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Subunit-Specific Photocontrol of Glycine Receptors by Azobenzene-Nitrazepam Photoswitcher. eNeuro 2021; 8:ENEURO.0294-20.2020. [PMID: 33298457 PMCID: PMC7877471 DOI: 10.1523/eneuro.0294-20.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 11/04/2020] [Accepted: 11/23/2020] [Indexed: 12/24/2022] Open
Abstract
Photopharmacology is a unique approach that through a combination of photochemistry methods and advanced life science techniques allows the study and control of specific biological processes, ranging from intracellular pathways to brain circuits. Recently, a first photochromic channel blocker of anion-selective GABAA receptors, the azobenzene-nitrazepam-based photochromic compound (Azo-NZ1), has been described. In the present study, using patch-clamp technique in heterologous system and in mice brain slices, site-directed mutagenesis and molecular modeling we provide evidence of the interaction of Azo-NZ1 with glycine receptors (GlyRs) and determine the molecular basis of this interaction. Glycinergic synaptic neurotransmission determines an important inhibitory drive in the vertebrate nervous system and plays a crucial role in the control of neuronal circuits in the spinal cord and brain stem. GlyRs are involved in locomotion, pain sensation, breathing, and auditory function, as well as in the development of such disorders as hyperekplexia, epilepsy, and autism. Here, we demonstrate that Azo-NZ1 blocks in a UV-dependent manner the activity of α2 GlyRs (GlyR2), while being barely active on α1 GlyRs (GlyR1). The site of Azo-NZ1 action is in the chloride-selective pore of GlyR at the 2’ position of transmembrane helix 2 and amino acids forming this site determine the difference in Azo-NZ1 blocking activity between GlyR2 and GlyR1. This subunit-specific modulation is also shown on motoneurons of brainstem slices from neonatal mice that switch during development from expressing “fetal” GlyR2 to “adult” GlyR1 receptors.
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Abstract
The inhibitory glycine receptor is a member of the Cys-loop superfamily of ligand-gated ion channels. It is the principal mediator of rapid synaptic inhibition in the spinal cord and brainstem and plays an important role in the modulation of higher brain functions including vision, hearing, and pain signaling. Glycine receptor function is controlled by only a few agonists, while the number of antagonists and positive or biphasic modulators is steadily increasing. These modulators are important for the study of receptor activation and regulation and have found clinical interest as potential analgesics and anticonvulsants. High-resolution structures of the receptor have become available recently, adding to our understanding of structure-function relationships and revealing agonistic, inhibitory, and modulatory sites on the receptor protein. This Review presents an overview of compounds that activate, inhibit, or modulate glycine receptor function in vitro and in vivo.
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Affiliation(s)
- Ulrike Breitinger
- Department of Biochemistry, German University in Cairo, New Cairo 11835, Egypt
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Nguyen HTT, Jang SH, Park SJ, Cho DH, Han SK. Potentiation of the Glycine Response by Bisphenol A, an Endocrine Disrupter, on the Substantia Gelatinosa Neurons of the Trigeminal Subnucleus Caudalis in Mice. Chem Res Toxicol 2020; 33:782-788. [PMID: 31997638 DOI: 10.1021/acs.chemrestox.9b00405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Lamina II, also called the substantia gelatinosa (SG) of the medullary dorsal horn (the trigeminal subnucleus caudalis, Vc), is thought to play an essential role in the control of orofacial nociception because it receives the nociceptive signals from primary afferents, including thin myelinated Aδ- and unmyelinated C-fibers. Glycine, the main inhibitory neurotransmitter in the central nervous system, plays an essential role in the transference of nociceptive messages from the periphery to higher brain regions. Bisphenol A (BPA) is reported to alter the morphological and functional characteristics of neuronal cells and to be an effector of a great number of ion channels in the central nervous system. However, the electrophysiological effects of BPA on the glycine receptors of SG neurons in the Vc have not been well studied. Therefore, in this study, we used the whole-cell patch-clamp technique to determine the effect of BPA on the glycine response in SG neurons of the Vc in male mice. We demonstrated that in early neonatal mice (0-3 postnatal day mice), BPA did not affect the glycine-induced inward current. However, in the juvenile and adult groups, BPA enhanced the glycine-mediated responses. Heteromeric glycine receptors were involved in the modulation by BPA. The interaction between BPA and glycine appears to have a significant role in regulating transmission in the nociceptive pathway.
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Affiliation(s)
- Hoang Thi Thanh Nguyen
- Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Jeonbuk National University, Jeonju, 54896, Republic of Korea.,Faculty of Odonto-Stomatology, Hue University of Medicine and Pharmacy, Hue University, Hue, Vietnam
| | - Seon Hui Jang
- Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Jeonbuk National University, Jeonju, 54896, Republic of Korea
| | - Soo Joung Park
- Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Jeonbuk National University, Jeonju, 54896, Republic of Korea
| | - Dong Hyu Cho
- Department of Obstetrics and Gynecology, Jeonbuk National University Medical School, Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute and Institute for Medical Sciences, Jeonbuk National University Hospital, Jeonju, 54907, Republic of Korea
| | - Seong Kyu Han
- Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Jeonbuk National University, Jeonju, 54896, Republic of Korea
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Nishimon S, Yamaguchi M, Muraki H, Sakai N, Nishino S. Intraperitoneal injection of ginkgolide B, a major active compound of Ginkgo biloba, dose-dependently increases the amount of wake and decreases non-rapid eye movement sleep in C57BL/6 mice. Neurosci Lett 2020; 722:134832. [PMID: 32050100 DOI: 10.1016/j.neulet.2020.134832] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 02/06/2020] [Accepted: 02/07/2020] [Indexed: 12/22/2022]
Abstract
The terpene lactones of Ginkgo biloba extract, namely ginkgolides (A, B, and C) and bilobalide, possess antioxidant, anti-inflammatory, and neuroprotective effects. They are widely prescribed for the treatment of cerebral dysfunctions and neurological impairments. In addition, they demonstrate antagonistic action at the gamma-aminobutyric acid type A and glycine receptors, which are members of the ligand-gated ion channel superfamily. In the present study, the effects of ginkgolides (A, B, and C) and bilobalide on sleep in C57BL/6 mice were investigated. Ginkgolide B was found to dose-dependently increase the amount of wake and decrease that of non-rapid eye movement sleep without changes in the electroencephalography power density of each sleep/wake stage, core body temperature and locomotor activity for the first 6 h after intraperitoneal injection. Of note, the amount of wake after injection of 5 mg/kg of ginkgolide B showed a significant increase (14.9 %) compared with that of vehicle (P = 0.005). In contrast, there were no significant differences in the amount of sleep, core body temperature, and locomotor activity in the mice injected with ginkgolide A and C. Bilobalide briefly induced a decrease in locomotor activity but did not exert significant effects on the amounts of sleep and wake. The modes of action of the wake-enhancing effects of ginkgolide B are unknown. However, it may act through the antagonism of gamma-aminobutyric acid type A and glycine receptors because it is established that these inhibitory amino acids mediate sleep and sleep-related physiology. It is of interest to further evaluate the stimulant and awaking actions of ginkgolide B on the central nervous system in clinical and basic research studies.
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Affiliation(s)
- Shohei Nishimon
- Sleep and Circadian Neurobiology Laboratory, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Mai Yamaguchi
- Sleep and Circadian Neurobiology Laboratory, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Hisae Muraki
- Sleep Medical Center, Osaka Kaisei Hospital, Osaka, Japan
| | - Noriaki Sakai
- Sleep and Circadian Neurobiology Laboratory, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Seiji Nishino
- Sleep and Circadian Neurobiology Laboratory, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, CA, USA.
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5
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Maleeva G, Peiretti F, Zhorov BS, Bregestovski P. Voltage-Dependent Inhibition of Glycine Receptor Channels by Niflumic Acid. Front Mol Neurosci 2017; 10:125. [PMID: 28559795 PMCID: PMC5432571 DOI: 10.3389/fnmol.2017.00125] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2017] [Accepted: 04/12/2017] [Indexed: 01/11/2023] Open
Abstract
Niflumic acid (NFA) is a member of the fenamate class of nonsteroidal anti-inflammatory drugs. This compound and its derivatives are used worldwide clinically for the relief of chronic and acute pain. NFA is also a commonly used blocker of voltage-gated chloride channels. Here we present evidence that NFA is an efficient blocker of chloride-permeable glycine receptors (GlyRs) with subunit heterogeneity of action. Using the whole-cell configuration of patch-clamp recordings and molecular modeling, we analyzed the action of NFA on homomeric α1ΔIns, α2B, α3L, and heteromeric α1β and α2β GlyRs expressed in CHO cells. NFA inhibited glycine-induced currents in a voltage-dependent manner and its blocking potency in α2 and α3 GlyRs was higher than that in α1 GlyR. The Woodhull analysis suggests that NFA blocks α1 and α2 GlyRs at the fractional electrical distances of 0.16 and 0.65 from the external membrane surface, respectively. Thus, NFA binding site in α1 GlyR is closer to the external part of the membrane, while in α2 GlyR it is significantly deeper in the pore. Mutation G254A at the cytoplasmic part of the α1 GlyR pore-lining TM2 helix (level 2') increased the NFA blocking potency, while incorporation of the β subunit did not have a significant effect. The Hill plot analysis suggests that α1 and α2 GlyRs are preferably blocked by two and one NFA molecules, respectively. Molecular modeling using Monte Carlo energy minimizations provides the structural rationale for the experimental data and proposes more than one interaction site along the pore where NFA can suppress the ion permeation.
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Affiliation(s)
- Galyna Maleeva
- INSERM, INS, Institut de Neurosciences des Systèmes, Aix-Marseille UniversityMarseille, France.,Department of Cytology, Bogomoletz Institute of PhysiologyKyiv, Ukraine
| | - Franck Peiretti
- INSERM 1062, INRA 1260, NORT, Aix-Marseille UniversityMarseille, France
| | - Boris S Zhorov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of SciencesSt. Petersburg, Russia.,Department of Biochemistry and Biomedical Sciences, McMaster UniversityHamilton, ON, Canada
| | - Piotr Bregestovski
- INSERM, INS, Institut de Neurosciences des Systèmes, Aix-Marseille UniversityMarseille, France.,Department of Physiology, Kazan State Medical UniversityKazan, Russia
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6
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Lynch JW, Zhang Y, Talwar S, Estrada-Mondragon A. Glycine Receptor Drug Discovery. ADVANCES IN PHARMACOLOGY 2017; 79:225-253. [DOI: 10.1016/bs.apha.2017.01.003] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Nakahata Y, Eto K, Murakoshi H, Watanabe M, Kuriu T, Hirata H, Moorhouse AJ, Ishibashi H, Nabekura J. Activation-Dependent Rapid Postsynaptic Clustering of Glycine Receptors in Mature Spinal Cord Neurons. eNeuro 2017; 4:ENEURO.0194-16.2017. [PMID: 28197549 PMCID: PMC5292596 DOI: 10.1523/eneuro.0194-16.2017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 01/05/2017] [Accepted: 01/17/2017] [Indexed: 12/02/2022] Open
Abstract
Inhibitory synapses are established during development but continue to be generated and modulated in strength in the mature nervous system. In the spinal cord and brainstem, presynaptically released inhibitory neurotransmitter dominantly switches from GABA to glycine during normal development in vivo. While presynaptic mechanisms of the shift of inhibitory neurotransmission are well investigated, the contribution of postsynaptic neurotransmitter receptors to this shift is not fully elucidated. Synaptic clustering of glycine receptors (GlyRs) is regulated by activation-dependent depolarization in early development. However, GlyR activation induces hyperpolarization after the first postnatal week, and little is known whether and how presynaptically released glycine regulates postsynaptic receptors in a depolarization-independent manner in mature developmental stage. Here we developed spinal cord neuronal culture of rodents using chronic strychnine application to investigate whether initial activation of GlyRs in mature stage could change postsynaptic localization of GlyRs. Immunocytochemical analyses demonstrate that chronic blockade of GlyR activation until mature developmental stage resulted in smaller clusters of postsynaptic GlyRs that could be enlarged upon receptor activation for 1 h in the mature stage. Furthermore, live cell-imaging techniques show that GlyR activation decreases its lateral diffusion at synapses, and this phenomenon is dependent on PKC, but neither Ca2+ nor CaMKII activity. These results suggest that the GlyR activation can regulate receptor diffusion and cluster size at inhibitory synapses in mature stage, providing not only new insights into the postsynaptic mechanism of shifting inhibitory neurotransmission but also the inhibitory synaptic plasticity in mature nervous system.
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Affiliation(s)
- Yoshihisa Nakahata
- Division of Homeostatic Development, Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki 444-8585, Japan
- Department of Physiological Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan
| | - Kei Eto
- Division of Homeostatic Development, Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki 444-8585, Japan
- Department of Physiological Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan
| | - Hideji Murakoshi
- Department of Physiological Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan
- Supportive Center for Brain Research, National Institute for Physiological Science, Okazaki 444-8585, Japan
- PRESTO, Japan Science and Technology Agency (JST), Kawaguchi 332-0012, Japan
| | - Miho Watanabe
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan
| | - Toshihiko Kuriu
- Department of Neurophysiology, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima 769-2193, Japan
| | - Hiromi Hirata
- PRESTO, Japan Science and Technology Agency (JST), Kawaguchi 332-0012, Japan
- Division of Molecular and Developmental Biology, National Institute of Genetics, Mishima 411-8540, Japan
- Department of Genetics, The Graduate University for Advanced Studies (SOKENDAI), Mishima 411-8540, Japan
- Department of Chemistry and Biological Science, Graduate School of Science and Engineering, Aoyama Gakuin University, Sagamihara 252-5258, Japan
| | - Andrew J. Moorhouse
- Department of Physiology, School of Medical Sciences, University of New South Wales, Sydney 2052, Australia
| | - Hitoshi Ishibashi
- Division of Homeostatic Development, Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki 444-8585, Japan
- Department of Physiological Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan
- Department of Physiology, Kitasato University School of Allied Health Sciences, Sagamihara 252-0373, Japan
| | - Junichi Nabekura
- Division of Homeostatic Development, Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki 444-8585, Japan
- Department of Physiological Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan
- CREST, Japan Science and Technology Agency (JST), Kawaguchi 332-0012, Japan
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Maleeva G, Buldakova S, Bregestovski P. Selective potentiation of alpha 1 glycine receptors by ginkgolic acid. Front Mol Neurosci 2015; 8:64. [PMID: 26578878 PMCID: PMC4624854 DOI: 10.3389/fnmol.2015.00064] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Accepted: 10/16/2015] [Indexed: 12/18/2022] Open
Abstract
Glycine receptors (GlyRs) belong to the superfamily of pentameric cys-loop receptor-operated channels and are involved in numerous physiological functions, including movement, vision, and pain. In search for compounds performing subunit-specific modulation of GlyRs we studied action of ginkgolic acid, an abundant Ginkgo biloba product. Using patch-clamp recordings, we analyzed the effects of ginkgolic acid in concentrations from 30 nM to 25 μM on α1–α3 and α1/β, α2/β configurations of GlyR and on GABAARs expressed in cultured CHO-K1 cells and mouse neuroblastoma (N2a) cells. Ginkgolic acid caused an increase in the amplitude of currents mediated by homomeric α1 and heteromeric α1/β GlyRs and provoked a left-shift of the concentration-dependent curves for glycine. Even at high concentrations (10–25 μM) ginkgolic acid was not able to augment ionic currents mediated by α2, α2/β, and α3 GlyRs, or by GABAAR consisting of α1/β2/γ2 subunits. Mutation of three residues (T59A/A261G/A303S) in the α2 GlyR subunit to the corresponding ones from the α1 converted the action of ginkgolic acid to potentiation with a distinct decrease in EC50 for glycine, suggesting an important role for these residues in modulation by ginkgolic acid. Our results suggest that ginkgolic acid is a novel selective enhancer of α1 GlyRs.
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Affiliation(s)
- Galyna Maleeva
- Aix Marseille Université, INS UMR_S 1106 Marseille, France ; INSERM, UMR_S 1106 Marseille, France ; Department of Cytology, Bogomoletz Institute of Physiology Kyiv, Ukraine
| | - Svetlana Buldakova
- Aix Marseille Université, INS UMR_S 1106 Marseille, France ; INSERM, UMR_S 1106 Marseille, France
| | - Piotr Bregestovski
- Aix Marseille Université, INS UMR_S 1106 Marseille, France ; INSERM, UMR_S 1106 Marseille, France
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Ude C, Schubert-Zsilavecz M, Wurglics M. Ginkgo biloba Extracts: A Review of the Pharmacokinetics of the Active Ingredients. Clin Pharmacokinet 2013; 52:727-49. [DOI: 10.1007/s40262-013-0074-5] [Citation(s) in RCA: 159] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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10
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Wang L, Li WG, Huang C, Zhu MX, Xu TL, Wu DZ, Li Y. Subunit-specific inhibition of glycine receptors by curcumol. J Pharmacol Exp Ther 2012; 343:371-9. [PMID: 22892339 DOI: 10.1124/jpet.112.195669] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Emerging evidence has suggested that inhibitory glycine receptors (GlyRs) are an important molecular target in the treatment of numerous neurological disorders. Rhizoma curcumae is a medicinal plant with positive neurological effects. In this study, we showed that curcumol, a major bioactive component of R. curcumae, reversibly and concentration-dependently inhibited the glycine-activated current (IGly) in cultured rat hippocampal neurons. The inhibitory effect was neither voltage- nor agonist concentration-dependent. Moreover, curcumol selectively inhibited homomeric α2-containing, but not α1- or α3-containing, GlyRs. The addition of β subunit conferred the curcumol sensitivity of α3-containing, but not α1-containing, GlyRs. Site-directed mutagenesis analysis revealed that a threonine at position 59 of the α2 subunit is critical for the susceptibility of GlyRs to curcumol-mediated inhibition. Furthermore, paralleling a decline of α2 subunit expression during spinal cord development, the degree of IGly inhibition by curcumol decreased with prolonged culture of rat spinal dorsal horn neurons. Taken together, our results suggest that the GlyRs are novel molecular targets of curcumol, which may underlie its pharmaceutical effects in the central nervous system.
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Affiliation(s)
- Li Wang
- Institute of Chinese Materia Medica, Shanghai Key Laboratory of Complex Prescription, Shanghai University of Traditional Chinese Medicine, Shanghai, China
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Thompson AJ, Duke RK, Lummis SCR. Binding sites for bilobalide, diltiazem, ginkgolide, and picrotoxinin at the 5-HT3 receptor. Mol Pharmacol 2011; 80:183-90. [PMID: 21505038 PMCID: PMC3127528 DOI: 10.1124/mol.111.071415] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Accepted: 04/18/2011] [Indexed: 11/22/2022] Open
Abstract
Bilobalide (BB), ginkgolide B (GB), diltiazem (DTZ), and picrotoxinin (PXN) are 5-hydroxytryptamine type 3 (5-HT(3)) receptor antagonists in which the principal sites of action are in the channel. To probe their exact binding locations, 5-HT(3) receptors with substitutions in their pore lining residues were constructed (N-4'Q, E-1'D, S2'A, T6'S, L7'T, L9'V, S12'A, I16'V, D20'E), expressed in Xenopus laevis oocytes, and the effects of the compounds on 5-HT-induced currents were examined. EC(50) values at mutant receptors were less than 6-fold different from those of wild type, indicating that the mutations were well tolerated. BB, GB, DTZ, and PXN had pIC(50) values of 3.33, 3.14, 4.67, and 4.97, respectively. Inhibition by BB and GB was abolished in mutant receptors containing T6'S and S12'A substitutions, but their potencies were enhanced (42- and 125-fold, respectively) in S2'A mutant receptors. S2'A substitution also caused GB ligand trap. PXN potency was modestly enhanced (5-fold) in S2'A, abolished in T6'S, and reduced in L9'V (40-fold) and S12'A (7-fold) receptors. DTZ potency was reduced in L7'T and S12'A receptors (5-fold), and DTZ also displaced [(3)H]granisetron binding, indicating mixed competitive/noncompetitive inhibition. We conclude that regions close to the hydrophobic gate of M2 are important for the inhibitory effects of BB, GB, DTZ, and PXN at the 5-HT(3) receptor; for BB, GB, and PXN, the data show that the 6' channel lining residue is their major site of action, with minor roles for 2', 9', and 12' residues, whereas for DTZ, the 7' and 12' sites are important.
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Affiliation(s)
- A J Thompson
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
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12
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Thompson AJ, Jarvis GE, Duke RK, Johnston GAR, Lummis SCR. Ginkgolide B and bilobalide block the pore of the 5-HT₃receptor at a location that overlaps the picrotoxin binding site. Neuropharmacology 2010; 60:488-95. [PMID: 21059362 PMCID: PMC3070799 DOI: 10.1016/j.neuropharm.2010.11.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 11/01/2010] [Accepted: 11/01/2010] [Indexed: 12/02/2022]
Abstract
Extracts from the Ginkgo biloba tree are widely used as herbal medicines, and include bilobalide (BB) and ginkgolides A and B (GA and GB). Here we examine their effects on human 5-HT3A and 5-HT3AB receptors, and compare these to the effects of the structurally related compounds picrotin (PTN) and picrotoxinin (PXN), the two components of picrotoxin (PTX), a known channel blocker of 5-HT3, nACh and GABAA receptors. The compounds inhibited 5-HT-induced responses of 5-HT3 receptors expressed in Xenopus oocytes, with IC50 values of 470 μM (BB), 730 μM (GB), 470 μM (PTN), 11 μM (PXN) and >1 mM (GA) in 5-HT3A receptors, and 3.1 mM (BB), 3.9 mM (GB), 2.7 mM (PTN), 62 μM (PXN) and >1 mM (GA) in 5-HT3AB receptors. Radioligand binding on receptors expressed in HEK 293 cells showed none of the compounds displaced the specific 5-HT3 receptor antagonist [3H]granisetron, confirming that they do not act at the agonist binding site. Inhibition by GB at 5-HT3A receptors is weakly use-dependent, and recovery is activity dependent, indicating channel block. To further probe their site of action at 5-HT3A receptors, BB and GB were applied alone or in combination with PXN, and the results fitted to a mathematical model; the data revealed partially overlapping sites of action. We conclude that BB and GB block the channel of the 5-HT3A receptor. Thus these compounds have comparable, although less potent, behaviour than at some other Cys-loop receptors, demonstrating their actions are conserved across the family.
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Affiliation(s)
- Andrew J Thompson
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
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Jensen AA, Bergmann ML, Sander T, Balle T. Ginkgolide X is a potent antagonist of anionic Cys-loop receptors with a unique selectivity profile at glycine receptors. J Biol Chem 2010; 285:10141-10153. [PMID: 20106969 DOI: 10.1074/jbc.m109.079319] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The novel ginkgolide analog ginkgolide X was characterized functionally at human glycine and gamma-aminobutyric acid type A receptors (GlyRs and GABA(A)Rs, respectively) in the fluorescence-based FLIPR(TM) Membrane Potential assay. The compound inhibited the signaling of all GABA(A)R subtypes included in the study with high nanomolar/low micromolar IC(50) values, except the rho 1 receptor at which it was a significantly weaker antagonist. Ginkgolide X also displayed high nanomolar/low micromolar IC(50) values at the homomeric alpha1 and alpha2 GlyRs, whereas it was inactive at the heteromeric alpha 1 beta and alpha 2 beta subtypes at concentrations up to 300 microm. Thus, the functional properties of the compound were significantly different from those of the naturally occurring ginkgolides A, B, C, J, and M but similar to those of picrotoxin. In a mutagenesis study the 6' M2 residues in the GlyR ion channel were identified as the primary molecular determinant of the selectivity profile of ginkgolide X, and a 6' M2 ring consisting of five Thr residues was found to be of key importance for its activity at the GABA(A)R. Conformational analysis and docking of low-energy conformations of the native ginkgolide A and ginkgolide X into a alpha1 GlyR homology model revealed two distinct putative binding sites formed by the 6' M2 residues together with the 2' residues and the 10' and 13' residues, respectively. Thus, we propose that the distinct functionalities of ginkgolide X compared with the other ginkgolides could arise from different flexibility and thus different binding modes to the ion channel of the anionic Cys-loop receptor.
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Affiliation(s)
- Anders A Jensen
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
| | - Marianne L Bergmann
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Tommy Sander
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Thomas Balle
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
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Nonaka K, Kondratskaya E, Maeda M, Yamaga T, Murayama N, Shin MC, Akaike N. Modulation of Glycinergic Transmission in the Rat Spinal Dorsal Commissural Nucleus by Ginkgolide B. NEUROPHYSIOLOGY+ 2010. [DOI: 10.1007/s11062-010-9104-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Maksay G, Laube B, Schemm R, Grudzinska J, Drwal M, Betz H. Different binding modes of tropeines mediating inhibition and potentiation of α1 glycine receptors. J Neurochem 2009; 109:1725-32. [DOI: 10.1111/j.1471-4159.2009.06083.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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16
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Schumann T, Grudzinska J, Kuzmin D, Betz H, Laube B. Binding-site mutations in the α1 subunit of the inhibitory glycine receptor convert the inhibitory metal ion Cu2+ into a positive modulator. Neuropharmacology 2009; 56:310-7. [DOI: 10.1016/j.neuropharm.2008.08.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2008] [Revised: 07/31/2008] [Accepted: 08/08/2008] [Indexed: 10/21/2022]
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17
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Lynch JW. Native glycine receptor subtypes and their physiological roles. Neuropharmacology 2008; 56:303-9. [PMID: 18721822 DOI: 10.1016/j.neuropharm.2008.07.034] [Citation(s) in RCA: 286] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2008] [Revised: 07/24/2008] [Accepted: 07/27/2008] [Indexed: 01/17/2023]
Abstract
The glycine receptor chloride channel (GlyR), a member of the pentameric Cys-loop ion channel receptor family, mediates inhibitory neurotransmission in the spinal cord, brainstem and retina. They are also found presynaptically, where they modulate neurotransmitter release. Functional GlyRs are formed from a total of five subunits (alpha1-alpha4, beta). Although alpha subunits efficiently form homomeric GlyRs in recombinant expression systems, homomeric alpha1, alpha3 and alpha4 GlyRs are weakly expressed in adult neurons. In contrast, alpha2 homomeric GlyRs are abundantly expressed in embryonic neurons, although their numbers decline sharply by adulthood. Numerous lines of biochemical, biophysical, pharmacological and genetic evidence suggest the majority of glycinergic neurotransmission in adults is mediated by heteromeric alpha1beta GlyRs. Immunocytochemical co-localisation experiments suggest the presence of alpha2beta, alpha3beta and alpha4beta GlyRs at synapses in the adult mouse retina. Immunocytochemical and electrophysiological evidence also implicates alpha3beta GlyRs as important mediators of glycinergic inhibitory neurotransmission in nociceptive sensory neuronal circuits in peripheral laminae of the spinal cord dorsal horn. It is yet to be determined why multiple GlyR synaptic subtypes are differentially distributed in these and possibly other locations. The development of pharmacological agents that can discriminate strongly between different beta subunit-containing GlyR isoforms will help to address this issue, and thereby provide important insights into a variety of central nervous system functions including retinal signal processing and spinal pain mechanisms. Finally, agents that selectively potentiate different GlyR isoforms may be useful as therapeutic lead compounds for peripheral inflammatory pain and movement disorders such as spasticity.
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Affiliation(s)
- Joseph W Lynch
- Queensland Brain Institute and School of Biomedical Sciences, University of Queensland, Brisbane QLD 4072, Australia.
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18
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Chen X, Cromer B, Webb TI, Yang Z, Hantke J, Harvey RJ, Parker MW, Lynch JW. Dihydropyridine inhibition of the glycine receptor: subunit selectivity and a molecular determinant of inhibition. Neuropharmacology 2008; 56:318-27. [PMID: 18657556 DOI: 10.1016/j.neuropharm.2008.07.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2008] [Revised: 06/24/2008] [Accepted: 07/01/2008] [Indexed: 01/29/2023]
Abstract
The dihydropyridines (DHPs), nifedipine and nicardipine, modulate native glycine receptors (GlyRs) at micromolar concentrations. Nicardipine has a biphasic potentiating and inhibitory effect, whereas nifedipine causes inhibition only. The present study sought to investigate (1) the molecular mechanism by which these compounds inhibit recombinant GlyRs, and (2) their potential utility as subunit-selective inhibitors of alpha1, alpha1beta, alpha3 and alpha3beta GlyRs. The rate of onset of inhibition in the open state was accelerated by pre-application of DHP in the closed state, with the degree of acceleration proportional to the concentration of pre-applied DHP. This implies a non-inhibitory binding site close to the DHP inhibitory site. DHP inhibition was use-dependent and independent of glycine concentration, consistent with a pore-blocking mode of action. DHP sensitivity was abolished by the G2'A mutation, providing a strong case for a DHP binding site in the pore. Nifedipine exhibited an approximately 10-fold higher inhibitory potency at alpha1-containing relative to alpha3-containing receptors, whereas nicardipine was only weakly selective for alpha1-containing GlyRs. The differential sensitivities of nifedipine and nicardipine for different GlyR isoforms suggest that DHPs may be a useful resource to screen as pharmacological tools for selectively inhibiting different synaptic GlyR isoforms.
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Affiliation(s)
- Xuebin Chen
- School of Biomedical Sciences and Queensland Brain Institute, University of Queensland, Brisbane, QLD 4072, Australia
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19
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Lynch JW, Chen X. Subunit-specific potentiation of recombinant glycine receptors by NV-31, a bilobalide-derived compound. Neurosci Lett 2008; 435:147-51. [PMID: 18329806 DOI: 10.1016/j.neulet.2008.02.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2007] [Revised: 02/04/2008] [Accepted: 02/12/2008] [Indexed: 11/20/2022]
Abstract
Bilobalide, a major bioactive component of Ginkgo biloba herbal extracts, exhibits neuroprotective and anti-ischaemic activity. However, its therapeutic potential is limited because of its instability. Attempts to synthesise a more stable analogue culminated in the development of NV-31. This compound recapitulates some aspects of bilobalide pharmacology. However, although bilobalide inhibits recombinant glycine receptor Cl channels (GlyRs), NV-31 potentiates hippocampal neuron GlyRs. Because of the possible therapeutic relevance of this effect, the present study investigated the molecular mechanism and subunit specificity of NV-31 actions at recombinantly expressed alpha1, alpha1beta, alpha2 and alpha3 GlyRs. NV-31 potentiated alpha1 GlyRs by approximately 135% with an EC50 near 170 nM. Its potentiating effect was observed only at low (EC10) glycine concentrations. The magnitude of its potentiating effect was reduced at alpha1beta GlyRs and it had no effect at all at alpha2 and alpha3 GlyRs. NV-31 was unlikely to bind at the bilobalide pore-binding site as its efficacy was not affected by the alpha1 subunit G2'A and T6'S mutations. However, the S15'C mutation to the alcohol-binding site abolished its effects, suggesting that NV-31 modulates the GlyR via a specific (steric or allosteric) interaction with S15'. GlyRs are potential therapeutic targets for chronic anti-inflammatory pain and movement disorders. NV-31, as a positive modulator of these receptors, thus remains viable as a therapeutic candidate for these disorders.
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Affiliation(s)
- Joseph W Lynch
- School of Biomedical Sciences and Queensland Brain Institute, University of Queensland, Brisbane, QLD 4072, Australia.
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20
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Heads JA, Hawthorne RL, Lynagh T, Lynch JW. Structure-activity analysis of ginkgolide binding in the glycine receptor pore. J Neurochem 2008; 105:1418-27. [PMID: 18221374 DOI: 10.1111/j.1471-4159.2008.05244.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ginkgolides, active constituents of Ginkgo biloba extracts, potently block the glycine receptor chloride channel (GlyR). Ginkgolides A, B, C and J are structurally similar, varying only by the presence or absence of oxygens at their R1 and R2 positions. The aim of this study was to understand how variable ginkgolide groups bind to pore-lining 2' and 6' residues in the alpha1 GlyR. Ginkgolide potency was not affected by G2'A or G2'S mutations, suggesting 2' residues are not important for ginkgolide coordination. Analysis of the alpha1(T6'S) GlyR suggests that ginkgolides bind to this receptor via hydrogen bonds between T6'S and ginkgolide R1 hydroxyls. The abolition of block by the T6'A and T6'V mutations but not by the T6'S mutation implies the existence a second transmembrane domain alpha-helical kink formed by hydrogen bonding between 6' threonine and serine sidechains and backbone carbonyl oxygens. We also found that ginkgolide A binds in different orientations in the closed and open states of a mutant GlyR, possibly reflecting its enhanced flexibility relative to other ginkgolides. Together these results indicate that small variations in ginkgolide structure or pore structure can lead to drastic potency variations. This property may be exploited to create improved pharmacological probes for discriminating among anionic Cys-loop receptor isoforms with 6' structural variations.
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Affiliation(s)
- Judith A Heads
- School of Biomedical Sciences, University of Queensland, Brisbane, QLD, Australia
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21
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Pless SA, Dibas MI, Lester HA, Lynch JW. Conformational variability of the glycine receptor M2 domain in response to activation by different agonists. J Biol Chem 2007; 282:36057-67. [PMID: 17911099 DOI: 10.1074/jbc.m706468200] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Models describing the structural changes mediating Cys loop receptor activation generally give little attention to the possibility that different agonists may promote activation via distinct M2 pore-lining domain structural rearrangements. We investigated this question by comparing the effects of different ligands on the conformation of the external portion of the homomeric alpha1 glycine receptor M2 domain. Conformational flexibility was assessed by tethering a rhodamine fluorophore to cysteines introduced at the 19' or 22' positions and monitoring fluorescence and current changes during channel activation. During glycine activation, fluorescence of the label attached to R19'C increased by approximately 20%, and the emission peak shifted to lower wavelengths, consistent with a more hydrophobic fluorophore environment. In contrast, ivermectin activated the receptors without producing a fluorescence change. Although taurine and beta-alanine were weak partial agonists at the alpha1R19'C glycine receptor, they induced large fluorescence changes. Propofol, which drastically enhanced these currents, did not induce a glycine-like blue shift in the spectral emission peak. The inhibitors strychnine and picrotoxin elicited fluorescence and current changes as expected for a competitive antagonist and an open channel blocker, respectively. Glycine and taurine (or beta-alanine) also produced an increase and a decrease, respectively, in the fluorescence of a label attached to the nearby L22'C residue. Thus, results from two separate labeled residues support the conclusion that the glycine receptor M2 domain responds with distinct conformational changes to activation by different agonists.
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Affiliation(s)
- Stephan A Pless
- School of Biomedical Sciences, University of Queensland, Brisbane, Queensland 4072, Australia
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22
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Sun H, Cheng XP, You-Ye Z, Jiang P, Zhou JN. Quercetin subunit specifically reduces GlyR-mediated current in rat hippocampal neurons. Neuroscience 2007; 148:548-59. [PMID: 17664043 DOI: 10.1016/j.neuroscience.2007.06.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Revised: 06/04/2007] [Accepted: 06/08/2007] [Indexed: 10/23/2022]
Abstract
Quercetin is a substance of low molecular weight found in vascular plants with a wide range of biological activities including antioxidative and anti-inflammatory activities. In the present study, the effects of quercetin on native glycine receptors (GlyRs) in cultured rat hippocampal neurons were investigated using a whole-cell patch-clamp technique. Quercetin reversibly and concentration-dependently depressed glycine-induced current (I(Gly)), with an IC50 of 10.7+/-0.24 microM and a Hill coefficient of 1.08+/-0.12. Quercetin depressed maximum I(Gly) and significantly changed the EC50 for glycine and the Hill coefficient. Kinetic analysis indicated that quercetin accelerated the rates of desensitization. Interestingly, after the end of glycine with quercetin coapplication, a transient rebound occurred. The quercetin effects also displayed voltage-dependence, being greater at positive membrane potentials. These effects suggested that quercetin may act as an open channel blocker. Furthermore, in the sequential application protocol, quercetin inhibited the peak amplitude of I(Gly) to a macroscopic degree while slowing GlyR desensitization. These effects implied that quercetin has a depressant effect independent of GlyR channel's opening, which maybe caused by an allosteric mechanism. Strikingly, quercetin inhibited the amplitude of recombinant-induced current mediated by alpha2-, alpha2beta-, alpha3- and alpha3beta-GlyRs but had no effects on alpha1- and alpha1beta-GlyRs that were expressed in HEK293T cells. We also investigated the effects of quercetin on I(Gly) in spinal neurons during development in vitro. The extent of blockade by quercetin on I(Gly) was slighter in spinal neurons than in hippocampal neurons in a development-dependent manner. Taken together, our results suggest that quercetin has possible effects in information processing within a neuronal network by inhibition of I(Gly) and may be useful as a pharmacological probe for identifying the subunit types of GlyRs.
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Affiliation(s)
- Hao Sun
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Neurobiology and Biophysics, School of Life Science, University of Science and Technology of China, Anhui, China
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23
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Jensen AA, Begum N, Vogensen SB, Knapp KM, Gundertofte K, Dzyuba SV, Ishii H, Nakanishi K, Kristiansen U, Strømgaard K. Probing the pharmacophore of ginkgolides as glycine receptor antagonists. J Med Chem 2007; 50:1610-7. [PMID: 17352465 DOI: 10.1021/jm070003n] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ginkgolides are antagonists of the inhibitory ligand-gated ion channels for the neurotransmitters glycine and gamma-aminobutyric acid (GABA). In this study the ginkgolide structure was modified in order to investigate the minimum structural requirements for glycine receptor antagonism. The five native ginkgolides and a series of 29 ginkgolide derivatives were characterized at the three glycine receptor subtypes alpha1, alpha1beta, and alpha2, which revealed that only minor changes in the ginkgolide skeleton were allowed for maintaining glycine receptor antagonism. A pharmacophore model was generated and applied in a virtual screening of a compound database (300000 compounds), resulting in the identification of 31 hits. Twenty-seven of these hits were screened for biological activity, but none displayed antagonist activity at the glycine receptors. This strongly suggests the importance of other pharmacophore components in the binding of ginkgolides to glycine receptors, and we propose that the structural rigidity of the ginkgolide molecule may be crucial for its glycine receptor activity.
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Affiliation(s)
- Anders A Jensen
- Department of Medicinal Chemistry, The Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
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24
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Hawthorne R, Cromer BA, Ng HL, Parker MW, Lynch JW. Molecular determinants of ginkgolide binding in the glycine receptor pore. J Neurochem 2006; 98:395-407. [PMID: 16805834 DOI: 10.1111/j.1471-4159.2006.03875.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Ginkgolides are potent blockers of the glycine receptor Cl- channel (GlyR) pore. We sought to identify their binding sites by comparing the effects of ginkgolides A, B and C and bilobalide on alpha1, alpha2, alpha1beta and alpha2beta GlyRs. Bilobalide sensitivity was drastically reduced by incorporation of the beta subunit. In contrast, the sensitivities to ginkgolides B and C were enhanced by beta subunit expression. However, ginkgolide A sensitivity was increased in the alpha2beta GlyR relative to the alpha2 GlyR but not in the alpha1beta GlyR relative to the alpha1 GlyR. We hypothesised that the subunit-specific differences were mediated by residue differences at the second transmembrane domain 2' and 6' pore-lining positions. The increased ginkgolide A sensitivity of the alpha2beta GlyR was transferred to the alpha1beta GlyR by the G2'A (alpha1 to alpha2 subunit) substitution. In addition, the alpha1 subunit T6'F mutation abolished inhibition by all ginkgolides. As the ginkgolides share closely related structures, their molecular interactions with pore-lining residues were amenable to mutant cycle analysis. This identified an interaction between the variable R2 position of the ginkgolides and the 2' residues of both alpha1 and beta subunits. These findings provide strong evidence for ginkgolides binding at the 2' pore-lining position.
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Affiliation(s)
- Rebecca Hawthorne
- School of Biomedical Sciences, University of Queensland, Brisbane, Queensland, Australia
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25
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Betz H, Laube B. Glycine receptors: recent insights into their structural organization and functional diversity. J Neurochem 2006; 97:1600-10. [PMID: 16805771 DOI: 10.1111/j.1471-4159.2006.03908.x] [Citation(s) in RCA: 212] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Strychnine-sensitive glycine receptors (GlyRs) are known to mediate synaptic inhibition in spinal cord, brainstem and other regions of the CNS. During the past 5 years, considerable progress has been made in delineating structural determinants of ligand binding and channel activation in recombinant GlyRs. Furthermore, immunohistochemical and gene inactivation studies have disclosed distinct distributions and functions of differentially expressed GlyR subtypes in retina, hippocampus and the dorsal horn of the spinal cord. Accordingly, GlyRs regulate not only the excitability of motor and sensory neurones, but are also essential for the processing of photoreceptor signals, neuronal development and inflammatory pain sensitization. Hence, these receptors constitute promising targets for the development of clinically useful compounds.
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Affiliation(s)
- Heinrich Betz
- Abteilung Neurochemie, Max-Planck-Institut für Hirnforschung, Frankfurt am Main, Germany.
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26
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Bolshakov S, Dzyuba SV, Decatur J, Nakanishi K. A concise synthesis of ginkgolide M, a minor component of a terpene trilactone fraction from ginkgo biloba roots. JOURNAL OF NATURAL PRODUCTS 2006; 69:429-31. [PMID: 16562852 DOI: 10.1021/np050403i] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Ginkgolide M (GM), which is found only in the roots of the Ginkgo biloba tree and is an inhibitor of ligand-operated ion channels in the central nervous system, has been prepared in three steps from 10-benzylginkgolide C, an intermediate generated during the isolation and separation of ginkgolides from Ginkgo biloba leaf extract. The described synthetic sequence can be applied to access GM derivatives for biological studies.
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Affiliation(s)
- Sergei Bolshakov
- Department of Chemistry, Columbia University, New York, New York 10027, USA
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