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Effects of Hyssopus Officinalis Hydroalcoholic Extract on Pentylenetetrazol-Induced Convulsive Seizures in Rat. Neurochem Res 2022; 47:3792-3804. [DOI: 10.1007/s11064-022-03759-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 08/22/2022] [Accepted: 09/10/2022] [Indexed: 11/25/2022]
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2
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Uddin MS, Mamun AA, Rahman MA, Kabir MT, Alkahtani S, Alanazi IS, Perveen A, Ashraf GM, Bin-Jumah MN, Abdel-Daim MM. Exploring the Promise of Flavonoids to Combat Neuropathic Pain: From Molecular Mechanisms to Therapeutic Implications. Front Neurosci 2020; 14:478. [PMID: 32587501 PMCID: PMC7299068 DOI: 10.3389/fnins.2020.00478] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 04/17/2020] [Indexed: 01/10/2023] Open
Abstract
Neuropathic pain (NP) is the result of irregular processing in the central or peripheral nervous system, which is generally caused by neuronal injury. The management of NP represents a great challenge owing to its heterogeneous profile and the significant undesirable side effects of the frequently prescribed psychoactive agents, including benzodiazepines (BDZ). Currently, several established drugs including antidepressants, anticonvulsants, topical lidocaine, and opioids are used to treat NP, but they exert a wide range of adverse effects. To reduce the burden of adverse effects, we need to investigate alternative therapeutics for the management of NP. Flavonoids are the most common secondary metabolites of plants used in folkloric medicine as tranquilizers, and have been claimed to have a selective affinity to the BDZ binding site. Several studies in animal models have reported that flavonoids can reduce NP. In this paper, we emphasize the potentiality of flavonoids for the management of NP.
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Affiliation(s)
- Md Sahab Uddin
- Department of Pharmacy, Southeast University, Dhaka, Bangladesh.,Pharmakon Neuroscience Research Network, Dhaka, Bangladesh
| | - Abdullah Al Mamun
- Department of Pharmacy, Southeast University, Dhaka, Bangladesh.,Pharmakon Neuroscience Research Network, Dhaka, Bangladesh
| | - Md Ataur Rahman
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology, Seoul, South Korea
| | | | - Saad Alkahtani
- Department of Zoology, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Ibtesam S Alanazi
- Department of Biology, Faculty of Sciences, Univesity of Hafr Al Batin, Hafr Al Batin, Saudi Arabia
| | - Asma Perveen
- Glocal School of Life Sciences, Glocal University, Saharanpur, India
| | - Ghulam Md Ashraf
- King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia.,Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - May N Bin-Jumah
- Department of Biology, College of Science, Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia
| | - Mohamed M Abdel-Daim
- Department of Zoology, College of Science, King Saud University, Riyadh, Saudi Arabia.,Pharmacology Department, Faculty of Veterinary Medicine, Suez Canal University, Ismailia, Egypt
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3
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Abbasi E, Nassiri-Asl M, Shafeei M, Sheikhi M. Neuroprotective effects of vitexin, a flavonoid, on pentylenetetrazole-induced seizure in rats. Chem Biol Drug Des 2012; 80:274-8. [PMID: 22554436 DOI: 10.1111/j.1747-0285.2012.01400.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Flavonoids are important constituents of food and beverages and have several neuropharmacological activities. Many of these compounds are ligands for γ-aminobutyric acid type A receptors in the central nervous system. This study aimed to investigate the anticonvulsant effects of intracerebroventricularly administered vitexin (5, 7, 4-trihydroxyflavone-8-glucoside), a flavonoid found in plants, in rats treated with pentylenetetrazole (90 mg/kg, intraperitoneally) and to clarify the underlying mechanism. Vitexin (100 and 200 μm, i.c.v) affected minimal clonic seizures and generalized tonic-clonic seizures induced by pentylenetetrazole by increasing the seizure onset time. Pretreatment with flumazenil suppressed the anticonvulsant effects of vitexin during the onset of both the seizures. These results indicate that vitexin has anticonvulsant effects in the brain, possibly through interaction at the benzodiazepine site of the γ-aminobutyric acid type A receptor complex.
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Affiliation(s)
- Esmail Abbasi
- Department of Pharmacology, Qazvin University of Medical Sciences, Qazvin, Iran
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4
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Abstract
Benzodiazepines are the most widely prescribed class of psychoactive drugs in current therapeutic use, despite the important unwanted side effects that they produce, such as sedation, myorelaxation, ataxia, amnesia, and ethanol and barbiturate potentiation and tolerance. They exert their therapeutic effects via binding to the benzodiazepine binding site of gamma-aminobutyric acid (GABA) type A receptors, and allosterically modulating the chloride flux through the ion channel complex. First isolated from plants used as tranquilizers in folkloric medicine, some natural flavonoids have been shown to possess selective affinity for the benzodiazepine binding site with a broad spectrum of central nervous system effects. Since the initial search for alternative benzodiazepine ligands amongst the flavonoids, a list of successful synthetic derivatives has been generated with enhanced activities. This review provides an update on research developments that have established the activity of natural and synthetic flavonoids on GABA type A receptors. Flavonoids are prominent drugs in the treatment of mental disorders, and can also be used as tools to study modulatory sites at GABA type A receptors and to develop GABA type A selective agents further.
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Affiliation(s)
- Cristina Wasowski
- Instituto de Química y Fisicoquímica Biológicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Mariel Marder
- Instituto de Química y Fisicoquímica Biológicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
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5
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Abstract
There has been a resurgence of interest in synthetic and plant-derived flavonoids as modulators of γ-amino butyric acid-A (GABA(A) ) receptor function influencing inhibition mediated by the major inhibitory neurotransmitter GABA in the brain. Areas of interest include (i) flavonoids that show subtype selectivity in recombinant receptor studies in vitro consistent with their behavioural effects in vivo, (ii) flumazenil-insensitive modulation of GABA(A) receptor function by flavonoids, (iii) the ability of some flavonoids to act as second-order modulators of first-order modulation by benzodiazepines and (iv) the identification of the different sites of action of flavonoids on GABA(A) receptor complexes. An emerging area of interest is the activation of GABA(A) receptors by flavonoids in the absence of GABA. The relatively rigid shape of flavonoids means that they are useful scaffolds for the design of new therapeutic agents. Like steroids, flavonoids have wide-ranging effects on numerous biological targets. The challenge is to understand the structural determinants of flavonoid effects on particular targets and to develop agents specific for these targets.
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Affiliation(s)
- Jane R Hanrahan
- Faculty of Pharmacy Department of Pharmacology, The University of Sydney, NSW, Australia.
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6
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Ren L, Chan WM, Wang F, Xu Z, Zhao C, Mat WK, Chai Y, Wong JTF, Tsang SY, Xue H. Effects of flavone 6-substitutions on GABAA receptors efficacy. Eur J Pharmacol 2011; 670:121-9. [DOI: 10.1016/j.ejphar.2011.08.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Revised: 08/01/2011] [Accepted: 08/24/2011] [Indexed: 12/01/2022]
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7
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Nassiri-Asl M, Shariati-Rad S, Zamansoltani F. Anticonvulsive effects of intracerebroventricular administration of rutin in rats. Prog Neuropsychopharmacol Biol Psychiatry 2008; 32:989-93. [PMID: 18262708 DOI: 10.1016/j.pnpbp.2008.01.011] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 01/14/2008] [Accepted: 01/14/2008] [Indexed: 10/22/2022]
Abstract
Various synthetic derivatives of natural flavonoids are known to have neuroactive properties. The aim of the present study was to investigate the anticonvulsant effects of rutin (3, 3', 4', 5, 7-pentahydrohyflavone-3-rhamnoglucoside), a flavonoid which is an important dietary constituent of food and plant-based beverages. To this end, we assessed the anticonvulsant effects of rutin in rats treated with pentylenetetrazole (PTZ) (90 mg/kg, i.p.) and sought to clarify this mechanism. Intracerebroventricular (i.c.v.) injection of rutin dose-dependently affected minimal clonic seizures (MCS) and generalized tonic-clonic seizures (GTCS) induced by PTZ, through increments in seizure onset. Additionally, pretreatment with flumazenil (5 nM, i.c.v.) abolished the anticonvulsant effects of rutin during the onset of both seizures. These results indicate that rutin has anticonvulsant effects in the brain, possibly through positive allosteric modulation of the GABA(A) receptor complex via interaction at the benzodiazepine site.
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Affiliation(s)
- Marjan Nassiri-Asl
- Department of Pharmacology, School of Medical Sciences, Qazvin University, Qazvin, Iran.
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8
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Singh OV, Muthukrishnan M, Raj G. Manganese(III) Acetate Mediated Oxidation of Flavanones: A Facile Synthesis of Flavones. SYNTHETIC COMMUN 2006. [DOI: 10.1080/00397910500214490] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Om V. Singh
- a Phytochemistry Division , Tropical Botanic Garden and Research Institute , Thiruvananthapuram-695 562, Kerala, India
| | - M. Muthukrishnan
- a Phytochemistry Division , Tropical Botanic Garden and Research Institute , Thiruvananthapuram-695 562, Kerala, India
| | - Gopan Raj
- a Phytochemistry Division , Tropical Botanic Garden and Research Institute , Thiruvananthapuram-695 562, Kerala, India
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Hall BJ, Chebib M, Hanrahan JR, Johnston GAR. 6-Methylflavanone, a more efficacious positive allosteric modulator of γ-aminobutyric acid (GABA) action at human recombinant α2β2γ2L than at α1β2γ2L and α1β2 GABAA receptors expressed in Xenopus oocytes. Eur J Pharmacol 2005; 512:97-104. [PMID: 15840393 DOI: 10.1016/j.ejphar.2005.02.034] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2004] [Revised: 02/17/2005] [Accepted: 02/22/2005] [Indexed: 11/26/2022]
Abstract
6-Methylflavanone acted as a positive allosteric modulator of gamma-aminobutyric acid (GABA) responses at human recombinant alpha1beta2gamma2L, alpha2beta2gamma2L and alpha1beta2 GABA(A) receptors expressed in Xenopus laevis oocytes. It was essentially inactive at rho1 GABA(C) receptors. The EC50 values for 6-methylflavanone for the positive modulation of the EC(10-20) GABA responses were 22 microM, 10 microM and 6 microM and the maximum potentiations were 120%, 417% and 130% at alpha1beta2gamma2L, alpha2beta2gamma2L and alpha1beta2 GABA(A) receptors respectively. Thus 6-methylflavanone was much more efficacious as a positive modulator at alpha2beta2gamma2L than at alpha1beta2gamma2L and alpha1beta2 GABA(A) receptors. This may be significant since diazepam-induced anxiolysis is considered to be mediated via alpha2-containing GABA(A) receptors, while sedation is thought to be mediated via alpha1-containing GABA(A) receptors. We have previously reported that 6-methylflavone (1-100 microM) produced positive allosteric modulation at alpha1beta2gamma2L and alpha1beta2 GABA(A) receptors with no significant difference between the enhancement seen at either receptor subtype. In the present study, 6-methylflavone was tested at alpha2beta2gamma2L GABA(A) receptors and found to maximally potentiate the EC(10-20) GABA response by 183+/-39% which is similar to that previously observed for 6-methylflavone at alpha1beta2gamma2L GABA(A) receptors. Thus, 6-methylflavone did not show a preference for alpha2beta2gamma2L over alpha1beta2gamma2L GABA(A) receptors in terms of efficacy. Compared to 6-methylflavone, 6-methylflavanone is more efficacious as a positive allosteric modulator at alpha2beta2gamma2L GABA(A) receptors, and less efficacious at alpha1beta2gamma2L GABA(A) receptors. This may represent a relatively unique type of selectivity for positive modulators of GABA-A receptor subtypes based on efficacy as distinct from potency. As was previously shown for 6-methylflavone at alpha1beta2gamma2L GABA(A) receptors, the positive modulation of GABA responses at alpha1beta2gamma2L and alpha2beta2gamma2L GABA(A) receptors by 6-methylflavanone was insensitive to antagonism by flumazenil, indicating that this action is not mediated via "high-affinity" benzodiazepine sites.
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Affiliation(s)
- Belinda J Hall
- Adrien Albert Laboratory of Medicinal Chemistry, Department of Pharmacology, Faculty of Medicine, University of Sydney, Sydney, NSW 2006, Australia
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10
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Roberts AA. Testing efficacy of natural anxiolytic compounds. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2004; 546:181-91. [PMID: 15584374 DOI: 10.1007/978-1-4757-4820-8_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Affiliation(s)
- A A Roberts
- Department of Pathology and Laboratory Medicine, University of California, A7-149 Center for Health Sciences, Los Angeles, CA 90095, USA
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11
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Hall BJ, Chebib M, Hanrahan JR, Johnston GAR. Flumazenil-independent positive modulation of γ-aminobutyric acid action by 6-methylflavone at human recombinant α1β2γ2L and α1β2 GABAA receptors. Eur J Pharmacol 2004; 491:1-8. [PMID: 15102527 DOI: 10.1016/j.ejphar.2004.03.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2003] [Revised: 02/26/2004] [Accepted: 03/03/2004] [Indexed: 11/21/2022]
Abstract
In view of the ability of flavones to displace radiolabelled benzodiazepines from brain tissue and the interesting behavioural profile of these compounds, the present study investigated the activity of 6-methylflavone at ionotropic gamma-aminobutyric acid (GABA) receptors expressed in Xenopus laevis oocytes. 6-Methylflavone (1-100 microM) was found to be a positive allosteric modulator at alpha1beta2gamma2L and alpha1beta2 GABAA receptors with no significant difference between the enhancement seen at either receptor subtype. At 100 microM, 6-methylflavone enhanced the response to 5 microM GABA by 183+/-20% at alpha1beta2gamma2L GABAA receptors. The methyl substituent was important since the parent flavone was significantly weaker as a positive modulator (103+/-24% enhancement of 5 microM GABA by 100 microM flavone). This enhancement is not mediated via high-affinity benzodiazepine sites as it was not inhibited by the classical benzodiazepine antagonist flumazenil under conditions where flumazenil inhibits the potentiation of the GABA response to diazepam. 6-Methylflavone (60 microM) did not significantly affect the GABA dose-response curve at rho1 GABAC receptors. 6-Methylflavone acts as a positive modulator of recombinant GABAA receptors at sites independent of flumazenil-sensitive benzodiazepine sites.
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Affiliation(s)
- Belinda J Hall
- Adrien Albert Laboratory of Medicinal Chemistry, Department of Pharmacology, Faculty of Medicine, University of Sydney, Sydney, NSW 2006, Australia
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12
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Huen MSY, Hui KM, Leung JWC, Sigel E, Baur R, Wong JTF, Xue H. Naturally occurring 2'-hydroxyl-substituted flavonoids as high-affinity benzodiazepine site ligands. Biochem Pharmacol 2004; 66:2397-407. [PMID: 14637197 DOI: 10.1016/j.bcp.2003.08.016] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Screening of traditional medicines has proven invaluable to drug development and discovery. Utilizing activity-guided purification, we previously reported the isolation of a list of flavonoids from the medicinal herb Scutellaria baicalensis Georgi, one of which manifested an affinity for the benzodiazepine receptor (BDZR) comparable to that of the synthetic anxiolytic diazepam (K(i)=6.4 nM). In the present study, this high-affinity, naturally occurring flavonoid derivative, 5,7,2'-trihydroxy-6,8-dimethoxyflavone (K36), was chosen for further functional and behavioral characterization. K36 inhibited [3H]flunitrazepam binding to native BDZR with a K(i) value of 6.05 nM. In electrophysiological experiments K36 potentiated currents mediated by rat recombinant alpha(1)beta(2)gamma(2) GABA(A) receptors expressed in Xenopus oocytes. This potentiation was characterized by a threshold (1 nM) and half-maximal stimulation (24 nM) similar to diazepam. This enhancement was demonstrated to act via the BDZR, since co-application of 1 microM of the BDZR antagonist Ro15-1788 reversed the potentiation. Oral administration of K36 produced significant BDZR-mediated anxiolysis in the mice elevated plus-maze, which was abolished upon co-administration of Ro15-1788. Sedation, myorelaxation and motor incoordination were not observed in the chosen dosage regimen. Structure-activity relationships utilizing synthetic flavonoids with different 2' substituents on the flavone backbone supported that 2'-hydroxyl-substitution is a critical moiety on flavonoids with regard to BDZR affinities. These results further underlined the potential of flavonoids as therapeutics for the treatment of BDZR-associated syndromes.
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Affiliation(s)
- Michael S Y Huen
- Department of Biochemistry, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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13
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Huen MSY, Leung JWC, Ng W, Lui WS, Chan MNS, Wong JTF, Xue H. 5,7-Dihydroxy-6-methoxyflavone, a benzodiazepine site ligand isolated from Scutellaria baicalensis Georgi, with selective antagonistic properties. Biochem Pharmacol 2003; 66:125-32. [PMID: 12818372 DOI: 10.1016/s0006-2952(03)00233-8] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
As part of an effort to identify naturally occurring GABA(A) receptor benzodiazepine binding site (BDS) ligands from traditional medicinal herbs, we previously reported that flavonoid derivatives isolated from Scutellaria baicalensis (S. baicalensis) Georgi exhibited significant affinities for the BDS. The present study describes the characterization of 5,7-dihydroxy-6-methoxyflavone (oroxylin A), one of the major components of the herbal extract. Oroxylin A inhibited [3H]flunitrazepam binding to rat cerebral cortical membrane with a IC(50) value of 1.09+/-0.07 microM. A GABA ratio of 1.09+/-0.04 suggests that oroxylin A interacts as an antagonist at the recognition site. In neuropharmacological studies, oral administration of oroxylin A (3.75-60 mg kg(-1)) did not result in significant changes in animal models routinely employed for benzodiazepine (BD) evaluation. However, oroxylin A selectively abolished the anxiolytic, myorelaxant and motor incoordination, but not the sedative and anticonvulsant effects elicited by diazepam, a BDS agonist. These results add oroxylin A to the list of CNS active flavonoids, and as the first naturally occurring member endowed with selective antagonistic actions via the BDS.
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Affiliation(s)
- Michael S Y Huen
- Department of Biochemistry, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
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14
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Goutman JD, Waxemberg MD, Doñate-Oliver F, Pomata PE, Calvo DJ. Flavonoid modulation of ionic currents mediated by GABA(A) and GABA(C) receptors. Eur J Pharmacol 2003; 461:79-87. [PMID: 12586201 DOI: 10.1016/s0014-2999(03)01309-8] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The modulation of ionotropic gamma-aminobutyric acid (GABA) receptors (GABA-gated Cl(-) channels) by a group of natural and synthetic flavonoids was studied in electrophysiological experiments. Quercetin, apigenin, morine, chrysin and flavone inhibited ionic currents mediated by alpha(1)beta(1)gamma(2s) GABA(A) and rho(1) GABA(C) receptors expressed in Xenopus laevis oocytes in the micromolar range. alpha(1)beta(1)gamma(2s) GABA(A) and rho(1) GABA(C) receptors differ largely in their sensitivity to benzodiazepines, but they were similarly modulated by different flavonoids. Quercetin produced comparable actions on currents mediated by alpha(4)beta(2) neuronal nicotinic acetylcholine, serotonin 5-HT(3A) and glutamate AMPA/kainate receptors. Sedative and anxiolytic flavonoids, like chrysin or apigenin, failed to potentiate but antagonized alpha(1)beta(1)gamma(2s) GABA(A) receptors. Effects of apigenin and quercetin on alpha(1)beta(1)gamma(2s) GABA(A) receptors were insensitive to the benzodiazepine antagonist flumazenil. Results indicate that mechanism/s underlying the modulation of ionotropic GABA receptors by some flavonoids differs from that described for classic benzodiazepine modulation.
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MESH Headings
- Animals
- Apigenin
- Benzoflavones/pharmacology
- Female
- Flavonoids/pharmacology
- Humans
- Membrane Potentials/drug effects
- Microinjections
- Oocytes/drug effects
- Oocytes/physiology
- Quercetin/pharmacology
- RNA, Complementary/administration & dosage
- RNA, Complementary/genetics
- Rats
- Receptors, GABA/drug effects
- Receptors, GABA/genetics
- Receptors, GABA/physiology
- Receptors, GABA-A/drug effects
- Receptors, GABA-A/genetics
- Receptors, GABA-A/physiology
- Receptors, Neurotransmitter/drug effects
- Receptors, Neurotransmitter/genetics
- Receptors, Neurotransmitter/physiology
- Xenopus laevis
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Affiliation(s)
- Juan D Goutman
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad de Buenos Aires) (INGEBI (CONICET-UBA)), Capital Federal (1428), Buenos Aires, Argentina
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15
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Marder M, Estiú G, Blanch LB, Viola H, Wasowski C, Medina JH, Paladini AC. Molecular modeling and QSAR analysis of the interaction of flavone derivatives with the benzodiazepine binding site of the GABA(A) receptor complex. Bioorg Med Chem 2001; 9:323-35. [PMID: 11249125 DOI: 10.1016/s0968-0896(00)00250-9] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A large number of structurally different classes of ligands, many of them sharing the main characteristics of the benzodiazepine (BDZ) nucleus, are active in the modulation of anxiety, sedation, convulsion, myorelaxation, hypnotic and amnesic states in mammals. These compounds have high affinity for the benzodiazepine binding site (BDZ-bs) of the GABA(A) receptor complex. Since 1989 onwards our laboratories established that some natural flavonoids were ligands for the BDZ-bs which exhibit medium to high affinity in vitro and anxiolytic activity in vivo. Further research resulted in the production of synthetic flavonoid derivatives with increased biochemical and pharmacological activities. The currently accepted receptor/pharmacophore model of the BDZ-bs (Zhang, W.; Koeler, K. F.; Zhang, P.; Cook, J. M. Drug Des. Dev. 1995, 12, 193) accounts for the general requirements that should be met by this receptor for ligand recognition. In this paper we present a model pharmacophore which defines the characteristics for a ligand to be able to interact and bind to a flavone site, in the GABA(A) receptor. closely related to the BDZ-bs. A model of a flavone binding site has already been described (Dekermendjian, K.; Kahnberg, P.; Witt, M. R.; Sterner, O.; Nielsen, M.; Liljerfors, T. J. Med. Chem. 1999, 42, 4343). However, this alternative model is based only on graphic superposition techniques using as template a non-BDZ agonist. In this investigation all the natural and synthetic flavonoids found to be ligands for the BDZ-bs have been compared with the classical BDZ diazepam. A QSAR regression analysis of the parameters that describe the interaction demonstrates the relevance of the electronic effects for the ligand binding, and shows that they are associated with the negatively charged oxygen atom of the carbonyl group of the flavonoids and with the nature of the substituent in position 3'.
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Affiliation(s)
- M Marder
- Instituto de Química y Fisicoquímica Biológicas, Faultad de Farmacia y Bioquímica, Buenos Aires, Argentina
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16
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Viola H, Marder M, Wasowski C, Giorgi O, Paladini AC, Medina JH. 6,3'-dibromoflavone and 6-nitro-3'-bromoflavone: new additions to the 6,3'-disubstituted flavone family of high-affinity ligands of the brain benzodiazepine binding site with agonistic properties. Biochem Biophys Res Commun 2000; 273:694-8. [PMID: 10873666 DOI: 10.1006/bbrc.2000.2979] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
6,3'-dibromoflavone and 6-nitro-3'-bromoflavone inhibited [(3)H]flunitrazepam binding to the benzodiazepine binding site of the gamma amino butyric acid receptor complex with K(i) values between 17 and 36 nM in different brain regions. Their gamma amino butyric acid ratio for [(3)H]flunitrazepam binding to cerebral cortex membranes indicated partial agonistic properties. Both compounds had similar pharmacological effects: they produced anxiolytic-like effects at low doses but did not alter locomotor activity or muscle tonicity; sedation was caused only at doses higher than 30 mg/kg in mice. These synthetic flavone derivatives join an existing family of 6,3'-disubstituted flavone compounds with high affinity for the benzodiazepine binding site and partial agonistic profiles.
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Affiliation(s)
- H Viola
- Facultad de Medicina, Instituto de Biología Celular y Neurociencias, Paraguay 2155, Buenos Aires, (1121), Argentina
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