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Voon SM, Ng KY, Chye SM, Ling APK, Voon KGL, Yap YJ, Koh RY. The Mechanism of Action of Salsolinol in Brain: Implications in Parkinson's Disease. CNS & NEUROLOGICAL DISORDERS-DRUG TARGETS 2021; 19:725-740. [PMID: 32881676 DOI: 10.2174/1871527319666200902134129] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 07/26/2020] [Accepted: 07/29/2020] [Indexed: 11/22/2022]
Abstract
1-Methyl-1,2,3,4-tetrahydroisoquinoline-6,7-diol, commonly known as salsolinol, is a compound derived from dopamine. It was first discovered in 1973 and has gained attention for its role in Parkinson's disease. Salsolinol and its derivatives were claimed to play a role in the pathogenesis of Parkinson's disease as a neurotoxin that induces apoptosis of dopaminergic neurons due to its structural similarity to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and its ability to induce Parkinsonism. In this article, we discussed the biosynthesis, distribution and blood-brain barrier permeability of salsolinol. The roles of salsolinol in a healthy brain, particularly the interactions with enzymes, hormone and catecholamine, were reviewed. Finally, we discussed the involvement of salsolinol and its derivatives in the pathogenesis of Parkinson's disease.
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Affiliation(s)
- Shee Man Voon
- Division of Applied Biomedical Science and Biotechnology, School of Health Sciences, International Medical University, Kuala Lumpur, Malaysia
| | - Khuen Yen Ng
- School of Pharmacy, Monash University Malaysia, Bandar Sunway, Malaysia
| | - Soi Moi Chye
- Division of Applied Biomedical Science and Biotechnology, School of Health Sciences, International Medical University, Kuala Lumpur, Malaysia
| | - Anna Pick Kiong Ling
- Division of Applied Biomedical Science and Biotechnology, School of Health Sciences, International Medical University, Kuala Lumpur, Malaysia
| | - Kenny Gah Leong Voon
- Pathology Division, School of Medicine, International Medical University, Kuala Lumpur, Malaysia
| | - Yiing Jye Yap
- Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Malaysia
| | - Rhun Yian Koh
- Division of Applied Biomedical Science and Biotechnology, School of Health Sciences, International Medical University, Kuala Lumpur, Malaysia
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Kurnik-Łucka M, Panula P, Bugajski A, Gil K. Salsolinol: an Unintelligible and Double-Faced Molecule-Lessons Learned from In Vivo and In Vitro Experiments. Neurotox Res 2017; 33:485-514. [PMID: 29063289 PMCID: PMC5766726 DOI: 10.1007/s12640-017-9818-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 08/19/2017] [Accepted: 09/08/2017] [Indexed: 12/29/2022]
Abstract
Salsolinol (1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline) is a tetrahydroisoquinoline derivative whose presence in humans was first detected in the urine of Parkinsonian patients on l-DOPA (l-dihydroxyphenylalanine) medication. Thus far, multiple hypotheses regarding its physiological/pathophysiological roles have been proposed, especially related to Parkinson’s disease or alcohol addiction. The aim of this review was to outline studies related to salsolinol, with special focus on in vivo and in vitro experimental models. To begin with, the chemical structure of salsolinol together with its biochemical implications and the role in neurotransmission are discussed. Numerous experimental studies are summarized in tables and the most relevant ones are stressed. Finally, the ability of salsolinol to cross the blood–brain barrier and its possible double-faced neurobiological potential are reviewed.
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Affiliation(s)
- Magdalena Kurnik-Łucka
- Department of Pathophysiology, Jagiellonian University Medical College, Czysta 18, 30-121, Krakow, Poland.
| | - Pertti Panula
- Department of Anatomy and Neuroscience Centre, University of Helsinki, Helsinki, Finland
| | - Andrzej Bugajski
- Department of Pathophysiology, Jagiellonian University Medical College, Czysta 18, 30-121, Krakow, Poland
| | - Krzysztof Gil
- Department of Pathophysiology, Jagiellonian University Medical College, Czysta 18, 30-121, Krakow, Poland
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Wang R, Qing H, Liu XQ, Zheng XL, Deng YL. Iron contributes to the formation of catechol isoquinolines and oxidative toxicity induced by overdose dopamine in dopaminergic SH-SY5Y cells. Neurosci Bull 2008; 24:125-32. [PMID: 18500384 DOI: 10.1007/s12264-008-1214-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVE The selective loss of dopaminergic neurons in Parkinson's disease is suspected to correlate with the increase of cellular iron, which may be involved in the pathogenesis of PD by promotion of oxidative stress. This research investigated dopamine-induced oxidative stress toxicity contributed by iron and the production of dopamine-derived neurotoxins in dopaminergic SH-SY5Y cells. METHODS After the SH-SY5Y cells were pre-incubated with dopamine and Fe2+ for 24 h, the cell viability, hydroxyl radical, melondialdehyde, cell apoptosis, and catechol isoquinolines were measured by lactate dehydrogenase assay, salicylic acid trapping method, thiobarbuteric acid assay, Hoechst 33258 staining and HPLC-electrochemical detection (HPLC-ECD), respectively. RESULTS (1) Optimal dopamine (150 micromol/L) and Fe2+ (40 or 80 micromol/L) significantly increased the concentrations of hydroxy radicals and melondialdehyde in SH-SY5Y cells. (2) Induction with dopamine alone or dopamine and Fe2+ (dopamine/Fe2+) caused cell apoptosis. (3) Compared with untreated cells, the catechol isoquinolines, salsolinol and N-methyl-salsolinol in dopamine/Fe2+-induced cells were detected in increasing amounts. CONCLUSION Due to dopamine/Fe2+-induced oxidative stress similar to the state in the parkinsonian substantia nigra neurons, dopamine and Fe2+ impaired SH-SY5Y cells could be used as the cell oxidative stress model of Parkinson's disease. The catechol isoquinolines detected in cells may be involved in the pathogenesis of Parkinson's disease as potential neurotoxins.
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Affiliation(s)
- Ran Wang
- School of Life Science and Technology, Beijing Institute of Technology, Beijing, China
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Naoi M, Maruyama W, Nagy GM. Dopamine-Derived Salsolinol Derivatives as Endogenous Monoamine Oxidase Inhibitors: Occurrence, Metabolism and Function in Human Brains. Neurotoxicology 2004; 25:193-204. [PMID: 14697894 DOI: 10.1016/s0161-813x(03)00099-8] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Salsolinol, 1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline, is an endogenous catechol isoquinoline detected in humans by M. Sandler. In human brain, a series of catechol isoquinolines were identified as the condensation products of dopamine or other monoamines with aldehydes or keto-acids. Recently selective occurrence of the (R)enantiomers of salsolinol derivatives was confirmed in human brain, and they are synthesized by enzymes in situ, but not by the non-enzymatic Pictet-Spengler reaction. A (R)salsolinol synthase catalyzes the enantio-specific synthesis of (R)salsolinol from dopamine and acetaldehyde, and (R)salsolinol N-methyltransferase synthesizes N-methyl(R)salsolinol, which is further oxidized into 1,2-dimethyl-6,7-dihydroxyisoquinolinium ion by non-enzymatic and enzymatic oxidation. The step-wise reactions, N-methylation and oxidation, induce the specified distribution of the N-methylated and oxidized derivatives in the human nigro-striatum, suggesting that these derivatives may be involved in the function of dopamine neurons under physiological and pathological conditions. As shown by in vivo and in vitro experiments, salsolinol derivatives affect the levels of monoamine neurotransmitters though the inhibition of enzymes related in the metabolism of catechol- and indoleamines. In addition, the selective neurotoxicity of N-methyl(R)salsolinol to dopamine neurons was confirmed by preparation of an animal model of Parkinson's disease in rats. The involvement of N-methyl(R)salsolinol in the pathogenesis of Parkinson's disease was further indicated by the increase in the N-methyl(R)salsolinol levels in the cerebrospinal fluid and that in the activity of its synthesizing enzyme, a neural (R)salsolinol N-methyltransferase, in the lymphocytes prepared from parkinsonian patients. N-methyl(R)salsolinol induces apoptosis in dopamine neurons, which is mediated by death signal transduction in mitochondria. In addition, salsolinol was found to function as a signal transmitter for the prolactin release in the neuro-intermediate lobe of the brain. These results are discussed in relation to role of dopamine-derived endogenous salsolinol derivatives as the regulators of neurotransmission, dopaminergic neurotoxins and neuro-hormonal transmitters in the human brain.
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Affiliation(s)
- Makoto Naoi
- Department of Brain Sciences, Institute of Applied Biochemistry, Yagi Memorial Park, Matake, Gifu 505-0116, Japan.
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Stokes AH, Xu Y, Daunais JA, Tamir H, Gershon MD, Butkerait P, Kayser B, Altman J, Beck W, Vrana KE. p-ethynylphenylalanine: a potent inhibitor of tryptophan hydroxylase. J Neurochem 2000; 74:2067-73. [PMID: 10800950 DOI: 10.1046/j.1471-4159.2000.0742067.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Tryptophan hydroxylase (TPH) is the initial and rate-limiting enzyme in serotonin biosynthesis. The enzyme activity is dependent on molecular oxygen, a tetrahydropterin cosubstrate, and ferrous iron. The present study demonstrates that TPH is inhibited by a novel compound, p-ethynylphenylalanine (pEPA), produced by the Heck reaction of trimethylsilylacetylene with N-tertbutyloxycarbonyl-4-iodo-L-phenylalanine methyl ester. pEPA is a more potent and specific inhibitor of TPH than p-chlorophenylalanine (pCPA). In the present study, pEPA was demonstrated to inhibit competitively and reversibly TPH in vitro (Ki = 32.6 +/- 6.2 microM vs. tryptophan). pEPA displayed little inhibitory activity toward tyrosine hydroxylase (EC 1.14.16.2), the initial and rate-limiting enzyme for catecholamine biosynthesis, and no inhibition of phenylalanine hydroxylase or tyrosinase. In addition, pEPA was a poor ligand for the serotonin transporter and several serotonin receptors. Administration of pEPA (30 mg/kg) to rats produced a 95 +/- 5% decrease in TPH activity in brain homogenates and a concomitant decrease in serotonin and 5-hydroxyindole-3-acetic acid levels (85%) at 24 h after injection. In contrast, pCPA produced a similar effect (87 +/- 5% decrease in TPH activity) only at 10 times the concentration (300 mg/kg). These results suggest that pEPA is a selective, reversible, and potent inhibitor of TPH both in vitro and in vivo. The potential for pEPA to inhibit selectively and reversibly the biosynthesis of serotonin may contribute to the characterization of the role of serotonin in behavioral and physiological activities.
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Affiliation(s)
- A H Stokes
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157-1083, USA
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Affiliation(s)
- T. Joseph Kappock
- Department of Chemistry, Yale University, P.O. Box 208107 New Haven, Connecticut 06520-8107
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Matsubara K, Kobayashi Y, Tanabe Y, Maruyama W, Ishinaga Y, Idzu T, Kimura K, Naoi M. Modulation of tryptophan hydroxylase activity in vitro by ethanol depends on biopterin cofactor concentration. Alcohol 1996; 13:455-9. [PMID: 8888941 DOI: 10.1016/0741-8329(96)00033-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The mechanism of ethanol action at serotonergic neuronal systems in the brain was investigated by examining the effects of alcohols on the activity of tryptophan hydroxylase (TPH) in vitro using natural type of biopterin as cofactor. Alcohols inhibited the activity of TPH prepared from rat brain in a noncompetitive manner with respect to both the biopterin cofactor and the L-tryptophan substrate. The rank order of inhibitory potency of the tested alcohols was n-propanol > iso-propanol > ethanol > methanol. The kinetic study indicated that alcohols more potently affected the enzyme interaction with cofactor than substrate. Ethanol, at concentrations that can be reasonably attained in vivo (i.e., 25-100 mM) significantly decreased TPH activity in the presence of a physiological concentration of cofactor. However, the reduction was only approximately 5% of control activity, because Ki, values of ethanol for the enzyme were very high (800-1000 mM). From the present results, it was concluded that the direct inhibition of the synthetic enzyme itself by ethanol would contribute little to in vivo effects of ethanol on serotonergic neuronal systems.
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Affiliation(s)
- K Matsubara
- Legal Medicine Department, Shimane Medical University, Izumo, Japan
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Naoi M, Maruyama W, Dostert P. Dopamine-derived 6,7-dihydroxy-1,2,3,4-tetrahydroisoquinolines; oxidation and neurotoxicity. PROGRESS IN BRAIN RESEARCH 1995; 106:227-39. [PMID: 8584658 DOI: 10.1016/s0079-6123(08)61219-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- M Naoi
- Department of Biosciences, Nagoya Institute of Technology, Japan
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