Letters in Drug Design & Discovery - Volume 16, Issue 1, 2019

Background: A novel copper-catalyzed synthesis of substituted-1,2,3-triazole derivatives has been developed and performed by Huisgen 1,3-dipolar cycloaddition reaction of azides with alkynes. The reaction is one-pot multicomponent. Objective: We state the advancement and execution of a methodology allowing for the synthesis of some new substituted 1,2,3-triazole analogues with antimicrobial activity. Methods: A series of triazole derivatives was synthesized by Huisgen 1,3-dipolar cycloaddition reaction of azides with alkynes. The structures of the synthesized compounds were elucidated and confirmed by 1H NMR, IR, MS and elemental analysis. All the synthesized compounds were tested for their antimicrobial activity against a series of strains of Bacillus subtilis, Staphylococcus aureus and Escherichia coli for antibacterial activity and against the strains of Candida albicans, Aspergillus flavus and Aspergillus nigar for antifungal activity, respectively. Results and Conclusion: From the antimicrobial data, it was observed that all the newly synthesized compounds showed good to moderate level of antibacterial and antifungal activity.

Background: B-cell Lymphoma Extra Large (Bcl-XL) belongs to B-cell Lymphoma two (Bcl-2) family. Due to its over-expression and anti-apoptotic role in many cancers, it has been proven to be a more biologically relevant therapeutic target in anti-cancer therapy. In this study, a Quantitative Structure Activity Relationship (QSAR) modeling was performed to establish the link between structural properties and inhibitory potency of benzothiazole hydrazone derivatives against Bcl-XL. Methods: The 53 benzothiazole hydrazone derivatives have been used for model development using genetic algorithm and multiple linear regression methods. The data set is divided into training and test set using Kennard-Stone based algorithm. The best QSAR model has been selected with statistically significant r2 = 0.931, F-test =55.488 RMSE = 0.441 and Q2 0.900. Results: The model has been tested successfully for external validation (r2 pred = 0.752), as well as different criteria for acceptable model predictability. Furthermore, analysis of the applicability domain has been carried out to evaluate the prediction reliability of external set molecules. The developed QSAR model has revealed that nThiazoles, nROH, EEig13d, WA, BEHv6, HATS6m, RDF035u and IC4 descriptors are important physico-chemical properties for determining the inhibitory activity of these molecules. Conclusion: The developed QSAR model is stable for this chemical series, indicating that test set molecules represent the training dataset. The model is statistically reliable with good predictability. The obtained descriptors reflect important structural features required for activity against Bcl-XL. These properties are designated by topology, shape, size, geometry, substitution information of the molecules (nThiazoles and nROH) and electronic properties. In a nutshell, these characteristics can be successfully utilized for designing and screening of novel inhibitors.

Background: Apart from the “hit drugs”, there are many others being studied for their potent activity against several hostilities. To date, anticancer research has been exploited on the inherent versatility and active core skeleton of the compounds. Literature suggests that nitrogen rich molecules are most active and found in their potent cancer activity. Purine-based compounds such as olomoucine and roscovitine, which contain other heterobicyclic ring systems, are useful for the cell proliferation inhibitors in the treatment of many types of cancer. Methods: We put forward the novel purine based compounds, aryl amino-quinoline-purine by a two-step procedure. In the first step, nitrogen rich molecule was synthesized by the coupling of 2,6- dichloropurine with 3-aminoquinoline in an acidic reaction conditions at the C-6 position of purine. Aryl amines were introduced at the C-2 position by acid catalyst and using polar solvent at comparatively higher reaction conditions to furnish the desired products. Results: Stereochemical aspect was introduced for the identification of attachment of 3- aminoquinoline at the C-2/ C-6 position of purine and it was concluded by the spectral analysis (HMBC spectrum). The spectral data revealed that the first chloro-amine coupling was directed at the C-6 position rather than C-2 and the second chloro-amine coupling by various aryl amines were directed at the C-2 position. The applications of synthesized compounds were identified by their cytotoxic study against NCI-60 cell-lines. Out of nine selected molecules by NCI, 5a has shown promising response in a single dose study and GI50 value, 7.57 μM indicated that it has 7.57% lethality over HOP-92 cell-line (non-small cell lung cancer panel). Conclusion: Two straightforward novelties were introduced, first stereochemical identification for chloro-amine coupling in purine either at the C-2 or C-6 position on the basis of HMBC spectrum. And a second type of uniqueness was to identify better anti-cancer agents out of synthesized scaffolds. Overall study shows that compound 5a is a novel therapeutic agent after modification for the treatment of non-small cell lung and it satisfied determined threshold growth inhibition criteria at a single dose level.

Background: A series of novel 2,6-dichloro-4-(trifluoromethyl)phenyl)-3-(difluoromethyl)- 1H-pyrazole-4-carboxamide derivatives were designed and synthesized. Methods: All the title compounds were confirmed by 1H NMR and MS. Results and Conclusion: The primarily nematicidal activity results indicated that some of them exhibited moderate control efficacy against the tomato root-knot nematode disease caused by Meloidogyne incognita.

Background: A series of novel cinnamic acid piperazine amide derivatives has been designed and synthesized, and their biological activities were also evaluated as potential tyrosinase inhibitors. Methods: Compounds 9, 11 and 17 showed the most potent biological activity (IC50 = 66.5, 61.1 and 66 μM, respectively). In silico docking simulation was performed to position compound 11 into the Agaricus bisporus mushroom tyrosinase's active site to determine the putative binding interactions. Results and Conclusion: The results indicated that compound 11 could serve as a promising lead compound for further development of potent tyrosinase inhibitors.

Background: In this study, nine novel compounds, bearing N-[2-(4-substituted piperazine-1-yl)acetyl]-N'-[bis-(4-fluorophenyl)methyl]piperazine structures were synthesized. Methods: Their cytotoxic properties were evaluated in vitro by NCI-60 Sulforhodamine B (SRB) assay against human cancer cell lines: Huh7 (hepatocellular), MCF7 (breast) and HCT116 (colorectal). Results and Conclusion: According to the activity data, most of the compounds are more cytotoxic than 5-fluorouracil against Huh7 and HCT116 cancer cell lines.

Background: Recently, we reported synthesis and neuroprotective activity of some new 1,2,4-triazine derivatives against H2O2 and β-amyloid toxicity in two neurotic cell lines, SHSY5Y and PC12. Methods: The promising results obtained prompted us to further study on these potent neuroprotective agents. In the current study, in vivo anti-inflammatory effect and also genoprotective activity of these compounds in endosulfan-mediated toxicity were investigated. Compounds RT and SMO exhibited high anti-inflammatory effect at 3 and 4 hours after injection in 20 mg/kg, and were even more effective than Indomethacin (20 mg/kg). Results: Interestingly, compound SMO in 200 μM was the best compound in reducing micronuclei significantly (P value <0.0001) in lymphocytes treated with endosulfan compared to control group. Conclusion: Herein, we report SMO as a genoprotective agent and a new drug candidate for endosulfan mediated toxicity.

Background: In the present study, the formation of 2, 4, 4-trimethyl-7,2'4'-trihydroxy flavan has been used as the key feature for the formation of new 1,3-benzoxazines. This reaction was carried out via Mannich-condensation reaction, the 7-hydroxy group of flavan was reacted with different primary amines in the presence of formaldehyde. Methods: All the synthesized compounds were characterized on the basis of FT-IR, NMR, MS and elemental analysis (CHN). Disk diffusion and 96-well plate assay methods were employed for the zone of inhibition and minimum inhibitory concentration determination, respectively to investigate the antibacterial activities. Results and Conclusion: Our studies showed that compound with electron withdrawing group on the benzene ring of 1,3-benzoxazines has promising antibacterial activities. An oral dose of 10 mg/kg body weight was administered to albino mice for acute toxicity of synthesized compounds. In vivo anti-inflammatory and in-vitro cyclooxygenase-2 (COX-2) studies showed that compound 11 was the most potent anti-inflammatory agent which inhibited induced edema by 62.7% while 68.7% inhibition of COX-2 was observed. The plausible binding mode of this compound in COX-2 enzyme was also determined using molecular docking simulations.

Background: In view of the estrogenic receptor inhibitory properties of coumarin nucleus, long chain nature of fatty acid and anti-breast cancer activity of fatty acids, it was proposed to attach long chain fatty acids at 3rd,4th and 7th position of coumarin nucleus and evaluate for their anti-breast cancer activity through suitable in-vitro methods. Methods: The present study focuses a library of fatty acid coumarin conjugates as ligands to the ligand-binding domain of the human estrogen receptor α (PDB ID 2IOG) and their binding affinities using GLIDE module of Schrodinger after ascertaining their drug-likeness with QIKPROP. The compounds LNAC 8, SAC 1 and OAC 5 are the best hits based on their docking scores as well as the Prime MM-GBSA free energy of binding. Based on the in-silico results and synthetic feasibility the compounds SAC 1 PAC 1 and OAC 1 are synthesized, characterized and investigated for their time interval growth inhibitory effect on MCF-7 which is an ER positive breast cancer cell lines. Results: SAC 1, showed better in vitro growth inhibitory effect in sub micromolar range as compared to Tamoxifen, a standard estrogen receptor modulator. Conclusion: Conclusively, in silico molecular docking studies have been very useful in predicting the pharmacokinetic profiles and the binding affinities of new hits before a detailed preclinical and clinical evaluation.

Background: Azoles are commonly used in the treatment and prevention of fungal infections. They suppress fungal growth by acting on the heme group of lanosterol 14α-demethylase enzyme (CYP51), thus blocking the biosynthesis of ergosterol. Objectives: Due to the importance of pyrazolines in the field of antifungal drug design, we aimed to design and synthesize new pyrazoline-based anticandidal agents. Methods: New pyrazoline derivatives were synthesized via the reaction of 1-(chloroacetyl)-3-(2- thienyl)-5-(1,3-benzodioxol-5-yl)-2-pyrazoline with aryl thiols. These compounds were evaluated for their in vitro antifungal effects on Candida species. Docking studies were performed to predict the affinity of the most effective anticandidal agents to substrate binding site of CYP51. Furthermore, MTT assay was performed to determine the cytotoxic effects of the compounds on NIH/3T3 mouse embryonic fibroblast cell line. A computational study for the prediction of ADME properties of all compounds was also carried out. Results: Compounds 5, 8, 10 and 12 were found as the most potent anticandidal agents against Candida albicans and Candida glabrata in this series with the same MIC values of ketoconazole and they also exhibited low toxicity against NIH/3T3 cells. Docking results indicated that all these compounds showed good binding affinity into the active site of CYP51. In particular, chloro substituted compounds 8 and 12 bind to CYP51 through direct coordination with the heme group. According to in silico studies, compound 8 only violated one parameter of Lipinski's rule of five, making it a potential orally bioavailable agent. Conclusion: Compound 8 was defined as a promising candidate for further in vitro and in vivo studies.

Background: A series of chalcones and flavones were synthesized from 2'-hydroxyacetophenone and substituted aromatic aldehydes via Simmons-Schmidt condensation followed by oxidative cyclization. Methods: Characterization of the obtained structures was established on the basis of their spectroscopic data. The synthesized compounds were screened for their antimicrobial activities against five bacterial strains (Citrobacter freundii, Staphylococcus aureus, Listeria monocytogenes, Salmonella braenderup, Escherichia coli.) and two fungal strains (Candida albicans, Candida krusei). Results: The in vitro bioassay results indicated that some target compounds displayed moderate (4d, 4e) to high (4a) antifungal activity against the pathogenic fungi C. albicans and C. krusei. Conclusion: For the antibacterial activity, only products 3d and 4d showed a weak antibacterial activity. These compounds can lead to the design of new drugs with specific antifungal activity.