Indoleamines Research Articles

Evaluation of the anti-inflammatory, analgesic, anti-pyretic and anti-ulcerogenic potentials of synthetic indole derivatives

A large number of new synthetic compounds are synthesized in the field of heterocyclic chemistry having a variety of biological potentials. In the present study, some synthetic indole derivatives are used to check anti-inflammatory, analgesic, antipyretic and gastroprotective activity in albino mice. Albino mice of either sex of reproductive age were used for each study (n = 5). In anti-inflammatory activity, the negative control (NC) and positive control group animals were treated with normal saline and 10 mg/kg of indomethacin respectively. The treated groups received the twenty four different synthetic chemicals, after 30 min of sub cutaneous injection of carrageenan. In analgesic activity, hot-plate method is used and for each group the latency period was recorded at zero moment of the provision of required dose and after 30, 60, 90, 120 and 180 min. In anti-pyretic activity, Pyrexia was induced by using Brewer's yeast method. Before any treatment and then after duration of 18 h, the rectal temperatures were recorded. Among all the chemicals, only those chemicals which show any potential related to above mentioned activities were selected for gastroprotective activity. The gastroprotective activity was performed to check the gastric ulcers by using 300 mg/kg of single oral dose of indomethacin to animals of all groups except NC group. This study helped to screen out the most potent indole derivatives 3a-II and 4a-II from the 24 synthetic indole derivatives which demonstrated the best biological potential (anti-inflammatory, analgesic, antipyretic, and gastroprotection) as compared to the remaining ones. The micrometric and biochemical results also support the histological findings. Out of the twenty-four novel indole amines tested, 3a-II and 4a-II have shown the effective pharmacological capacity and additionally have not shown any overt and systemic toxicity. Thus these two indole amines need further in-depth pharmacokinetic and pharmacodynamics studies before they are recommended for any pre-clinical trial.

Synthesis, characterization, and in vitro anti-cholinesterase screening of novel indole amines.

The present study involved the targeted synthesis and characterization of novel indole amines with anti-acetylcholinesterase profiling. A series of proposed indole amines was virtually screened against human acetylcholinesterase. A few indole amines (23, 24, and 25) showing strong enzyme binding in the in silico studies were synthesized in the laboratory and characterized using spectroscopic (IR, UV, NMR, single crystal XRD) and spectrometric (EIMS, HR-EIMS) methods. The indole amine 23 was crystallized from EtOH and analyzed with single crystal XRD. These ligands interacted with the PAS site in the enzyme, and their binding may disrupt the activity. The in vitro acetylcholinesterase inhibition studies revealed that the IC50 values for indole amines 25 and 24 (4.28 and 4.66 μM, respectively) were comparable to that of galantamine (4.15 μM) and may be studied further as cost-effective acetylcholinesterase inhibitors.

Synthesis and antioxidant screening of Novel indole amines

Synthesis and antioxidant screening of Novel indole amines

D−A−D based pyrido-pyrazino[2,3-b]indole amines as blue-red fluorescent dyes: Photophysical, aggregation-induced emission, electrochemical and theoretical studies

Herein donor−acceptor−donor (D−A−D) structured, pyridopyrazino[2,3-b]indole amines 2–6 were designed and synthesized via C–N coupled Buchwald-Hartwig amination reaction and characterized by spectroscopic methods. C–N coupling in molecules offers intramolecular charge transfer (ICT) transitions at longer wavelengths (λmax = 400–459 nm) in absorption spectra reminiscent D−A assembly. Dyes covers broad range of emission and emit in blue to red region with emission maxima 433–600 nm in solvent and solid film. Dyes 2, 5 and 6 explore the aggregation-induced emission (AIE) characteristics. Further C–N blending of various donor with pyridopyrazino[2,3-b]indole acceptor results in suppressed band gap (1.99–2.43 eV) and comparable HOMO (−5.17 to −5.71 eV) and LUMO (−3.18 to −3.28 eV) energies with reported small organic ambipolar materials. DFT and TDDFT calculations agree with the experimental opto-electrochemical data. Moreover, computed small singlet and triplet excitation energy difference (ΔEST (0.01–0.14 eV)) suggest thermally activated delayed fluorescent (TADF) emitting properties of dyes. Thus pyridopyrazino[2,3−b]indole amine dyes propose their potential application in optoelectronic devices.

Synthesis of Azepino[1,2‐a]indole‐10‐amines via [6+1] Annulation of Ynenitriles with Reformatsky Reagent

AbstractLewis acid‐catalyzed [6+1] annulation reactions of 2‐cyano‐1‐propargyl‐ and 2‐alkynyl‐1‐cyanomethyl‐indoles with Reformatsky reagent are described. 8‐Aryl, 8‐alkyl‐, 8‐hetaryl‐, 9‐aryl, and 9‐alkyl‐azepino[1,2‐a]indole amines were obtained through a 7‐endo‐mode cyclization of the β‐aminoacrylate intermediates. The antiproliferative activity of the azepino[1,2‐a]indoles analogs against the HCT‐116 cells were also examined.

Identification of phenylamide phytoalexins and characterization of inducible phenylamide metabolism in wheat

Changes in specialized metabolites were analyzed in wheat leaves inoculated with Bipolaris sorokiniana, the causal agent of spot blotch of Poaceae species. HPLC analysis detected the accumulation of six compounds in B. sorokiniana-infected leaves. Of these, we purified two compounds by silica gel and ODS column chromatography and preparative HPLC, and identified them as cinnamic acid amides, N-cinnamoyl-9-hydroxy-8-oxotryptamine and N-cinnamoyl-8-oxotryptamine, by spectroscopic analyses. The remaining four compounds were predicted to be p-coumaric acid amides of hydroxyputrescine, hydroxyagmatine, hydroxydehydroagmatine, and agmatine by mass spectrometry. The accumulation of two cinnamic acid amides was also induced by Fusarium graminearum infection, and by treatment with CuCl2, jasmonic acid, and isopentenyladenine. Antifungal activity of these amides was shown by inhibition of conidial germination and germ tube elongation of F. graminearum and Alternaria brassicicola, indicating that they act as phytoalexins. The accumulation of these amides also detected in barley leaves treated with CuCl2. We examined the accumulation of 25 phenylamides in B. sorokiniana-infected wheat leaves using LC-MS/MS. Hydroxycinnamic acid amides of tryptamine, serotonin, putrescine, and agmatine, were induced after infection with B. sorokiniana. Thus, the induced accumulation of two groups of phenylamides, cinnamic acid amides with indole amines, and p-coumaric acid amides with putrescine and agmatine related amines, represents a major metabolic response of wheat to pathogen infection.

NMR analysis of G-protein βγ subunit complexes reveals a dynamic Gα-Gβγ subunit interface and multiple protein recognition modes

G-protein betagamma (Gbetagamma) subunits interact with a wide range of molecular partners including: G(alpha) subunits, effectors, peptides, and small molecule inhibitors. The molecular mechanisms underlying the ability to accommodate this wide range of structurally distinct binding partners are not well understood. To uncover the role of protein flexibility and alterations in protein conformation in molecular recognition by Gbetagamma, a method for site-specific (15)N-labeling of Gbeta-Trp residue backbone and indole amines in insect cells was developed. Transverse Relaxation Optimized Spectroscopy-Heteronuclear Single-Quantum Coherence Nuclear Magnetic Resonance (TROSY-HSQC NMR) analysis of (15)N-Trp Gbetagamma identified well-dispersed signals for the individual Trp residue side chain and amide positions. Surprisingly, a wide range of signal intensities was observed in the spectrum, likely representing a range of backbone and side chain mobilities. The signal for GbetaW99 indole was very intense, suggesting a high level of mobility on the protein surface and molecular dynamics simulations indicate that GbetaW99 is highly mobile on the nanosecond timescale in comparison with other Gbeta tryptophans. Binding of peptides and phosducin dramatically altered the mobility of GbetaW99 and GbetaW332 in the binding site and the chemical shifts at sites distant from the direct binding surface in distinct ways. In contrast, binding of G(alpha)(i1)-GDP to Gbetagamma had relatively little effect on the spectrum and, most surprisingly, did not significantly alter Trp mobility at the subunit interface. This suggests the inactive heterotrimer in solution adopts a conformation with an open subunit interface a large percentage of the time. Overall, these data show that Gbetagamma subunits explore a range of conformations that can be exploited during molecular recognition by diverse binding partners.

Degradation of tetrahydro-beta-carbolines in the presence of nitrite: HPLC-MS analysis of the reaction products.

Motivated by the identification of numerous novel tetrahydro-beta-carboline-carboxylic acids in food samples, we studied the reactions of tetrahydro-beta-carbolines in the presence of nitrosating agents. The anticipated formation of nitroso derivatives from unsubstituted tetrahydro-beta-carbolines, and from tetrahydro-beta-carboline-3-carboxylic acids was indicated by HPLC-MS/MS analysis and validated by the characteristic product ion spectra of the respective nitroso compounds. In addition, oxidative decarboxylation resulted in formation of the corresponding dihydro-beta-carbolines, and in the generation of the beta-carbolines harman or norharman. Subsequently, we studied the reactivity of tetrahydro-beta-carboline-1-carboxylic acids derived from the Pictet-Spengler condensation of indole amines with alpha-oxo acids. Again, in the presence of nitrosating agents the rapid disappearance of the starting material was obvious, but no nitroso derivatives could be observed. Instead, further HPLC-MS/MS studies demonstrated that dihydro-beta-carbolines were the major products of tetrahydro-beta-carboline-1-carboxylic acids. Finally, we demonstrated that freshly isolated nitroso-precursors spontaneously decomposed to yield harman alkaloids. In conclusion, we revealed that nitroso-tetrahydro-beta-carbolines can represent intermediates involved in the generation of beta-carbolines, and we established a novel pathway for the formation of harman alkaloids from nutritional tetrahydro-beta-carbolines.

Red light suppresses N-acetylserotonin but does not elevate 5-HT and 5-HIAA of the rat pineal glands at night.

HPLC with EC detector was used to study the red light effect on the rhythmicity of catecholamines (NE, DOPAC and dopamine) and indoleamines (NAS, 5-HT, 5-HIAA) in the pineal glands and retinas of the Sprague-Dawley rat. We found the prominent nocturnal elevations of NAS in rat pineal glands and the suppression of the NAS but not the elevation of 5-HT and 5-HIAA after red light exposure at night. Our data show two findings: metabolic pathway of the indoleamines (5-HT, 5-HIAA and NAS) after red light exposure at night may be different from those by white light. Second, the increased HIOMT activity that effects on 5-HT and 5-HIAA may also be involved in the indoleamine formation after red light exposure at night.

Three dimensional culture of pineal cell aggregates: a model of cell-cell co-operation.

Three dimensional (3-D) cultures of pineal cell aggregates were obtained by constant gyratory shaking the heterogenous cell populations, obtained from the rat pineals, in the DMEM (Dulbecco's modified Eagle's medium). Within 4 days, the pineal cells became organized into a tissue like configuration appearing as a compact ball, evidenced by the scanning electron microscopy. The 3-D aggregates seemed to be mainly composed of pinealocytes (round-oval cells), glial (elongated cells) and other unknown cells. The heterogenous cells were separated by intercellular spaces. The ultrastructural characteristics revealed by transmission electron microscopy exhibited the presence of granular lysosomes, typical of pinealocytes actively involved in the secretion. These pineal cell aggregates secreted melatonin and other indole amines i.e. 5-methoxytryptamine (5-MT), indole acetic acid (IAA), 5-methoxy-3-indole acetic acid (5-MIAA), tryptophol (TOL) and 5-methoxytryptophol (5-MTL) in the culture medium, indicating the functional aspect of pinealocytes. The 3-D aggregates cultures had advantages over the pineal monolayer cultures as, after 4 days of culture, the amounts of indole amines secreted by 3-D aggregates were higher than those secreted by monolayer cultures. Besides, the 3-D aggregates remained functional till 24 days in the gyratory culture conditions. In the continuous perifusion system, the 3-D aggregates secreted melatonin while challanged with isoproterenol. This 3-D model of pineal cell aggregates might be useful, in future, to perform other kinetic studies of the release of indole amines in perifusion experiments as this system allows the maintenance of pineal cells for a long period of time.

Rat pineal cell aggregates: Ultrastructural and functional characteristics

The aggregates were obtained by constant gyratory shaking of suspension cells freshly isolated from adult rat pineal glands. Their sizes ranged from 60 to 120 μm. Within 4–5 days, the aggregates formed by pinealocytes, astrocytes, and other unidentified cells became organized in a tissue-like configuration. There was no proliferation of the fibroblast cells. Ultrastructural characteristics of the aggregates were revealed by the presence of granular lysosomes, which are typical of pinealocytes, and are actively involved in the secretion. Functional characteristics were studied in static incubation. The aggregates secreted melatonin and other indole amines in culture medium. Basal melatonin release was detected until Day 24 of culture. This secretion was stimulated 230% with Isoproterenol (β-adrenergic agonist), 725% with Epinephrine (α- and β-adrenergic agonists), and 140% with Vasoactive Intestinal Peptide after 5 days in culture, then > 1200% with Forskolin 9 days later (14-day-old aggregates). The results indicate that three-dimensional aggregates obtained from isolated pineal gland cells were the functional multicellular structures with in vivo characteristics.

Hypothalamic melatonin receptor sites revealed by autoradiography

125I-Melatonin was used to localize and characterize the melatonin receptor sites in the rat hypothalamus. Autoradiography revealed that displaceable 125I-melatonin binding occurred in suprachiasmatic nuclei and median eminence only. Further studies performed on crude membrane fractions from median eminences revealed high affinity ( K d = 21 pM) melatonin binding sites ( B max = 8.5 fmol/mg protein). The order of potency of various indole amines to inhibit 125I-melatonin binding was melatonin ⪢ N-acetyl-5-hydroxytryptamine > 5-methoxytryptamine > 5-hydroxytryptamine.

Preliminary report on the effect of elf magnetic pulsations on human subjects

During the last decade considerable interest has been evinced by scientists on the possible control of earth's electromagnetic environment on human physiology. The present paper discusses the effects of oscillatory magnetic fields in the extremely low frequency range on electrophysiological and biochemical parameters in human subjects. Normal subjects and practitioners of Yoga and meditation were exposed to sinusoidally oscillating magnetic fields in the frequency range of 0.01 to 10 Hz and with amplitudes of ±5 and ±50 nT generated inside a special controlled magnetic field enclosure with the subjects' heads oriented in the four cardinal directions and also in sitting posture, and against ambient magnetic fields of about 40000 nT (local geomagnetic field) and half this value (or 20000 nT). The ECG, finger blood flow and respiration were recorded continuously on a polygraph. The EEG was also recorded on an 8-channel machine with split-up of waves into alpha, beta, delta and theta components. Biochemical assays were carried out on the blood and urine. Certain decisive changes were observed in the electrophysiology, such as, for instance, a sharp inhibition of the brain's electrical activity with the head towards the North and, in contrast, an accentuation of activity in the East orientation. Alterations in the levels of metabolites of catechol and indole amines were seen in the North orientation.

Indole amines and amino acids in various brain regions after infusion of branched chain amino acids into hepatectomized rats.

This study was designed to determine regional changes of amino acids and indole amines in the brain and possible interactions between amino acids and indole amines 18 h after hepatectomy in rats. Hepatectomy and glucose infusion alone resulted in a profound increase of most large neutral amino acids (LNAA) in plasma and in the brain except for the branched-chain amino acids (BCAA), which maintained normal or somewhat lower values in plasma. Hepatectomy and infusion of glucose combined with BCAA sharply reduced the plasma and brain amino acid concentrations of other LNAA. Simultaneously the concentrations of serotonin and 5-hydroxyindoleacetic acid were decreased in all brain regions. In both groups of hepatectomized rats there were regional variations of the amino acid and the indole amine concentrations in the brain, but the response to BCAA infusion was generally the same in all brain regions. No difference in survival between the 2 groups could be found.

Degradation study of catecholamines, indole amines and some of their metabolites in different extraction media by chromatography and electrochemical detection

Optimal conditions for the extraction from brain tissue and the simultaneous quantification of catechol and indole derivatives were determined after a systematic degradation study in water and perchloric acid. The roles of three parameters, namely temperature, presence of antioxidant agents, and time, were considered. Adrenaline, noradrenaline, dopamine, homovanillic acid, 5-hydroxytryptophan, 5-hydroxyindole acetic acid, serotonin, and epinephrine were separated by HPLC and detected electrochemically. The results indicated a great instability of the indole derivatives at an ambient temperature, in an acid medium, and in the absence of a protective agent. Therefore, when perchloric acid has to be used for deproteinization, the lowest concentration (0.1 m) is preferable. The samples have to be kept on ice, in darkness, and protected by ascorbic acid and sodium ethylenediamine tetracetate.

The effects of imidazole-4-acetic acid on cerebral indole amine metabolism.

The effects of imidazole-4-acetic acid (IMA, 100--400 mg/kg) on indole amine metabolism were studied by measurement of the cerebral hemisphere and brain stem contents of tryptophan, 5-hydroxytryptophan (5-HTP), 5-hydroxytryptamine (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA). The results indicated that IMA does not alter the steady-state contents of brain indole amines. Furthermore, IMA failed to alter the levels of 5-HTP, 5-HT, or 5-HIAA in animals pretreated with 3-hydroxybenzyl hydrazine (a decarboxylase inhibitor), pargyline (a monoamine oxidase inhibitor), or probenecid (a compound which blocks 5-HIAA transport out of brain). These results suggest that altered serotonin metabolism is not a factor in the genesis of the behavioral or electroencephalographic changes produced by IMA.

The effect of pronounced hypoglycemia on monoamine metabolism in rat brain.

The cerebral metabolism of catechol and indole amines was studied in paralyzed and lightly anesthetized (70% N2O) rats in which severe hypoglycemia was induced by insulin. When blood glucose concentrations fell towards 1 μmol·g−1 and the electrocorticogram (EEG) showed high-amplitude slow waves with interspersed polysplkes, the tissue contents of dopamine (DA), norepinephrine (NE), and 5-hydroxytryptamine (5-HT) were reduced. The rate of hydroxylation of tyrosine, measured as accumulation of dihydroxyphenylalanine (dopa) following inhibition of aromatic L-amino acid decarboxylase with NSD 1015, rose in cortex and striatum, while tryptophan hydroxylation increased moderately in cortical tissue. Aggravation of the hypoglycemia with cessation of spontaneous EEG activity was accompanied by progressive reduction in tissue contents of DA, NE, and 5-HT and by accumulation of 5-hydroxyindole acetic acid (5-HIAA). In this period, tyrosine hydroxylation rate was reduced in limbic areas and in striatum, but not in the cortex, while tryptophan hydroxylation was reduced in limbic areas only. When recovery was induced for 45 min by i.v. glucose following 30 min recording of isoelectric EEG, there was extensive recovery of tissue concentrations of DA and 5-HT but incomplete recovery of NE concentrations. Tyrosine hydroxylation rate was increased in all areas, but tryptophan hydroxylation either remained at control levels (striatum and cortex) or fell (limbic area). It is concluded that severe hypoglycemia leads to a gross derangement of brain monoamine metabolism, which seems to include an increase in NE turnover during both the precomatose phase and the recovery phase.

The effects of acute hypercapnia on cerebral indole amine metabolism

The effects of 1-h exposure to hypercapnia (PaCO2, 90-110 MMHg) on cerebral indole amine metabolism were studied in rats by measurement of cerebral hemisphere contents of tryptophan, 5-hydroxytryptophan (5-HTP), 5-hydroxytryptamine (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA), 5-HIAA content was increased after 1-h exposure to hypercapnia, whereas tryptophan, 5-HTP, and 5-HT remained unchanged from control. The accumulation of 5-HTP after decarboxylase inhibition with 3-hydroxybenzyl hydrazine was increased in hypercapnic rats and indicated an increased activity of tryptophan hydroxylase. During the 1-h exposure to hypercapnia there was increased accumulation of 5-HT after monoamine oxidase inhibition with pargyline and increased accumulation of 5-HIAA arter probenecid. The results indicate an increased synthesis and degradation of indole amines in acute hypercapnia.

DC Potential Shifts Associated With Convulsive Seizures and Brain Monoamine Changes in Rabbits

SUMMARYRecordings were made of changes in the cerebral direct current potential (DC potential) as well as in polygraphic patterns occurring in association with convulsive seizures, various kinds of stimuli, sleep and brain amine changes in some 50 rabbits. Careful scrutiny of tracings thus obtained led to the following conclusions: The cortical and caudate DC potentials showed a negative shift of approximately 2 mV in conjunction with convulsive seizures induced by 25 mg/kg bemegride. A similar DC shift was observable during seizures provoked by pentetrazol or brain damage, These negative DC shifts were more rapid and of greater magnitude in the cerebral cortex than in the caudate nucleus. Stimulation with sound as well as with flash light gave rise to a negative shift of the cortical DC potential, with a habi‐tuation to these sensory stimuli of evoked DC potential changes being observed. Pen‐tobarbital‐induced sleep as well as spontaneous sleep shifted the caudate and cortical DC potentials to positivity, the response being more rapid and greater in magnitude in the caudate nucleus. The subcutaneous administration of 25–50 mg/kg L‐SHTP was followed by a negative shift (2–2.5 mV) of both the caudate and cortical DC potentials, whereas a 100–200 mg/kg subcutaneous dose of L‐DOPA was accompanied by a shift to positivity (1.0–1.5 mV) of the DC potential evoked in these brain areas. When administered by intraventricular injection, 100–200 pg serotonin caused a negative DC shift of 3–4 mV, while 100–200 μg dopamine and 200–300 μg noradrenaline were associated with a positive DC shift (approximately 1 mV and 1–2 mV, respectively). The latency of these responses was longer with precursors than with amines, being 30 minutes with L‐SHTP and 10 minutes with serotonin as well as 30 minutes with L‐DOPA, 15 minutes with dop‐amine and 5 minutes with noradrenaline. These figures suggest that the observed changes in DC potential are a phenomenon which is correlated with the metabolic process of biogenic amines. With the substance of the catecholamine series, a polygraphic pattern of slight waking reaction type with a concomitant increase in motor activity was observed in association with a positive DC shift. By contrast, a polygraphic pattern characteristic of sleep was seen with serotonin in conjunction with a negative DC shift, and motor activity tended to be diminished both with L‐SHTP and serotonin. While the administration of L‐DOPA in rabbits was followed by a tendency toward depressed amplitude of deep EEG activity, a dose of L‐5HTP or serotonin (intraventricular) was accompanied by convulsive seizures in some cases. In all two of two cases pretreated with MAOI, the administration of L‐SHTP was associated with the appearance of seizure discharges and, in one of them, even with fatal convulsions. In an epileptic patient who was on an oral antiepileptic medication, the oral administration of 100 mg L‐SHTP resulted in an elevation of serum serotonin level with concurrent activation of seizure discharges and the subsequent use of 200 mg L‐DOPA proved effective in antagonizing this activating action of L‐5HTP. In experimental epilepsy of rabbits, L‐DOPA exhibited an inhibitory action on kindled convulsion, but L‐SHTP had an equivocal effect of activating seizure activity. The results of OUT present study suggest that convulsive seizures, sensory stimulation, decreased cerebral levels of cate‐cholamines and increased levels of indole amines are associated with a negative cerebral DC potential shift, while suppressed convulsions, sleep, elevated cerebral levels of catecholamines and lowered levels of indole amines are accompanied by a positive DC potential shift.

Brain amines in fever and sleep cycle changes caused by streptococcal mucopeptide

Intravenous injection of streptococcal mucopeptide 2mg/kg to rats is followed by a marked temperature elevation and a significant decrease of paradoxical sleep. The measurement of turnover rates of 5-hydroxytryptamine and noradrenaline in hypothalamus and midbrain, areas involved in temperature and sleep control, demonstrated a significant increase of 5-hydroxytryptamine turnover in both areas during the fever and paradoxical sleep deprivation. This suggests the activation of 5-hydroxytryptamine neurones and brings further support to the concept relating the indole amines to temperature and sleep regulation.