Potential of Tryptamine Derivatives as Multi-Target Directed Ligands for Alzheimer's Disease: AChE, MAO-B, and COX-2 as Molecular Targets.

Extensive research has been dedicated to develop compounds that can target multiple aspects of Alzheimer's disease (AD) treatment due to a growing understanding of AD's complex multifaceted nature and various interconnected pathological pathways. In the present study, a series of biological assays were performed to evaluate the potential of the tryptamine analogues synthesized earlier in our lab as multi-target-directed ligands (MTDLs) for AD. To assess the inhibitory effects of the compounds, various in vitro assays were employed. Three compounds, SR42, SR25, and SR10, displayed significant AChE inhibitory activity, with IC50 values of 0.70 µM, 0.17 µM, and 1.00 µM, respectively. These values superseded the standard drug donepezil (1.96 µM). In the MAO-B inhibition assay, SR42 (IC50 = 43.21 µM) demonstrated superior inhibitory effects as compared to tryptamine and other derivatives. Moreover, SR22 (84.08%), SR24 (79.30%), and SR42 (75.16%) exhibited notable percent inhibition against the COX-2 enzyme at a tested concentration of 100 µM. To gain insights into their binding mode and to validate the biological results, molecular docking studies were conducted. Overall, the results suggest that SR42, a 4,5 nitro-benzoyl derivative of tryptamine, exhibited significant potential as a MTDL and warrants further investigation for the development of anti-Alzheimer agents.

Determination of ionization constant and drug-likeness prediction of synthetic isoniazid derivatives.

Determination of ionization constant, commonly termed pKa is of prime interest in a wide range of pharmaceutical Research fields. The pKa of a compound is critical as it influences on its physicochemical parameters in biological and environmental systems. The study of pKa is also essential not only for the formulation of drugs and optimization of a variety of novel analytical methods, establishing new pharmaceutical dosage forms yet the exploration of the mechanism of action of drugs. In this research work, we have determined pKa values of isoniazid (INH) derivatives; N'-[(4-methyl benzoyl)] pyridine-4-carbohydrazide (I) and [2-oxo-2-(4-phenyl phenyl) ethyl] (pyridine-4-yl formamido) azanium bromide (II) through UV- spectrophotometry, a method is known for the accuracy and precision of results. These two compounds (I and II) were synthetically prepared in our lab by derivatizing INH and reported by Naeem et al in the year 2014. The mean pKa values for compounds I and II were experimentally determined as 7.37 and 3.76 respectively. The study is helpful in understanding the physicochemical behavior of these compounds in a biological system. Different pharmacokinetic parameters were also predicted using online web tools which ensured significant drug-likeness for both compounds.

Synthesis, biological screening and docking studies of some indole derivatives as potential antioxidant.

The present study envisioned some antioxidant candidates having 1,2,3,4-tetrahydro-9H-pyrido[3,4-b]indole (TRY), 3-(2-bromoethyl)indole (BEI) and 7-azindole (AI) nucleus. Derivatives of these indole molecules were synthesized and their scavenging activity for reactive oxygen species (ROS) investigated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. T3, T42 exhibited significant radical scavenging potential which is comparable to ascorbic acid (standard), while T36 appeared as most potent antioxidant by displaying better scavenging activity than standard molecule. Molecular docking study revealed good binding score and interactions of T36 with target human antioxidant enzyme (PDB code: 3MNG) validating the results of biological activity.

1,3-di-4-piperidylpropane derivatives as potential acetyl cholinesterase antagonists: Molecular docking, synthesis, and biological evaluation.

Acetylcholine esterase (AChE) is a key biological target responsible for the management of cholinergic transmission, and its inhibitors are used for the therapy of Alzheimer's disease. In the present study, a small library of molecules with 1,3-di-4-piperidylpropane nucleus were docked on AChE. The selected compounds were synthesized and evaluated for their enzyme inhibition. P25 and P17 expressed significantly higher AChE inhibition than standards with IC50 values of 0.591µM and 0.625µM, respectively. Binding mode of derivatives in the active site of AChE revealed dual binding of molecules in peripheral anionic site (PAS) and catalytic anionic site (CAS) of enzyme cavity.

Computation-based experimentation: Identification of piperazine containing antidepressants.

Depression, a common mental disorder, is one of the major contributors to the overall global burden with more than 264 million individuals affected worldwide. Monoamine oxidase inhibitors (MAOIs) have well-known efficacy for treating depression and other related disorders. Herein we report the implementation of extensive in-silico calculations to predict the mono-amine inhibitory potential of an in-house library of piperazine-based compounds. In this connection, a multistep virtual screening protocol based on pharmacophore modeling, molecular docking and Quantitative Structure-Activity Relationship (QSAR) was carried out by MOE. Further, to assess its ability to cross the blood brain barrier, ADME properties of the compounds were predicted. Compounds predicted the highest enzyme inhibition by QSAR was synthesized for experimental validation. Both the synthesized compounds (I15 and I21) presented good strength against Monoamine Oxidase in in vitro enzyme inhibitory activity.

Molecular docking, synthesis and biological evaluation of phenacyl derivatives of 9-aminoacridine as anti-Alzheimer's agent.

Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder mainly characterized by progressive deterioration of memory and impaired cognitive function. The most promising approach for symptomatic relief of AD is to inhibit acetylcholinesterase (AChE). On the basis of this approach in-house library of 9-aminoacridine derivatives were constructed and allowed to docked against human acetylcholinesterase (hAChE) (PDB ID: 4EY7), using MOE 2018.01 and PyRx 0.9.2 (AutoDock Vina). Top ranked and best fitted molecules were synthesized by targeting the 9-amino group of aminoacridine with substituted phenacyl halides. Anti-Alzheimer's potential was checked by in vitro AChE inhibition, antioxidant activity (DPPH scavenging ability) and fibril disaggregation. Subjected ligands suggested as promising multitargeted candidate with pronounced results in term of IC50 values (AChE inhibition 2.400-26.138µM), however, none of them showed potential towards fibril inhibition.

Analgesic activity of alkyl piperidine derivatives.

Piperidine is the most significant scaffold which reveals therapeutic potential because of its conformationally flexible nature. During the course of present investigations synthetic quaternary salts of alkyl piperidine with various phenacyl bromides were explored for their possible analgesic activity. Compounds I analogs (1a-1f) and compound II analogs (IIa-IIf) showed varying degree of analgesic activity when compared with pethidine as standard and its duration by tail immersion method.

Synthesis of 9-Aminoacridine Derivatives as Anti-Alzheimer Agents.

In the present study, some 9-aminoacridine derivatives have been synthesized by condensation of 9-aminoacridine with substituted phenacyl, benzoyl, and benzyl halides (RM1-RM6). Compounds were investigated for acetylcholinesterase and butyrylcholinesterase inhibition potential, considering these enzymes playing a key role in Alzheimer's disease. All derivatives showed better inhibition of enzymes than the standard galantamine, whereas except RM4, all exhibit better results than tacrine, a well-known acridine derivative used for the treatment of Alzheimer's disease.

Antimicrobial and antioxidant screening of N¢-substituted sulphonyl and benzoyl derivatives of 4-Pyridine carboxylic acid hydrazide.

In this research program, the antibacterial, antifungal and antioxidant activities of six N'-substituted sulfonyl and benzoyl derivatives of lead molecule PCH were reported. Out of these compounds, sulphonyl derivatives 2,3 and benzoyl derivative 5 showed moderate to good activity against different strains of gram-positive and gram-negative bacteria including B. cereus, B. subtilis, B. thruingiensis and S. pyogenes, S. fecalis and E. coli ATCC 8739. Moreover, upon antifungal screening, the compound, N¢-[(2,4,6-trimethylbenzene) sulfonyl]pyridine-4-carbohydrazide possessed good antifungal activity against Candida species, a causative agent of systemic fungal infections. Antioxidant study demonstrated more than 50% inhibition in DPPH assay for sulphonyl derivative 2 indicating its potential as antioxidant while the other derivatives expressed low level of radical scavenging property.

Synthesis of novel derivatives of 4-pyridine carboxylic acid hydrazide and their activity on central nervous system.

Six novel derivatives (2-7) of 4-Pyridine carboxylic acid hydrazide (PCH) were synthesized by treating this lead molecule with substituted arylsulphonyl and benzoyl chlorides. The molecular structures of the newly derived products were characterized by the help of UV Visible, IR, FAB, 1HNMR spectroscopy and CHN analysis. During the preliminary pharmacological screening, it was observed that the synthesized compounds induced noticeable changes on motor activity of the animals. Interesting structure activity relationship was also observed among the synthesized molecules. Because of the interesting affect on motor activity, the newly synthesized derivatives can further be evaluated for their effects on CNS.

Synthesis and cytotoxic activity of some derivatives of alkyl piperidine.

Synthesis of novel phenacyl derivatives of alkyl piperidine as cytotoxic agents via simple and single step reaction procedure is going to be reported here. Twelve new compounds were successfully synthesized in moderate yield and in solid form. Their synthesis was confirmed by TLC, melting point, CHN analysis and through different spectral studies such as UV, IR, Mass and proton NMR. The advantages of this synthetic route are simple operation, mild reaction conditions and good yields. These newly synthesized derivatives were extensively explored for their cytotoxicity by brine shrimp lethality assay.

Investigation of piperidine derivatives in ex vivo models of pain and platelet aggregation.

Piperidine derivatives are known to exhibit analgesic activities and are likely to possess the ability to block the effects of prostaglandins through inhibition of downstream signaling pathways. The present study investigated the activity of five derivatives (PD2-6) of 4-(4'-bromophenyl)-4-piperidinol (PD1), against pain and platelet aggregation mediated by the release of prostaglandins and thromboxane A2, respectively. The results showed that compound PD1 and its two phenacyl derivatives PD3 and PD5 exhibited a highly significant analgesic effect (p < 0.01), whereas PD4 and PD6 also showed significant activity. PD3, the most active analgesic compound when docked to the opioid receptor, had interactions between the oxygen of its nitro group and the amino group of ARG 573, indicating a distance of 1.2563 Å. The antiplatelet data showed that compound PD5 (4-(4'-bromo-phenyl)-4-hydroxy-1-[2-(2″,4″-dimethoxyphenyl)-2-oxo-ethyl]-piperidinium bromide) had an IC(50) = 0.06 mM, which was the most active compound, whereas PD3 was the second most active compound against platelet aggregating factor-induced aggregation with an IC(50) = 80 mM. Acetyl salicylic acid (IC(50) = 150 µM) was used as a positive control.

Behavioral and neurochemical profile of some novel phenacyl based isonipecotamide derivatives.

Study of natural products led to the development of new molecules of potential biological activity. Piperidine nucleus constitutes one of the components of various alkaloids and drugs. During the course of our project regarding the synthesis of derivatives of piperidine carboxamide to study the effects of these compounds as anti-depressive agents, some of the compounds exhibited significant effects at all three doses, through open field activity thus establishing a direct relationship between dose and locomotion. Moreover, these compounds have also shown the decreased level of 5-HT alone with increased level of dopamine as an indication of their antagonism towards 5-HT receptor.

Characterisation of Plasmodium falciparum aspartic protease inhibition by piperidine derivatives.

Piperidine derivatives are reported to exhibit a variety of pharmacological activities. In this article, synthesis and aspartic protease inhibitory activity of three nitrophenacyl derivatives of N-methyl-4-hydroxy piperidine are reported. Enzyme assays showed that the attachment of a nitro group in the benzene ring plays an important role in the inhibition of plasmepsin-II of Plasmodium falciparum. The compound 1-methyl-1-(4'-nitrophenacyl)-4-hydroxypiperidinium bromide (3), consisting of a nitro group at the para position, was the most active at the concentration of 1.0 µM. The activity of the compounds was evaluated through the observed orientation and diagrammatic representation of nitrophenacyl derivatives of 4-hydroxy piperidine.

Synthesis of some novel analogues of 4-(1-Pyrrolidinyl) Piperidine and their effect on plasma glucose level.

In the present study some compounds of 4-(1-Pyrrolidinyl) Piperidine (I) have been synthesized. Structures of compounds were confirmed by using HNMR, IR, Mass and UV spectrophotometer techniques. All the derivatives (II, III, IV and V) and the parent compound (I) at the dose of 100 mg/kg were evaluated for their effect on plasma glucose level. Compound (II) was the only derivative which showed effect on plasma glucose level.

Synthesis and pharmacological activities of 7-azaindole derivatives.

As a part of our program to discover novel analogues of 7-azaindole (1H-Pyrrolo[2,3-b] pyridine) having useful biological activities, some derivatives have been synthesized and evaluated for their analgesic and hypotensive activity. Compounds evaluated by thermal stimuli (tail immersion method) at the dose of 50 mg/kg of body weight revealed significant analgesic activity. Pethidine was used as reference drug. Same compounds tested at the dose of 75 mg/kg of body weight showed toxicity. Compounds tested for their effect on blood pressure in normotensive rat produced slight fall in blood pressure.

Antibacterial activity of 1-methyl-7-methoxy-beta-carboline and its phenacyl and coumarine analogues.

Antibacterial activity of 1-methyl-7-methoxy-beta-carboline (harmaline) and its phenacyl and coumarine analogues 1-(3-nitro-phenyl)-(2-(7-methoxy-1-methyl-1,3,4,9-tetrahydro-beta-carbolin-2-yl)-ethanone (II), 1-(3,4-dihydroxy-phenyl)-2-(7-methoxy-1-methyl-1,3,4,9-tetrahydro-beta-carbolin-2-yl)-ethanone (III) 7-(methoxy-beta-carboline),15-24,de-hydro(19,20-dimethoxy)coumarine (IV), 7-(methoxy-beta-carboline)15-24,dehydro(20-methoxy)coumarine (V) were studied by disc diffusion method. All compounds were tested against three gram positive and four gram-negative bacteria. Parent compound showed good activity. All compounds revealed better results against gram positive as compared to gram-negative bacteria. 1-(3,4-Dihydroxy-phenyl)-2-(7-methoxy-1-methyl-1,3,4,9-tetrahydro-beta-carbolin-2-yl)-ethanone (III) was found most potent compound showing broad spectrum activity when compared with all synthesized analogues. Coumarine analogues showed more or less same activity indicating that number and position of methoxy groups are not important regarding antimicrobial activity.

Synthesis and pharmacological activity of 4-(4'-(chlorophenyl)-4-hydroxypiperidine) derivatives.

A new series of 4-(4'-chlorophenyl)-4-hydroxypiperidine derivatives (2-5), substituted at nitrogen, were synthesized and tested as potential analgesic compounds as well as evaluated for their effect on hypotensive activity. Results showed that all the derivatives exhibit significant analgesic activity in male Wistar rats at a dose of 50 mg/kg of body weight after intramuscular injection, when tested by thermal stimuli (tail flick test). Pethidine was used as reference drug. Compounds 2, 3 and 5 produced reduction in blood pressure in normotensive rat.

Neurochemical estimations of some new quaternary phenacyl-bromopiperidinium compounds.

Considering the fact that N-alkyl substituted quaternary ammonium salts of piperidinium bromide induce brain catecholamine and indoleamine metabolism (Black et al., 1986), we thought it may be valuable to investigate the effects of three selected phenacyl derivatives (I, V and VIII) of piperidine on brain monoamines metabolism in mice (100mg/kg body weight) assuming that these derivatives might alter the brain indoleamine and catecholamine levels differently. Studies are carried out by using HPLC technique. It was found that compound VIII possessed greater neuroleptic activity as compared to compounds I and V.

Effect of diazepam on the CNS excitation and behavioural changes induced by harmaline and its newly synthesized analogues.

The neuropharmacologic profile of harmala alkaloids has been studied and found to have central effects like convulsions, catalepsy, or altered startle response. In number of studies the effects of diazepam, on harmaline and other beta carboline containing compounds-induced tremors were investigated. The present study was undertaken to examine the effect of diazepam on pretreated animals with harmaline and its synthesized phenacyl and coumarine analogues. Diazepam successfully inhibited the tremor and convulsions and attenuated the other behavioural response produced by harmaline and its derivatives.