Isoergine

Pharmaceutical compound From Wikipedia, the free encyclopedia

Isoergine, also known as isolysergic acid amide (iso-LSA or iso-LA-819), isolysergamide, or erginine, is a serotonergic psychedelic of the ergoline and lysergamide families related to ergine (lysergic acid amide; LSA) and lysergic acid diethylamide (LSD).^[2]^[3]^[4]^[5]^[1] It is the epimer of ergine inverted at the 8 position.^[5]^[6]^[7]^[8] Along with ergine and other ergolines, isoergine occurs naturally in morning glories.^[2]^[3]^[4]^[5]^[1]^[8] It is thought to be primarily responsible for the hallucinogenic effects of morning glory seeds.^[3]^[1]^[2]^[4]^[6]^[9]

Other namesIsolysergic acid amide; D-Isolysergic acid amide; Erginine; Isolysergamide; (+)-Isolysergic acid amide; Iso-LA; Iso-LA-819; Iso-LSA; d-Isolysergamide; 6-Methyl-9,10-didehydroergoline-8α-carboxamide

Routes of
administrationOral^[1]

Drug classSerotonin receptor modulator; Serotonergic psychedelic; Hallucinogen

ATC code

None

Quick facts Clinical data, Other names ...

Isoergine
Clinical data


Other names	Isolysergic acid amide; D-Isolysergic acid amide; Erginine; Isolysergamide; (+)-Isolysergic acid amide; Iso-LA; Iso-LA-819; Iso-LSA; d-Isolysergamide; 6-Methyl-9,10-didehydroergoline-8α-carboxamide
Routes of administration	Oral^[1]
Drug class	Serotonin receptor modulator; Serotonergic psychedelic; Hallucinogen
ATC code	None
Identifiers
IUPAC name (6aR,9S)-7-methyl-6,6a,8,9-tetrahydro-4H-indolo[4,3-fg]quinoline-9-carboxamide
CAS Number	2889-26-1
PubChem CID	12309749
ChemSpider	32698654
UNII	90DGH6Y8E9
CompTox Dashboard (EPA)	DTXSID80183082
Chemical and physical data
Formula	C₁₆H₁₇N₃O
Molar mass	267.332 g·mol⁻¹
3D model (JSmol)	Interactive image
SMILES CN1C[C@H](C=C2[C@H]1CC3=CNC4=CC=CC2=C34)C(=O)N
InChI InChI=1S/C16H17N3O/c1-19-8-10(16(17)20)5-12-11-3-2-4-13-15(11)9(7-18-13)6-14(12)19/h2-5,7,10,14,18H,6,8H2,1H3,(H2,17,20)/t10-,14+/m0/s1 Key:GENAHGKEFJLNJB-IINYFYTJSA-N

Use and effects

Isoergine occurs naturally in morning glory species, including Ipomoea tricolor (tlitliltzin), Ipomoea corymbosa (ololiuhqui), and Argyreia nervosa (Hawaiian baby woodrose).^[3]^[4]^[6] It has been found to constitute 8 to 35% of total alkaloid content relative to 5 to 58% for ergine.^[4]^[6]

Albert Hofmann, the discoverer of LSD's psychedelic effects, tried 2 mg isoergine orally and experienced feelings of unreality, detachment from the outside world, feelings of mental emptiness, tiredness, and apathy, though no specific sensory distortions were mentioned.^[4]^[5]^[1]^[8]^[10] He described its effects as similar to those of ergine, which he had tested at doses of up to 2 mg.^[10] Subsequently Heim and colleagues assessed ergine at higher doses of 3 to 6 mg orally and observed toxic-like effects, while isoergine at 2 to 5 mg orally produced notable hallucinogenic effects.^[2]^[3]^[1]^[9] The psychedelic effects of isoergine observed in this study included some euphoria, synaesthesia, and altered time perception.^[3]^[1]^[9] However, although hallucinogenic, isoergine's effects have been described as not LSD-like.^[2]^[11] The presence of hallucinogenic effects of isoergine has been described as quite unusual for an isolysergamide derivative.^[11]

It is thought that ergine and isoergine together may account for most or all of the effects of morning glory seeds, with ergine producing intoxication, sedation, and autonomic side effects and isoergine producing hallucinogenic effects.^[3]^[1]^[2]^[4]^[6]^[9]^[12] Conversely, other notable constituents, including elymoclavine, lysergol, and chanoclavine, produced no psychoactive or hallucinogenic effects in humans.^[1]^[2]^[13]^[14]^[15]^[16]^[8]^[9] Ergometrine, which is a minor constituent representing up to 8% of total alkaloids, is known to produce psychedelic effects only in higher amounts (2–10 mg) than those in typical doses of morning glory seeds and hence is thought to not contribute to the effects of the seeds either.^[16]^[1]^[3]^[17]^[18]^[4] Moreover, ergometrine is present in Ipomoea tricolor and Argyreia nervosa but not in Ipomoea corymbosa.^[1]^[3] Isoergine being responsible for the hallucinogenic effects of morning glory seeds is also supported by animal studies.^[3]^[1]^[12]

According to Alexander Shulgin in his 1997 book TiHKAL (Tryptamines I Have Known and Loved) however, both ergine and isoergine are "probably correctly dismissed" as not contributing to the effects of morning glory seeds.^[5] The poorly-stable lysergic acid hydroxyethylamides (LSHs) might alternatively be involved in the psychedelic effects of morning glory seeds per Shulgin.^[7]

Interactions

The interactions of isoergine and of morning glory seeds have been discussed.^[3]

Pharmacology

Pharmacodynamics

Isoergine shows affinity for serotonin receptors labeled with serotonin or LSD in rat brain membranes.^[19]^[20]^[21] It has about 10- to 25-fold lower affinity for these receptors than serotonin or LSD and has the same affinity as ergine and iso-LSD (IC₅₀Tooltip half-maximal inhibitory concentration = 100–200 nM for isoergine, 200 nM for ergine and iso-LSD, and 8–10 nM for LSD).^[19]^[20]^[21] No other receptor interaction data are available for isoergine as of 2020.^[3] However, computer-predicted receptor affinities are available for ergine/isoergine (stereochemistry not taken into account).^[22] The drug is said to have about 4.3% of LSD's antiserotonergic potency in vitro.^[23]^[24] It is 5- to 33-fold less potent than LSD in producing behavioral changes in the conditioned avoidance test in rodents.^[3]^[4]^[25]^[12]

Pharmacokinetics

The pharmacokinetics of isoergine in rodents have been studied.^[3]^[12] Isoergine is much less lipophilic than LSD, with log P values of 0.95 and 2.95, respectively.^[21] This might influence its pharmacological properties, for instance reducing its blood–brain barrier permeability.^[21] However, isoergine showed a similar ratio of brain-to-plasma levels as LSD in rodents.^[12]

Chemistry

Derivatives

Derivatives of isoergine include isolysergic acid diethylamide (iso-LSD), isolysergic acid hydroxyethylamide (iso-LSH), and ergometrinine (isoergometrine; isolysergic acid propanolamide), among others.^[2]^[26]^[4]^[27] With the apparent exception of isoergine, isolysergamides, such as iso-LSD, have been found to be inactive as psychedelics in humans.^[28]^[29]^[30]^[31]^[32]^[11]

History

Isoergine was first identified by Sidney Smith and Geoffrey Timmis in 1936 via hydrolysis of ergot alkaloids.^[1]^[33] This followed the identification of ergine in the same way in 1932.^[1]^[34] Isoergine was first synthesized by Albert Hofmann and colleagues by 1949.^[1]^[35] Subsequently, it was isolated by Hofmann and colleagues in morning glory seeds in 1960.^[36]^[8]^[37] The psychoactive effects of isoergine were first described by Hofmann in 1963.^[4]^[1]^[8] Heim and colleagues more clearly substantiated the hallucinogenic effects of isoergine and its role in producing the psychedelic effects of morning glory seeds in 1968.^[3]^[1]^[9]

Society and culture

Legal status

Canada

Isoergine is not a controlled substance in Canada as of 2025.^[38]

United States

Ergine is not an explicitly controlled substance in the United States.^[39] However, it could be considered a controlled substance under the Federal Analogue Act if intended for human consumption.

References

[1]
Brimblecombe RW, Pinder RM (1975). "Indolealkylamines and Related Compounds". Hallucinogenic Agents. Bristol: Wright-Scientechnica. pp. 98–144. ISBN 978-0-85608-011-1. OCLC 2176880. OL 4850660M. d-Lysergic acid amide (ergine) is the major constituent of the seeds of both Rivea corymbosa and Ipomoea violacea, together with smaller amounts of d-isolysergic acid amide (isoergine), chanoclavine, elymoclavine, and the N-(1-hydroxyethyl)amides of lysergic and isolysergic acids. [...] Lysergol is found in Rivea but not in Ipomoea, while ergometrine (ergonovine) is present in the latter but not the former (Hofmann and Tscherter, 1960; Hofmann, 1961b, 1964; Hofmann and Cerletti, 1961; Greger, 1963). [...] The constituents of these convolvulaceous plants were not new even in 1960; the isomeric lysergic acid amides had previously been obtained as cleavage products by hydrolysis of the ergot alkaloids (Smith and Timmis, 1932, 1936), [...] the isomeric amides had also been synthesized in the laboratories of the Sandoz group (Stoll, Hofmann, and Schlientz, 1949). It is clear that the pharmacologically active constituents of ololiuqui are the isomeric lysergic acid amides. [...] Oral doses of 2 mg. of isolysergic acid amide are reported to produce a feeling of mental emptiness and total detachment from the outside world. Heim and his colleagues suggest that the overall effects of ololiuqui are due to these two compounds, the d-lysergic acid amide giving intoxication with strong autonomic side-effects and the d-isolysergic acid amide producing some euphoria, synaesthesia, and altered time experience. Certainly elymoclavine, lysergol, chanoclavine, and ergometrine produce no psychic changes in man (Isbell and Gorodetzky, 1966; Hofmann, 1968), though the first two do produce central excitation in animals (Yui and Takeo, 1958). Moreover, the time-course of absorption and distribution of d-isolysergic acid amide in rat brain exactly paralleled the course of behavioural aberrations produced by intraperitoneal doses of 5 mg./kg. (Vogel, Carapellotti, Evans, and Der Marderosian, 1972). [...] Five-hundred seeds of certain ornamental Ipomoea varieties contain as much as 1 mg. of ergometrine, which is usually considered to be an effective oxytocic in doses as low as 0·2-0·5 mg.
[2]
Fanchamps A (1978). "Some Compounds With Hallucinogenic Activity". In Berde B, Schild HO (eds.). Ergot Alkaloids and Related Compounds. Handbook of Experimental Pharmacology (HEP). Vol. 49. Berlin, Heidelberg: Springer Berlin Heidelberg. pp. 567–614. doi:10.1007/978-3-642-66775-6_8. ISBN 978-3-642-66777-0. Archived from the original on 30 March 2025. The second main component was d-isolysergic acid amide, or Iso-LA819 (No. 18a). After its identification in ololiuqui, trials were performed in man with oral doses up to 5 mg; they revealed central effects which were not LSD-like (ISBELL, 1962) but chiefly consisted in relaxation, synesthesias, and altered time experience (HEIMANN, 1965; HElM et al., 1968). [...] Table 2. Psychotomimetic activity and some pharmacodynamic effects of structural analogues of LSD [...]
[3]
Chen W, De Wit-Bos L (2020). Risk assessment of Argyreia nervosa (PDF) (Report). doi:10.21945/rivm-2019-0210. A. nervosa contains ergot alkaloids, with D-lysergic acid amide (LSA) or ergine and its epimer iso-LSA or isoergine as main active components (see Chapter 3). [...] Human volunteer studies [...] Heim, Heimann & Lukács (1968) conducted experiments with increasing doses of LSA (0.04 or 0.09 mg/kg bw [3–6 mg total]), iso-LSA (0.03, 0.06 or 0.07 mg/kg bw [2–5 mg total]), or total alkaloids from the drug Ololiuqui (Rivea corymbosa; 0.02, 0.06, 0.08 or 0.10 mg/kg bw) in healthy volunteers. [...] Ingestion of LSA led to nausea, vomiting, an illness-like state with general fatigue, sweating and dizziness, vision problems, slower movements and speech (a state of lethargy and apathy), beginning approximately 45 minutes after ingestion and becoming more pronounced over the next hours. [...] Based on these results, the authors suggest that the vegetative symptoms are probably caused by LSA while iso-LSA leads to impairment of the thinking ability and effects on a persons' conscious (Heim, Heimann & Lukács, 1968). [...] Heim, E., Heimann, H., & Lukács, G., Die psychische Wirkung der mexikanischen Droge „Ololiuqui" am Menschen. Psychopharmacologia, 1968. 13(1): p. 35-48. doi:10.1007/BF00401617
[4]
Shulgin 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. ISBN 978-0-12-290559-9. TABLE II RANGES OF ALKALOIDS FOUND IN SEVERAL PLANT PRODUCTSa [...] Only a few limited pharmacological studies have been made on the individual drugs. [...] Conditioned avoidance studies with isoergine in the rat (Vogel et al., 1972) support its role as a psychoactive agent. [...] Hofmann (1963a) has described the action of isoergine in man. Following the administration of 2.0 mg orally, there was a feeling of mental emptiness and unreality, but no indication of specific sensory distortion. [...] It appears that the agents that are responsible for the human activity of these plants are ergine and isoergine, and possibly the corresponding α-hydroxyethylamides of lysergic acid which could serve as metabolic precursors.
[5]
Shulgin A, Shulgin A (September 1997). TiHKAL: The Continuation. Berkeley, California: Transform Press. ISBN 0-9630096-9-9. OCLC 38503252. https://www.erowid.org/library/books_online/tihkal/tihkal26.shtml "LA-111, Ergine, d-Lysergamide. This is an active compound and has been established as a major component in morning glory seeds. It was assayed for human activity, by Albert Hofmann in self-trials back in 1947, well before this was known to be a natural compound. An i.m. administration of a 500 microgram dose led to a tired, dreamy state with an inability to maintain clear thoughts. [...] The epimer, inverted at C-8, is isoergine or d-isolysergamide, and is also a component of morning glory seeds. Hofmann tried a 2 milligram dose of this amide, and as with ergine, he experienced nothing but tiredness, apathy, and a feeling of emptiness. Both compounds are probably correctly dismissed as not being a contributor to the action of these seeds. It is important to note that ergine, as well as lysergic acid itself, is listed as a Schedule III drug in the Controlled Substances Act, as a depressant. This is, in all probability, a stratagem to control them as logical precursors to LSD. [...] Although there are many other chemical treasures in the ergot fungal world, I would like to wrap this commentary up with a return to the topic of morning glory seeds. Four additional alkaloids of the ergot world must be acknowledged as being potentially participating factors in the MGS story. [...] These structures in effect define absolute obscurity, and most probably do not contribute to the morning glory intoxication state. But the others, some present is sizable amounts, may someday help explain why the pharmacology of these seeds is so different than that of the major isolates, the ergines."
[6]
Shulgin AT (1980). "Hallucinogens". In Burger A, Wolf ME (eds.). Burger's Medicinal Chemistry. Vol. 3 (4 ed.). New York: Wiley. pp. 1109–1137. ISBN 978-0-471-01572-7. OCLC 219960627. The alkaloid composition of these seeds is a fraction of a percent of their dry weight, but is made up largely of lysergic acid amide (60.34o) and the epimer isoergine (60.35). [...] The structures of the D ring portion of these several ergot-like alkaloids are illustrated, and the relative composition of the various morning glory seeds are listed in Table 60.5 [...] Table 60.5 Modifications of LSD [...] Human studies on ergine (60.34o) (150-152) and isoergine (60.35) (150) would indicate that these two alkaloids may account for much of the effects of the total seed, either directly or via the hydroxyethylamide precursors.
[7]
Shulgin AT (1972). "Hallucinogens, CNS Stimulants, And Cannabis". In Mulé, SJ, Brill H (eds.). Chemical and Biological Aspects of Drug Dependence. CRC Press. pp. 163–176. doi:10.1201/9780429260629-16. ISBN 978-0-87819-011-9. The major alkaloids present were found to be ergine (d-Lysergic acid amide, Figure 2; R1, R2, R3 = H) and the enantiomorph isoergine (d-Isolysergic acid amide, identical with ergine, but with the opposite epimeric configuration on the carbon atom that carries the amide carbonyl group). These two compounds have been shown to have some activity in man, but it is possible that their presence in the natural seed as the extremely labile acetaldehyde condensates (the hydroxyethylamides) may explain the activity of the seed compared to the lack of activity of the ergot isolates.8 [...] 8. Hofmann, A., Teonanacatl and Ololiuqui, two ancient magic drugs of Mexico, Bull. Narc., 23, 3, 1971.
[8]
Hofmann A (1963). "The Active Principles of the Seeds of Rivea Corymbosa and Ipomoea Violacea". Botanical Museum Leaflets, Harvard University. 20 (6). Harvard University Herbaria: 194–212. doi:10.5962/p.168542. ISSN 0006-8098. JSTOR 41762231. [...] chanoclavine, which has no outstanding pharmacological activity, appears to play no part in the occurrence of the psychic effects of badoh and badoh negro.
[9]
Heim E, Heimann H, Lukács G (1968). "Die psychische Wirkung der mexikanischen Droge "Ololiuqui" am Menschen" [Psychotomimetic effects of the mexican drug “Ololiuqui”]. Psychopharmacologia (in German). 13 (1): 35–48. doi:10.1007/BF00401617. ISSN 0033-3158. PMID 5675457.
[10]
Albert Hofmann (1970). "The Discovery of LSD and Subsequent Investigations on Naturally Occurring Hallucinogens". In Ayd FJ, Blackwell B (eds.). Discoveries in Biological Psychiatry. J.B. Lippincott Company. pp. 96–106. ISBN 978-0-397-59044-5. Archived from the original on 30 March 2025. Furthermore, the following minor alkaloids were isolated: isolysergic acid amide and isolysergic acid 1-hydroxyethylamide, chanoclavine, elymoclavine and lysergol. [...] Lysergic acid amide, the main component of ololiuqui, had been tested pharmacologically and clinically under the experimental drug designation LA-111 during the course of our investigations on LSD and related compounds long before it was known to be a natural component of a magic Mexican drug. Self-experiment and comparative systematic clinical investigations with lysergic acid amide (laboratory code name: LA-111) revealed psychotomimetic effects significantly different from those of lysergic acid diethylamide (LSD-25). The symptoms after oral ingestion of 1 mg to 2 mg of LA-111 were: indifference, decrease of psychomotor activity, tiredness, feeling of sinking into nothingness, and desire to sleep. Isolysergic amide produces similar symptoms. After taking 2.0 mg of isolysergic amide orally, I experienced tiredness, apathy, a feeling of mental emptiness and of the unreality and complete meaninglessness of the outside world.[11] These comparative experiments showed that the psychotomimetic constituents of ololiuqui are 20 to 40 times less active than LSD and that the general picture of activity is characterized by a pronounced depressive and narcotic component.
[11]
Nichols DE, Oberlender R, McKenna DJ (1991). "Stereochemical Aspects of Hallucinogenesis". In Watson RR (ed.). Biochemistry and Physiology of Substance Abuse. Vol. 3. Boca Raton, Fla.: CRC Press. pp. 1–39. ISBN 978-0-8493-4463-3. OCLC 26748320. Hallucinogenic activity does seem to depend on alkylation of the amide nitrogen since the primary amide, d-lysergamide, is not hallucinogenic in man but produces sedation, clouding of consciousness, and sleep.160 This, and the 8α-derivative, d-isolysergamide, were tested in man after their isolation from the seeds of Ipomoea violacea. Seeds from this plant, a member of the morning-glory family, were used for divinatory purposes by the Aztecs in a preparation known as ololiuqui. In doses up to 5 mg, the isolysergamide produced nonLSD-like central effects, although later studies revealed types of effects quite unsusual for an iso-derivative such as "relaxation, synesthesias, and altered time experience".160
[12]
Vogel WH, Carapellotti RA, Evans BD, Der Marderosian A (1972). "Physiological disposition of isoergine (from Argyreia nervosa (Burm. f.) Bojer Convolvulaceae) and its effect on the conditioned avoidance response in rats". Psychopharmacologia. 24 (2): 238–242. doi:10.1007/BF00403643. PMID 5031055.
[13]
Isbell H, Gorodetzky CW (1966). "Effect of alkaloids of ololiuqui in man". Psychopharmacologia. 8 (5): 331–339. doi:10.1007/BF00453511. PMID 5923939. He also found that in addition to d-lysergic acid amide, d-iso-lysergic acid amide, and chanoclavine, the seeds of both plants contained elymoclavine. [...] Elymoclavine elicits excitation and central stimulation in animals (Yui 1958), but ISBELL found that elymoclavine caused chiefly sedative effects in former addicts. [...] The results also agree with the sedative effects reported after d-lysergic amide amide (HOFMAN 1963; ISBELL; SOLMS 1956), d-iso-lysergic acid amide (HOFMANN 1963), and elymoclavine (ISBELL). [...] ISBELL, H. : Unpublished observations.
[14]
Heacock RA (1975). "Psychotomimetics of the Convolvulaceae". Prog Med Chem. Progress in Medicinal Chemistry. 11: 91–118. doi:10.1016/s0079-6468(08)70209-1. ISBN 978-0-7204-7411-4. PMID 1078534. Archived from the original on 30 March 2025. No psychological effects have been reported for ergometrine (6), a drug widely used in obstetrics, nor for chanoclavine (3).
[15]
Hofmann A (January–March 1971). "Teonanácatl and Ololiuqui, two ancient magic drugs of Mexico". Bulletin on Narcotics. 23 (1): 3–14. Archived from the original on 28 March 2025. Furthermore, chanoclavine, which has no outstanding pharmacological activity, appears to play no part in the occurrence of the psychic effects of ololiuqui.
[16]
Albert Hofmann (1968). "Psychotomimetic Agents". In Burger A (ed.). Drugs Affecting the Central Nervous System. Vol. 2. New York: M. Dekker. pp. 169–235. OCLC 245452885. OL 13539506M. Furthermore, chanoclavine, which has no outstanding pharmacological activity, appears to play no part in the occurrence of the psychic effects of ololiuqui. [...] Psychotomimetic effects are unknown for ergometrine, which is used to a large extent in obstetrics as a uterotonic and hemostatic agent. In small dosages, which are administered for this purpose, the alkaloid apparently has no action on the psychic functions. Its occurrence in the alkaloid mixture of ololiuqui can thus have no significant effects on its mental action.
[17]
Bigwood J, Ott J, Thompson C, Neely P (1979). "Entheogenic effects of ergonovine". J Psychedelic Drugs. 11 (1–2): 147–149. doi:10.1080/02791072.1979.10472099. PMID 522166. Archived from the original on 28 March 2025. In 1977 and 1978 Hofmann reported that ergonovine maleate was entheogenic,1 a surprising finding in view of its widespread use in obstetrics (Wasson, Hofmann & Ruck 1978; Hofmann 1977). This report was based on a self-experiment conducted by Hofmann on 1 April 1976, with 2.0 mg of ergonovine maleate taken orally. Hofmann reported that this dose manifested a "slightly hallucinogenic activity" lasting more than five hours.2 [...] Our experiments corroborate Hofmann's report that ergonovine possesses entheogenic properties. We found the active dose to lie between 5.0 and 10.0 mg, peroral. It is interesting to note that Hofmann experienced distinct entheogenic effects at 2.0 mg, while Wasson and Ruck did not. Similarly, J.B. experienced distinct entheogenic effects at 3.0 mg, whereas J.O. and P.N. did not. This underscores the importance of metabolic individuality in the uptake and metabolism of mind-altering drugs. With respect to entheogenic effects 10 mg of ergonovine maleate is roughly equivalent to 50 μg is, ergonovine possesses about that LSD-tartrate, 1/200th the entheogenic potency of LSD.
[18]
Hofmann A (2008) [1978]. "[Chapter Two:] A Challenging Question and My Answer" (PDF). In Robert Forte (ed.). The Road to Eleusis: Unveiling the Secret of the Mysteries (Thirtieth Anniversary ed.). Berkeley, California: North Atlantic Books. pp. 35–44. ISBN 978-1-55643-752-6.
[19]
Bennett JP, Snyder SH (September 1975). "Stereospecific binding of D-lysergic acid diethylamide (LSD) to brain membranes: relationship to serotonin receptors". Brain Res. 94 (3): 523–544. doi:10.1016/0006-8993(75)90234-6. PMID 239784. TABLE IV DISPLACEMENT OF D-[3H]LSD) BY ANALOGUES AND DRUGS [...] (1) Lysergic acid derivatives [...] D-LSD: ED50 (nM): 9.5. [...] D-iso-LSD: ED50 (nM): 200. D-isolysergic acid amide: ED50 (nM): 200. D-lysergic acid amide: ED50 (nM): 200. [...] D-lysergic acid: ED50 (nM): 10,000. L-LSD: ED50 (nM): 20,000.
[20]
Bennett JP, Snyder SH (May 1976). "Serotonin and lysergic acid diethylamide binding in rat brain membranes: relationship to postsynaptic serotonin receptors". Mol Pharmacol. 12 (3): 373–389. doi:10.1016/S0026-895X(25)10753-0. PMID 6896. Substrate specificity of [3H]5-HT and [3H]LSD binding. In confirmation of earlier studies (3–6), d-LSD inhibits d-[3H]LSD binding with an value of about 6–10 nM, while the psychotropically inactive isomer l-LSD has about 1000 times less affinity for the LSD binding sites (Table 1). d-LSD has about the same d-Isolysergic acid amide and methysergide have similar affinities for both [3H]5-HT and d-[3H]LSD binding sites, about 1/10 that of d-LSD itself. [...] TABLE 1 Displacement of specifically bound [3H]serotonin and d-[3H]LSD from rat cerebral cortex membranes [...] LSD analogues [...] d-LSD: IC50: [3H]5-HT: 10 [nM]. d-[3H]LSD: 8 [nM]. [...] d-Isolysergic acid amide. IC50: [3H]5-HT: 100 [nM]. d-[3H]LSD: 200 [nM]. [...] l-LSD. IC50: [3H]5-HT: 100,000 [nM]. d-[3H]LSD: 20,000 [nM].
[21]
Gupta SP, Singh P, Bindal MC (1 December 1983). "QSAR studies on hallucinogens". Chemical Reviews. 83 (6): 633–649. doi:10.1021/cr00058a003. ISSN 0009-2665.
[22]
Paulke A, Kremer C, Wunder C, Achenbach J, Djahanschiri B, Elias A, et al. (July 2013). "Argyreia nervosa (Burm. f.): receptor profiling of lysergic acid amide and other potential psychedelic LSD-like compounds by computational and binding assay approaches" (PDF). J Ethnopharmacol. 148 (2): 492–497. doi:10.1016/j.jep.2013.04.044. PMID 23665164.
[23]
Oberlender RA (May 1989). "Stereoselective aspects of hallucinogenic drug action and drug discrimination studies of entactogens". Purdue e-Pubs. Purdue University. Table 2. Relative potency values for lysergic acid amides. [...]
[24]
Kumbar M, Sankar DV (July 1973). "Quantum chemical studies on drug actions. 3. Correlation of hallucinogenic and anti-serotonin activity of lysergic acid derivatives with quantum chemical data". Res Commun Chem Pathol Pharmacol. 6 (1): 65–100. PMID 4734018. Archived from the original on 29 March 2025.
[25]
Vogel WH, Evans BD (May 1977). "Structure-activity-relationships of certain hallucinogenic substances based on brain levels". Life Sci. 20 (10): 1629–1235. doi:10.1016/0024-3205(77)90335-6. PMID 69244.
[26]
Shulgin AT (1971), "Chemistry and Sources", in Epstein SS, Lederberg J (eds.), Drugs of Abuse: Their Genetic and Other Chronic Nonpsychiatric Hazards, Cambridge, Massachusetts: MIT Press, pp. 3–26, ISBN 9780262050098, OCLC 208409, OL 22156530M, Table 1. Chemical Classification of Drugs of Abuse [...]
[27]
Rutschmann J, Stadler PA (1978). "Chemical Background". Ergot Alkaloids and Related Compounds. Berlin, Heidelberg: Springer Berlin Heidelberg. pp. 29–85. doi:10.1007/978-3-642-66775-6_2. ISBN 978-3-642-66777-0.
[28]
Gumpper RH, Nichols DE (October 2024). "Chemistry/structural biology of psychedelic drugs and their receptor(s)". Br J Pharmacol bph.17361. doi:10.1111/bph.17361. PMID 39354889.
[29]
Nichols DE (2018). Chemistry and Structure-Activity Relationships of Psychedelics. Current Topics in Behavioral Neurosciences. Vol. 36. pp. 1–43. doi:10.1007/7854_2017_475. ISBN 978-3-662-55878-2. PMID 28401524. It is only ergolines with the 5R,8R stereochemistry, as illustrated earlier in Fig. 1 that have biological activity. That isomer is dextrorotatory, so LSD is referred to as (+)-LSD or d-LSD. Receptor binding studies by Bennett and Snyder in 1976 first demonstrated that LSD had nanomolar affinity for [3 H]LSD-labeled binding sites in rat cortex (Bennett and Snyder 1976). By contrast, its 5S,8S enantiomer, (−)-LSD, had 2500-fold lower affinity. The 8-position epimerizes readily, particularly at acidic pH, to provide the 5R,8S epimer (+)-isolysergic acid diethylamide 22, which has about 30-fold lower receptor affinity and is inactive as a psychedelic.
[30]
Nichols DE (2012). "Structure–activity relationships of serotonin 5-HT2A agonists". Wiley Interdisciplinary Reviews: Membrane Transport and Signaling. 1 (5): 559–579. doi:10.1002/wmts.42. ISSN 2190-460X. FIGURE 11 | N, N-diethyllysergamide (LSD) and inactive epimeric iso-LSD. [...] Both carbons 5 and 8 are chiral, and it is only ergolines with the 5R,8R-configuration, as illustrated in Figure 1, which have biological activity. That isomer is dextrorotatory, so LSD is referred to as (+)-LSD or d-LSD. Early receptor binding studies by Bennett and Snyder25 demonstrated that (+)-LSD had nanomolar affinity for [3H]LSD-labeled sites in rat cortex, whereas its enantiomer, 5S,8S-(−)-LSD, had 2500-fold lower affinity. The 8-position readily epimerizes to provide (+)-isolysergic acid diethylamide, which has about 30-fold lower affinity and is inactive as an hallucinogen. This transformation is facile and occurs under slightly acidic pH (Figure 11).
[31]
Pfaff RC, Huang X, Marona-Lewicka D, Oberlender R, Nichols DE (1994). "Lysergamides revisited". NIDA Research Monograph. 146: 52–73. PMID 8742794. The stereochemistry is critical for the lysergic acid molecule. The R stereochemistries at both the C(5) and C(8) positions are essential. Inversion of either stereocenter abolishes hallucinogenic activity (Brimblecombe and Pinder 1975). C(5) inversion gives l-lysergic acid derivatives, as compared with the natural d-lysergic acid. Epimerization at the C(8) position gives the isolysergic acid or iso-LSD derivatives.
[32]
Anderson GM, Braun G, Braun U, Nichols DE, Shulgin AT (1978). "Absolute configuration and psychotomimetic activity". NIDA Research Monograph (22): 8–15. PMID 101890. Most of the known psychotomimetic agents have at least one chiral center within their structures but have been studied only as the racemic mixtures. All of those which have been studied in optically active form are consistent in that the more potent isomer is the isomer with the absolute "R" configuration at the chiral center carrying the nitrogen that corresponds to the amino group of the phenethylamine moiety. With LSD, the 5- "R",8-"R" isomer is effective in man within the dosage range of 0.05-0.1 mg, whereas the diastereo-isomeric l-iso-LSD (5-"S", 8-"R") is inactive in man at twenty times this dosage (Hofmann 1959).
[33]
Smith S, Timmis GM (1936). "311. The alkaloids of ergot. Part VII. isoErgine and isolysergic acids". Journal of the Chemical Society (Resumed): 1440. doi:10.1039/jr9360001440. ISSN 0368-1769.
[34]
Smith S, Timmis GM (1932). "98. The alkaloids of ergot. Part III. Ergine, a new base obtained by the degradation of ergotoxine and ergotinine". Journal of the Chemical Society (Resumed): 763–766. doi:10.1039/jr9320000763. ISSN 0368-1769.
[35]
Stoll A, Hofmann A, Troxler F (March 1949). "Über die Isomerie von Lysergsäure und Isolysergsäure. 14. Mitteilung über Mutterkornalkaloide" [About the isomerism of lysergic acid and isolysergic acid. 14. Report on ergot alkaloids]. Helv Chim Acta (in German). 32 (2): 506–521. Bibcode:1949HChAc..32..506S. doi:10.1002/hlca.19490320219. PMID 18116964. Archived from the original on 29 March 2025.
[36]
Abram Hoffer, Humphrey Osmond (1967). "Chapter II A d-Lysergic Acid Diethylamide". The Hallucinogens. Elsevier. pp. 83–236. doi:10.1016/B978-1-4832-3296-6.50005-7. ISBN 978-1-4832-3296-6. LCCN 66030086. OCLC 332437. OL 35255701M. Ololiuqui contains 2 active fractions. [...] The second fractions are ergot alkaloids. Hofmann and Tscherter (1960), Hofmann (1961a,b), and Hofmann and Cerletti (1961) extracted ergot indoles from Mexican R. corymbosa seeds and identified ergine (isolysergic acid amide), isoergine (lysergic acid amide), chanoclavine, clymoclavin and lysergol. Of these d-lysergic acid amide was the most powerful hallucinogen having one tenth the activity of LSD. [...]
[37]
Hofmann A, Tscherter H (1960). "Isolierung von Lysergsäure-Alkaloiden aus der mexikanischen Zauberdroge Ololiuqui (Rivea corymbosa (L.) Hall. f.)" [Isolation of lysergic acid alkaloids from the Mexican magic drug Ololiuqui (Rivea corymbosa (L.) Hall. f.)] (PDF). Experientia (in German). 16 (9): 414. doi:10.1007/BF02178840. ISSN 0014-4754. PMID 13715089. Retrieved 28 March 2025.
[38]
"Controlled Drugs and Substances Act". Department of Justice Canada. Retrieved 19 January 2026.
[39]
Orange Book: List of Controlled Substances and Regulated Chemicals (January 2026) (PDF), United States: U.S. Department of Justice: Drug Enforcement Administration (DEA): Diversion Control Division, January 2026