [7] These actions, such as the serotonin 5-HT6 and/or 5-HT7 receptor interactions, may be involved in the sedative and hypnotic effects of some of these compounds. [6] [7]
Synthetic tetrahydroisoquinoline analogues of phenethylamines, including AMPH-CR, METH-CR, PMMA-CR, DOM-CR, N-methyl-DOM-CR, DOB-CR, TDIQ (MDA-CR), and MDMTHIQ (MDMA-CR), have been developed and characterized. [8] [9] [10] [11] [12] In general, cyclization of stimulant, entactogen, and/or psychedelic phenethylamines into the corresponding tetrahydroisoquinolines results in abolition of the defining effects of these drugs as well as loss of their affinities for monoamine transporters and serotonin 5-HT2 receptors. [8] [9] [10] [11] [12] However, some of the tetrahydroisoquinoline forms, such as TDIQ, show selective affinity for α2-adrenergic receptors and associated effects. [12] [10]
| Structure | Name | Chemical Name | PEA Counterpart [a] |
|---|---|---|---|
| | Tetrahydroisoquinoline (THIQ) | 1,2,3,4-Tetrahydroisoquinoline | β-Phenethylamine |
| | Longimammosine | 2-Methyl-6-hydroxy-THIQ | meta-Tyramine |
| | Longimammidine | 2-Methyl-8-hydroxy-THIQ | meta-Tyramine |
| | Longimammatine | 6-Methoxy-THIQ | 3-Methoxyphenethylamine |
| | Weberidine | 7-Methoxy-THIQ | 4-Methoxyphenethylamine |
| | Norsalsolinol | 6,7-Dihydroxy-THIQ | Dopamine |
| | Longimammamine | 2-Methyl-4,8-dihydroxy-THIQ | meta-Octopamine |
| | Salsolinol | 1-Methyl-6,7-dihydroxy-THIQ | Dopamine |
| | Salsoline | 1-Methyl-6-hydroxy-7-methoxy-THIQ | 3-Hydroxy-4-methoxyphenethylamine |
| | Isosalsoline | 1-Methyl-6-methoxy-7-hydroxy-THIQ | 3-Methoxytyramine |
| | N-Methylisosalsoline | 1,2-Dimethyl-6-methoxy-7-hydroxy-THIQ | 3-Methoxytyramine |
| | Arizonine | 1-Methyl-7-methoxy-8-hydroxy-THIQ | 3-Hydroxy-4-methoxyphenethylamine |
| | Corypalline | 2-Methyl-6-methoxy-7-hydroxy-THIQ | 3-Methoxytyramine |
| | Isocorypalline | 2-Methyl-6-hydroxy-7-methoxy-THIQ | 3-Hydroxy-4-methoxyphenethylamine |
| | Uberine | 2-Methyl-5-methoxy-7-hydroxy-THIQ | 2-Methoxy-4-hydroxyphenethylamine |
| | Hedycarine | 1-(Hydroxymethyl)-2-methyl-6-methoxy-7-hydroxy-THIQ | 3-Methoxytyramine |
| | Lophocerine | 1-(2-Methylpropyl)-2-methyl-6-methoxy-7-hydroxy-THIQ | 3-Methoxytyramine |
| | Heliamine | 6,7-Dimethoxy-THIQ | 3,4-Dimethoxyphenethylamine |
| | Salsolidine | 1-Methyl-6,7-dimethoxy-THIQ | 3,4-Dimethoxyphenethylamine |
| | N-Methylheliamine | 2-Methyl-6,7-dimethoxy-THIQ | 3,4-Dimethoxyphenethylamine |
| | Lemaireocereine | 7,8-Dimethoxy-THIQ | 3,4-Dimethoxyphenethylamine |
| | Carnegine | 1,2-Dimethyl-6,7-dimethoxy-THIQ | 3,4-Dimethoxyphenethylamine |
| | Tepenine | 1,2-Dimethyl-7,8-dimethoxy-THIQ | 3,4-Dimethoxyphenethylamine |
| | Calycotomine | 1-(Hydroxymethyl)-6,7-dimethoxy-THIQ | 3,4-Dimethoxyphenethylamine |
| | Anhalamine | 6,7-Dimethoxy-8-hydroxy-THIQ | 3-Desmethylmescaline |
| | Isoanhalamine | 6-Hydroxy-7,8-dimethoxy-THIQ | 3-Desmethylmescaline |
| | Anhalidine | 2-Methyl-6,7-dimethoxy-8-hydroxy-THIQ | 3-Desmethylmescaline |
| | Isoanhalidine | 2-Methyl-6-hydroxy-7,8-dimethoxy-THIQ | 3-Desmethylmescaline |
| | Anhalonidine | 1-Methyl-6,7-dimethoxy-8-hydroxy-THIQ | 3-Desmethylmescaline |
| | Isoanhalonidine | 1-Methyl-6-hydroxy-7,8-dimethoxy-THIQ | 3-Desmethylmescaline |
| | Pellotine | 1,2-Dimethyl-6,7-dimethoxy-8-hydroxy-THIQ | 3-Desmethylmescaline |
| | Peyotine | 1,2,2-Trimethyl-6,7-dimethoxy-8-hydroxy-THIQ | 3-Desmethylmescaline |
| | Isopellotine | 1,2-Dimethyl-6-hydroxy-7,8-dimethoxy-THIQ | 3-Desmethylmescaline |
| | Gigantine | 1,2-Dimethyl-5-hydroxy-6,7-dimethoxy-THIQ | 2-Hydroxy-3,4-dimethoxyphenethylamine |
| | Deglucopterocereine | 1-(Hydroxymethyl)-2-methyl-5-hydroxy-6,7-dimethoxy-THIQ | 2-Hydroxy-3,4-dimethoxyphenethylamine |
| | Anhalinine | 6,7,8-Trimethoxy-THIQ | Mescaline |
| | N-Methylanhalinine | 2-Methyl-6,7,8-trimethoxy-THIQ | Mescaline |
| | O-Methylanhalonidine | 1-Methyl-6,7,8-trimethoxy-THIQ | Mescaline |
| | O-Methylpellotine | 1,2-Dimethyl-6,7,8-trimethoxy-THIQ | Mescaline |
| | Nortehaunine | 5,6,7-Trimethoxy-THIQ | Isomescaline |
| | Tehaunine | 2-Methyl-5,6,7-trimethoxy-THIQ | Isomescaline |
| | Hydrocotarnine | 2-Methyl-6,7-methylenedioxy-8-methoxy-THIQ | Lophophine |
| | Anhalonine | 1-Methyl-6-methoxy-7,8-methylenedioxy-THIQ | Lophophine |
| | Anhalotine | 2,2-Dimethyl-6,7-dimethoxy-8-hydroxy-THIQ | 3-Desmethylmescaline |
| | Lophophorine | 1,2-Dimethyl-6-methoxy-7,8-methylenedioxy-THIQ | Lophophine |
| | Lophotine | 1,2,2-Trimethyl-6-Methoxy-7,8-methylenedioxy-THIQ | Lophophine |
| | Peyophorine | 1-Methyl-2-ethyl-6-methoxy-7,8-methylenedioxy-THIQ | Lophophine |
| | Norweberine | 5,6,7,8-Tetramethoxy-THIQ | 2,3,4,5-Tetramethoxyphenethylamine |
| | Weberine | 2-Methyl-5,6,7,8-tetramethoxy-THIQ | 2,3,4,5-Tetramethoxyphenethylamine |
| | Pachycereine | 1-Methyl-5,6,7,8-tetramethoxy-THIQ | 2,3,4,5-Tetramethoxyphenethylamine |
| | Tehaunine N-oxide | 2-Methyl-2-oxo-5,6,7-trimethoxy-THIQ | Isomescaline |
| Structure | Name | Chemical Name | AMPH Counterpart |
|---|---|---|---|
| | Tetrahydroisoquinoline (THIQ; AMPH-CR) [10] | 1,2,3,4-Tetrahydroisoquinoline | Amphetamine |
| | N-Methyl-THIQ (METH-CR) [10] | 2-Methyl-THIQ | Methamphetamine |
| | PMMA-CR [10] | 2-Methyl-7-methoxy-THIQ | para-Methoxymethamphetamine (PMMA) |
| | DOM-CR [10] | 5,8-Dimethoxy-7-methyl-THIQ | 2,5-Dimethoxy-4-methylamphetamine (DOM) |
| | DOB-CR [10] | 5,8-Dimethoxy-7-bromo-THIQ | 2,5-Dimethoxy-4-bromoamphetamine (DOB) |
| | N-Methyl-DOM-CR [10] | 2,7-Dimethyl-5,8-dimethoxy-THIQ | Beatrice (N-methyl-DOM) |
| | TDIQ (MDTHIQ, MDA-CR) [10] | 6,7-Methylenedioxy-THIQ | 3,4-Methylenedioxyamphetamine (MDA) |
| | Hydrohydrastinine (MDMTHIQ, MDMA-CR) | 2-Methyl-6,7-methylenedioxy-THIQ | 3,4-Methylenedioxymethamphetamine (MDMA) |
| | Hydrastinine | 1-Hydroxy-2-methyl-6,7-methylenedioxy-THIQ | 3,4-Methylenedioxymethamphetamine (MDMA) |
TABLE 1: SIMPLE ISOQUINOLINE ALKALOIDS [...] TABLE II SIMPLE ISOQUINOLINE ALKALOIDS IN THE FAMILY OF CACTACEAE [...]
Nonetheless, it appears that conformational restriction of phenylalkylamine hallucinogens, stimulants, and designer drugs into a tetrahydroisoquinoline structure usually abolishes their respective actions (Malmusi et al., 1996b; Young et al., 1999a,b). [...] Table 6 Summary of stimulus generalization results of agents used in the present investigation [...]