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Background: Novel carboxamides and thioureas of 2,3-dihydro-5,6-dimethoxy-2-((piperidin- 4-yl)methyl) inden-1-one were synthesized and their potential anticholinesterase activities were evaluated. The inhibition potency of the compounds 17a-j and 19a-j against AChE was measured and evaluated using Ellman’s spectrophotometric method. Among carboxamides series, compound 17f, 17i, 17j and among thiourea series, compound 19a, 19b were found to be the most active. Methods: The scaffold 2,3-dihydro-5,6-dimethoxy-2-((piperidin-4-yl)methyl) inden-1-one 16, key intermediate of drug donepezil has been synthesised in three steps and derivatised as carboxamides and thioureas for SAR studies. Compounds 17a-j and 19a-j were characterised by 1H NMR and LCMS. The inhibitory activity and antiamnesic effect were studied using different sources such as electric eel AChE, human serum AChE and rat brain homogenate AChE. Results: The results of bioassays indicated that among all the synthesized compounds tested, five compounds 17f, 17i, 17j, 19a and 19b shows IC50 at a dose of 67, 42, 64, 52 and 63 nM respectively against electric eel, human serum and rat brain homogenate, which lead to the suggestion that compound 17i might be considered to be a potent AChE inhibitor. Conclusion: Derivatives of 2,3-dihydro-5,6-dimethoxy-2-((piperidin-4-yl)methyl)inden-1-one with different substitutions were synthesised and tested for their AChE activity. The order of potency is 17i>17j>17f and 19a>19b. The other compounds screened failed to elicit any inhibition of acetyl cholinesterase from rat brain homogenate. It may be concluded from this study that, for effective binding and blocking the AChE activity, molecule needs to bind with peripheral site and active site of the enzyme. Therefore, it can be summarized that by changing the functional group and substitution in the scaffold 2,3-dihydro-5,6-dimethoxy-2-((piperidin-4-yl)methyl)inden-1-one needs to be studied for better AChE inhibitory activity in future research.

New thiazole derivatives (2a-l) were synthesized via the reaction of 2-(3-cyano-4-isobutoxyphenyl)-4-methylthiazole-5-carboxylic acid with substituted phenyl amines. The anticancer activity of the synthesized thiazole derivatives was examined against MCF-7 (human breast), MDA-MB-231 (mammary carcinomas), HeLa (Cervical cancer), HT-29, HCT 116 (Colon cancer), and normal chang liver cancer cell lines, whereas cisplatin was employed as a positive control. The anticancer mechanisms were studied via apoptosis assessments, as well as molecular docking. The molecular docking study of potent compounds was carried out against the human epidermal growth factor receptor (HER2, PDB ID: 3RCD) as a possible target for anticancer activity using Auto Dock vina. ADMET results indicated that tested compounds have significant results within the close agreement of Lipinski’s rule of five. In addition, computational work employing density functional theory (DFT) was also carried out at the B3LYP/6-31G (d,p) level to investigate the electronic properties of the potent compounds. The frontier molecular orbital energy and atomic net charges were discussed.

A novel 5-(2-phenyl-1H-benzo[d]imidazol-1-yl)quinolin-8-ol ligand (PBIQ) ligand was used to synthesize a series of Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) complexes. Elemental analysis, FTIR, 1H NMR, UV-Visible and mass spectra were utilized to characterize the newly synthesized ligand and its transition metal complexes. The antimicrobial activity of the ligand and complexes were evaluated against four bacterial and one fungal strain using the minimum inhibitory concentration method (MIC). The minimum inhibition concentration observed was compared against the standard antibiotic rifampicin and the antifungal drug fluconazole. The studies revealed that Cu(II) and Zn(II) complexes are more effective against tested bacterial and fungal strains compared to the ligand and other complexes. Molecular docking techniques revealed that the Cu(II)-PBIQ complex associated with the target protein (PDB ID: 4HL2 ) had a greater binding affinity with π-σ, π-alkyl and hydrophobic interactions. Density function theory (DFT) calculations were applied to evaluate the optimized geometrical structures and to calculate the global reactivity descriptors of the more active Cu(II) and Zn(II) complexes. Besides, the in-silico pharmacokinetics showed that all the examined metal complexes compounds obeyed Lipinski's Rule of five with one violation.

In the title compound, C15H12O4, the arene rings are inclined at an angle of 65.97 (6)°. The pendant methyl ester substituent has an extended conformation. In the crystal, molecules are linked by C—H...π interactions, forming chains propagating along theb-axis direction. The chains are linkedviaoffset π–π interactions [intercentroid distance = 3.640 (1) Å], forming sheets parallel to (10-1).

A series of novel 1-benzhydryl-4-(3-(piperidin-4-yl)propyl)piperidine sulphonamide derivatives 8(a-j) was synthesized in good yield and met the structural requirements essential for anticonvulsant properties. The structures of the synthesized compounds were confirmed on the basis of their spectral data and elemental analysis. All the compounds were evaluated for their possible anticonvulsant activity by Maximal Electroshock Seizure (MES) test and their neurotoxic effects were determined by rotorod test. Majority of the compounds were active in MES tests. Compounds 8f and 8g have shown a significant and protective effect on seizure, when compared with standard drug phenytoin. Compound 8f and 8g without a fluoro group showed anticonvulsant activity in MES test as compared with compound 8a and 8b with fluoro substituents. From this study, it is quite apparent that there are at least three parameters for the activity of anticonvulsant drugs, that is, a lipophilic domain, a distal hydrophobic center and two-electron donor (-C-N-) system.

Series of 2-[4-(2,4-dimethoxy-benzoyl)-phenoxy]-1-[4-(3-piperidin-4-yl-propyl)-piperidin-1-yl]-ethanone derivatives 9 ( a – d ) and 10 ( a – d ) were synthesized in good yield. The synthesized compounds were characterized by 1 H NMR, LC–MS, FTIR and elemental analysis. All the compounds were screened for in vivo wound-healing activity by incision and dead space wound models on Swiss albino rats. Significant wound healing was observed in 10b and 10d treated groups as also the epithelialization of the incision wound was faster with a high rate of wound contraction in these groups. The tensile strength of the incision wound was significantly increased in 10b and 10d compared to the Nitrofurazone, the standard skin ointment. In dead space wound model also the weight of the granulation was higher indicating increase in collagenation. The SAR correlation studies revealed that the thioamide functional linkage and electron withdrawing groups influence the wound-healing activity.

A series of novel diphenyl(piperidin-4-yl)methanol derivatives 10(a–n) were synthesized and characterized by 1H NMR, LC/MS, FTIR, and elemental analyses. All the synthesized compounds were evaluated for cell proliferation by MTT assay. The antiproliferative effects of the synthesized compounds were tested against viable human skin fibroblast cell line and carcinoma cell lines, namely HeLa cells, HT-29 cells, MCF-7 cells, and HepG-2 cells in comparing the positive and negative control. Among the synthesized compounds, (10b) and (10g) have been identified as potent antiproliferative agents.

A series of novel 6-fluoro-3-(4-piperidinyl)-1,2-benzisoxazole derivatives 5(a-m) were synthesized with different substituted aromatic/heterocyclic acid chlorides (R-CO-Cl) and characterized by (1)H NMR, LC/MS, FTIR and elemental analyses. All the compounds synthesised were evaluated for their antiproliferative activity by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. The antiproliferative effects of the synthesised compounds were tested against viable human skin fibroblast cells and carcinoma cells namely HeLa cells, HT-29 cells, MCF-7 cells, HepG-2 cells by adopting positive and negative control. The importance of the aromatic and heterocyclic moiety was confirmed. From the SAR studies, it reveals that, the substitution at N-terminal of 6-fluoro-3-(4-piperidinyl)-1,2-benzisoxazole by the heterocyclic ring plays a dominant role and was responsible for the antiproliferative activity. Among the synthesized compounds 5a, 5d and 5k have showed potent antiproliferative activity on all the carcinoma cells tested.

The title compound, [1-(toluene-4-sulfonyl)-piperidin-4-yl]-methanol was synthesized by the condensation of diphenyl(piperidin-4-yl)methanol with p-toluenesulfonyl chloride in methylene dichloromethane as solvent and triethylamine as the base. The product obtained was characterized by spectroscopic techniques and the structure was investigated by X-ray crystallography. The compound crystallizes in the monoclinic crystal class in the space group P21/c with cell parameters a = 10.2490(13) A˚, b = 11.4710(9) A˚, c = 20.997(3) A˚, β = 116.344(3)°, V = 2212.2(5) A˚3 for Z = 4. The structure reveals that the piperidine ring is in a chair conformation. The geometry around the S atom is comparable with the classic tetrahedral value. The structure exhibits both inter and intramolecular hydrogen bonds of the type O–H · · · O and C–H · · · O.

In the course of structure-activity relationship studies and to explore the antiproliferative effect associated with the hydantoin framework, diversely substituted several diazaspiro hydantoins were synthesized. Variation in the functional group at N-terminal of the hydantoin ring and coupling of different substituted aromatic acids in 4-aminocyclohexanone ring led to three sets of compounds. The antiproliferative effect of the compounds was evaluated in vitro using the MTT colorimetric method against one normal cell line (NDF-103 skin fibroblast cells) and four human cancer cell lines (MCF-7 breast carcinoma cell line, HepG-2 hepatocellular carcinoma cell line, HeLa cervix carcinoma cell line and HT-29 colon carcinoma cell line) for the time period of 24 h. Among the series, some compounds exhibited interesting growth inhibitory effects against all four cell lines. From the SAR studies, it reveals that, the substitution at N-terminal in hydantoin ring plays key role in the antiproliferative activity.

A series of novel 5-(4-methyl-benzylidene)-thiazolidine-2,4-dione derivatives 6 (a-d) and 7 (a-g) were synthesized with different substituted aromatic sulfonyl chlorides (R-SO(2)-Cl) and alkyl halides (R-X) and were characterized by (1)H NMR, LC/MS, FTIR and elemental analyses. All the compounds synthesised were evaluated for their cell antiproliferation activity by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. The antiproliferative effects of the synthesised compounds were tested against viable human skin fibroblast cell line and carcinoma cell lines namely HeLa cells, HT-29 cells, MCF-7 cells, HepG-2 cells by adopting positive and negative control. The importance of the nitro group on thiazolidinone moiety was confirmed and it was concluded that the fourth position of the substituted aryl ring plays a dominant role and was responsible for the antiproliferative activity. Among the synthesized compounds only 6a, 7e and 7g have potent antiproliferative activity on all the carcinoma cell lines tested.

The title compound, C13H13N2O3, a hydantoin derivative, crystallized with two molecules (AandB) in an asymmetric unit. In moleculeA, the imidazolidine ring is twisted about the C—N bond involving the spiro C atom, while in moleculeBthis ring is flat (r.m.s. deviation = 0.010 Å). The pyran rings in both molecules have distorted half-chair conformations. The mean plane of the imidazolidine ring is inclined to the aromatic ring of the chroman unit by 79.71 (11)° in moleculeAand 82.83 (12)° in moleculeB. In the crystal, pairs of N—H...O hydrogen bonds link the individual molecules to formA–AandB–Binversion dimers. The dimers are linkedviaN—H...O and C—H...O hydrogen bonds, forming sheets lying parallel to thebcplane,viz.(011). Within the sheets, theAandBmolecules are linked by C—H...π interactions.

To study the structure activity relationship (SAR) on the cytotoxic activity and probe the structural requirement for the potent antitumor activity, a series of novel diazaspiro bicyclo hydantoin derivatives were designed and synthesized. Their structures were confirmed by H-1 NMR, LCMS and IR analyses. The antiproliferative effect of these compounds were determined against human leukemia, K562 (chronic myelogenous leukemia) and CEM (T-cell leukemia) cells using trypan blue and MTT assay, and the SAR associated with the position of N-terminal substituents in diazaspiro bicyclo hydantoin have also been discussed. It has been observed that these compounds displayed strong, moderate and weak cytotoxic activities. Interestingly, compounds having electron withdrawing groups at third and fourth position of the phenyl ring displayed selectively cytotoxic activities to both the cell lines tested with IC50 value lower than 50 mu M. In addition, the cytotoxic activities of the compounds 7(a-o) bearing the substituents at N-3 position of diazaspiro bicyclo hydantoin increases in the order alkene > ester > ether and plays an important role in determining their antitumor activities. The position and number of substituents in benzyl group attached to N-8 of diazaspiro bicyclo hydantoin nucleus interacted selectively with specific targets leading to the difference of biochemical and pharmacological effects.

A series of novel, potent, and selective muscarinic receptor 1 agonists (M1 receptor agonists) that employ a key N-substituted morpholine Arecoline moiety has been synthesized as part of research effort for the therapy of Alzheimer’s diseases. The ester group of arecoline (which is reported as muscarinic agonist) has been replaced by N-substituted morpholine ring. The structure–activity relationship reveals that the electron donating 4-substituted sulfonyl derivatives (9a, 9b, 9c, and 9e) on the nitrogen atom of the morpholine ring increases the affinity of M1 receptor binding 50- to 80-fold greater than the corresponding arecoline. Other derivatives also showed considerable M1 receptor binding affinity.

Alzheimer's disease (AD) is a neurodegenerative disorder affecting the central nervous system, which is also associated with progressive loss of memory and cognition. The development of numerous structural classes of compounds with different pharmacological profile could be an evolving, promising therapeutic approach for the treatment of AD. Thus, providing a symptomatic treatment for this disease are cholinomimetics with the pharmacological profile of Acetylcholinesterase (AChE) inhibitors. In view of this, we have synthesized novel 3-aryl-N-methyl-1,2,5,6-tetrahydropyridine derivatives 5a-k by Suzuki coupling and screened the efficacy of these derivatives for their AChE inhibitor activity.