1
|
Niveta JPS, John CM, Arockiasamy S. Monoamine oxidase mediated oxidative stress: a potential molecular and biochemical crux in the pathogenesis of obesity. Mol Biol Rep 2023; 51:29. [PMID: 38142252 DOI: 10.1007/s11033-023-08938-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 11/14/2023] [Indexed: 12/25/2023]
Abstract
Obesity has become a global health concern with an increasing prevalence as years pass by but the researchers have not come to a consensus on the exact pathophysiological mechanism underlying this disease. In the past three decades, Monoamine Oxidases (MAO), has come into limelight for a possible involvement in orchestrating the genesis of obesity but the exact mechanism is not well elucidated. MAO is essentially an enzyme involved in the catabolism of neurotransmitters and other biogenic amines to form a corresponding aldehyde, hydrogen peroxide (H2O2) and ammonia. This review aims to highlight the repercussions of MAO's catabolic activity on the redox balance, carbohydrate metabolism and lipid metabolism of adipocytes which ultimately leads to obesity. The H2O2 produced by these enzymes seems to be the culprit causing oxidative stress in pre-adipocytes and goes on to mimic insulin's activity independent of its presence via the Protein Kinase B Pathway facilitating glucose influx. The H2O2 activates Sterol regulatory-element binding protein-1c and peroxisome proliferator activated receptor gamma crucial for encoding enzymes like fatty acid synthase, acetyl CoA carboxylase 1, Adenosine triphosphate-citrate lyase, phosphoenol pyruvate carboxykinase etc., which helps promoting lipogenesis at the same time inhibits lipolysis. More reactive oxygen species production occurs via NADPH Oxidases enzymes and is also able activate Nuclear Factor kappa B leading to inflammation in the adipocyte microenvironment. This chronic inflammation is the seed for insulin resistance.
Collapse
Affiliation(s)
- J P Shirley Niveta
- Sri Ramachandra Institute of Higher Education and Research, Chennai, India
| | - Cordelia Mano John
- Sri Ramachandra Institute of Higher Education and Research, Chennai, India
| | | |
Collapse
|
2
|
Brenner SR. Reader Response: Association of Amount of Weight Lost After Bariatric Surgery With Intracranial Pressure in Women With Idiopathic Intracranial Hypertension. Neurology 2023; 100:544. [PMID: 36914274 PMCID: PMC10074459 DOI: 10.1212/wnl.0000000000207121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/15/2023] Open
|
3
|
Effects of Chemical Structures Interacting with Amine Oxidases on Glucose, Lipid and Hydrogen Peroxide Handling by Human Adipocytes. Molecules 2022; 27:molecules27196224. [PMID: 36234761 PMCID: PMC9571511 DOI: 10.3390/molecules27196224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 09/07/2022] [Accepted: 09/19/2022] [Indexed: 11/26/2022] Open
Abstract
Benzylamine is a natural molecule present in food and edible plants, capable of activating hexose uptake and inhibiting lipolysis in human fat cells. These effects are dependent on its oxidation by amine oxidases present in adipocytes, and on the subsequent hydrogen peroxide production, known to exhibit insulin-like actions. Virtually, other substrates interacting with such hydrogen peroxide-releasing enzymes potentially can modulate lipid accumulation in adipose tissue. Inhibition of such enzymes has also been reported to influence lipid deposition. We have therefore studied in human adipocytes the lipolytic and lipogenic activities of pharmacological entities designed to interact with amine oxidases highly expressed in this cell type: the semicarbazide-sensitive amine oxidase (SSAO also known as PrAO or VAP-1) and the monoamine oxidases (MAO). The results showed that SZV-2016 and SZV-2017 behaved as better substrates than benzylamine, releasing hydrogen peroxide once oxidized, and reproduced or even exceeded its insulin-like metabolic effects in fat cells. Additionally, several novel SSAO inhibitors, such as SZV-2007 and SZV-1398, have been evidenced and shown to inhibit benzylamine metabolic actions. Taken as a whole, our findings reinforce the list of molecules that influence the regulation of triacylglycerol assembly/breakdown, at least in vitro in human adipocytes. The novel compounds deserve deeper investigation of their mechanisms of interaction with SSAO or MAO, and constitute potential candidates for therapeutic use in obesity and diabetes.
Collapse
|
4
|
Rcheulishvili N, Papukashvili D, Deng Z, Wang S, Deng Y. Simulated microgravity alters the expression of plasma SSAO and its enzymatic activity in healthy rats and increases the mortality in high-fat diet/streptozotocin-induced diabetes. LIFE SCIENCES IN SPACE RESEARCH 2021; 30:24-28. [PMID: 34281661 DOI: 10.1016/j.lssr.2021.04.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 03/28/2021] [Accepted: 04/23/2021] [Indexed: 06/13/2023]
Abstract
Semicarbazide-sensitive amine oxidase (SSAO) activity is known to be associated with certain pathologies including diabetes. In this study, SSAO expression and enzymatic activity in blood plasma of healthy rats were significantly upregulated under simulated microgravity (SMG) condition. Significant mortality was observed in SMG group of diabetic rats. Results indicate that microgravity might increase the risks of SSAO-associated alterations.
Collapse
Affiliation(s)
- Nino Rcheulishvili
- School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | | | - Zixuan Deng
- School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Shibo Wang
- School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Yulin Deng
- School of Life Science, Beijing Institute of Technology, Beijing, 100081, China; Beijing Key Laboratory for Separation and Analysis in Biomedicine and Pharmaceuticals, Beijing, China.
| |
Collapse
|
5
|
Li H, Du S, Niu P, Gu X, Wang J, Zhao Y. Vascular Adhesion Protein-1 (VAP-1)/Semicarbazide-Sensitive Amine Oxidase (SSAO): A Potential Therapeutic Target for Atherosclerotic Cardiovascular Diseases. Front Pharmacol 2021; 12:679707. [PMID: 34322017 PMCID: PMC8312380 DOI: 10.3389/fphar.2021.679707] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 06/28/2021] [Indexed: 12/12/2022] Open
Abstract
Vascular adhesion protein-1 (VAP-1) is a semicarbazide-sensitive amine oxidase (SSAO), whose enzymatic activity regulates the adhesion/exudation of leukocytes in/from blood vessels. Due to its abundant expressions in vascular systems and prominent roles in inflammations, increasing attentions have been paid to the roles of VAP-1/SSAO in atherosclerosis, a chronic vascular inflammation that eventually drives clinical cardiovascular events. Clinical studies have demonstrated a potential value of soluble VAP-1 (sVAP-1) for the diagnosis and prognosis of cardiovascular diseases. Recent findings revealed that VAP-1 is expressed in atherosclerotic plaques and treatment with VAP-1 inhibitors alleviates the progression of atherosclerosis. This review will focus on the roles of VAP-1/SSAO in the progression of atherosclerotic lesions and therapeutic potentials of VAP-1 inhibitors for cardiovascular diseases.
Collapse
Affiliation(s)
- Hui Li
- Department of Cardiology, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Shiyu Du
- Department of Cardiology, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Panpan Niu
- Department of Pathophysiology, School of Biology and Basic Medical Sciences, Soochow University, Suzhou, China
| | - Xiaosong Gu
- Department of Cardiology, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Jun Wang
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, China
| | - Ying Zhao
- Department of Pathophysiology, School of Biology and Basic Medical Sciences, Soochow University, Suzhou, China
| |
Collapse
|
6
|
Novel Facet of an Old Dietary Molecule? Direct Influence of Caffeine on Glucose and Biogenic Amine Handling by Human Adipocytes. Molecules 2021; 26:molecules26133831. [PMID: 34201708 PMCID: PMC8270301 DOI: 10.3390/molecules26133831] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 06/17/2021] [Accepted: 06/18/2021] [Indexed: 12/12/2022] Open
Abstract
Caffeine is a plant alkaloid present in food and beverages consumed worldwide. It has high lipid solubility with recognized actions in the central nervous system and in peripheral tissues, notably the adipose depots. However, the literature is scant regarding caffeine's influence on adipocyte functions other than lipolysis, such as glucose incorporation into lipids (lipogenesis) and amine oxidation. The objective of this study was to explore the direct effects of caffeine and of isobutylmethylxanthine (IBMX) on these adipocyte functions. Glucose transport into fat cells freshly isolated from mice, rats, or humans was monitored by determining [3H]-2-deoxyglucose (2-DG) uptake, while the incorporation of radiolabeled glucose into cell lipids was used as an index of lipogenic activity. Oxidation of benzylamine by primary amine oxidase (PrAO) was inhibited by increasing doses of caffeine in human adipose tissue preparations with an inhibition constant (Ki) in the millimolar range. Caffeine inhibited basal and insulin-stimulated glucose transport as well as lipogenesis in rodent adipose cells. The antilipogenic action of caffeine was also observed in adipocytes from mice genetically invalidated for PrAO activity, indicating that PrAO activity was not required for lipogenesis inhibition. These caffeine inhibitory properties were extended to human adipocytes: relative to basal 2-DG uptake, set at 1.0 ± 0.2 for 6 individuals, 0.1 mM caffeine tended to reduce uptake to 0.83 ± 0.08. Insulin increased uptake by 3.86 ± 1.11 fold when tested alone at 100 nM, and by 3.21 ± 0.80 when combined with caffeine. Our results reinforce the recommendation of caffeine's potential in the treatment or prevention of obesity complications.
Collapse
|
7
|
Zhang Y, Yang Y, He X, Yang P, Zong T, Sun P, Sun RC, Yu T, Jiang Z. The cellular function and molecular mechanism of formaldehyde in cardiovascular disease and heart development. J Cell Mol Med 2021; 25:5358-5371. [PMID: 33973354 PMCID: PMC8184665 DOI: 10.1111/jcmm.16602] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 04/07/2021] [Accepted: 04/20/2021] [Indexed: 12/12/2022] Open
Abstract
As a common air pollutant, formaldehyde is widely present in nature, industrial production and consumer products. Endogenous formaldehyde is mainly produced through the oxidative deamination of methylamine catalysed by semicarbazide-sensitive amine oxidase (SSAO) and is ubiquitous in human body fluids, tissues and cells. Vascular endothelial cells and smooth muscle cells are rich in this formaldehyde-producing enzyme and are easily damaged owing to consequent cytotoxicity. Consistent with this, increasing evidence suggests that the cardiovascular system and stages of heart development are also susceptible to the harmful effects of formaldehyde. Exposure to formaldehyde from different sources can induce heart disease such as arrhythmia, myocardial infarction (MI), heart failure (HF) and atherosclerosis (AS). In particular, long-term exposure to high concentrations of formaldehyde in pregnant women is more likely to affect embryonic development and cause heart malformations than long-term exposure to low concentrations of formaldehyde. Specifically, the ability of mouse embryos to effect formaldehyde clearance is far lower than that of the rat embryos, more readily allowing its accumulation. Formaldehyde may also exert toxic effects on heart development by inducing oxidative stress and cardiomyocyte apoptosis. This review focuses on the current progress in understanding the influence and underlying mechanisms of formaldehyde on cardiovascular disease and heart development.
Collapse
Affiliation(s)
- Ying Zhang
- Department of Cardiac Ultrasound, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Yanyan Yang
- Department of Immunology, Basic Medicine School, Qingdao University, Qingdao, China
| | - Xiangqin He
- Department of Cardiac Ultrasound, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Panyu Yang
- Department of Cardiac Ultrasound, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Tingyu Zong
- Department of Cardiac Ultrasound, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Pin Sun
- Department of Cardiac Ultrasound, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Rui-Cong Sun
- Department of Cardiac Ultrasound, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Tao Yu
- Department of Cardiac Ultrasound, The Affiliated Hospital of Qingdao University, Qingdao, China.,Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Zhirong Jiang
- Department of Cardiac Ultrasound, The Affiliated Hospital of Qingdao University, Qingdao, China
| |
Collapse
|
8
|
Jargaud V, Bour S, Tercé F, Collet X, Valet P, Bouloumié A, Guillemot JC, Mauriège P, Jalkanen S, Stolen C, Salmi M, Smith DJ, Carpéné C. Obesity of mice lacking VAP-1/SSAO by Aoc3 gene deletion is reproduced in mice expressing a mutated vascular adhesion protein-1 (VAP-1) devoid of amine oxidase activity. J Physiol Biochem 2020; 77:141-154. [PMID: 32712883 DOI: 10.1007/s13105-020-00756-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 06/29/2020] [Indexed: 12/18/2022]
Abstract
The product of Aoc3 gene is known as vascular adhesion protein-1 (VAP-1), a glycoprotein contributing to leukocyte extravasation and exhibiting semicarbazide-sensitive amine oxidase activity (SSAO). Regarding the immune functions of VAP-1/SSAO, it is known that mice bearing Aoc3 gene knock-out (AOC3KO) exhibit defects in leukocyte migration similar to those of mice expressing a mutated VAP-1 lacking functional SSAO activity (knock-in, AOC3KI). However, it has not been reported whether these models differ regarding other disturbances. Thus, we further compared endocrine-metabolic phenotypes of AOC3KO and AOC3KI mice to their respective control. Special attention was paid on adiposity, glucose and lipid handling, since VAP-1/SSAO is highly expressed in adipose tissue (AT). In both mouse lines, no tissue SSAO activity was found, while Aoc3 mRNA was absent in AOC3KO only. Although food consumption was unchanged, both AOC3KO and AOC3KI mice were heavier and fatter than their respective controls. Other alterations commonly found in adipocytes from both lines were loss of benzylamine insulin-like action with unchanged insulin lipogenic responsiveness and adiponectin expression. A similar downregulation of inflammatory markers (CD45, IL6) was found in AT. Glucose handling and liver mass remained unchanged, while circulating lipid profile was distinctly altered, with increased cholesterol in AOC3KO only. These results suggest that the lack of oxidase activity found in AOC3KI is sufficient to reproduce the metabolic disturbances observed in AOC3KO mice, save those related with cholesterol transport. Modulation of SSAO activity therefore constitutes a potential target for the treatment of cardiometabolic diseases, especially obesity when complicated by low-grade inflammation.
Collapse
Affiliation(s)
- Valentin Jargaud
- Institute of Metabolic and Cardiovascular Diseases, INSERM, UMR1048, Toulouse, France.,University of Toulouse, UMR1048, Paul Sabatier University, Toulouse, France.,Sanofi, Translational Sciences Unit, Chilly-Mazarin, France
| | - Sandy Bour
- Institute of Metabolic and Cardiovascular Diseases, INSERM, UMR1048, Toulouse, France.,University of Toulouse, UMR1048, Paul Sabatier University, Toulouse, France
| | - François Tercé
- Institute of Metabolic and Cardiovascular Diseases, INSERM, UMR1048, Toulouse, France.,University of Toulouse, UMR1048, Paul Sabatier University, Toulouse, France
| | - Xavier Collet
- Institute of Metabolic and Cardiovascular Diseases, INSERM, UMR1048, Toulouse, France.,University of Toulouse, UMR1048, Paul Sabatier University, Toulouse, France
| | - Philippe Valet
- Institute of Metabolic and Cardiovascular Diseases, INSERM, UMR1048, Toulouse, France.,University of Toulouse, UMR1048, Paul Sabatier University, Toulouse, France
| | - Anne Bouloumié
- Institute of Metabolic and Cardiovascular Diseases, INSERM, UMR1048, Toulouse, France.,University of Toulouse, UMR1048, Paul Sabatier University, Toulouse, France
| | | | - Pascale Mauriège
- Dept. of Kinesiology, Fac. of Medicine and PEPS, Laval University, Québec, Canada
| | - Sirpa Jalkanen
- MediCity and Institute of Biomedicine, University of Turku, Turku, Finland
| | - Craig Stolen
- MediCity and Biotie Therapies Plc, Turku, Finland
| | - Marko Salmi
- MediCity and Institute of Biomedicine, University of Turku, Turku, Finland
| | | | - Christian Carpéné
- Institute of Metabolic and Cardiovascular Diseases, INSERM, UMR1048, Toulouse, France. .,University of Toulouse, UMR1048, Paul Sabatier University, Toulouse, France.
| |
Collapse
|
9
|
Papukashvili D, Rcheulishvili N, Deng Y. Correction: Papukashvili et al. "Attenuation of Weight Gain and Prevention of Associated Pathologies by Inhibiting SSAO" Nutrients, 2020, 12, 184. Nutrients 2020; 12:nu12071968. [PMID: 32630665 PMCID: PMC7400307 DOI: 10.3390/nu12071968] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 05/19/2020] [Indexed: 12/22/2022] Open
Affiliation(s)
- Dimitri Papukashvili
- School of Life Science, Beijing Institute of Technology, Beijing 100081, China; (D.P.); (N.R.)
| | - Nino Rcheulishvili
- School of Life Science, Beijing Institute of Technology, Beijing 100081, China; (D.P.); (N.R.)
| | - Yulin Deng
- School of Life Science, Beijing Institute of Technology, Beijing 100081, China; (D.P.); (N.R.)
- Beijing Key Laboratory for Separation and Analysis in Biomedicine and Pharmaceuticals, Beijing 100081, China
- Correspondence: ; Tel./Fax: +86-10-6891-4907
| |
Collapse
|
10
|
Comments to the Editor Re: Papukashvili et al. Nutrients 2020, 12, 184. Nutrients 2020; 12:nu12071965. [PMID: 32630834 PMCID: PMC7400195 DOI: 10.3390/nu12071965] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Accepted: 04/24/2020] [Indexed: 11/16/2022] Open
|
11
|
Papukashvili D, Rcheulishvili N, Deng Y. Beneficial Impact of Semicarbazide-Sensitive Amine Oxidase Inhibition on the Potential Cytotoxicity of Creatine Supplementation in Type 2 Diabetes Mellitus. Molecules 2020; 25:molecules25092029. [PMID: 32349282 PMCID: PMC7248702 DOI: 10.3390/molecules25092029] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 04/16/2020] [Accepted: 04/24/2020] [Indexed: 02/06/2023] Open
Abstract
Creatine supplementation of the population with type 2 diabetes mellitus (T2DM) combined with an exercise program is known to be a possible therapy adjuvant with hypoglycemic effects. However, excessive administration of creatine leads to the production of methylamine which is deaminated by the enzyme semicarbazide-sensitive amine oxidase (SSAO) and as a result, cytotoxic compounds are produced. SSAO activity and reaction products are increased in the serum of T2DM patients. Creatine supplementation by diabetics will further augment the activity of SSAO. The current review aims to find a feasible way to ameliorate T2DM for patients who exercise and desire to consume creatine. Several natural agents present in food which are involved in the regulation of SSAO activity directly or indirectly are reviewed. Particularly, zinc-α2-glycoprotein (ZAG), zinc (Zn), copper (Cu), histamine/histidine, caffeine, iron (Fe), and vitamin D are discussed. Inhibiting SSAO activity by natural agents might reduce the potential adverse effects of creatine metabolism in population of T2DM.
Collapse
Affiliation(s)
- Dimitri Papukashvili
- School of Life Science, Beijing Institute of Technology, Beijing 100081, China; (D.P.); (N.R.)
| | - Nino Rcheulishvili
- School of Life Science, Beijing Institute of Technology, Beijing 100081, China; (D.P.); (N.R.)
| | - Yulin Deng
- School of Life Science, Beijing Institute of Technology, Beijing 100081, China; (D.P.); (N.R.)
- Beijing Key Laboratory for Separation and Analysis in Biomedicine and Pharmaceuticals, Beijing 100081, China
- Correspondence: ; Tel./Fax: +86-10-68914907
| |
Collapse
|
12
|
Methylxanthines Inhibit Primary Amine Oxidase and Monoamine Oxidase Activities of Human Adipose Tissue. MEDICINES 2020; 7:medicines7040018. [PMID: 32252407 PMCID: PMC7235778 DOI: 10.3390/medicines7040018] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 03/26/2020] [Accepted: 03/28/2020] [Indexed: 12/13/2022]
Abstract
Background: Methylxanthines including caffeine and theobromine are widely consumed compounds and were recently shown to interact with bovine copper-containing amine oxidase. To the best of our knowledge, no direct demonstration of any interplay between these phytochemicals and human primary amine oxidase (PrAO) has been reported to date. We took advantage of the coexistence of PrAO and monoamine oxidase (MAO) activities in human subcutaneous adipose tissue (hScAT) to test the interaction between several methylxanthines and these enzymes, which are involved in many key pathophysiological processes. Methods: Benzylamine, methylamine, and tyramine were used as substrates for PrAO and MAO in homogenates of subcutaneous adipose depots obtained from overweight women undergoing plastic surgery. Methylxanthines were tested as substrates or inhibitors by fluorimetric determination of hydrogen peroxide, an end-product of amine oxidation. Results: Semicarbazide-sensitive PrAO activity was inhibited by theobromine, caffeine, and isobutylmethylxanthine (IBMX) while theophylline, paraxanthine, and 7-methylxanthine had little effect. Theobromine inhibited PrAO activity by 54% at 2.5 mM. Overall, the relationship between methylxanthine structure and the degree of inhibition was similar to that seen with bovine PrAO, although higher concentrations (mM) were required for inhibition. Theobromine also inhibited oxidation of tyramine by MAO, at the limits of its solubility in a DMSO vehicle. At doses higher than 12 % v/v, DMSO impaired MAO activity. MAO was also inhibited by millimolar doses of IBMX, caffeine and by other methylxanthines to a lesser extent. Conclusions: This preclinical study extrapolates previous findings with bovine PrAO to human tissues. Given that PrAO is a potential target for anti-inflammatory drugs, it indicates that alongside phosphodiesterase inhibition and adenosine receptor antagonism, PrAO and MAO inhibition could contribute to the health benefits of methylxanthines, especially their anti-inflammatory effects.
Collapse
|