Metabolism of Harmaline and Harmine
321
in the kinetic constants of liver microsomal harmine O-demethylation. Xenobiotica
:321–328.
Collins M (2002) Alkaloids, alcohol and Parkinson’s disease. Parkinsonism Relat
Disord 8:417–422.
Collins MA and Neafsey EJ (1985) Beta-carboline analogues of N-methyl-4-phenyl-
strate inhibition kinetics. Atypical enzyme kinetics were also
reported for P450-catalyzed reactions, such as substrate in-
hibition and activation of CYP3A4 (Korzekwa et al., 1998;
Shou et al., 2001). These findings have led to a better under-
standing of the active sites of P450 enzymes, including mul-
tiple sites for substrate binding (Shou et al., 2001).
It is noteworthy that whereas harmaline O-demethylation
is carried out preferentially by CYP2D6, other P450 isozymes
approach the activity of CYP2D6 with respect to harmine
O-demethylation. This difference between the isozyme pref-
erence of these two -carbolines is further demonstrated in
the experiments using MLM, whereby the CYP2D6-trans-
genic MLM had a high CYP2D6-specific harmaline O-de-
methylase activity, but a considerably poorer CYP2D6-spe-
cific harmine O-demethylase activity. These observations are
consistent with the relative affinities of the two substrates
6
1
,2,5,6-tetrahydropyridine (MPTP): endogenous factors underlying idiopathic par-
kinsonism? Neurosci Lett 55:179–184.
Collins MA, Neafsey EJ, Cheng BY, Hurley-Gius K, Ung-Chhun NA, Pronger DA,
Christensen MA, and Hurley-Gius D (1987) Endogenous analogs of N-methyl-4-
phenyl-1,2,3,6-tetrahydropyridine: indoleamine derived tetrahydro-beta-
carbolines as potential causative factors in Parkinson’s disease. Adv Neurol 45:
1
79–182.
Collins MA, Neafsey EJ, Matsubara K, Cobuzzi R Jr, Albores R Jr, Fields J, and
Rollema H (1992) Indole-N-methylation of beta-carbolines: the brain’s bioactiva-
tion route to toxins in Parkinson’s disease? Ann NY Acad Sci 648:263–265.
Corchero J, Granvil CP, Akiyama TE, Hayhurst GP, Pimprale S, Feigenbaum L, Idle
JR, and Gonzalez FJ (2001) The CYP2D6 humanized mouse: effect of the human
CYP2D6 transgene and HNF4alpha on the disposition of debrisoquine in the
mouse. Mol Pharmacol 60:1260–1267.
de Meester C (1995) Genotoxic potential of beta-carbolines: a review. Mutat Res
339:139–153.
Freedland CS and Mansbach RS (1999) Behavioral profile of constituents in ayahua-
sca, an Amazonian psychoactive plant mixture. Drug Alcohol Depend 54:183–194.
Fukushima S, Matsubara K, Akane A, and Shiono H (1992) 1-Methyl-tetrahydro-
beta-carboline-3-carboxylic acid is present in the rat brain and is not increased
after acute ethanol injection with cyanamide treatment. Alcohol 9:31–35.
(
harmaline Km rCYP2D6, 1.41 M, harmine Km rCYP2D6, 7.42
M, Table 3; harmaline Km HLMCYP2D6, 18.9 M, harmine Km
HLMCYP2D6, 62.1 M, Table 2). Thus, the difference between
the two substrates is almost certainly due to the less basic
Gearhart DA, Collins MA, Lee JM, and Neafsey EJ (2000) Increased beta-carboline
9
N-methyltransferase activity in the frontal cortex in Parkinson’s disease. Neuro-
biol Dis 7:201–211.
nature of harmine (pK 7.70) compared with harmaline (pKa
Gearhart DA, Neafsey EJ, and Collins MA (2002) Phenylethanolamine N-
methyltransferase has beta-carboline 2N-methyltransferase activity: hypothetical
relevance to Parkinson’s disease. Neurochem Int 40:611–620.
a
9
.80) (Budavri et al., 1996). Indeed, it was recently proposed
that CYP2D6 substrates must contain an ionized nitrogen
center at cellular pH to bind to the Glu-216 residue for
catalytic activity (Kirton et al., 2002). Based upon the fore-
Gelboin HV, Krausz KW, Gonzalez FJ, and Yang TJ (1999) Inhibitory monoclonal
antibodies to human cytochrome P450 enzymes: a new avenue for drug discovery.
Trends Pharmacol Sci 20:432–438.
Glennon RA, Dukat M, Grella B, Hong S, Costantino L, Teitler M, Smith C, Egan C,
Davis K, and Mattson MV (2000) Binding of beta-carbolines and related agents at
serotonin (5-HT(2) and 5-HT(1A)), dopamine (D(2)) and benzodiazepine receptors.
Drug Alcohol Depend 60:121–132.
Hedlund E, Gustafsson JA, and Warner M (2001) Cytochrome P450 in the brain; a
review. Curr Drug Metab 2:245–263.
Herraiz T (2002) Identification and occurrence of the bioactive beta-carbolines nor-
harman and harman in coffee brews. Food Addit Contam 19:748–754.
Husbands SM, Glennon RA, Gorgerat S, Gough R, Tyacke R, Crosby J, Nutt DJ,
Lewis JW, and Hudson AL (2001) Beta-carboline binding to imidazoline receptors.
Drug Alcohol Depend 64:203–208.
Iurlo M, Leone G, Schilstrom B, Linner L, Nomikos G, Hertel P, Silvestrini B, and
Svensson H (2001) Effects of harmine on dopamine output and metabolism in rat
striatum: role of monoamine oxidase-A inhibition. Psychopharmacology (Berl)
159:98–104.
Kim H, Sablin SO, and Ramsay RR (1997) Inhibition of monoamine oxidase A by
beta-carboline derivatives. Arch Biochem Biophys 337:137–142.
Kirton SB, Kemp CA, Tomkinson NP, St-Gallay S, and Sutcliffe MJ (2002) Impact of
incorporating the 2C5 crystal structure into comparative models of cytochrome
P450 2D6. Proteins 49:216–231.
Korzekwa KR, Krishnamachary N, Shou M, Ogai A, Parise RA, Rettie AE, Gonzalez
FJ, and Tracy TS (1998) Evaluation of atypical cytochrome P450 kinetics with
two-substrate models: evidence that multiple substrates can simultaneously bind
to cytochrome P450 active sites. Biochemistry 37:4137–4147.
Krausz KW, Goldfarb I, Buters JT, Yang TJ, Gonzalez FJ, and Gelboin HV (2001)
Monoclonal antibodies specific and inhibitory to human cytochromes P450 2C8,
going difference in pK values, at pH 7.4, for example, har-
a
maline will be over 100 times more ionized than harmine.
In summary, the cytochromes P450 that O-demethylate
the exogenous -carbolines harmaline and harmine have
been identified. The predominant isozymes are CYP1A2 and
polymorphic CYP2D6. Plant extracts containing the -carbo-
line alkaloids have been used in traditional medicine for
millennia and are of considerable ethnopharmacological in-
terest and importance. Both South American ayahuasca and
Asian Peganum harmala seeds employ the pharmacological
properties of the -carboline alkaloids to exert both their
healing and psychotropic properties. There remains the in-
triguing possibility that the pharmacologic and toxicological
properties of these traditional medicines are related to the
CYP2D6 polymorphism. Finally, we propose that CYP2D6
could potentially ameliorate the neurotoxicity of both endog-
enous and exogenous -carbolines by restricting the meta-
bolic flux through the N-methylation pathways.
2
C9 and 2C19. Drug Metab Dispos 29:1410–1423.
Lamchouri F, Settaf A, Cherrah Y, El Hamidi M, Tligui N, Lyoussi B, and Hassar M
2002) Experimental toxicity of Peganum harmala seeds. Ann Pharm Fr 60:123–
29.
Langston JW and Ballard P (1984) Parkinsonism induced by 1-methyl-4-phenyl-
,2,3,6-tetrahydropyridine (MPTP): implications for treatment and the pathogen-
(
1
Acknowledgments
We thank Dr. Timothy S. Tracy, West Virginia University, for
helpful discussions.
1
esis of Parkinson’s disease. Can J Neurol Sci 11:160–165.
Langston JW and Ballard PA Jr (1983) Parkinson’s disease in a chemist working
with 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine. N Engl J Med 309:310.
Langston JW, Irwin I, Langston EB, and Forno LS (1984) 1-Methyl-4-phenylpyri-
dinium ion (MPPϩ): identification of a metabolite of MPTP, a toxin selective to the
substantia nigra. Neurosci Lett 48:87–92.
Lutes J, Lorden JF, Beales M, and Oltmans GA (1988) Tolerance to the tremorogenic
effects of harmaline: evidence for altered olivo-cerebellar function. Neuropharma-
cology 27:849–855.
Mahgoub A, Idle JR, Dring LG, Lancaster R, and Smith RL (1977) Polymorphic
hydroxylation of debrisoquine in man. Lancet 2:584–586.
Matsubara K (1998) [Metabolic activation of azaheterocyclics induced dopaminergic
toxicity: possible candidate neurotoxins underlying idiopathic Parkinson’s dis-
ease]. Nippon Hoigaku Zasshi 52:301–305.
Matsubara K, Aoyama K, Suno M, and Awaya T (2002) N-methylation underlying
Parkinson’s disease. Neurotoxicol Teratol 24:593.
Matsubara K, Collins MA, Akane A, Ikebuchi J, Neafsey EJ, Kagawa M, and Shiono
H (1993) Potential bioactivated neurotoxicants, N-methylated beta-carbolinium
ions, are present in human brain. Brain Res 610:90–96.
McCann SJ, Pond SM, James KM, and Le Couteur DG (1997) The association
between polymorphisms in the cytochrome P-450 2D6 gene and Parkinson’s dis-
ease: a case-control study and meta-analysis. J Neurol Sci 153:50–53.
References
Abdel-Fattah AF, Matsumoto K, Gammaz HA, and Watanabe H (1995) Hypothermic
effect of harmala alkaloid in rats: involvement of serotonergic mechanism. Phar-
macol Biochem Behav 52:421–426.
Airaksinen MM and Kari I (1981) beta-Carbolines, psychoactive compounds in the
mammalian body. Part II: Effects. Med Biol 59:190–211.
Aoyama K, Matsubara K, Okada K, Fukushima S, Shimizu K, Yamaguchi S, Uezono
T, Satomi M, Hayase N, Ohta S, et al. (2000) N-methylation ability for azahetero-
cyclic amines is higher in Parkinson’s disease: nicotinamide loading test. J Neural
Transm 107:985–995.
Beck
tetrahydro-beta-carboline in tissues and body fluids of rat. Biochem Pharmacol
2:1507–1510.
O and Lundman A (1983) Occurrence of 6-hydroxy-1-methyl-1,2,3,4-
3
Boeira JM, Viana AF, Picada JN, and Henriques JA (2002) Genotoxic and recombi-
nogenic activities of the two beta-carboline alkaloids harman and harmine in
Saccharomyces cerevisiae. Mutat Res 500:39–48.
Budavri S, O’Neil MJ, Smith A, Heckelman PE, Kinneary JF, and O’Neill M (1996)
The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals, 12th ed,
CRC Press LLC, Boca Raton, FL.
Burke MD and Upshall DG (1976) Species and phenobarbitone-induced differences