Synthesis of some thiazolyl aminobenzothiazole derivatives as potential antibacterial, antifungal and anthelmintic agents

A series of 4-(6-substituted-1,3-benzothiazol-2-yl)amino-2-(4-substitutedphenyl)- amino-1,3-thiazoles, 9-24 have been synthesised from 2-chloro-N-(6-substituted-1,3-benzothiazol-2-yl)acetamides, 5-8. The structures of these compounds have been elucidated by spectral (IR, (1)H NMR, Mass) and elemental (C, H, N) analysis data. All the newly synthesised compounds (9-24) were screened for their antibacterial, antifungal and anthelmintic activities. Almost all of these compounds showed moderate to good antimicrobial activity against two gram negative bacteria (E. coli, P. aeruginosa), two gram positive bacteria (S. aureus, B. subtilis), pathogenic fungal strains (C. albicans, A. niger) and good anthelmintic activity against earthworm species (P. corethruses). Compounds 18 and 20 exhibited good antibacterial and antifungal activities, while compound 22 displayed the most significant anthelmintic activity.     

Synthesis of some newer derivatives of substituted quinazolinonyl-2-oxo/thiobarbituric acid as potent anticonvulsant agents

5-[1'-[3"-Aminoacetyl-2"-methyl-6",8"-dihalosubstitutedquinazolin-4"(3"H)-onyl]-thiosemicarbazido]-2-oxo/thiobarbituric acids 3a-3h and 5-[2'-amino-5'-[3"-aminomethylene-2"-methyl-6",8"-dihalosubstitutedquinazolin-4"(3"H)-onyl]-1',3',4'-thiadiazol-2'-yl]-2-oxo/thiobarbituric acid 5a-5h were prepared by incorporating 1-[3'-aminoacetyl-2'-methyl-6",8"-dihalosubstituted-quinazolin-4'(3'H)-onyl]-thiosemicarbazides 2a-2d and 2-amino-5-[3'-aminomethylene-2'-methyl-6',8'-dihalosubstituted-quinazolin-4'(3'H)-onyl]-1,3,4-thiadiazoles 4a-4 h respectively at 5(th) position of 2-oxo/thiobarbituric acids (via Mannich reaction). All the newly synthesized compounds were screened for their anti-convulsant activity in MES and PTZ models and were compared with standard drugs phenytoin sodium and sodium valproate. Interestingly, these compounds were found to be devoid of sedative and hypnotic activities when tested. Out of the compounds studied, the most active compound 5h, that is 5-[2'-amino-5'-[3"-aminomethylene-2"-methyl-6",8"-dibromoquinazolin-4"(3"H)-onyl]-1',3',4'-thiadiazol-2'-yl]-2-thiobarbituric acid showed activity (90%) more potent than the standard drug.     

Synthesis and anticonvulsant activity of aromatic tetramethylcyclopropanecarboxamide derivatives

As part of our ongoing research on potential new antiepileptic drugs (AEDs), a series of tetramethylcyclopropanecarboxamide derivatives containing benzene ring were designed, synthesized, and evaluated for anticonvulsant activities in the murine maximal electroshock (MES) and subcutaneous pentylenetetrazole (scMet) seizure tests. The most potent compound emerging from this study was N-(2,2,3,3-tetramethylcyclopropanecarboxamide)-p-phenyl-sulfonamide (21), possessing an ED(50) value of 26mg/kg in the rat-MES test and a remarkable PI (PI=TD(50)/ED(50)) value above 19. The better anticonvulsant potency of compound 21 and its wider safety margin compared to valproic acid (VPA) and zonisamide make it a potential candidate to become a new AED second-generation to VPA.     

Synthesis, in silico metabolic and toxicity prediction of some novel imidazolinones derivatives as potent anticonvulsant agents

A series of 1,2,4-trisubstituted 5-imidazolinone derivatives were synthesized by Erlenmeyer condensation of benzoylglycine (hippuric acid) with different aldehydes in the presence of sodium acetate and acetic anhydride. The derivatives of the compounds were prepared by condensation of some known sulpha drugs with 5-oxazolone derivatives. The anticonvulsant activity of the compounds was determined by the protection of pentylenetetrazole-induced convulsions that was ranged from 10 to 60%. The compounds with p-OCH?, p-OH and o-Cl substitutions in the phenyl ring on 4(th) position of the imidazolinone ring exhibited good anticonvulsant activity. In silico metabolic and toxicity studies showed that all the compounds in the series are not likely to exhibit toxicity except the compounds IIIa, IIIb, VIa and VIb, that is predicted to show 29% mutagenicity and 53% irritation in comparison to the other compounds. The predicted lethal effect and hERG toxicity of the compounds showed that IIa, IVa, Va and Vb might be toxic at higher concentrations. The results successfully establish the synthesized imidazolinone derivatives as novel compounds with anticonvulsant properties, low predicted cardiotoxicity and lethal effects thus can be promising leads for further development as novel anticonvulsants.     

Synthesis and anthelmintic activity of arctigenin derivatives against Dactylogyrus intermedius in goldfish

To control the parasitic disease of Dactylogyrus intermedius, a series of new arctigenin derivatives were designed, synthesized and tested in our study. The anthelmintic activity of most of the derivatives ranged from 1 to 10 mg/L. Compared to traditional drug praziquantel (EC₅₀ = 2.69 mg/L), ether derivatives 2g and 2h exhibited slightly higher anti-parasitic activity, with the EC₅₀ values of 2.48 and 1.52 mg/L, respectively. Furthermore, the arctigenin-imidazole hybrids 4a and 4b also removed D. intermedius effectively, with the EC₅₀ values of 2.13 and 2.07 mg/L, respectively. The structure-activity relationship analysis indicated that four carbon atoms length of linker and imidazole substitute group could significantly increase the anthelmintic activity, and reduced the toxicity. Through the scanning electron microscope observation, compounds 4a and 4b caused the D. intermedius tegumental damage such as intensive wrinkles, holes and nodular structures. Overall, the structural optimization analysis of arctigenin suggested that 4a and 4b can be used for preventing and controlling Dactylogyrus infections and considered as promising lead compounds for the development of commercial drugs.     

Synthesis and biological evaluation of amino analogs of Ludartin: Potent and selective cytotoxic agents

Diverse amino analogs of Ludartin, a cytotoxic guaianolide and a position isomer of an anticancer drug, Arglabin were prepared through Michael type addition at its highly active α-methylene-γ-lactone motif. The semisynthetic derivatives were subjected to sulphorhodamine B cytotoxicity assay against a panel of four different human cancer cell lines viz. lung (A-549), leukemia (THP-1), prostate (PC-3) and colon (HCT-116) to look into structure–activity relationship. Few of the analogs displayed potent selective cytotoxicity compared to the parent molecule-Ludartin (1). (11R)-13-(Diethyl amine)-11,13-dihydroludartin (6) and (11R)-13-(piperidine)-11,13-dihydroludartin (10) showed almost same cytotoxicity against leukemia cell lines (THP-1) as that of parent molecule-Ludartin, but were more active against colon (HCT-116) cancer cells. (11R)-13-(Morpholine)-11,13-dihydroludartin (11) displayed selectively better cytotoxicity against Leukemia cancer cells (THP-1) exhibiting IC₅₀ of 2.8 μM. (11R)-13-(6-Nitroindazole)-11,13-dihydroludartin (17) was four times more potent than Ludartin with selective cytotoxic effects against prostate cancer cells (2.2 μM) while as (11R)-13-(6-nitroindazole)-11,13-dihydroludartin (18) exhibited three-fold selective cytotoxicity for Lung (A-549) cancer cell lines exhibiting IC₅₀ of 2.6 μM.     

Azole antimicrobial pharmacophore-based tetrazoles: Synthesis and biological evaluation as potential antimicrobial and anticonvulsant agents

The azole pharmacophore is still considered a viable lead structure for the synthesis of more efficacious and broad spectrum antimicrobial agents. Potential antibacterial and antifungal activities are encountered with some tetrazoles. Therefore, this study presents the synthesis and antimicrobial evaluation of a new series of substituted tetrazoles that are structurally related to the famous antimicrobial azole pharmacophore. A detailed discussion of the structural elucidation of some of the newly synthesized compounds is also described. Antimicrobial evaluation revealed that twenty compounds were able to display variable growth inhibitory effects on the tested Gram positive and Gram negative bacteria with special efficacy against the Gram positive strains. Meanwhile, six compounds exhibited moderate antifungal activity against Candida albicans and Aspergillus fumigatus. Structurally, the antibacterial activity was encountered with tetrazoles containing a phenyl substituent, while the obtained antifungal activity was confined to the benzyl variants. Compounds 16, 18, 24 and 27 were proved to be the most active antibacterial members within this study with a considerable broad spectrum against all the Gram positive and negative strains tested. A distinctive anti-Gram positive activity was displayed by compound 18 against Staphylococcus aureus that was equipotent to ampicillin (MIC 6.25 μg/mL).On the other hand, twelve compounds were selected to be screened for their preliminary anticonvulsant activity against subcutaneous metrazole (ScMet) and maximal electroshock (MES) induced seizures in mice. The results revealed that five compounds namely; 3, 5, 13, 21, and 24 were able to display noticeable anticonvulsant activity in both tests at 100 mg/kg dose level. Compounds 5 and 21 were proved to be the most active anticonvulsant members in this study with special high activity in the ScMet assay (% protection: 100% and 80%, respectively).     

Synthesis,anticonvulsant and antimicrobial activities of some new 2-acetylnaphthalene derivatives

In this study, as a continuation of our research for new (arylalkyl)imidazole anticonvulsant compounds, the design, synthesis and anticonvulsant/antimicrobial activity evaluation of a series of 2-acetylnaphthalene derivatives have been described. Molecular design of the compounds has been based on the modification of nafimidone [1-(2-naphthyl)-2-(imidazol-1-yl)ethanone], which is a representative of the (arylalkyl)imidazole anticonvulsant compounds as well as its active metabolite, nafimidone alcohol (3, 4). In general, these compounds were variously substituted at the alkyl chain between naphthalene and imidazole rings and subjected to some other modifications to evaluate additional structure–activity relationships. The anticonvulsant activity profile of those compounds was determined by maximal electroshock seizure (MES) and subcutaneous metrazol (scM) seizure tests, whereas their neurotoxicity was examined using rotarod test. All the ester derivatives of nafimidone alcohol (5a–h), which were designed as prodrugs, showed anticonvulsant activity against MES-induced seizure model. Four of the most active compounds were chosen for further anticonvulsant evaluations. Quantification of anticonvulsant protection was calculated via the ip route (ED₅₀ and TD₅₀) for the most active candidate (5d). Observed protection in the MES model was 38.46 mg kg^?1 and 123.83 mg kg^?1 in mice and 20.44 mg kg^?1, 56.36 mg kg^?1 in rats, respectively. Most of the compounds with imidazole ring also showed antibacterial and/or antifungal activities to a certain extent in addition to their anticonvulsant activity.     

The triphenyltin(VI) complexes of NSAIDs and derivatives. Synthesis, crystal structure and antiproliferative activity. Potent anticancer agents

The novel triphenyltin(IV) esters of flufenamic acid (1), Hflu, [Ph₃Sn(flu)] (2), and of [2-(2,3-dichlorophenylamino)benzoic acid] (3), Hdcpa, [Ph₃Sn(dcpa)] (4) have been structurally characterized by means of vibrational and ¹H, ¹³C NMR spectroscopic studies. The crystal and molecular structures of [SnPh₃(dcpa)(DMSO)] 4a are described. The molecular structure of 4a reveals that the Sn atom has a distorted trigonal bipyramidal coordination geometry with equatorial phenyl groups and the carboxylate and dimethylsulfoxide oxygen atoms occupying axial positions. The crystal structure of 4a is self-assembled by C-H---π and π-π stacking interactions. The in vitro cytotoxic activity of 1-4 and of the related non-steroidal anti-inflammatory drugs, NSAIDs, [2-(2,6-dimethylphenylamino)benzoic acid], Hdmpa (5), [Ph₃Sn(dmpa)] (6), [2-(2,3-dimethylphenylamino)benzoic acid], mefenamic acid, Hmef (7) and [Ph₃Sn(mef)] (8) has been evaluated against the cancer cell lines MCF-7, T-24, A-549 and L-929. The ligands exhibited very poor cytotoxic activity against the four cancer cell lines. Complex 6 exhibits the highest activity and selectivity against A-549 and MCF-7 cancer cell lines and complex 8 the highest activity and selectivity against T-24 cancer cell line. The cytotoxic results indicate that coupling of Hdmpa and Hmef with R₃Sn(IV) metal center results in complexes with important biological properties and remarkable cytotoxic activity, since they display IC₅₀ values in a μΜ range better to that of the antitumor drug cis-platin. Complexes 6 and 8 are considered as excellent antitumor compounds and the results of this study represent the discovery of triphenyltin(IV)esters as a potential novel class of anticancer agents.     

Enaminones 11. An examination of some ethyl ester enaminone derivatives as anticonvulsant agents

In this paper, we investigated the previously synthesized anticonvulsant enaminone ethyl ester analogs using the computational gaussian 03 programs. The significant chemical features of the enaminone compounds that lead to positive anticonvulsant activity were identified. From our analyses, we believe that the neutrality of the phenyl ring may be important for binding in the hydrophobic pocket of the active site and that the binding of the phenyl substituent is the main reason why some analogs are active and others are inactive.     

Synthesis of chalcone derivatives as potential anti-diabetic agents

Chalcones bearing electron donating or electron withdrawing substitutions were prepared and their glucose uptake activity was evaluated. Chalcone derivatives were synthesized in one step protocol with high purity and yield. Chalcones with chloro, bromo, iodo and hydroxy substitutions at position 2 on A-ring exhibited the highest activity with glucose medium concentration (210 to 236 mg/dl) compared to pioglitazone and rosiglitazone (230 and 263 mg/dl, respectively). Also chalcones with iodo substitution at position 3 on A-ring were comparably active (≤238 mg/dl). The structure-activity relationship of the tested chalcones was studied and the findings were supported statistically.     

Synthesis of chimeric tetrapeptide-linked cholic acid derivatives: impending synergistic agents

Tetrapeptides derived from glycine and beta-alanine were hooked at the C-3beta position of the modified cholic acid to realize novel linear tetrapeptide-linked cholic acid derivatives. All the synthesized compounds were tested against a wide variety of microorganisms (gram-negative bacteria, gram-positive bacteria and fungi) and their cytotoxicity was evaluated against human embryonic kidney (HEK293) and human mammary adenocarcinoma (MCF-7) cell lines. While relatively inactive by themselves, these compounds interact synergistically with antibiotics such as fluconazole and erythromycin to inhibit growth of fungi and bacteria, respectively, at 1-24 microg/mL. The synergistic effect shown by our novel compounds is due to their inherent amphiphilicity. The fractional inhibitory concentrations reported are comparable to those reported for Polymyxin B derivatives.     

Synthesis of pro-apoptotic indapamide derivatives as anticancer agents

Abstract

4-Chloro-3-({[(substitutedamino)carbonothioyl]amino}sulfonyl)-N-(2-methyl-2,3-dihydro-1H-indole-1-yl)benzamide (1–20) and 4-chloro-3-({[3-(substituted)-4-oxo-1,3-thiazolidine-2-ylidene]amino}sulfonyl)-N-(2-methyl-2,3-dihydro-1H-indole-1-yl)benzamide derivatives (21–31) were synthesized from 4-chloro-N-(2-methyl-2,3-dihydroindol-1-yl)-3-sulfamoylbenzamide (indapamide). 4-Chloro-3-({[(4-chlorophenyl) amino) carbonothioyl]amino}sulfonyl)-N-(2-methyl-2,3-dihydro-1H-indole-1-yl)benzamide 12 demonstrated the highest proapoptotic activity among all synthesized compounds on melanoma cell lines MDA–MB-435 with 3.7% growth inhibition at the concentration of 10?µM. Compound 12 (SGK 266) was evaluated in vitro using the MTT colorimetric method against melanoma cancer cell line MDA–MB435 growth inhibition for different doses and exhibited anticancer activity with IC₅₀ values of 85–95?µM against melanoma cancer cell line MDA–MB435. In addition, this compound was investigated as inhibitors of four physiologically relevant human carbonic anhydrase isoforms, hCA I, II, IX and XII. The compund inhibited these enzymes with IC₅₀ values ranging between 0.72 and 1.60?µM.     

Synthesis of diaryl-azo derivatives as potential antifungal agents

As compared with a commercially available agricultural fungicide hymexazol, some phenyl-azo phenol derivatives (e.g., 4a, 4b, 4f, 4n, 4q, 4u, and 4v) exhibited the more promising and pronounced antifungal activities in vitro against seven phytopathogenic fungi. It seemed that 4-((un)substituted phenylazo)-phenol and 4-((un)substituted phenylazo)-3-methylphenol might be considered as new lead structures for further design of agricultural fungicides.     

Synthesis of new 2,5-disubstituted-1,3,4-thiadiazole derivatives and their in vivo anticonvulsant activity

A series of 2,5-disubstituted-1,3,4-thiadiazole derivatives were synthesized by the reaction of 3-(2-cyanopropan-2-yl)-N-(5-(piperazine-1-yl)-1,3,4-thiadiazol-2-yl)benzamide with various sulfonyl chlorides and evaluated for their anticonvulsant activity in MES test. Rotorod method was employed to determine the neurotoxicity. The purity of the compounds is confirmed on the basis of their elemental analysis. The structures of all the new compounds are established on the basis of ¹H NMR and mass spectral data. Out of fifteen compounds, three were found to be potent anticolvunstants. The same compounds showed no neurotoxicity at the maximum dose administered (100 mg/kg).     

New, potent anthelmintic and acaricidal agents: 4″-deoxy-4″-thio-substituted avermectin derivatives

Sulfonylation of the 4″-(or β)-hydroxyl of 5-OTBDMS-avermectin B_1a with trifluoromethanesulfonic anhydride yield triflates which were displaced stereospecifically with diverse sulfur nucleophiles. This sulfonylation/substitution protocol also was performed on the 4′-(or β)-hydroxyl of the corresponding avermectin monosaccharide. The sulfides, sulfoxides and sulfones thus obtained exhibited potent, broad spectrum anthelmintic and acaricidal activity.     

Synthesis and characterisation of celastrol derivatives as potential anticancer agents

In the present study, three series of novel celastrol derivatives were designed and synthesised by modifying the carboxylic acid at the 20th position with amino acid, amine, and triazole derivatives. All the synthesised compounds were screened for their anticancer activities using MTT assay against AGS, MGC-803, SGC-7901, HCT-116, A549, HeLa, BEL-7402, and HepG-2 cell lines. Most of the synthesised compounds exhibited potent antiproliferative effects. The most promising compound 3-Hydroxy-9β,13α-dimethyl-2-oxo-24,25,26-trinoroleana-1(10),3,5,7-tetraen-29-oic amide, N-(R)-methyl-3-(1H-indol-2-yl)propanoate (11) showed considerable high anticancer activity against AGS cell lines, with an IC₅₀ value of 0.44?μM, and considerably higher activities against HCT-116, BEL-7402, and HepG-2 cell lines, with IC₅₀ values of 0.78, 0.63, and 0.76?μM, respectively. The results of apoptosis tests and molecular docking study of compound 11 binding to Caspase-3 revealed that its mechanism of action with antiproliferative was possibly involved in inducing apoptosis by inducing the activation of caspase-3.     

Synthesis and evaluation of unsymmetrical polyamine derivatives as antitumor agents

A series of unsymmetrically substituted polyamine derivatives were prepared and their cytotoxicities in mouse leukemia L1210, melanoma B16, and HeLa cells were investigated. The in vitro cytotoxicity revealed that these conjugates could recognize the polyamine transporter, and the N-ethyl modified homospermidine moiety may be another efficient carrier as homospermidine even though the introduction of terminal alkyl groups led to reduced cytotoxicity in comparison with the un-substituted counterpart 1. The ornithine decarboxylase and topoisomerase II inhibition experiments indicated that ODC and TOPO II were potential, but not unique targets of these conjugates. Furthermore, the in vivo antitumor activities illustrated that the representative conjugate 2f and the homospermidine analogue 1 evidently inhibited the tumor growth and significantly increased the survival time of mice-bearing sarcoma 180 cells.     

Synthesis and investigation of novel benzimidazole derivatives as antifungal agents

The rise and emergence of resistance to antifungal drugs by diverse pathogenic fungal strains have resulted in an increase in demand for new antifungal agents. Various heterocyclic scaffolds with different mechanisms of action against fungi have been investigated in the past. Herein, we report the synthesis and antifungal activities of 18 alkylated mono-, bis-, and trisbenzimidazole derivatives, their toxicities against mammalian cells, as well as their ability to induce reactive oxygen species (ROS) in yeast cells. Many of our bisbenzimidazole compounds exhibited moderate to excellent antifungal activities against all tested fungal strains, with MIC values ranging from 15.6 to 0.975 μg/mL. The fungal activity profiles of our bisbenzimidazoles were found to be dependent on alkyl chain length. Our most potent compounds were found to display equal or superior antifungal activity when compared to the currently used agents amphotericin B, fluconazole, itraconazole, posaconazole, and voriconazole against many of the strains tested.