REVIEW ARTICLE Medical Biology 59: 21-34, 1981

,8-CARBOLINES, PSYCHOACTIVE COMPOUNDS IN THE MAMMALIAN BODY

PART I: OCCURRENCE, ORIGIN AND METABOLISM

M. M. AIRAKSINEN and I. KARl

FROM THE DEPARTMENT OF PHARMACOLOGYAND TOXICOLOGY, AND DEPARTMENT OF PHARMACY, UNIVERSITY OF KUOPIO, KUOPIO, FINLAND

ABSTRACT

We review the occurrence in nature and the formation and biotransformation in mammals of /3-car- bolines, the condensation products of tryptophan and indolealkylamines with aldehydes, with special reference to their possible role in man. They are found in many plants, some of which have been used as hallucinogens and drugs. They also occur as minor constitutients in tobacco smoke. In man tetra- hydro-p' -carboline (tetrahydronorharman), formed from condensed with formaldehyde, oc- curs normally in plasma and is highly concentrated in platelets. The corresponding products from s-hvdroxvtrvntamlne and 5-methoxytryptamine have been identified in rats but their concentrations in man have not yet been assessed. I-Methyltetrahydro-p'-carboline (tetrahydroharman) is formed in the body as the acetaldehyde condensate after alcohol intake and its concentration is usually greatest at the time of hang-over. Its oxidation product, I-methyl-p'-carboline (harman), has also been found in human urine and platelets. Tetrahydro-/3-carbolines may be oxidized to corresponding dihydro-/3-car- bolines and f3-carbolines, at least in vitro. Due to the interesting biochemical and pharmacological effects (see part II) of .B-carbolines, several hypotheses about their role in the body can be made. The concentrations and roles of .B-carbolines in different neuropsychiatric diseases, however, remain to be determined, as suitable evaluation methods have only been developed in recent years.

KEY WORDS: /I-CARBOLINES; HARMALA ; TRYPTOLINES; HALLUCINOGENS;ALCOHOL; ALDEHYDES

INTRODUCTION The major interest in ,8-carbolines has been prompted by the following findings: Since 1961 when McIsaac (69) reported the There is increasing evidence that some formation of ,8-carbolines in mammalian body ,8-carbohnes are normal constituents in as condensation products of indole alkyl- the human body and some are formed in amines with aldehydes, several reviews have special conditions such as after alcohol mentioned some aspects of these »natural intake (as described later in this review). hallucinogens» (3, 5, 18, 21, 25, 26, 28, 37, 39, ,8-Carbol'ines (Harm ala alkaloids) are 45, 46, 79, 91, 99); three of them appeared found in plants which have been used as while we were writing this review.,8-car- ha'llucinogens, and some pure ,8-carbolines bolines have often been described in the con- have known hallucinogenic properties (83, text of alcoholism together with tetrahydro- 84). A possible role in mental disease has isoquinolines, the corresponding condensation been suggested (70). products of catecholamines, these latter com- Tetrahydro-,8-carboline has been claimed pounds perhaps attracting most attention. to increase ethanol preference in rats (80, General interest in ,8-carbolines has, how- 81) and ,8-carbolines formed in the human ever, recently greatly increased and research body by acetaldehyde may be connected on them has consequently. intensified. The ·to alcohol dependence. Many of their ef- development of methods allowing a reliable fects in man (83) correspond to those of demonstration of the occurrence of some alcohol withdrawal. tetrahydro-,8-carbolines in human body and Some ,8-car'bolines induce tremor and har- some recent receptor studies has opened up maline has been used to produce experi- new aspects of their role and mode of action. mental tremor (33, 66, 94, 108, 123). 22 M. M. Airaksinen and I. Kari

R'~COOH1 --;. R'~COOH1 --? R'lOt;YCOOHI - -.,. R'0lOI;VCOOH1 N NH2 RCHO N NH N ~N N ~NH H HR HR HR IA ][A mA I I I ~ ~ ~

R~ ---.;.R~ __.,.R'~I R' Vr\i3!J NH2 RCHO ~~>-y-'NH V'N;>'l --~'OrH H HR HR HR IB /-11 ][B mB / RCO~ / 'i' / I R' I

~H~N)J ~ H c=o I c R Fig. 1. Possible routes of mammalian synthesis of tetrahydro-,s'-carbolines (THBCs, I), dihydro-ji- carbolines (DHBCs, II) and ji'-carbolines (BCs, III).R' = H, OH or OCH3; R = H, CHR (or other radi- cal). The dotted arrows indicate more uncertain routes.

- Some tB-carbolines are competitive inhi'bi- the literature. tB-Carboline (Fig. 1, III B; R = tors of the saturable sodium transport and R' = H) itself is usually known as norhar- harmaline has 'been used in studies of mane and I-methyl-tB-carboline (III B; R = sodium-dependent transport of amino CH~,R' = H) as (with or without an acids etc.(105). e on the end). The primary condensation pro- tB-Carholines inhibrt ducts of indole-ethylamines, however, are (MAO) (38, 42), particularly A-type (19, 85), 1,2,3,4-tetrahydro-~-carbolines (THBCs) (Fig. and 'have 'been used as short acting MAO 1, I) or 2,3,4,9-tetrahydro-1H-pyrido[3,4-bJin- inhibitors. doles or 1,2,3,4-tetrahydronorharmane deriva- Some tetrahydro-zi-carbolines effectively tives, also named tryptolines by the Barchas' inhibitthe uptake of 5-hydroxytryptamine group (9). These as well as (1,2- 'Or) 3,4-di- (5-HT)(8, 53) and increase 5-HT concen- hydro-ji-carbobines, 4,9-dihydl'o-3H-pyrido- tration in the brain (72) and they have [3,4..;bJindolesor dihydronorharmanes (Fig. 1, sometimes been used experimentally as II)(the probable site of the double bond is serotonergic drugs. 1,2 but it has not often been determined) Effective binding of some ~-carbolines to may be oxidized (aromatized) to tB-carbolines benzadiazepine receptors has recently at least in vitro, perhaps also in vivo. been shown (6, 16, 31, 94) and they have Different numbering systems for the atoms been suggested as the natural ligands of in ~-carbolines have been used and even the »benzodiazepine» receptors, Binding to present most official numbering system dif- opiate receptors has also been described fers from that used in (Fig. 1). (6). Thus, for example, the tryptamine 5-position Some tB-carbolines occurring in tobacco is 6-position .in ~-carbolines. The »tryptoIine» smoke and pyrolysis products of proteins naming of tetrahydro-ri-carbolines, however, in food are comutagenic (115, 116) and may uses principally the same numbering as for have carcinogenic or cocarcinogenic pro- tryptamines.Even editors of some scientific perties. journals 'have ,been confused because, for instance, 6-methoxy-tetrahydro-tB-carbohne St1"uctu1"es and nomenclatu1"e is the same as 5-methoxytryptoline. Here we ~-Carbolines or 2-carbolines is the often re- wil'l use the tB-carboline nomenclature and commended name for i9H-pyrido[3,4-bJindo- their usual numbering system. The term ~- les, but Chemical Abstracts uses the latter carbo lines refers .to the group which also in- names and a jungle of 'Other names occurs in cludes dihydro-ri-carbolines (DHBCs) and (J-Ca1'bolines in the mammalian body 23 tetrahydro-zi-carbolines (TRBCs) or to the plants seem to make mainly nonsaturated »fully aromatized» derivatives (BCs) of the BCs and DRBCs, but some, e.g. Elaeagnus specific compound p-carboline (BC). The niger L., also TRBCs. Some plants produce shortening Be is used only for the latter several p-carbolines, some are rather specific. meaning. Although the tryptol:ine naming is After a feeding of Passiflora edulis with [14C]- shorter and logical it has only been made tryptophan nearly all the radioactivity found for tetrahydro-zi-carbolines. The names ori- was in [14C]-harman (22). ginally given to the plant alkaloids or those Some other alkaloids with larger molecules derived from harman and other Harrnala al- contain a fJ-cal"boline ring system as part of kaloids are probably the 'best known but less a complicated skeleton. The effects of these logical. alkaloids usually differ from those of simple fJ-carbolines. The Rauwolfia alkaloids may be the best known representatives of such P-CARBOLINES IN PLANTS compounds, which are not dealt with in this The people living in various parts of South review. Ho (39) has reviewed the effects of America, Asia and Africa have known for yohimbine in the context of p-carbolines. thousands of years the potent psychoactivity p-Carbolines in food and tobacco of several plants containing p-carbolines (63, 84). Ancient Greeks and also Europeans of Aromatic p-carbolines, BC (norharman) and our centuries used Peganum tuirmaia L. 1-Me-BC(harman) have been described as among others in a »truth serum» (56). In being formed as pyrolysis products of trypto- India it had been used in religious ceremonies phan and proteins (55, 115, 116) which have (27, 63). West American natives have used been identified in cigarette smoke (90) and extracts from Passiiiora species (edulis and in the surface of charred meat and fish (82). incarnata) for several indications e.g. insom- The concentration of p-carbolines was con- nia, spasms and cramps (63). A drink called siderable if the surface was dark brown but ayahuasca, caapi, natema, pinde or yaje and very small if the meat remained only light made from the South American liane Banis- brown. teriopsis caapi, Spr. ex Griseb. (named Banis- teria caapi by Spruce) and preparations from /:i-CARBOLINES IN MAMMALS some other plants of the Malpighiaceae have INCLUDING MAN been used by Indians as narcotic and hallu- cinogenic agents in religious rituals (2, 44, 84, As shown later in this paper, TRBCs are 102, 103, 113) and sometimes also in other easily formed in vitro in various mammalian situations e.g. »to see the future» before tissues. Consequently many investigators have selecting a wife. Even habituation may have presented hypotheses about the possible form- occurred (61). Moreover, the anthelmintic ef- ation of p-carbolines in vivo.Until now nine fect of some plants containing p-carbolines p-carboline derivatives have been reported has been known to the natives for centuries to occur in various mammalian tissues and (24). Of course, the real role of p-carbolines excretory SUbstances, including human blood in these effects is not clear, since there are and urine (Table 2). many other potent substances like N-methyl- As early as 1961 McIsaac (69) found 6- tryptamines in these plants and different methoxy-1-methyl-TRBC, the condensation p-carbolines may have opposite effects. More- product of 5-methoxytryptamine (5-MeOT) over, several plants have often been mixed in with acetaldehyde, in the urine of rats treated the potions of the witchdoctors and shamans. with 5-MeOT, a monoamine oxidase inhibitor, On the other hand, some modern-day studies ethanol and disulfiram (which inhibits the confirm many of these earlier observations. oxidation of acetaldehyde formed). The iden- p-Carbolines are often called Harmala alka- tification was based mainly on Rf-values in loids, since they were found first in the seeds paper chromatography and McIsaac later of Peganum harmala. It was proved later said (personal communication) that other me- that p-carbolines are not typical alkaloids oc- tabolites like 5-methoxytryptophol may curring only in Peganum harmala but are have participated in forming the spot. In the found in many other plants a'Swell (Table 1). pineal gland of the dog Farrell and McIsaac Sometimes animal fodder may contain these (30) also described another p-carboline, 6- plants and some of them (e.g. passionfruit) methoxy-1-methyl-3,4-dihydro-BC (6-metho- have been used as spice or food by man. The xyharmalan, 10-methoxyharmalan), which 24 M. M. Ai7·aksinen and T. Ka1·i

TABLE 1 /3-Carbo!ines in plants. Only the genus of the plants is given because the same /3-carboLines may be found in severa! species of the genus. Often, however, only one or two species of the genus have been investigated.

Chemical name" Synonym names Genus Reference

7-Methoxy-l-metfuyl-DHBC Harmaline Banisteria 1, 2, 63, 65, 92 Banisteriopsis Peganum 7-Hydroxy-l-methyl-DHBC Harmalol Peganum 65, 92

I-Methyl-Be Arabine Arariba 1, 63, 65, 92 Galligonum base-4 Carex Harman Elaeagnus Loturine Kochia Ophiorrhiza Passiflora Symplocos Zygophyllum I-Methyl-BC Harman-3-COOH Aspidosperma 1, 63, 65, 92 3-carboxylic acid 1,2-Dimethyl-BC N-Methylharman Strychnos 1, 65, 92 Melinonine-F 1,2-Dimethyl-THBC N-Methyltetrahydro- Acacia 1, 92 harman Arthrophytum 1, 92 Leptoc1adine Hammada I-Methyl-THBC Tetrahydroharman Acacia 1, 65, 92 Calligonine Ca.lligonum Elaeagnine Elaeagnus Hammada Leptaetinia Petalostylis I-Methyl-THBC-2N-oxide Tetrahydroharman- Galligonum 92 N-oxide Galligonum base-3 Elaeagnine-N -oxide I-Methyl-BC-N-oxide Harman-N -oxide Galligonum 92 Harmanine 7-Methyl-l-methyl-BC Harmine Banisteriopsis 2, 65, 92 Banisterine Banisteria Yageirie Cabi Telepathine Calycanthus Kochia Passiflora Peganum Zygophyllum 7-Methoxy-l-methyl-THBC Tetrahydroharmine Banisteria 1, 44, 65, 92 Elaeagnus Leptaflorine Leptactinia Peganum 7-Hydroxy-l-methyl-BC Harmol Passiflora 1, 65, 92 Zygophyllum 7-Hydroxy-l,2-dimetlhyl-THBC N-Methyl-tetra- Elaeagnus 65, 92 hydroharmol 7-Hydroxy-l-methyl-THBC Tetrahydroharmol Elaeagnus 65, 92

2-Methyl-THBC Arthrophytom 65, 92 Gymnacranthera 65, 92 Hammada 1- Carbomethoxy- BC Pleiocarpa 92 2-Methoxy-l-vinyl- BC Picrasma 121 fJ-carbolines in the mammalian bo::ly 25

Table 1 continued

Chemical name Synonym names Genus Reference

6-Methoxy-2-methyl-THBC Phalaris 67, 119 6-Methoxy-2,9-dimethyl-THBC Phalaris 119 4-Hydroxy-l-oxo-BC Picrasma 68 4-Hydroxy-BC Picrasma 68 I-methylcarboxylate l-Acetyl-3'(methoxycarbonyl)-BC Vestica 93 5-Methoxy-l,2-dimethyl-THBC Banisteriopsis 35 I-Methyl-7-methoxy-8-hydroxy- Dihydroruine Peganum 86 glucosyl-DHBC I-Methyl-7-methoxy-8~hydroxy- Ruine Peganum 86 glucosyl-BC

* BC = /I-carboline, DHBC = 3,4-dihydro-!J-carboline, THBC = 1,2,3,4-tetrahydro-(i-carboline.

was thought to be formed by direct cyc1ization The background of these phenomena re- of melatonin. This kind of cyclization (Fig. 1, mained unresolved until the latter part of C) is known .in plants (24) and in vitro for the the 1970s. In 1'978 Honesker and Rommels- synthesis of dihydro-fJ-carbolines, but no pacher (48) described THBC in human urine evidence has been presented for its occurrence and in rat brain using a complicated separa- in mammals. The identification could not he tion method.After extraction into diethyl- replicated by others or by the authors them- ether, they separated THBC by thin layer selves later and it was thought to be some chromatography (TLC), acetylated it with ra- other fJ~carboline with a related structure dio'labelled acetic anhydride and isolated the (69).In 1963, 7-hydroxy-3-ethyl-THBC was re- labelled compound by two dimensional TLC. ported as a urinary metabolite of a-methyl The identification was also verified using -tryptamine in man (37), suggesting formal- mass spectrometry. To calculate the amount dehyde condensation of this drug or its 6- of THBC in the samples they used both radio- hydroxymetabolite. metric and UV-spectrophotometric methods.

TABLE 2

(J-Ca1'bolines reported to OCCU1in' mammalian tissues 01' excretions.

Compound* Tissue or excrete Reference

I-Me-6-MeO-DHBC? Dog pineal 30 I-Me-6-MeO-THBC Rat urine (treated animals) 69 6-MeO-THBC Rat arcuate nucleus, rat brain 10, 106 and adrenal THBC Human urine, human blood platelets 11, 47, 48, 51, 52 and plasma, rat brain 6-0H-THBC Human urine (after administration 96 of precursor), rat platelets I-Me-THBC Human urine, human plasma and 89, 97, our unpublished platelets, rat urine and -brain (after observations ethanol intake), goat CSF 1-Me-BC Human urine (after ethanol intake), 14, 97, 106, 107 human platelets and rat arcuate nucleus BC-3-carboxylic acid? Human urine 16 1-Me-BC-3-carboxylic acid Milk, urine and rumen of cows 13

* For full names and structures see Fig, 1 and the text. 26 M. M. Airaksinen and I. Kal'i

THBC concentration seemed to be about 50 Recently 1-methyl-p-carbolines have also ng/g in rat brain tissue in normal conditions been demonstrated in mammals. Rommels- and it increased after loading with tryptophan pacher et al. (97) and our group (7, 89) have (150 mg/kg) and tryptamine (150 mg/kg) to confirmed the earlier hypothesis that some 110 ng/g and 930 ng/g, respectively. The p-carbolines are formed in the body after amount of THBC 'in human morning urine va- ethanol administration. Rommelspacher et al. ried widely (40-1060 ng per sample, or have reported excretion of I-methyl-THBC 190-350 ng/ml). and I-m~thyl-BC into the urine of man and Our group (50, 51) and Barker et al. (11) rat after ethanol intake. The compounds used gas chromatography and mass fragmen- were separated by gel filtration, further tography (selected ion monitoring) to deter- purified by HPLC and the identification was mine THBC. By applying mass spectrometry, performed by mass spectrometry.For our we identified and quanti-fied THBC from hu- part, using mass fragmentography, we have man blood platelets and plasma using a simple identified and quantified I-methyl-THBC in extraction (and separation) procedure. The human blood platelets and plasma in the same concentrations of THBC in human platelet- conditions. Identification was also verified rich plasma, platelet-poor plasma, and pla- by running the whole mass spectra of I-Me- telets were about 10 ng/ml, 5.5 ng/ml, and 18 THBC. The concentrations of this during the pg per 108 platelets, respectively. Barker and intoxication and hang-over period varied coworkers identified and quantified the same widely, being 0.5 to 19 ng/ml in platelet poor substance in rat brain using a different ex- plasma. traction method. The concentrations which On the other hand, Shoemaker and co- they found were Iow, about 12 pmoles/g workers have identified 1-methyl-BC as a (2 ng/g) wet wt tissue. When we were writing normal constituent in rat arcuate nucleus 'and this review also Honecker et al. (47) reported human platelets (14, 107). They extracted the the finding of THBC in human platelets with compound with diethylether and separated it TLC and making of [SH]-ac.etylderivatives (as with silica column chromatography and thin in their urine study). The values (9.3-25.6 layer chromatography. The identification of pmoles or about 1.5-4 ng per 10 ml platelet- the I-methyl-BC was accomplished using rich plasma) were, however, much Iower than fluorometry, gas chromatography and mass ours and the intake of tryptophan or trypta- spectrometry. In human platelets the con- mine seemed to have no effect on them. centrations of this compound were not meas- In 1978 Shoemaker et al. (106) localized at urable and in rat arcuate nucleus very low least one p-carboline in rat arcuate nucleus (1.3 pmole/mg tissue). by laser-fluorometry and suggested that it When attempting to find the natural ligand was 6-methoxy-THBC. Later, Barker and of 'benzodiazepine receptors, Braestrup and Harrison (10) verified with mass spectro- coworkers (16), extracted the active fraction metry the presence of 6-methoxy-THBC in rat from a large amount of human urine. After brain and measured its concentration. Higher its final purification they were able to iden- concentrations were found in adrenal glands tify BC-3-carboxylic acid ethyl ester. This (1.1 ,ug/g) than in the brain (36 ng/g). compound, however, was formed during the extraction procedure where ethanol In 1979 Rommelspacher et al. (96) showed was used. Thus the original compound that 6-hydroxy-THBC appeared in human may have been BC-3-carboxyhc acid or, urine after "loading with5-hydroxytrypto- if oxidization had also occurred during the phan. They also showed it in rat brain, and procedure, DHBC-3-carboxylic acid, or even both showed and quantified it in rat blood THBC-3-carboxylic acid, the primary con- platelets under normal conditions. The se- densation product of tryptophan. However, parationof 6-0H-THBC from other sub- the latter is quite stable, while DHBC de- stances in the tissue extract was performed rivatives are easily oxidized to BC derivatives by high performance liquid chromatography (39). (HPLC) and thin layer chromatography. I-Methyl-BC-3-catboxylic acid has been Identification of the compound was based on identified with h'igh resolution mass spectro- the mass spectrum. The amount of 6-0H- metry from the milk and urine of cows fed THBC in rat platelets was found to be about with corn silage (13). It was quantified using 50 ng per 108 platelets, when measured by spectrofluorometry. Its average concentration making labelled acetyl derivatives. in milk, urine and rumen of control cows was (3-Cal'bo!ines in the mammalian body 27

dimethylglycine

H202X.FAD dimethyl- 0, " ~""' oxidase 5- methyl- THF FADH2-f-' HCHOI sarcosine H202Y--FAD o,--\..... uy~,oo,;",oxidase FADH2r I HCHOI glycine

Fig. 2. Some metabolic routes synthesizing formaldehyde which may be used in THBC formation in tissues. THF = 5,6,7,8-tetrahydrofolate.

0.08, 0.54 and 0.2 ,u.g/ml while during the corn nonsaturated BCs and DHBCs are common silage feeding the concentration increased in plants and the plant p-carbolines usually five-fold in milk, 100-fold in urine and 30-fold have I-methyl-group and 7-methoxy- or 7- in the rumen. The authors state, however, hydroxy-group, the mammalian tissues seem that the control values in particular might to form primarily THBes, with or without be erroneously high due to other disturbing the methoxy- 'Or hydroxy-group in 6-position. fluorescent compounds. However, they could not find a measurable concentration of 1-Me- Mode of f01'mation of THBCs in mammalian BC-3-carboxylic acid in the silage, thus the tissues acid is most probably formed by bacteria in It has 'been long known that the Pictet-Speng- the rumen. Similar p-carboline synthesis in ler reaction between indole-ethylamines and goats' rumens may also explain our prelimi- some aldehydes produces THBCs and in 1934 nary finding of 1-methyl-THBC as a normal it was shown to occur easily in 37°C at neu- constituent in the cerebrospinal fluid of goats, tral pH, i.e., conditions which also occur though this compound could not normally be in tissues (36). Saheb and Dajani (23, 101)later found in human cerebrospinal fluid. Nothing incubated 5HT with acetaldehyde in rat brain is known about the possible fi-carboline forma- homogenate and found that a compound was tion by intestinal bacteria in other mamma- synthesized which corresponded to 1-Me-6- lian species, including man. OH-THBC in TLC. The concentrations of p-carbolines in mam- In 1972-74 several groups reported that in malian tissues are rather low and several mammalian tissue homogenates 5-methyltet-- problems - for example, the occurrence of r ahydrofolate (methyl-T'Hb') was a good me- artefacts - are often associated with the thyl donor in the enzymatic N-mebhyla.tion of analysis of p-carholines from urine and tis- indolealkylamines.Exact analysis of the re- sues, since THBCs, as we know, are so easily action products, however, showed that they formed in vitro. This possibility has been were not N-methylated indoles but THBCs checked in most but not all of the studies (34, 59, 62, 64, 74, 122). On the other hand, real mentioned in the text. The quantitation of N-methylation usually occurred when S- the substances also seems to be a problem as adenosylme'thionine was the methyl donor, the concentrations are low. Thus reliable but THBC production may also be possible quantitative results are included only in a from S-adenosylmet'hion'ine (73). Both trypta- few reports. Though some p-carbolines in mine, 5-HT and5-methoxytryptamine (5- mammalian body may originate from plants MeaT), and N-methyltryptamines served as and food making, the differences in the substrates in the formation of TRBCs (12, 64, structure already suggest that some are really 122) and the reaction was often demonstrated formed in the mammalian body. While the in rat brain homogenate, but also in other 28 M. M. Airaksinen and I. Kari tissues and species, including human platelets THBC formation, although the values were (9, 114) and human brain homogenate (122). generally lower in schizophrenics (29). Pos- The reaction in vitro seems to go so that sible significant changes in some subgroups in the presence of NADP+ and N°NIO-methy- of schizophrenia, including a rare folate Ienetetrahydrotola te reductase (EC.1.1.1.68) responsive schizophreniformic psychosis (76), methyl-THF forms 5,10-methylenetetrahydro~ have not yet been excluded. Studies on folate (methylene-THF) and further tetra- the enzymes of other possible routes of hydrofolate (THF) and formaldehyde, which formaldehyde production (75) in schizophre- condenses with the tryptamines to THBCs nics are lacking. nonenzymatically (Fig. 2) (34, 50, 58, 60, 87, 95, In our synthesis of THBCin vitro the 100, 118). Supporting this scheme is the find- condensation of tryptamine with glyoxalic ing that THBC formation from tryptam'ine acid and decarboxylation of the product has also increased in the presence of serine hyd- given better yield than the condensation roxymethyltransferase (EC.2.1.2.1.), which of tryptamine with formaldehyde. Although generates methylene-THF by transferring the glyoxal ate occurs normally in mammalian j1-carbon of serine into THF (88). The non en- body the function of this mute of THBC for- zymatical formation of p-carbolines fr-om in- mation in vivo is without any experimental dolealkylamines and formaldehyde as the ba- proof. sis for histochemical detection of indole alkyl- amines had already been shown (15, 20). In Distt'ibution and biotmnsformation of addition to the dissociation of methylene- p-carbolines in mammals THF many other demethylations, e.g. that of Very little information about the fate of 13- sarcosine and dime'thylglycine (Fig. 2) and carbolines in man is available, though the the microsomal demethylation reactions of centra} effect of these drugs' shews that they drugs and 'Other foreign compounds, may pro- are absorbed and can be transferred into the duce formaldehyde. It is unclear if formalde- central nervous system. However, the phar- hyde forms a Schiff base 'Or a car'binolamine macokinetics of different j1-carbolines is as intermediate before cyclization (39). highly dependent on their lipop'hilicity, as The discovery of similar development of shown by Zetler et al. (123) in rats. In 1911 THBC synthesis from tryptamine and meth- Flury (32) had already reported that harma- ylene-ji-phenylethylimine synthesis from line (7-MeO-DHBC) metabolizes to harmine phenylethylamine in different parts 'Of rat (7-MeO-l-Me-BC), harmalol (7-0H-I-Me- brain (49) is natural, because the same mecha- DHBC), harminic acid (fi-azaindole-zSvdicar- nism produces formaldehyde for both con- boxylic acid) and unidentified compound. densations. Because methylene-THF re- Later Villeneuve and Sourkes (120), Slotkin ductase in vivo usually works in the direc- and DiStefano (110, 111) and Ho et al. (40) tian of methyl-THF - i.e. it eliminates studied the distribution and metabolism of formaldehyde - its low activity may favour Harmala alkaloids in rats.The studies showed THBC synthesis.It is not known if the activi- the metabolic rate 'Of harmalol and harman ty of methylene-THF reductase, or some steps (l-Me-BC) to be very fast and that of harmine in formaldehyde production, e.g. serine hyd- quite fast, wh'ile a high concentration 'Ofhar- roxymethyltransferase activity, or the avail- maline or its metabolites was found to re- ability of the amine is the main regulator in main in the tissues much longer. The fluoro- the synthesis of THBCs in vivo. For instance, metric results were verified with total body the availability 'Of5-HT may be limited by its autoradiography and isotope counting (40), storage in granules. Harmine seemed to have 'Only'Onemetabolite, If the methylene-THF reductase is in harmol (7-0H-1-Me-BC) and its sulphate and some way a ,limiting factor the assay of glucuronide conjugates, Harmaline was cor- the activity of this enzyme, e.g. in human respondingly demethylated to harmalol, which blood platelets, could provide a means to was oxidized to harrncl. Neither harmine nor estimate possible pathological amine cycli- harminic acid formation was found in rats. zations in human diseases, including schizo- An autoradiographic study was also per- phrenia. However, a study where this was formed in monkeys showing uneven distribu- measured in autopsied brain parts of chro- tion of harmaline in different brain areas (41). nic schizophrenics and controls no significant In general the results were similar to those differences between these groups were faund in rats. The conjugation of harmol has been in methylene-PH, reductase activity or in studied in several species as a model demon- {J-Ca1·bol.ines in the mammalian body 29 strating species specific differences (77), and transport through the blood brain barrier. the influence of many other factors on con- Thus we can conclude that the metabolites jugation processes. formed in peripheral tissues do not have Slotkin et al. (112) administered harmine much central effect. 6-0H-THBC given to to some human volunteers and found that its rats intraperrtoneally did not increase brain fate was rather similar to that in rats. It dis- 5-HT, as did 6-MeO-THBC (43). The finding appeared rapidly from the blood and was ex- of 'both THBC and N-methyl-THBC as the creted in urine as the glucuronide and sul- metabol'ites of N,N-dimethyrtryptamine in rat phate of harrnol. Excretion of unconjugated brain homogenate (12) suggests demethyla- harmol accounted only for 0.3 Ofo and that tion of N-methyl-THBC, but the demethyla- of unchanged harmine for 0.6 % of the total. tion may have occurred as well in the parent The metabolism of [14CJ-labelled 6-met- amine and N'-methyl tryptamine. hoxy-THBC was studied in rats by Ho et al. 1972 (43). 6-MeO-THBC was effectively taken up by tissues, including the brain, which had GENERAL COMMENTS a 10 to 20 times higher concentration 'than blood. In addition to demethylation of the As described 'before there is good evidence 6-methoxy group, the compound was also that some THBCs are formed in the mam- hydroxylated in the 7-position and the con- malian body. There are many aldehydes and jugates of 6~hydroxy-THBC and 6-methoxy- ketones which theoretically could form 7-hydroxy-THBC were excreted in urine THBCs with tryptamine, 5-HT and 5-MeOT. in nearly equal amounts. The same compounds Formaldehyde, however, is more reactive were also found in bile, and 9 Ofo from the than the higher naiural aldehydes, and irrtr aper'itoneally administered radioacti vity THBCs synthesized as the condensation pro- was found in 72 h in faeces, while 71 % ap- ducts of formaldehyde have clearly been peared in the urine. shown to be natural constitutients in the We then showed an active, high-rate uptake body. Acetaldehyde is also a reactive com- of [3H]-6-MeO-THBC by rabbit blood platelets pound than; occurs in significant concentra- in vitro (4), the uptake being competitive tions in human body after alcohol intake, with 5-HT and also inhibited by a 5-HT an- when it can form 1-methyl-THBCs.It re- tagonist cinanser'ine. Its intracellular distri- mains to be shown if harman (l-methyl-BC) bution, however, differed from that of 5-HT. reported to occur in human platelets (14) is This suggest that it uses the uptake mecha- really formed in the body or is of dietary nism of 5-HT'into the cell 'but is not similarly origin or is derived from tobacco smoke (the bound in intracellular granules. High con- authors did not state whether the subjects centrations of THBC (51, 52), 1-Me-THBC (7, were smokers). 89) and 6-0H-I-Me-THBC (96) in human and The site of synthesis of THBCs in vivo is rat platelets in comparison to those in plasma unknown, but in vitro studies suggest that also suggest a similarly active uptake for several tissues may produce formaldehyde other THBCs. As shown by Rornmelspacher and form THBCs. The same is true after alco- and Submar ian (98) [3H]-THBC was also taken hol intake for acetaldehyde, though the main up by rat hypothalamic slices, possibly largely site of alcohol metabolism is the liver. Be- by 5-HT neurons, and released by K+, the cause a large proportion of tryptamine may release being Ca+ + -dependent, thus resemb- be produced 'by intestinal bacteria (3) some ling neurotransmitters or neuromodulators. THBCs formed by it may already be syn- 'The metabolism of' non-methoxylated fJ- thesized in the gut, though all tissues with carbolines is not known. Because harmaline aromatic amino acid decarboxylase may be or harmine were only demethylated and did sites of synthesis as well. fJ-Carbolines with- not form additional OH-groups and because out hydrophilic groups easily pass through melatonin (54, 57) and N-dimethyltryptamine the blood-brain 'harrier - a property also (117) are hydroxylated only in the 6-position implied by their central effects - but the (corresponds to 7-pos'ition in fJ-carbolines), it condensation products of 5-HT, if occurring is probable that THEC, I-Me-THBC and their in the brain, are probably formed there. Also, nonsaturated derivatives are oxidised in the fJ-carbohnes from 5-methoxytryptamine are 6-position. Formation of the OH-group either probably synthesized in the brain and pineal by hydroxylation or demethylation decreases gland, where the parent amine is found. Even the hpophihcrty of fJ-carbolines and thus also so, after pineal (our unpublished results) the 30 M. M. Airaksinen and I.Kari next highest concentration of 6-methoxy- longer than those of alcohol and acetalde- THBC has been reported from adrenal gland hyde. The peak time of l-MeTHBC seems to (10). fit to the time of hangover best of all com- Four research groups have independently pounds connected with the hangover symp- shown that BCs are effectively bound to tomatology so far. bem:odiazepine receptors in rat brain syn- aptosomal membranes (6, 16, 31, 94). Of all REFERENCES the natural compounds studied they have the highest affinity. However, only the non- 1. Abramovitch RA, Spencer LD: The car- saturated BCs appear to be active (6, 31) in bolines. Adv Heterocycl Chem 3: 79-207, the micro molar concentrations which seem to 1964 occur in mammalian body, while THBCs are 2. Agurell S, Holmstedt B, Lindgren J: Alka- loid content of Banisteriopsis Rysbyana. J practically inactive. Although THBCs may be Am Pharmacol 140: 148-151, 1968 oxidized to the corresponding BCs, at least 3. Airaksinen EM, Airaksinen MM: Tryptophan in vitro, no mechanism for direct synthesis in mental abnormalities.In: in of these nonsaturated BCs has so far been mental disorders, p. 183-223. Ed. D. Boulldn, John Wiley and Sons,Chichester 1978 demonstrated. Th'is is probably the main 4. Airaksinen MM, Huang JT, Ho BT, T,ayl07' D, obstacle to claiming that BCs are the natural Walker K: The uptake of 6-methoxy-1,2,3,4- ligands 'Ofbenzod'iazepine receptors. Thus we tetrahydro-,B-carboline and its effect on 5- cannot yet rename them 'beta-carboline re- hydroxytryptamine uptake and release in ceptors'. blood platelets. Acta Pharmacol Toxicol 43: 375-380, 1978 In addition to a possibly increased syn- 5. Airaksinen MM, McIsaac WM: Indoilealkyl- thesis of formaldehyde in some types of amines and behavior. Ann Med Exp BioI schizophrenia (34), some schizophrenic pa- Fenn 46: 367-381, 1968 tients also have a lowered MAO activity in 6. Aimksinen MM, Mikkonen E: Affinity of platelets (78), although probably not in their /3-carbolines on rat brain benzodiazepine and opiate binding sites.Med Biol 58: 341-344 brain tissues (104). Increased excretion of 1980 tryptamine has also been reported (17). Thus 7. Airaksinen MM, Peura P, Kari I: 1-Methyl- other routes of indolealkylamine metabolism, 1,2,3,4-tetrahydro-,B-carboline in man after including the synthesis of BCs, may be in- alcohol drinking. In: Synaptic constituent in health and disease, p. 524. Ed. M. Brzin, D. creased. Because some BCs themselves are Sket and H. Baohelard. Mladinska Knijka- effective MAO inhibitors (19, 38, 42), the pos- Pergamon Press, Ljubljana-Oxford 1980 sibility of a vicious circle has been considered 8. Airaksinen MM, Svensk H, Tuomisto J, Ko- (5, 70). So far, however, no results are avail- muLainen H: Tetrahydro-,B-carbolines and ab'le to show if the concentrations of fJ-car- corresponding tryptamines:In vitro inhibi- tion of serotonin and dopamine uptake in bolines in any neuropsychiatric diseases dif- blood platelets. Acta Pharmacol Toxieol 46: fer from those of healthy persons. In healthy 308-313, 1980 persons after alcohol intake an abnormal oc- 9. Barchas JD, Elliot GR, DoAmaral J, Erdelyi currence of I-methyl-fJ-carbolines has been E, O'C0n7W7' S, Bowden M, Brodie HKH, shown, but carboline levels in alcoholics im- Berger PA, Renson J, Wyatt RJ: Tryptolines: Formation from tryptamines and 5-MTHF by mediately after a long drinking period and human platelets. Arch Gen Psychiat 31: 862- during withdrawal have not been reported. 867, 1974 Alcoholics have been found to excrete more 10. Barker SA, Harrison RE, Monti JA, Brown salsolinol, the corresponding condensation GB, ChTistian ST: Identification and quantifi- cation of 1,2,3,4-tetrahydro-,B-carboline, 2- product of acetaldehyde with dopamine, in methyl-1;2,3,4-tetrahydro-,B-carboline, and 6- their urine than do healthy persons, but its methoxY-1;2,3,4-tetrahydro-/!-carboline as in concentrations in the urine and cerebrospinal vivo constituents of rat brain and adrenal fluid of healthy persons were the same 'before gland. Biochern Pharmacal 30: 9-17, 1981 and after alcohol intake (109). On the con- 11. Barker SA, Harrison RE, Brown GB, Chris- tian ST: Gas chromatographic mass spectro- trary, the concentrations of I-methyl-THBC metric evidence for the identification of in plasma and platelets (7, 89) and of 1,2,3,4-t·etmhYdro-/!-carboline as in vivo con- I-methyl-THBC and l-methyl-BC in urine stituent of rat brain. Biochem Biophys Res (97) were measurable only after alcohol in- Commun 87: 146-154, 1979 take. Furthermore, in our preliminary studies 12. Barker SA, Monti JA, Christian ST: Meta- bolism of the hallucinogen N,N-dimethyl- the concentration of I-methyl-THBC in- tryptamine in rat brain homogenates. Bdo- creased during the intoxication and remained chem Pharmacol 29: 1049-1057, 1980 high all the time of hangover, i.e. much 13. Bertoni G, Merlini L, Nasani, Abenaim U: f3-Carbolines in the mammaLian body 31

1-Methyl-{3-carboHne-3-carboxylic acid, an Steppenraute (Peganum Harmala). Arch Exp unusual metabolite from cows fed with corn Pathol Pharmakol 64: 105-125, 1911 silage. J Agric Food Chem 28: 672-673, 1980 33. Fuentes JA, Longo VG: An investigation on 14. Bidder TG, Shoemaker DW, Boettqer HG, the central effects harmine, harmaline and Evans M, Cummins JT: Harman in human related f3-carbolines. Neuropharmacology 10: platelets. Life Sci 25: 157-164, 1980 15-23, 1971 15. Bjorklund A, Falck B, Hakansson R: Histo- 34. FulleT RW: The rise and fall of MTHF as a chemical demostration of tryptamine. Pro- methyl donor in biogenic amine metabolism. perties of formaldehyde-induced fluorophores Life Sci 19: 625-628, 1976 of tryptamine and related indole compound 35. GhosaL S, MazumdeT UK: Alkaloids of the in models. Acta Physiol Scand, Supp!. 318, 'leaves of BanisteTiopsis aTgentea. Phyto- 1968 chemistry 10: 2840-2841, 1971 16. Braestrup C, Nielsen M, Olsen C-E: Urinary 36. Hahn G, Ludevig H: Syrithese von Tetra- and brain {3-carboline-3-carboxylates as po- hydroharman-Derivaten unter physiolo- tent inhibitors of brain benzodiazepine re- gischen Bedienungen. I (Verlauf) Mitteil ceptors. Proc Natl Acad Sci USA 77: 2288- Chem Gesell 67: 2031-2035, 1934 2292, 1980 37. Heinzelman RV, Szmuszkovics J: Recent 17. Brune GG, Himwich HE: Indole metabolites studies in the field of indole compounds. in psychiatric patients.Arch Gen Psychiat 6: Fortschr ArzneimiHelforsch 6: 75-150, 1963 324-328, 1962 38. Ho BT: Monoamine oxidase inhibitors. J 18. Buckholtz N: Neurobiology of tetrahydro-{3- Pharm Sci 61: 821-837, 1972 carbolines. Life Sci 27: 893-903, 1980 39. Ho BT: Pharmacological and biochemical 19. BuckhoLtz N, Boggan WO: Monoamine oxi- studies with P'-carboline analogs. Curl' Dev dase inhibition in brain and liver produced Psychopharmacol 4: 215-247, 1979 by {3-carbOlines: Structure-activity relation- 40. Ho BT, Estevez V, Fritchie GE, Tansey LW, ship and substrate specifity. Biochem Phar- Idiinpiiiin-HeikkiUi JE, McIsaac WM: Metab- macol 26: 1991-1996, 1977 olism of harmaline in rats. Biochem Pharma- 20. Casperson T, Hillarp NA, Ritzen M: Fluore- col 20: 1313-1319, 1970 scence microspectrophotometry of cellular 41. Ho BT, FTitchie GE, Idiinpiiiin-Heikkilii JE, catecholamines and 5-hydroxytryptamine. Tans.ey LW, McIsaac WM: (3H}Harmaline Exp Cell Res 42: 415-428, 1966 distriJbution in monkey brain, pharmacological 21. Cohen G: production in the meta- and autoradiographic study. Brain Res 22: bolism of alcohol and biogenic amines. Bio- 397-401, 1970 chem Pharmacol 25: 1123-1128, 1976 42. Ho BT, McIsaac WM, WalkeT KE, Estevez 22. Copeland L, Slay tor M: The excretion of the V: Inhibitors of monoamine oxidase. J Pharrn j3-carboline alkaloid harman in passionfruit. Sci 57: 269-273, 1968 Physiol Plant 31: 372-329, 1974 43. Ho BT, Taylo)' D, Walker KE, McIsaac WM: 23. Dajani RM, Saheb SE: A further insight into Metabolism of 6-methoxy-tetrahydro-p'-car- the metabolism of certain {3-carbolines. Ann boline in rats. Xenobiotica 2: 349-362, 1972 NY Acad Sci 215: 120-123, 1973 44. Hochstein F, PaTadies A: Abkaloids of Banis- 24. Dalton DR: The alkaloids, p. 423-425. Mar- teria Caapi and Pres bonia Amazonum. J Am cel Dekker Inc., New York 1979 Chem Soc 79: 5735-5737, 1957 25. Davis VE, Walsh MJ: Effect of ethanol on 45. Holman RB, Elliot GR, Faull K, Barctias JD: neuroamine metabolism. In: Biological basis Tryptol'ines: The role of mdoleamine-aldehyde of alcoholism, p. 73-102. Ed. Y. Israel and condensation products in the effects of alko- J. Marondes. Wdley-Interscience, New York hol, In: The psychopharmacology of alcohol, 19.71 p. 155-169. Ed. M. Sandler. Raven Press, New 26. Deitrich R, Erwin W: Biogenic amine-alde- York 1980 hyde condensation products: Tetrahydroiso- 46. Holman RB, Elliot GR, SeagTaves E, DoAma- quinolines and tryptolines (j3-carbolines). ral JR, VeTnikos-Da'niellis J, KellaT KJ, Ann Rev Pharmacol 'I'oxicol 20: 55-80, 1980 Barhas JD: Tryptolines: Their potential role 27. De Ropp RS: Drugs and mind. St Martin's in the effects of ebhanol. In: The role of ace- Press Inc., New York 1957 taldehyde in the actions of ethano!. Ed. X.O. 28. Emot GR, HoLman RB: Tryptolines as pa- Lindros and C. J. P. Eriksson, p. 207-216. tenti·al modulators of serotonergic function. The Finnish Foundation for Alcohol Studies, In: Neuroregulators and psychiatric disor- 23. Helsinki 1975 ders, p. 220-226. Ed. E. Usdin. Oxford Uni- 47. Honecker H, Coper H, FiihndTich C, Rom- versity Press, New York 1977 me!spacheT H: Tetrahydronorharmane (tet- 29. ElLiot GR, Sutherland K, E1'delyi E, Ciara- rahydro-{3-carboline) in human blood plate- neno RD, Barchas JD, Wyatt RJ: N5,10_ lets. J Clin Ohem Clin Biochern 18: 133-135, Methylenetetrahydrofolate reductase activity '1980 in autopsied parts of chronic schizophrenics 48.Hotiecker H, RommelspacheT H: Tetrahydro- and controls and in vitro tryptoline forma- norharmane (tetrahydro-ji-carboline) a phy- tion. BioI Psychiat 13: 695-708, 1978 siologicalty occuring compound of indole me- 30. Farrell G, McIsaac WM: Adrenoglomerulo- tabolism. Naunyn Schmiedeberg's Arch Phar- tropin. Arch Biochem 94: 543-544, 1961 macol 305: 135-141, 1978 31. Feshke KJ, Borbe HO, Milner WE, Rommel- 49. Hsu LL: Formation of 1,2,3,4-tetrahydro-p'- spncher H, WolleTt U: {3-carbolines, potent carboline and methylene-{3-phenylethylimine inhibitors of speci·fic 3H-flunitratzepam bind- from 5-methyltetrahydrofolate and .amines in ing. Naunyn Schmiedeberg's Arch Pharmacol tissues from developing rat brain. Life Sci 313, Suppl: R34, 1980 19: 493--496, 1976 32. FLUTY F: Beitrage zur Pharmakologie der 50. Hsu LL, Mandell AJ: Enzymatic formation 32 M. M. Aimksinen and I. Kari

of tetrahydro-{1-carboline from tryptamine cGMP content elicited by harmaline. Brain and 5-methyltetrahydrofolic acid in rat brain Res 83: 516-519, 1975 fractions: Regional and subcellular distribu- 67. Marum P, Hovin AW, Marten GC: Inheri- tion. J Neurochem 24: 631-636, 1975 tance of three groups of indole alkaloids in 51. Kari I, Peura P, Aimksinen MM: Mass trag- reed canarygrass, Crop Sci 19: 539-544, mentographic determination of tetrahydro- 1979 ti-carboline in human blood platelets and 68. 1I'latsumum S, Enomoto H, Aoyagi Y, Nomi- plasma.Med BioI 57: 412-414, 1979 yama Y, Kono T, Matsuda M, Tanaka H: 52. Kari I, Peura P, Ai1'aksinen MM: Quantita- Indole derivatives. Chem Abstracts 93: 114- tive gas chromatographic mass spectrometric 195, 1980 determination of 1,2,3,4-tetrahydro-{1-carbo- 69. McIsaac WM: Formation of I-methyl-6- line in ,human plasma and platelet. Biorned methoxy-I ,2,3,4- tetrahydro- {1-carboline under Mass Spectrom 7: 549-552, 1980 physiological conditions. Biochem Biophys 53. Komu!ainen H, Tuomisto J, Aimksinen MM, Acta 52: 607-609, 1961 Kari I, Peurti P, Poilari L: Tetrahydro-{1- 70. McIsaac WM: A Biochemical concept of men- carboldnes and corresponding tryptamines: tal diseases. Postgard Med J 30: 111-118, In vitro inhibition of serotonin, dopamine and 1961 noradrenaline uptake in rat brain synapto- 71. McIsaac WM, Fane!! G, Ttiborskn; RG, Tay- somes,Acta Pharmacol Toxicol 46: 299-307, lor AN: Indole compounds isolation from 1980 pineal tissue. Science 148: 102: 102-103, 1965 54. Kopin IJ, Pare CM, Axe!rod J, Weissbach H: 72. McIsaac WM, Taylor D, Walker KE, Ho 6-Hydroxylation: The major metabolic path- BT: 6-MethoxY-l,2,3,4-tetrahydro-{1-carbo- way for melatonin. Biochim Biophys Acta 40: linear serotonin elevator. J Neurochem 19: 377-378, 1960 1203-1206, 1972 55. Kosuge T, Tsuji K, Wakabayski K, Okomoto 73. Melle?' E, Rosengarten H, Fl'iedhoff AJ: Con- T, Shudo K, Titaka Y, Itai A, Sugimura T, version of CI4-S-adenosylmethionine to C14- Kawachi T, Nagao M, Yahagi T, Seino Y: formaldehyde and condensation with indol- Isolation and structure studies of mutagenic amines: A side reaction in N-me"thyltransfer- principles in amino acid pyrolysates. Chern ase assay in blood. Life Sci 14: 2167-2178, Pharm Bull 26: 611-619, 1978 1974 56. Krieg M: Grona mediciner. Rard McNally 74. Me!!er E, Rosengarten H, Friedhoff AJ, Steb- Co., Uddevalla 1965 bins RD, Silb er R: 5-Methyltetrahydrofolic 57.Kveder S, McIsaac WM: Metabolism of mela- acid is not a methyl donor for biogenic ami- tonin (N-acetyl-5-methoxytryptamine) and 5- nes: Enzymatic formation of formaldehyde. methoxytryptamine. J BioI Chem 236: 3214- Science 187: 171-173, 1975 3220, 1960 75. Michel G (ed.): Biochemical pathways. Boeh- 58. Laduron P, Leysen J: Enzymatic formalde- ringer Mannheim GMBH. Biochemical Di- hyde production from 5-methyltetrahydro- vision, 'I'utzing 1972 folic acid: Prior step to alkaloid formation. 76. Mudd SH, Freeman JM: N5,10-methylene Biochem Pharmacol 24: 929-932, 1975 tetrahydrofolate reductase defiency and 59. Lauewers W, Leysen J, Vel'hoeven H, Ladu- schizophrenia: A working hypothesis. J Psy- ron P: Identification of alkaloids: The con- chiatRes 11: 259-262, 1974 densation products of biogenic amines with 77, Mulder GJ, Bleeker B: UDP glucuronyltrans- formaldehyde, enzymatically formed from 5- ferase and phenolsuUotransferase from rat methyltetrahydrofol'ic acid. Biomed Mass liver in vivo and in vitro - IV: Species dif- Spectrom 2: 15-22, 1975 ferences in harrnol conjugation and elimina- 60. Leysen J, Laduron P: Characterization of an tion in bile and urine in vivo. Biochem Phar- enzy.me yielding formaldehyde from 5-tetra- macol 24: 1481-1484, 1975 hydrofolic acid. FEBS Lett 47: 299-303, 1974 78. MUTphy DL, Wyatt RJ: Reduced monoamine 61. Lewin L: Phantastica, die betauberiden und oxidase activity in blood platelets from schi- erregenden Genussmitte1. G. Stilke, Berlin zophrenic patients. Nature 238: 225-226, 1972 1924; English reprint: Phantastica, narcotic 79. Myers RD: Pharmacology of alcohol. Annu and stimulating drugs. E. P. Dutton and Co., Rev Pharmacol Toxicol 18: 125-144, 1978 New York 1964 80. Myers RD, Melcior CL: Differential actions 62. Lin RL, Narasinhachar N: Evidence for ab- on voluntary alcohol intake of tetrahydro- sence of amine-N-methylation and O-methyl- isoquinolines and a p-carboline infused chro- ation in indolebhylamines with methyltetra- nicailly in the ventricle of the rat. Pharrnacol hydrofolic acid-dependent N -methyltransfer- Biochem Behav 7: 381-392, 1977 ase. Res Commun Chern Pathol Pharmacol 8: 81. Myers RD, Oblinger MM: Alcohol drinking 535-542, 1974 in the rat induced by an acute intracerebral 63. List PH, HorhammeT L: Hagel'S Handbuch infusion of two tetrahydroisoquinolines and del' pharmaceutischen Praxis. Springer- Ver- a p-carboline. Drug Alcohol Depend 2: 463- lag, Berlin 1977 483, 1977 64. MandeU LW, Rosegray A, Walker RW, Van- 82. Nagao M, Honda M, Seino Y, Yahagi T, Sugi- denheuvel WJA:5-Methyltetrahydrofolic acid rnurc T: Mutagenetics of smoke condensates us a mediator of the formation of pyrido- and the charred surface of fish and meat. indoles. Science 186: 741-743, 1974 Cancer Lett 2: 221-226, 1977 65. Manske R:The alkaloids, vol. VII. Academic 83. Naranjo P: Psychotropic properties of Har- Press, New York 1968 mala alkaloids. In: Ethnopharmacological 63. Mao CC, Guidotti A, Costa E: Inhibition by search for psychoactive drugs. p. 385-391. Ed, diazepam of tremor and increase of cerebellar D. H. Efron, B. Holmstedt and N. S. Kline fJ-CaTbolines in the mammalian body 33

U.S. Public Health Service Publication No 100. Rosenga1·ten H, Meller E, Friedhoff AJ: Syn- 1645, Washington DC 1967 thesis of tctrahydro-d-carbolines from indole- 84. Namnjo P: Hallucinogenic plant use and re- amines via enzymatic formation of formal- lated indigenous belief systems in the Equa- dehyde from 5-methy-ltetrahydrofolic acid. dorian Amazon. J Ethnopharmacol 1: 121- Biochem Pharmacol 24: 1759-1762, 1975 145, 1979 101. Saheb SE, Dajani RM: I-Methyl-s-hydr oxy- 85. Neff NH, Fuentes JA: The use of selective tetrahydrocarboline: A possible product of monoamine oxidase inhibitor drugs for ethanol and tryptophan metabolism. Comp evaluating pharmacological and physiological Gen Pharmacol 4: 225-227, 1973 mechanism. In: Monoamine oxidase and its 102. SchuLtes RE, Hoffman A: The botany and inhibition, p. 163-179. Ciba Foundation Sym- chemistry of haLlucinogens, p. 101-112. C. C. posium 39 (new series). Elsevier, Amsterdam Thomas, Springfield 1973 1976 103. Sch'ultes RE: Evolution of the identification 86. Nettleship L, Slay tor M: Limitations of fee- of the major South American narcotic plants. ding experiments in studying 'alkaloid bio- J Psychedel Drugs 11: 119-134, 1979 synthesis in Peganum haTmala callus cul- 104. Schwartz MA, Aikens AM, Wyatt RJ: Mono- tures. Phytochemistry 13: 735-742, 1974 amine oxidase activity in brains from schizo- 87. Pearson AG, Turne1' AJ: Folate-dependent-1- phrenic and mentally normal individuals. carbon transfer to biogenic amines mediated Psychopharrnacologia 38: 319-328, 1974 by methylenetetrahydrofolate reductase.Na- 105. SepuLveda FV, Buclon M, Robinson JWL: ture 258: 173-174, 1975 L'harmaline, un inhibiteur des processus de 88. PeaTson AG, TurneT AJ: The formation of transport intestinal associes aux movements beta-carboline alkaloids mediated by serine des ions sodium. Gastroenterol Clin Bioi 1: hydroxymethyltransferase. FEBS Lett 98: 87-93, 1977 96-98, 1979 106. ShoemakeT DW, Cummins JT, Bidder TG: 89. Peura P, Kari I, Aimksinen MM: Identifi- p-Carbolines in rat arcuate nucleus. Neuro- cation by selective ion monitoring of I-methyl science 3: 233-239, 1978 1,2,3,4-tetrahydro-fi'-carboline in human 107. Shoemaker DW, Cummins JT, Bidder TG, platelets and plasma after ethanol intake. Boettger HG, Evans M: Identification of har- Biomed Mass Spectrom 7: 553-555, 1980 man in the rat arcuate nucleus. Naunyn 90. Poindexter EH, Curpenter RD: The isolation Schmiedeberg's Arch Pharmacol 310: 227- of harmane and norharmane from tobacco 230, 1980 and cicarette smoke.Phytochemistry 1: 215- 108. Simantov R, Snuder SH, Oster-Granite ML: 221, 1962 Harmaline induced tremor in the rat: Aboli- 91. Rahwan RG: Toxic effects of ethanol: Pos- tion by 3-acetylpyridine destruction of ce- sible role of acetaldehyde, tetrahydroisoquino- rebellar climbing fibers. Brain Res 114: 141- lines and tetrahydro-j3-carbolines. Toxicol 151, 1976 Appl Pharmacol 34: 3-27, 1975 109. Sjoquist B, BOTg S, Kvande H: The presence 92. Rauffauf RF: A handbook of alkaloids and of salsolinol in urine and cerebrospinal fluid alkaloid containing plants. Wiley-Interscien- from healthy voluunteers. In:Synaptic con- ce, New York 1969 stituents in health and disease, p. 448. Ed. 93. RazmiLic I, Castillo M, Lopez JT: New syn- Brzin, D. Sket and H. Bachelard, Mladinska thesis of 1-acetyl-3-(metJhoxycarbonyl)-j3-car- Knijka-Pergamon Press, Ljubljana-Oxford boline. J Heterocyc1 Chern 17: 595-596, 1980 1980 94. Robertson HA: Harmaline-induced tremor: 110. Slotkin TA, DiStefano V: A model or harmine The benzodiazepine receptor ar a site of metabol-ism in the rat. J Pharmacol Exp Ther action. Eur J Pharmacol 67: 129-132, 1980 174: 456-462, 1970 95. Rommelspacher H, Coper H, Strause S: On 111. Slotkin TA, DiStefano V: Urinary metaboli- the mode of formation of tetrahydro-ri-carbo- tes of harmine in the rat and their inhibi- lines. Life Sci 18: 81-88, 1976 tion of monoamine oxidase. Biochem Pharrna- 96. Rommelspacher H, Honecker H, Barbei; M, col 19: 125-131, 1970 Meinke B: 6-Hydroxytetrahydronorharmane 112. Slotkin TA, DiStefano V, Au WYW: Blood (6-hydroxy-tetrahydro-j3-ca:rboline), a new levels and urinary excretion of harmine and active metabolite of indole-alkylamines in its metabolites in man and rats. J Pharrna- man and rat. Naunyn Schrrriedeberg's Arch col Exp Ther 173: 26-30, 1970 Pharmacol 310: 35-41, 1979 113. Spruce R: Notes of a botanist on the Amazon 97. Rommelspacher H, Strauss S, Lindemann J: and Andes. Ed. A. R. Waltace. Macmillan, Excretion of tetrahydroharmane and har- London 1908 mane into the urine of man and rat after 114. Stebbins RD, Meller E, Rosengarten H, Fried- load with ethanol. FEBSLett 109: 209-212, hoff A, Silber R: Identification of N5,N10- 1980 methylene tetrahydrofolate reductase as the 98. RommelspacheT H, Subramanian N:Tetra- enzyme involved in the s-methyl-tetrahydro- hydroharmane modulates the depolarisation- folate dependent formation of a .B-carboline induced efflux of 5-hydroxytryptamine and derivative of 5-hydroxytryptamine in human dopamine and is released by high potassium pia telets. Arch Biochem Biophys 173: 673- concentration from rat brain slices. Eur J 679, 1976 Pharmacol 56: 81-86, 1979 115. Sugimura T, Kawachi T, Nagao M, Yahagi T, 99. Rosengarten H, Friedhoff AJ: A review of re- Seino Y, Okomoto T, Shudo K, Kosuge T, cent studies of the biosynthesis and excretion Tsuji K, Wakabayashi K, Litaka Y, Itai A: of hallucinogenins formed by methylation of Mutagenic principles in tryptophan and phe- neurotransmitters or related substances. nylalanine pyrolysis products. Proc Japan Schizophrenia Bull 2: 90-105, 1976 Acad 53: 58-61, 1977 3 34 M. M. Airaksinen and I. Kari

116. SugimU1'a Sato S, Nagao Matsushima T, M, T, 121. Wagner H, Nestle?' T, Neszmetui A: N-met- Seino Y, Takeuchi M, Kawachi T: Overlap- thoxy-l-v,inyl-(3-carboline from Picrasma ping in carcinogens and mutagens. In: Fun- exelsa. Tetrahedron Lett 2777-277;8, 1978 damentals in cancer prevention. Ed. P. N. Magee, S. Takayama, T. Sugimura and T. 122. Wyatt RJ, Erdeleyi E, DoAmara! JR, Elliot Matsushrma, p. 191-215. University of To- GR, Renson J, Barchas JD: Tryptoline forma- kio Press, Tokio 1976 tion by preparation from brain with 5-methyl- 117. Szara S, Hearst E: The 6-hydruxyl-ation of tetrahydrofoldc acid. and tryptamine. Science tryptamines, a way of producing ·psychoactive 187: 853-855, 1975 rnetabohtas. Ann NY Acad Sci 96: 134-141, 123. Zetler G, Singbm·t G, Sciosser L: Cerebral 1962 pharmacokinetics of tremor-producing har- 118. Taylor RT, Hanna ML: 5-Methyltetrahydro- mala and iboga alkaloids. Pharmacology 7: folate aromatic alkylamine N-methy'ltrans- 237-248, 1972 ferase: An artefact of 5,10-methylenetelra- hydrofolate reductase activity. Life Sci 17: 111-120, 1975 Received for publication: November 6, 19'80 119. Vijayanager HM, Ardetti RCS, Bolan J, Clark KW: Phytochemical investigation of Manni- Address: M. M. Airaksinen bita plants, III Identification of two (3-car- Department of Pharmacology and Toxi- bolines from Phalaris crundiacea. Llyodia 38: cology 442-443, 1975 University of Kuopio 120. Villeneuve A, Sourkes T: Metabolism of P.O. Box 138 harmaline and harmine in the rat. Rev Can SF-70101 Kuopio 10 Biol 25: 231-239, 1966 Finland