^abcdefShulgin A,Shulgin A (September 1997).TiHKAL: The Continuation.Berkeley, California:Transform Press.ISBN0-9630096-9-9.OCLC38503252. "How can something that is not orally active be orally active? A possible explanation is the presence of another indole with a one-carbon shorter chain. This is gramine, or 3-(N,N-dimethylaminomethyl)indole which is synthesized in the plant with an entirely different set of enzymes. Its human pharmacology is not known. A related homologue, one carbon longer, is the three-carbon chain compound 3-[3-(dimethylamino)propyl]indole, produced by the Upjohn Company. It has been studied clinically under the code name U-6056, at levels of up to 70 milligrams in 10 subjects, by i.m. injection. There were no reports of visual, auditory or tactile disturbances. Physically, there was a slight increase in blood pressure anad pulse rate. Certainly there were no psychological effects."
^abcShulgin AT (1976)."Psychotomimetic Agents". In Gordon M (ed.).Psychopharmacological Agents: Use, Misuse and Abuse. Medicinal Chemistry: A Series of Monographs. Vol. 4. Academic Press. pp. 59–146.doi:10.1016/b978-0-12-290559-9.50011-9.ISBN978-0-12-290559-9.Turner and Merlis (1959) have found only vague restlessness at [DMT] levels of 25 mg im and give the lowest effective dose in man as 50 mg. Orally, even 350 mg was without effect. [...] One additional homologous system has been evaluated in man. This is the three-carbon chain homolog (XXVI) of N,N-dimethyltryptamine. This compound, intramuscularly administered to normal subjects at levels of up to 80 mg, gave no central stimulation (Turner and Merlis, 1959).
^abShulgin AT (1980)."Hallucinogens". In Burger A, Wolf ME (eds.).Burger's Medicinal Chemistry. Vol. 3 (4 ed.). New York: Wiley. pp. 1109–1137.ISBN978-0-471-01572-7.OCLC219960627.The lengthening of the side chain of DMT to three carbon atoms results in 60.32, which was without central effects following parenteral administration of 80 mg (33).
^abcdNichols DE, Glennon RA (1984)."Medicinal Chemistry and Structure-Activity Relationships of Hallucinogens". In Jacobs BL (ed.).Hallucinogens: Neurochemical, Behavioral, and Clinical Perspectives. New York: Raven Press. pp. 95–142.ISBN978-0-89004-990-7.OCLC10324237.Lengthening of the side chain of DMT by a single methylene group produces N,N-dimethylhomotryptamine (DMHT; 76, R = H, n = 3). which produced hyperthermia when administered to rabbits (7,232) but was found to be inactive in man (235). Intravenous administration of 5 and 10 mg and intramuscular injection of 20 to 70 mg DMHT was without psychologic effect in 10 human subjects (235). Additional studies on DMHT homologs (i.e., 76, n = 4–10) did not show any interesting activity (7,232).
^abGlennon RA, Gessner PK (April 1979). "Serotonin receptor binding affinities of tryptamine analogues".Journal of Medicinal Chemistry.22 (4):428–432.doi:10.1021/jm00190a014.PMID430481.Comparing DMT with compounds 18 and 16, it appears that extending the side chain by one methylene unit or replacing the indole nitrogen by a sulfur atom has no effect on affinity. [...] As revealed in Table I, increasing the chain length of DMT (1) by one methylene unit to DMHT (18) has no effect on affinity. Perhaps by varying the conformation of the propylamine side chain, the terminal amine function of DMHT (18) can approximate that distance from the indole ring which is usually achieved by the terminal amine of DMT (1).
^Glennon RA, Peroutka SJ, Dukat M (1991). "Binding Characteristics of a Quaternary Amine Analog of Serotonin: 5-HTQ".Serotonin: Molecular Biology, Receptors and Functional Effects. Basel: Birkhäuser Basel. pp. 186–191.doi:10.1007/978-3-0348-7259-1_17.ISBN978-3-0348-7261-4. Retrieved11 November 2025.Because the possibility exists that 5-HT3 receptors may accommodate ligands with a greater ring-to-amine distance than that found in 5-HT, we examined two "extended" tryptamine analogs, or tryptamine analogs where an additional methylene group has been inserted in the alkyl side chain: homotryptamine [i.e., 3-(3-amino-n-propyl)indole] and N,N-dimethylhomotryptamine. Homotryptamine binds at 5-HT3 receptors with low affinity (Ki > 2,000 nM). N,N-Dimethylhomotryptamine also binds with low affinity (Ki = 730 nM) but reveals that the two terminal amine methyl groups contribute to binding. Additional studies with these types of agents are in progress.
^Schmitz WD, Denhart DJ, Brenner AB, Ditta JL, Mattson RJ, Mattson GK, et al. (March 2005). "Homotryptamines as potent and selective serotonin reuptake inhibitors (SSRIs)".Bioorganic & Medicinal Chemistry Letters.15 (6):1619–1621.doi:10.1016/j.bmcl.2005.01.059.PMID15745809.Table 1. SERT binding affinitiesa of homotryptamines [...] Compound: 2B [...]
^Glennon RA, Rosecrans JA (1982). "Indolealkylamine and phenalkylamine hallucinogens: a brief overview".Neuroscience and Biobehavioral Reviews.6 (4):489–497.doi:10.1016/0149-7634(82)90030-6.PMID6757811.Animal data are also available on a number of other related compounds such as 4,5,6-trimethoxy and 5,6,7-trimethoxy DMT, 5-OMe-6-OH DMT and dimethylhomotryptamine [52, 70, 71, 74], but human data are unavailable.
^Trubitsyna TK, Mashkovskiĭ MD (1970). "[Pharmacological properties of some tryptamine homologues]" [Pharmacological properties of some tryptamine homologues].Farmakologiia I Toksikologiia (in Russian).33 (4):387–392.PMID5525947.
^abFedorova VS, Orlova IA, Trubitsyna TK (1970). "The synthesis and pharmacological properties of tryptamine homologs".Khimiko-Farmatsevticheskii Zhurnal.4:10–14.
