Drug repurposing: small molecules against Cu(II)-amyloid-ß and free radicals.

Alzheimer's disease (AD) presents a complex pathology entangling numerous pathological factors, including amyloid-ß (Aß), metal ions, and reactive oxygen species (ROS). Increasing evidence reveals pathological connections among these distinct components in AD. For instance, the association between the amyloid cascade and metal ion hypotheses has introduced a novel pathogenic target: metal-bound Aß. Investigation of such interconnections requires substantial research and can be expedited by chemical reagents that are able to modify multiple pathogenic factors in AD. Drug repurposing is an efficient approach for rediscovering previously utilized molecules with desirable biological and pharmaceutical properties as chemical reagents. Herein, we report the evaluation of three pre-approved drug molecules, selected based on their chemical structure and properties, as chemical reagents that can be used for elucidating the complicated pathology of AD.

Design, synthesis and evaluation of resveratrol-indazole hybrids as novel monoamine oxidases inhibitors with amyloid-ß aggregation inhibition.

Novel hybrids with MAO and Aß (1-42) self-aggregation inhibitory activities were designed and synthesized with the employment of indazole moiety and resveratrol. The biological screening results indicated that most compounds displayed potent inhibitory activity for Aß (1-42) self-aggregation, and obvious selective inhibition to MAO-B. Among these compounds, compound 6e was the most potent inhibitor not only for hMAO-B (IC50 = 1.14 µM) but also for Aß (1-42) self-aggregation (58.9% at 20 µM). Molecular modeling and kinetic studies revealed that compound 6e was a competitive MAO-B inhibitor, which can occupy the active site of MAO-B, and interact with Aß (1-42) via π-π and cation-π stacking interactions. In addition, compound 6e had no toxicity on PC12 cells and could cross the BBB. Collectively, all these results suggested that compound 6e might be a promising multi-target lead compound worthy of further investigation.

[Pseudo-pheochromocytoma due to iproniazid: A case report]. / Pseudo-phéochromocytome médicamenteux sous iproniazide : à propos d'un cas.

INTRODUCTION: Pheochromocytoma is suggested by the presence of severe and paroxysmal hypertension associated with hyperadrenergy clinical signs. If the diagnosis of pheochromocytoma is ruled out, a pseudo-pheochromocytoma should be considered. We report a clinical observation of pseudo-pheochromocytoma due to iproniazid, a non-selective irreversible monoamine oxidase (MAO) A and B inhibitor in a patient with bipolar disorder. CASE REPORT: A 78-year-old Caucasian male patient treated by iproniazid was hospitalized for depressive relapse. After several episodes of syncopes related to orthostatic hypotension, the patient presented hypertensive crisis. Urinary normetanephrines were increased to twice the upper limit of the normal range. Iproniazid was discontinued. Patient hemodynamic was rapidly stabilized and sympathetic hypertonia diminished. The urinary measurements normalized within two months. The abdominal imaging eliminated an adrenal tumor. CONCLUSION: Iproniazid could be responsible for severe irregular blood pressure associated with abnormal catecholamine metabolism (i.e. pseudo-pheochromocytoma).

Characterization of 3-iodothyronamine in vitro dynamics by mathematical modeling.

3-Iodothyronamine (T1AM) is regarded as a hormone-like substance thanks to its endogenous nature, its interaction with specific receptors trace amine-associated receptor 1 and its biological effects. We characterized T1AM transport and conversion in an in vitro culture of H9c2 murine cells, after a T1AM bolus injection. Samples of cell medium culture and cell lysate were assayed by high-performance liquid chromatography coupled to tandem mass spectrometry. We performed comparative experiments by adding to T1AM bolus amino oxidase inhibitors as iproniazid, pargyline (monoamine oxidase, MAO inhibitors), aminoguanidine, and semicarbazide (semicarbazide-sensitive amino oxidase, SSAO inhibitors). A mathematical model was developed, based on the assumption that T1AM is transported with a mechanism that is typical of hormone transport (i.e., EGF or insulin). We noticed that surface receptors downregulation could play a major role in T1AM dynamics. We also estimated that T1AM catabolism is mainly affected by MAO inhibitors, which produce a dramatic decrease in the kinetic constants related to T1AM degradation, while no significant changes were observed in experiments with SSAO inhibitors.

Xanthoangelol and 4-Hydroxyderricin Are the Major Active Principles of the Inhibitory Activities against Monoamine Oxidases on Angelica keiskei K

Monoamine oxidase inhibitors (MAOI) have been widely used as antidepressants. Recently, there has been renewed interest in MAO inhibitors. The activity-guided fractionation of extracts from Angelica keiskei Koidzumi (A. keiskei K.) led to the isolation of two prenylated chalcones, xanthoangelol and 4-hydroxyderricin and a flavonoid, cynaroside. These three isolated compounds are the major active ingredients of A. keiskei K. to inhibit the MAOs and DBH activities. Xanthoangelol is a nonselective MAO inhibitor, and a potent dopamine beta-hydroxylase (DBH) inhibitor. IC50 values of xanthoangelol to MAO-A and MAO-B were calculated to be 43.4 microM, and 43.9 microM. These values were very similar to iproniazid, which is a nonselective MAO inhibitor used as a drug against depression. The IC50 values of iproniazid were 37 microM, and 42.5 microM in our parallel examination. Moreover, IC50 value of xanthoangelol to DBH was calculated 0.52 microM. 4-Hydroxyderricin is a potent selective MAO-B inhibitor and also mildly inhibits DBH activity. The IC50 value of 4-hydroxyderricin to MAO-B was calculated to be 3.43 microM and this value was higher than that of deprenyl (0.046 microM) used as a positive control for selective MAO-B inhibitor in our test. Cynaroside is a most potent DBH inhibitor. The IC50 value of cynaroside to DBH was calculated at 0.0410 microM. Results of this study suggest that the two prenylated chalcones, xanthoangelol and 4-hydroxyderricin isolated from A. keiskei K., are expected for potent candidates for development of combined antidepressant drug. A. keiskei K. will be an excellent new bio-functional food material that has the combined antidepressant effect.

MAO inhibitory activity modulation: 3-Phenylcoumarins versus 3-benzoylcoumarins.

With the aim of finding the structural features for the human MAO inhibitory activity and selectivity, in the present communication we report the synthesis, pharmacological evaluation and a comparative study of a new series of 3-phenylcoumarins (compounds 1-4) and 3-benzoylcoumarins (compounds 5-8). A bromo atom and a methoxy/hydroxy substituent were introduced in these scaffolds, at six and eight positions of the coumarin moiety, respectively. The synthesized compounds 1-8 were evaluated as MAO-A and B inhibitors using R-(-)-deprenyl and iproniazide as reference compounds. The presence or absence of a carbonyl group between the coumarin and the phenyl substituent in 3 position remarks, respectively, the MAO-A or MAO-B inhibitory activity. Some of the new compounds showed MAO-B inhibitory activities in the low nanomolar range. Compound 2 (IC(50)=1.35nM) showed higher inhibitory activity than the R-(-)-deprenyl (IC(50)=19.60nM) and higher MAO-B selectivity, with more than 74,074-fold inhibition level, respecting to the MAO-A isoform.

Serendipity and psychopharmacology.

This article describes several examples where the development of drugs and devices for use in psychiatry followed from initial serendipitous observations. The potential psychotropic properties of chlorpromazine (Thorazine(®)) were first noted in surgical patients when the drug was being investigated as a potentiator of anesthesia. Similar findings were noted with iproniazid (Marsilid(®)), developed for the treatment of tuberculosis, and the drug was later released for clinical use as an antidepressant agent. The development of meprobamate (Miltown(®)), an approved treatment for anxiety, evolved from initial efforts to find a chemical that would inhibit the enzymatic destruction of the antibiotic drug penicillin. The psychiatric uses of lamotrigine (Lamictal(®)) and vagus nerve stimulation were prompted by initial observations that epilepsy patients receiving these treatments had positive mood effects. Nurses should be familiar with the concept of serendipity, as they often are in the best position to observe, record, and report on unexpected clinical effects in patients taking any kind of prescription or nonprescription medication.

Inhibition of monoamine oxidase activity by cannabinoids.

Brain monoamines are involved in many of the same processes affected by neuropsychiatric disorders and psychotropic drugs, including cannabinoids. This study investigated in vitro effects of cannabinoids on the activity of monoamine oxidase (MAO), the enzyme responsible for metabolism of monoamine neurotransmitters and affecting brain development and function. The effects of the phytocannabinoid Delta(9)-tetrahydrocannabinol (THC), the endocannabinoid anandamide (N-arachidonoylethanolamide [AEA]), and the synthetic cannabinoid receptor agonist WIN 55,212-2 (WIN) on the activity of MAO were measured in a crude mitochondrial fraction isolated from pig brain cortex. Monoamine oxidase activity was inhibited by the cannabinoids; however, higher half maximal inhibitory concentrations (IC(50)) of cannabinoids were required compared to the known MAO inhibitor iproniazid. The IC(50) was 24.7 micromol/l for THC, 751 micromol/l for AEA, and 17.9 micromol/l for WIN when serotonin was used as substrate (MAO-A), and 22.6 micromol/l for THC, 1,668 micromol/l for AEA, and 21.2 micromol/l for WIN when phenylethylamine was used as substrate (MAO-B). The inhibition of MAOs by THC was noncompetitive. N-Arachidonoylethanolamide was a competitive inhibitor of MAO-A and a noncompetitive inhibitor of MAO-B. WIN was a noncompetitive inhibitor of MAO-A and an uncompetitive inhibitor of MAO-B. Monoamine oxidase activity is affected by cannabinoids at relatively high drug concentrations, and this effect is inhibitory. Decrease of MAO activity may play a role in some effects of cannabinoids on serotonergic, noradrenergic, and dopaminergic neurotransmission.

Inhibition of monoamine oxidase activity by antidepressants and mood stabilizers.

OBJECTIVE: Monoamine oxidase (MAO), the enzyme responsible for metabolism of monoamine neurotransmitters, has an important role in the brain development and function, and MAO inhibitors have a range of potential therapeutic uses. We investigated systematically in vitro effects of pharmacologically different antidepressants and mood stabilizers on MAO activity. METHODS: Effects of drugs on the activity of MAO were measured in crude mitochondrial fraction isolated from cortex of pig brain, when radiolabeled serotonin (for MAO-A) or phenylethylamine (for MAO-B) was used as substrate. The several antidepressants and mood stabilizers were compared with effects of well known MAO inhibitors such as moclobemide, iproniazid, pargyline, and clorgyline. RESULTS: In general, the effect of tested drugs was found to be inhibitory. The half maximal inhibitory concentration, parameters of enzyme kinetic, and mechanism of inhibition were determined. MAO-A was inhibited by the following drugs: pargyline > clorgyline > iproniazid > fluoxetine > desipramine > amitriptyline > imipramine > citalopram > venlafaxine > reboxetine > olanzapine > mirtazapine > tianeptine > moclobemide, cocaine >> lithium, valproate. MAO-B was inhibited by the following drugs: pargyline > clorgyline > iproniazid > fluoxetine > venlafaxine > amitriptyline > olanzapine > citalopram > desipramine > reboxetine > imipramine > tianeptine > mirtazapine, cocaine >> moclobemide, lithium, valproate. The mechanism of inhibition of MAOs by several antidepressants was found various. CONCLUSIONS: It was concluded that MAO activity is acutely affected by pharmacologically different antidepressants at relatively high drug concentrations; this effect is inhibitory. There are differences both in inhibitory potency and in mechanism of inhibition between both several drugs and the two MAO isoforms. While MAO inhibition is not primary biochemical effect related to their therapeutic action, it can be supposed that decrease of MAO activity may be concerned in some effects of these drugs on serotonergic, noradrenergic, and dopaminergic neurotransmission.

Metabolism of dopamine by the nasal mucosa.

The nasal route of administration offers several advantages over oral and intravenous administration, including the ability to avoid hepatic first pass metabolism. Dopamine deficiency has been associated with several neurological disorders; it has been shown to have good systemic bioavailability and significant uptake into the CNS following intranasal administration. The purpose of these studies was to investigate the limiting role of mucosal metabolism of dopamine during nasal absorption. In vitro transport and initial rate studies were carried out using nasal mucosal explants to study dopamine permeability and metabolism. Dihydroxyphenylacetic acid (DOPAC) was the only metabolite detected. Monoamine oxidase (MAO), the enzyme responsible for DOPAC formation, was localized to the submucosal region of the nasal explants. The amount of DOPAC formed during the transport studies was less than 0.5% of the initial amount of dopamine placed into the system. Iproniazid, an MAO inhibitor, blocked DOPAC formation but had no effect on dopamine transport. The limited extent of dopamine metabolism compared to its mucosal transport demonstrates that nasal dopamine transport is not significantly reduced by mucosal metabolism and suggests that the nasal route may be promising for the efficient delivery of dopamine to the CNS.

(-)-Trans-epsilon-viniferin, a polyphenol present in wines, is an inhibitor of noradrenaline and 5-hydroxytryptamine uptake and of monoamine oxidase activity.

(-)-Trans-epsilon-viniferin (epsilon-viniferin, 5-200 microM), a dimer of resveratrol, concentration-dependently inhibited the uptake of [3H]noradrenaline and [3H]5-HT by synaptosomes from rat brain (being slightly but significantly more selective against [3H]noradrenaline) and the uptake of [3H]5-HT by human platelets. On the other hand, epsilon-viniferin (5-200 microM) concentration-dependently inhibited the enzymatic activity of commercial (human recombinant) monoamine oxidase (MAO) isoform (MAO-A and MAO-B) activity, being slightly but significantly more selective against MAO-B than against MAO-A. Taking into account that the principal groups of drugs used to treat major depression are noradrenaline/5-HT uptake or MAO inhibitors, under the assumption that epsilon-viniferin exhibits a similar behaviour in humans in vivo, our results suggest that this natural polyphenol may be of value as a structural template for the design and development of new antidepressant drugs with two important biochemical activities combined in the same chemical structure: noradrenaline/5-HT uptake and MAO inhibitory activity.

Hydrazide derivatives produce active oxygen species as hydrazine.

It is well documented that some hydrazines are quite sensitive to oxidation and may serve as the electron donor for the reduction of oxygen, whereas hydrazides are not believed to react directly with oxygen. Data presented in this paper show that both hydrazides and hydrazines share an N-N moiety, which is assumed to react with atmospheric oxygen and produce oxygen radicals, at various degrees of efficiency. Since spectrometric measurements of hydrazide just after solubilization showed that the molecular mass remains constant in the absence of oxygen, we can conclude that hydrazides do not react with the oxygen through a slow spontaneous hydrolytic release of hydrazine. However, hydrazine is more reactive than hydrazide, which requires hours rather than minutes to produce measurable quantities of radical species. Differences were also apparent for various substituted derivatives. The reaction was significantly enhanced by the presence of metal ions. Data reported here demonstrate that hydrazides cause irreversible damage to the prosthetic group of proteins as well as causing degradation of the polypeptide chain into small fragments.

Fast-flow EPR spectroscopic observation of the isoniazid, iproniazid, and phenylhydrazine hydrazyl radicals.

Hydrazyl radical intermediates have been suggested as important intermediates in the biochemistry of hydrazides and hydrazines. Although spin-trapping studies have intercepted those species previously, there has been no report of the direct observation of the unstable hydrazyl radicals of isoniazid and iproniazid. We have employed the fast-flow technique in electron paramagnetic resonance (EPR) spectroscopy to measure spectra for the short-lived hydrazyl radicals of a family of hydrazides, including the pharmacologically important compounds isoniazid and iproniazid, as well as for a series of phenylhydrazines. Our investigations of the phenylhydrazine radical and the related chloro-substituted analogues have allowed definitive assignments of the hyperfine coupling constants of that toxicologically important free radical. Theoretical values of hyperfine coupling constants, calculated by density functional formalism, provided a guide to assignments for the hydrazyl species and confirmed the experimentally based assignments for phenylhydrazyl radical.

Open space swimming test to index antidepressant activity.

Depression is characterized by a lack of "motivation" rather than a lack of "physical space" to move around. This study was designed to evaluate predictivity of an open space swimming test for antidepressant activity of various antidepressants in rats. Without drug treatment, rats showed a significant reduction in the distance moved (increased immobility) over successive trials in an open space water pool. Three major classes of antidepressants and a selective serotonin reuptake inhibitor (SSRI) were tested. Repeated treatment (10 mg/kg x 3 per day) of imipramine, a prototypical tricyclic antidepressant, iproniazid, a monoamine oxidase inhibitor, mianserin, an atypical antidepressant, and alaproclate, an SSRI, all significantly reduced the immobility. These results suggest that the open space swimming test is highly predictive of antidepressant action and is more sensitive to the drug treatments. The measurement is more objective than that of the forced swimming test and does not involve judging and scoring the animals' movement or lack of movement by investigators. The demonstrated effectiveness of three major types of antidepressants and an SSRI suggests that the effects on the test are not restricted to a particular underlying molecular mechanism of action. Thus, this swimming test shows promising potential as a screen for novel antidepressants and, perhaps, for revealing some of the underlying pathophysiology of depression.

Psychiatric Side Effects of Psychotropic Drugs(II): Clinical & Pathophysiological Implications / 대한정신약물학회지

The psychotropic effects of the original psychotropics currently in use, such as chlorpromazine, iproniazide, imipramine, lithium, and clozapine, have been applied to clinical practice through fortuitous discoveries of their psychiatric side effects (PSE). The etiopathophysiology of various psychiatric disorders have been deduced from the action mechanism of original psychotropics, and the designed drugs which selectively act on those neurotransmitters involved in the therapeutic effects of the original drugs are being developed as novel drugs. Psychiatric side effects cannot be considered to necessarily anti-therapeutic, as seen throughout the history of psychopharmacology. The clinical and pathophysiological significance of PSE deduced from their analyses according to the psychiatric symptoms manifested as PSEs are as follows: 1) PSEs are manifested according to the biological characteristics of the patient across diagnosis. This reflects the lack of biological basis in the current diagnostic system. 2) Psychotropics are important as in vivo pharmacological probes or challenges which, upon administration, allow for the biological characterization of the patient brain, i.e. pharmaco-biological typing of the patient may be performed based on the patient responses to the agent (both therapeutic and adverse effects). Such data may be of importance in subsequent prescription of the patient. 3) The hierarchy of a psychiatric disorder may be modified by drug administration, converting the disorder into that of a lower rank and thus into what is more easily treated. 4) A pharmacological approach, rather than a diagnosis-based one, is required. Consequently, more research into the still unknown psychotropic effects of each psychotropic is desired. In the process, clinically significant psychotropic effects currently undefined from the point of diagnosis-based approach may be discovered.

A possible indirect sympathomimetic action of metformin in the arterial vessel wall of spontanously hypertensive rats.

The antidiabetic drug metformin (MF) typically achieves only micromolar levels in plasma with normal therapeutic use. However, it is also known to accumulate in various tissues up to several times higher after standard oral dosing and we now have evidence from both in vivo and in vitro experiments with spontaneously hypertensive rats (SHR) that millimolar levels stimulate release of norepinephrine (NE) from vascular sympathetic nerve endings (SNEs). As shown in the present work with SHR tail arterial tissue (rich in SNEs), the known vasodilator effect of millimolar levels of MF on the smooth muscle (even if contracted with a nonadrenergic agonist), is attenuated by the presence of the SNEs unless phentolamine (an alpha receptor blocker) is present. We reasoned that the mechanism for this apparent NE-releasing action of MF is not exocytotic release as that would require depolarization of the neuronal cell membranes in SNEs, and MF at millimolar levels is known to repolarize (not depolarize) membranes of other cells. Thus, we tested the possibility that MF releases NE by an indirect sympathomimetic-like action. Such an action should be amplified by monoamine oxidase inhibitors (e.g. iproniazid) and blocked by NE-carrier inhibitors (e.g. desipramine). Accordingly, we found that the abovementioned attenuating effect of intact SNEs on MF's relaxation of SHR tail arterial tissue (compared to tissues in which SNEs were experimentally removed with 6-hydroxydopamine) was amplified nearly 3-fold by iproniazid (p<0.05) and blocked by desipramine (p<0.05). These results support an indirect sympathomimetic action of MF and raise the question whether commonly used antidepressants with properties similar to iproniazid and desipramine might alter MF's beneficial vasodilatory (and thus antihypertensive) effectiveness in diabetic patients with hypertension.

Inhibition of type A monoamine oxidase by coptisine in mouse brain.

The inhibitory effects of coptisine, a protoberberine isoquinoline alkaloid, on type A and type B monoamine oxidase (MAO-A and MAO-B) activities in mouse brain were investigated. Coptisine showed an inhibitory effect on MAO-A activity in a concentration-dependent manner using a substrate kynuramine, but coptisine did not inhibit MAO-B activity. Coptisine exhibited 54.3% inhibition of MAO-A activity at 2 microM. The values of Km and Vmax of MAO-A were 151.9 +/- 0.6 microM and 0.40 +/- 0.03 nmol/min/mg protein, respectively (n=5). Coptisine competitively inhibited MAO-A activity with kynuramine. The Ki value of coptisine was 3.3 microM. The inhibition of MAO-A by coptisine was found to be reversible by dialysis of the incubation mixture. These results suggest that coptisine is a potent reversible inhibitor of MAO-A, and that coptisine functions to regulate the catecholamine content.

Characterization of phentermine and related compounds as monoamine oxidase (MAO) inhibitors.

Phentermine was shown in the 1970s to inhibit the metabolism of serotonin by monoamine oxidase (MAO), but never was labeled as an MAO inhibitor; hence, it was widely used in combination with fenfluramine, and continues to be used, in violation of their labels, with other serotonin uptake blockers. We examined the effects of phentermine and several other unlabeled MAO inhibitors on MAO activities in rat lung, brain, and liver, and also the interactions of such drugs when administered together. Rat tissues were assayed for MAO-A and -B, using serotonin and beta-phenylethylamine as substrates. Phentermine inhibited serotonin-metabolizing (MAO-A) activity in all three tissues with K(i) values of 85-88 microM. These potencies were similar to those of the antidepressant MAO inhibitors iproniazid and moclobemide. When phentermine was mixed with other unlabeled reversible MAO inhibitors (e.g. pseudoephedrine, ephedrine, norephedrine; estradiol benzoate), the degree of MAO inhibition was additive. The cardiac valvular lesions and primary pulmonary hypertension that have been reported to be associated with fenfluramine-phentermine use may have resulted from the intermittent concurrent blockage of both serotonin uptake and metabolism.

[Auxiliary hepatic transplantation in iproniazid-induced subfulminant hepatitis. Should iproniazid still be sold in France?]. / Transplantation hépatique auxiliaire pour hépatite subfulminante à l'iproniazide. Doit-on maintenir la commercialisation de l'iproniazide en France?

We report a new case of subfulminant hepatitis due to iproniazid, a MAO-inhibitor antidepressant, in a 27-year-old man. An auxiliary liver transplantation was performed. Liver function returned to normal and the patient was discharged from the hospital. However, the patient's native liver did not regenerate, and immunosuppressive therapy had to be maintained. Iproniazid hepatotoxicity is characterized by jaundice in 1% of cases, with a fulminant or subfulminant course in 20% of icteric patients. Although iproniazid is no longer sold in most countries, it is still commercialized in France. Because of the frequency and severity of hepatic injury, commercialization of iproniazid in France should no longer be authorized.