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Thentu JB, Bhyrapuneni G, Padala NP, Chunduru P, Pantangi HR, Nirogi R. Evaluation of monoamine oxidase A and B type enzyme occupancy using non-radiolabelled tracers in rat brain. Neurochem Int 2021; 145:105006. [PMID: 33636211 DOI: 10.1016/j.neuint.2021.105006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 02/18/2021] [Accepted: 02/18/2021] [Indexed: 11/18/2022]
Abstract
Monoamine oxidase (MAO) enzymes, type A and B metabolise the amine neurotransmitters of the body. Selective inhibition of either enzyme is an approach for treating neurodegenerative and stress-induced disorders, and inhibition of an enzyme is proportional to the binding of the MAO inhibitor. Conventionally, the binding of test compounds to enzymes is assessed by radiolabelled ligands in ex vivo and in vivo occupancy assays. Regulatory restrictions and turnaround time are the limitations of the methods that use radiolabelled ligands. But the use of non-radiolabelled tracers and sensitive mass spectrometry (LC-MS/MS) based assays accelerated the determination of target occupancy in pre-clinical species. A report on use of non-radiolabelled ligand in in vivo MAO occupancy assay is not available. The objectives of the present study were to optimise non-radiolabelled harmine and deprenyl as selective tracers in MAO-A and MAO-B occupancy assays and evaluate MAO occupancy of test compounds in rat brain. Tracer optimisation resulted in a detectable, stable, and low ratio (<3.0) of tracer concentrations between any two brain tissues. In occupancy assay, tracer was intravenously administered (10 μg/kg, harmine or 60 μg/kg, L-deprenyl) after the treatment with test compound (clorgyline or tranylcypromine or pargyline or phenelzine or thioperamide). Specific brain tissues were isolated at a defined interval and tracer concentrations were quantified using LC-MS/MS method. Pre-treatment with MAO inhibitors resulted in a decrease (maximum, 80-85%) in harmine or an increase (maximum, 85-300%) in L-deprenyl concentrations. But we considered the change in tracer concentration, relative to the vehicle and positive control groups to calculate MAO occupancy. The observed selectivity and ratio of occupancies (ED50) of test compound towards MAO-A and MAO-B are comparable with the results from in vitro radiolabelled ligand-based inhibition assay. The results demonstrated the application of these non-radiolabelled tracers as suitable pre-clinical tools to determine MAO occupancy.
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Affiliation(s)
- Jagadeesh Babu Thentu
- Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad, India.
| | - Gopinadh Bhyrapuneni
- Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad, India.
| | - Nagasurya Prakash Padala
- Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad, India.
| | - Prathyusha Chunduru
- Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad, India.
| | - Hanumanth Rao Pantangi
- Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad, India.
| | - Ramakrishna Nirogi
- Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad, India.
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Nirogi R, Mohammed AR, Shinde AK, Ravella SR, Bogaraju N, Subramanian R, Mekala VR, Palacharla RC, Muddana N, Thentu JB, Bhyrapuneni G, Abraham R, Jasti V. Discovery and Development of 3-(6-Chloropyridine-3-yloxymethyl)-2-azabicyclo[3.1.0]hexane Hydrochloride (SUVN-911): A Novel, Potent, Selective, and Orally Active Neuronal Nicotinic Acetylcholine α4β2 Receptor Antagonist for the Treatment of Depression. J Med Chem 2020; 63:2833-2853. [PMID: 32026697 DOI: 10.1021/acs.jmedchem.9b00790] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
A series of chemical optimizations guided by in vitro affinity at the α4β2 receptor in combination with selectivity against the α3β4 receptor, pharmacokinetic evaluation, and in vivo efficacy in a forced swim test resulted in identification of 3-(6-chloropyridine-3-yloxymethyl)-2-azabicyclo[3.1.0]hexane hydrochloride (9h, SUVN-911) as a clinical candidate. Compound 9h is a potent α4β2 receptor ligand with a Ki value of 1.5 nM. It showed >10 μM binding affinity toward the ganglionic α3β4 receptor apart from showing selectivity over 70 other targets. It is orally bioavailable and showed good brain penetration in rats. Marked antidepressant activity and dose-dependent receptor occupancy in rats support its potential therapeutic utility in the treatment of depression. It does not affect the locomotor activity at doses several folds higher than its efficacy dose. It is devoid of cardiovascular and gastrointestinal side effects. Successful long-term safety studies in animals and phase-1 evaluation in healthy humans for safety, tolerability, and pharmacokinetics paved the way for its further development.
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Affiliation(s)
- Ramakrishna Nirogi
- Discovery Research, Suven Life Sciences Ltd., Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Abdul Rasheed Mohammed
- Discovery Research, Suven Life Sciences Ltd., Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Anil K Shinde
- Discovery Research, Suven Life Sciences Ltd., Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Srinivasa Rao Ravella
- Discovery Research, Suven Life Sciences Ltd., Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Narsimha Bogaraju
- Discovery Research, Suven Life Sciences Ltd., Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Ramkumar Subramanian
- Discovery Research, Suven Life Sciences Ltd., Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Venkat Reddy Mekala
- Discovery Research, Suven Life Sciences Ltd., Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Raghava Choudary Palacharla
- Discovery Research, Suven Life Sciences Ltd., Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Nageswararao Muddana
- Discovery Research, Suven Life Sciences Ltd., Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Jagadeesh Babu Thentu
- Discovery Research, Suven Life Sciences Ltd., Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Gopinadh Bhyrapuneni
- Discovery Research, Suven Life Sciences Ltd., Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Renny Abraham
- Discovery Research, Suven Life Sciences Ltd., Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Venkat Jasti
- Discovery Research, Suven Life Sciences Ltd., Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
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