Tobacco Smoke Extract Modulates Activity and Expression of Monoamine Oxidase and μ Opioid Receptor in Cultured Human Neuroblastoma Cells

<p>Tobacco addiction is a major public health concern and is responsible for approximately five million deaths globally each year. Although most current smokers express a desire to quit, few are successful in their attempts. Nicotine is the primary neurobiologically active component in tobacco smoke and acts through the nicotinic acetylcholine receptor (nAChR) to sustain addiction. However, nicotine replacement therapies have proven to be remarkably ineffective at helping smokers quit. This indicates that nicotine alone cannot fully account for the intense and enduring nature of tobacco addiction. Previous research has provided strong evidence that monoamine oxidase (MAO) enzymes and the endogenous opioid system may also play a role in tobacco dependence. The present study compared and contrasted the influence of nicotine and the non-nicotine components of tobacco smoke on the enzyme activity of MAO-A and MAO-B. Gene expression of MAO and the mu opioid receptor (MOR) in SH-SY5Y human neuroblastoma and U-118 MG glioma cell lines was also investigated. Using a kynuramine-based enzymatic assay adapted and optimised for this study, the MAO inhibitory activity of tobacco-based samples were tested, including total particulate matter (TPM) extracts from a range of New Zealand tobacco products, Quest(R) nicotine-free cigarettes, and fluid from the RUYAN(R) Electronic cigarette. TPM from both standard tobacco and Quest(R) significantly inhibited MAO-A and MAO-B activity in vitro and in cultured cells. Differences between the types and brands of tobacco products were observed. TPM derived from loose-leaf tobacco inhibited MAO enzymes more potently than samples from manufactured cigarettes. This difference was attributed to a significantly higher tar:nicotine ratio in loose-leaf tobacco. Standard TPM and Quest(R) TPM also inhibited total MAO activity in SH-SY5Y cells treated for 24 hours; whereas the weak activity in U-118 MG remained unchanged. However, MAO activity was highly dependent on the cell culture conditions, with activity increasing in SH-SY5Y cells when treated with a 5-day exposure regimen. This finding was unique to the present study. The gene expression of MAO-A, MAO-B, and MOR was examined using a qRT-PCR assay. All three genes were significantly up-regulated by standard and denicotinized TPM extracts after a 5-day treatment regimen. This finding was correlated with an increase in protein abundance for MOR, but not MAO-A or MAO-B, as assayed by Western blot. Up-regulation of MAO and MOR gene expression was abolished when cells were treated with TPM extracts in conjunction with the nAChR antagonist mecamylamine, suggesting that up-regulation of MAO and MOR genes was dependent, at least in part, on nAChR signalling. Both standard TPM and TPM from denicotinized Quest(R) cigarettes induced inhibition of MAO and up-regulation of MAO and MOR gene expression. This demonstrates that non-nicotine compounds within tobacco smoke can significantly influence the behaviour of cultured neuronal cells. Further research is required to fully elucidate the mechanisms behind the MAO and MOR gene response, and a better understanding of these mechanisms may provide a framework for the development of novel smoking cessation therapies.</p>

Tobacco Smoke Extract Modulates Activity and Expression of Monoamine Oxidase and μ Opioid Receptor in Cultured Human Neuroblastoma Cells

<p>Tobacco addiction is a major public health concern and is responsible for approximately five million deaths globally each year. Although most current smokers express a desire to quit, few are successful in their attempts. Nicotine is the primary neurobiologically active component in tobacco smoke and acts through the nicotinic acetylcholine receptor (nAChR) to sustain addiction. However, nicotine replacement therapies have proven to be remarkably ineffective at helping smokers quit. This indicates that nicotine alone cannot fully account for the intense and enduring nature of tobacco addiction. Previous research has provided strong evidence that monoamine oxidase (MAO) enzymes and the endogenous opioid system may also play a role in tobacco dependence. The present study compared and contrasted the influence of nicotine and the non-nicotine components of tobacco smoke on the enzyme activity of MAO-A and MAO-B. Gene expression of MAO and the mu opioid receptor (MOR) in SH-SY5Y human neuroblastoma and U-118 MG glioma cell lines was also investigated. Using a kynuramine-based enzymatic assay adapted and optimised for this study, the MAO inhibitory activity of tobacco-based samples were tested, including total particulate matter (TPM) extracts from a range of New Zealand tobacco products, Quest(R) nicotine-free cigarettes, and fluid from the RUYAN(R) Electronic cigarette. TPM from both standard tobacco and Quest(R) significantly inhibited MAO-A and MAO-B activity in vitro and in cultured cells. Differences between the types and brands of tobacco products were observed. TPM derived from loose-leaf tobacco inhibited MAO enzymes more potently than samples from manufactured cigarettes. This difference was attributed to a significantly higher tar:nicotine ratio in loose-leaf tobacco. Standard TPM and Quest(R) TPM also inhibited total MAO activity in SH-SY5Y cells treated for 24 hours; whereas the weak activity in U-118 MG remained unchanged. However, MAO activity was highly dependent on the cell culture conditions, with activity increasing in SH-SY5Y cells when treated with a 5-day exposure regimen. This finding was unique to the present study. The gene expression of MAO-A, MAO-B, and MOR was examined using a qRT-PCR assay. All three genes were significantly up-regulated by standard and denicotinized TPM extracts after a 5-day treatment regimen. This finding was correlated with an increase in protein abundance for MOR, but not MAO-A or MAO-B, as assayed by Western blot. Up-regulation of MAO and MOR gene expression was abolished when cells were treated with TPM extracts in conjunction with the nAChR antagonist mecamylamine, suggesting that up-regulation of MAO and MOR genes was dependent, at least in part, on nAChR signalling. Both standard TPM and TPM from denicotinized Quest(R) cigarettes induced inhibition of MAO and up-regulation of MAO and MOR gene expression. This demonstrates that non-nicotine compounds within tobacco smoke can significantly influence the behaviour of cultured neuronal cells. Further research is required to fully elucidate the mechanisms behind the MAO and MOR gene response, and a better understanding of these mechanisms may provide a framework for the development of novel smoking cessation therapies.</p>

Tobacco smoke extract modulates activity and expression of monoamine oxidase and μ opioid receptor in cultured human neuroblastoma cells

<p>Tobacco addiction is a major public health concern and is responsible for approximately five million deaths globally each year. Although most current smokers express a desire to quit, few are successful in their attempts. Nicotine is the primary neurobiologically active component in tobacco smoke and acts through the nicotinic acetylcholine receptor (nAChR) to sustain addiction. However, nicotine replacement therapies have proven to be remarkably ineffective at helping smokers quit. This indicates that nicotine alone cannot fully account for the intense and enduring nature of tobacco addiction. Previous research has provided strong evidence that monoamine oxidase (MAO) enzymes and the endogenous opioid system may also play a role in tobacco dependence. The present study compared and contrasted the influence of nicotine and the non-nicotine components of tobacco smoke on the enzyme activity of MAO-A and MAO-B. Gene expression of MAO and the mu opioid receptor (MOR) in SH-SY5Y human neuroblastoma and U-118 MG glioma cell lines was also investigated. Using a kynuramine-based enzymatic assay adapted and optimised for this study, the MAO inhibitory activity of tobacco-based samples were tested, including total particulate matter (TPM) extracts from a range of New Zealand tobacco products, Quest(R) nicotine-free cigarettes, and fluid from the RUYAN(R) Electronic cigarette. TPM from both standard tobacco and Quest(R) significantly inhibited MAO-A and MAO-B activity in vitro and in cultured cells. Differences between the types and brands of tobacco products were observed. TPM derived from loose-leaf tobacco inhibited MAO enzymes more potently than samples from manufactured cigarettes. This difference was attributed to a significantly higher tar:nicotine ratio in loose-leaf tobacco. Standard TPM and Quest(R) TPM also inhibited total MAO activity in SH-SY5Y cells treated for 24 hours; whereas the weak activity in U-118 MG remained unchanged. However, MAO activity was highly dependent on the cell culture conditions, with activity increasing in SH-SY5Y cells when treated with a 5-day exposure regimen. This finding was unique to the present study. The gene expression of MAO-A, MAO-B, and MOR was examined using a qRT-PCR assay. All three genes were significantly up-regulated by standard and denicotinized TPM extracts after a 5-day treatment regimen. This finding was correlated with an increase in protein abundance for MOR, but not MAO-A or MAO-B, as assayed by Western blot. Up-regulation of MAO and MOR gene expression was abolished when cells were treated with TPM extracts in conjunction with the nAChR antagonist mecamylamine, suggesting that up-regulation of MAO and MOR genes was dependent, at least in part, on nAChR signalling. Both standard TPM and TPM from denicotinized Quest(R) cigarettes induced inhibition of MAO and up-regulation of MAO and MOR gene expression. This demonstrates that non-nicotine compounds within tobacco smoke can significantly influence the behaviour of cultured neuronal cells. Further research is required to fully elucidate the mechanisms behind the MAO and MOR gene response, and a better understanding of these mechanisms may provide a framework for the development of novel smoking cessation therapies.</p>

Tobacco smoke extract modulates activity and expression of monoamine oxidase and μ opioid receptor in cultured human neuroblastoma cells

<p>Tobacco addiction is a major public health concern and is responsible for approximately five million deaths globally each year. Although most current smokers express a desire to quit, few are successful in their attempts. Nicotine is the primary neurobiologically active component in tobacco smoke and acts through the nicotinic acetylcholine receptor (nAChR) to sustain addiction. However, nicotine replacement therapies have proven to be remarkably ineffective at helping smokers quit. This indicates that nicotine alone cannot fully account for the intense and enduring nature of tobacco addiction. Previous research has provided strong evidence that monoamine oxidase (MAO) enzymes and the endogenous opioid system may also play a role in tobacco dependence. The present study compared and contrasted the influence of nicotine and the non-nicotine components of tobacco smoke on the enzyme activity of MAO-A and MAO-B. Gene expression of MAO and the mu opioid receptor (MOR) in SH-SY5Y human neuroblastoma and U-118 MG glioma cell lines was also investigated. Using a kynuramine-based enzymatic assay adapted and optimised for this study, the MAO inhibitory activity of tobacco-based samples were tested, including total particulate matter (TPM) extracts from a range of New Zealand tobacco products, Quest(R) nicotine-free cigarettes, and fluid from the RUYAN(R) Electronic cigarette. TPM from both standard tobacco and Quest(R) significantly inhibited MAO-A and MAO-B activity in vitro and in cultured cells. Differences between the types and brands of tobacco products were observed. TPM derived from loose-leaf tobacco inhibited MAO enzymes more potently than samples from manufactured cigarettes. This difference was attributed to a significantly higher tar:nicotine ratio in loose-leaf tobacco. Standard TPM and Quest(R) TPM also inhibited total MAO activity in SH-SY5Y cells treated for 24 hours; whereas the weak activity in U-118 MG remained unchanged. However, MAO activity was highly dependent on the cell culture conditions, with activity increasing in SH-SY5Y cells when treated with a 5-day exposure regimen. This finding was unique to the present study. The gene expression of MAO-A, MAO-B, and MOR was examined using a qRT-PCR assay. All three genes were significantly up-regulated by standard and denicotinized TPM extracts after a 5-day treatment regimen. This finding was correlated with an increase in protein abundance for MOR, but not MAO-A or MAO-B, as assayed by Western blot. Up-regulation of MAO and MOR gene expression was abolished when cells were treated with TPM extracts in conjunction with the nAChR antagonist mecamylamine, suggesting that up-regulation of MAO and MOR genes was dependent, at least in part, on nAChR signalling. Both standard TPM and TPM from denicotinized Quest(R) cigarettes induced inhibition of MAO and up-regulation of MAO and MOR gene expression. This demonstrates that non-nicotine compounds within tobacco smoke can significantly influence the behaviour of cultured neuronal cells. Further research is required to fully elucidate the mechanisms behind the MAO and MOR gene response, and a better understanding of these mechanisms may provide a framework for the development of novel smoking cessation therapies.</p>

Green Oxidation of Amines by a Novel Cold-Adapted Monoamine Oxidase MAO P3 from Psychrophilic Fungi Pseudogymnoascus sp. P3

The use of monoamine oxidases (MAOs) in amine oxidation is a great example of how biocatalysis can be applied in the agricultural or pharmaceutical industry and manufacturing of fine chemicals to make a shift from traditional chemical synthesis towards more sustainable green chemistry. This article reports the screening of fourteen Antarctic fungi strains for MAO activity and the discovery of a novel psychrozyme MAOP3 isolated from the Pseudogymnoascus sp. P3. The activity of the native enzyme was 1350 ± 10.5 U/L towards a primary (n-butylamine) amine, and 1470 ± 10.6 U/L towards a secondary (6,6-dimethyl-3-azabicyclohexane) amine. MAO P3 has the potential for applications in biotransformations due to its wide substrate specificity (aliphatic and cyclic amines, pyrrolidine derivatives). The psychrozyme operates at an optimal temperature of 30 °C, retains 75% of activity at 20 °C, and is rather thermolabile, which is beneficial for a reduction in the overall costs of a bioprocess and offers a convenient way of heat inactivation. The reported biocatalyst is the first psychrophilic MAO; its unique biochemical properties, substrate specificity, and effectiveness predispose MAO P3 for use in environmentally friendly, low-emission biotransformations.

Pharmacological Modulation of Behaviour, Serotonin and Dopamine Levels in Daphnia magna Exposed to the Monoamine Oxidase Inhibitor Deprenyl

This study assessed the effects of the monoamine oxidase (MAO) inhibitor deprenyl in Daphnia magna locomotor activity. The mechanisms of action of deprenyl were also determined by studying the relationship between behaviour, MAO activity and neurotransmitter levels. Modulation of the D. magna monoamine system was accomplished by 24 h exposure to two model psychotropic pharmaceuticals with antagonistic and agonistic serotonin signalling properties: 10 mg/L of 4-chloro-DL-phenylalanine (PCPA) and 1 mg/L of deprenyl, respectively. Contrasting behavioural outcomes were observed for deprenyl and PCPA reflected in decreased basal locomotor activity and enhanced habituation for the former compound and delayed habituation for the latter one. Deprenyl exposure inhibited monoamine oxidase (MAO) activity and increased the concentrations of serotonin, dopamine and the dopamine metabolite 3-methoxytyramine in whole D. magna extracts. Our findings indicate that D. magna is a sensitive and useful nonvertebrate model for assessing the effects of short-term exposure to chemicals that alter monoamine signalling changes.

Deciphering the Interactions of Bioactive Compounds in Selected Traditional Medicinal Plants against Alzheimer’s Diseases via Pharmacophore Modeling, Auto-QSAR, and Molecular Docking Approaches

Neurodegenerative diseases, for example Alzheimer’s, are perceived as driven by hereditary, cellular, and multifaceted biochemical actions. Numerous plant products, for example flavonoids, are documented in studies for having the ability to pass the blood-brain barrier and moderate the development of such illnesses. Computer-aided drug design (CADD) has achieved importance in the drug discovery world; innovative developments in the aspects of structure identification and characterization, bio-computational science, and molecular biology have added to the preparation of new medications towards these ailments. In this study we evaluated nine flavonoid compounds identified from three medicinal plants, namely T. diversifolia, B. sapida, and I. gabonensis for their inhibitory role on acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and monoamine oxidase (MAO) activity, using pharmacophore modeling, auto-QSAR prediction, and molecular studies, in comparison with standard drugs. The results indicated that the pharmacophore models produced from structures of AChE, BChE and MAO could identify the active compounds, with a recuperation rate of the actives found near 100% in the complete ranked decoy database. Moreso, the robustness of the virtual screening method was accessed by well-established methods including enrichment factor (EF), receiver operating characteristic curve (ROC), Boltzmann-enhanced discrimination of receiver operating characteristic (BEDROC), and area under accumulation curve (AUAC). Most notably, the compounds’ pIC50 values were predicted by a machine learning-based model generated by the AutoQSAR algorithm. The generated model was validated to affirm its predictive model. The best models achieved for AChE, BChE and MAO were models kpls_radial_17 (R2 = 0.86 and Q2 = 0.73), pls_38 (R2 = 0.77 and Q2 = 0.72), kpls_desc_44 (R2 = 0.81 and Q2 = 0.81) and these externally validated models were utilized to predict the bioactivities of the lead compounds. The binding affinity results of the ligands against the three selected targets revealed that luteolin displayed the highest affinity score of −9.60 kcal/mol, closely followed by apigenin and ellagic acid with docking scores of −9.60 and −9.53 kcal/mol, respectively. The least binding affinity was attained by gallic acid (−6.30 kcal/mol). The docking scores of our standards were −10.40 and −7.93 kcal/mol for donepezil and galanthamine, respectively. The toxicity prediction revealed that none of the flavonoids presented toxicity and they all had good absorption parameters for the analyzed targets. Hence, these compounds can be considered as likely leads for drug improvement against the same.

Synthesis of 2′-(1,2,3-triazoyl)-acetophenones: molecular docking and inhibition of in vitro monoamine oxidase activity

The synthesis of 2′-(1,2,3-triazoyl)-acetophenones by a CuAAC using thiourea as a ligand, molecular docking and MAO activity analyses were performed.