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Fifteen N 4-benzyl-substituted isatin-3-thiosemicarbazones 5a–o were synthesized and evaluated for their urease and glycation inhibitory potential. Lemna aequinocitalis growth and Artemia salina assays were also done to determine their phytotoxic and toxic effects. All compounds are potent inhibitors of the urease enzyme, displaying inhibition [half maximal inhibitory concentration (IC50)=1.08±0.12–11.23±0.19 μm] superior to that of the reference inhibitor thiourea (IC50=22.3±1.12 μm). Compounds 5c, 5d, 5h, 5j,k are potent antiglycating agents, showing glycation inhibitory activity better than that of the reference inhibitor rutin (IC50 values 209.87±0.37–231.70±6.71 vs. 294.5±1.5 μm). In the phytotoxicity assay, 11 thiosemicarbazones 5a–d, 5g, 5h, 5j–l, 5n,o are active, demonstrating 5–100% growth inhibition of L. aequinocitalis at the highest tested concentrations (1000 or 500 μg/mL). In the brine shrimp (A. salina) lethality bioassay, three derivatives 5b, 5j and 5o are active with median lethal dose (LD50) values of 3.63×10−5, 2.90×10−5 and 2.31×10−4 m, respectively.

A series of fifteen N4-benzyl substituted 5-nitroisatin-3-thiosemicarbazones 5a–o was synthesized and evaluated for urease inhibitory, phytotoxic and cytotoxic influences. All the compounds proved to be highly potent inhibitors of the enzyme, showing inhibitory activity (IC50 = 0.87 ± 0.25–8.09 ± 0.23 μM) much better than the reference inhibitor, thiourea (IC50 = 22.3 ± 1.12 μM) and may thus act as persuasive leads for further studies. In phytotoxicity assay, twelve out of fifteen thiosemicarbazones tested i.e. 5a–e, 5g, 5i and 5k–o appeared to be active, exhibiting weak or non-significant (5–35%) growth inhibition at the highest tested concentrations (1000 or 500 μg/mL). In contrast, only one compound i.e. 5i was active in the brine shrimp (Artemia salina) lethality bioassay, demonstrating cytotoxic activity with LD50 value 2.55 × 10−5 M. Molecular docking studies of compounds 5a–o were also performed to identify their probable binding modes in the active site of the enzyme.

A new series of thirty nine 5-trifluoromethoxy/fluoro/chloro-isatin 3-hydrazonothiazolines 5a–n, 6a–o and 7a–j were synthesized by cyclization of the corresponding intermediate N4-aryl-substituted isatin-3-thiosemicarbazones 3 (prepared by condensation of appropriate isatin 1 with appropriate N4-aryl-substituted 3-thiosemicarbazides 2) with 4-chlorophenacyl bromide 4 in absolute ethanol or ethanol–benzene mixture and screened for their cytotoxicity, phytotoxicity, antifungal and urease inhibitory potential. All the synthesized compounds were found to be almost inactive in a brine shrimp (Artemia salina) bioassay, demonstrating IC50 values > 1.62 × 10−4 to 2.17 × 10−4 M. In a phytotoxicity assay, out of thirty-nine compounds tested, six i.e. 5i, 6h, 6i, 6k, 7c and 7h proved to be active, showing weak or non-significant (5–30%) activity at the highest tested concentration (500 μg mL−1). Similarly, in antifungal assay, twenty-six compounds i.e. 5a, 5b, 5d–f, 5h–j, 5m, 6a, 6b, 6d, 6j, 6l–o, 7a, 7b and 7d–j were found to be active against one, two, or three selected fungal strains, exhibiting weak or non-significant inhibition (10–30%). Of these, 6d and 6o displayed a relatively better activity profile in terms of the number of organisms inhibited. On the other hand, in a urease inhibition bioassay, all the synthesized hydrazonothiazolines proved to be potent enzyme inhibitors, demonstrating inhibitory activity with IC50 values ranging from 3.70 ± 0.62 to 849 ± 2.26 μM. Compounds 5c, 5g–i, 5k, 5n, 6b, 6c, 6i, 6k, 6l, 6n, 6o, 7a, 7e, 7i and 7j were, however, found to be relatively very potent, displaying outstanding enzymatic activity (IC50 = 3.70 ± 0.62 to 20.9 ± 0.57 μM), even better than the reference inhibitor thiourea (IC50 = 22.3 ± 1.12 μM), and may thus act as valid leads for further studies. Molecular docking studies of the synthesized isatin–thiazolines 5a–n, 6a–o and 7a–j were also carried out to elucidate their relationship with the binding pockets of the enzyme. This study offers the first example of exhibition of urease inhibitory potential by isatin–thiazolines and as such provides a solid basis for further research on these compounds to develop more potent antiurease compounds of medicinal/agricultural interest.

Several isatin-3-thiosemicarbazones (a class of Schiff bases) from our earlier studies have been validated as promising cytotoxic agents and urease inhibitors. Also, a number of isatin-derived imines (Schiff bases) and their Cu(II) complexes have been reported in the literature to exhibit potential cytotoxic activity towards different cells. In view of this, a series of seven new 5-(un)-substituted isatin-derived bis-Schiff bases/ligands 3a–g and their Cu(II) complexes 5a–g were synthesized and evaluated for their cytotoxic and urease inhibitory activities. All the Schiff base ligands 3a–g proved to be active in sulforhodamine B (SRB) bioassay, displaying promising cytotoxic activity against lung carcinoma (H157) cells. Compound 3b was found to be the most potent inhibitor of H157 cells, exhibiting an IC50 value of 2.32 ± 0.11 μM. Similarly, all the metal complexes 5a–g proved to be active in this assay, demonstrating enhanced cytotoxic activity in each case, occurring as a result of coordination of the Schiff base ligands to the metal ion. Compound 5d proved to be the most potent inhibitor of H157 cells, showing cytotoxic activity comparable to that of the standard drug, vincristine (VCN) (IC50 = 1.29 ± 0.06 vs. 1.03 ± 0.04 μM). In the urease inhibition assay, all the synthesized Schiff base ligands except 3f proved to be highly potent enzyme inhibitors, displaying inhibitory activity even better than that of the reference inhibitor, thiourea (IC50 = 0.04 ± 0.004–5.86 ± 0.09 vs. 22.3 ± 1.12 μM), and thus may act as promising lead molecules for further studies. Molecular docking studies were also carried out for bis-Schiff bases 3a–g to elucidate their relationship with the binding pockets of the enzyme.

A series of fifteen N4-benzyl substituted 5-chloroisatin-3-thiosemicarbazones 5a–o were synthesized and screened mainly for their antiurease and antiglycation effects. Lemna aequinocitalis growth and Artemia salina assays were carried out to determine their phytotoxicity and cytotoxicity potential. All the compounds proved to be extremely effective urease inhibitors, demonstrating enzyme inhibition much better than the reference inhibitor, thiourea (IC50 values 1.31 ± 0.06 to 3.24 ± 0.15 vs. 22.3 ± 1.12 μM). On the other hand, eight out of fifteen compounds tested, i.e. 5b, 5c, 5h–k, 5m and 5n were found to be potent glycation inhibitors. Of these, five viz. 5c, 5h–j and 5n proved to be exceedingly efficient, displaying glycation inhibition greater than the reference inhibitor, rutin (IC50 values 114.51 ± 1.08 to 229.94 ± 3.40 vs. 294.5 ± 1.5 μM).

A novel fused isocoumarin skeleton has been synthesized through selective domino multicyclizations by mixing homothallic acid and 2,3-diphenylacryloyl chloride at 200 °C under catalyst and solvent free reaction conditions. Six fused rings with two stereogenic centers were assembled in a convenient one-pot operation in good yield. The resulting hexacyclic fused isocoumarin skeleton and its stereochemistry was fully characterized and unambiguously confirmed by X-ray diffraction analysis.

An interesting isatin–thiazoline hybrid molecule having C N N N bonds has been synthesized and its solid state self-assembly behaviour was studied by X-ray diffraction technique. A layered structure based on hexameric supracycles, which are formed through three different self-complementary dimeric motifs, was obtained. The supramolecular forces involved in the stabilization of this structure are NH–O, CH–O, CH–N, CH–π, π–π, CH–Cl and unconventional N–O interactions.

A series of fifteen N

A series of N 4-aryl-substituted 5-fluoroisatin-3-thiosemicarbazones 3a–3l was synthesized and evaluated for selected biological activities. The brine shrimp lethality bioassay was carried out to study their in vitro cytotoxicity potential and besides, their antifungal, phytotoxic and urease inhibitory effects were also investigated. Seven compounds i.e. 3a, 3d, 3f, 3g, 3h, 3j and 3k proved to be active in the brine shrimp assay, displaying promising cytotoxicity (LD50 = 6.89 × 10−5–2.79 × 10−4 M). Amongst these, 3a and 3h were found to be the most active ones (LD50 = 6.89 × 10−5 and 9.79 × 10−5 M, respectively). Compounds 3i, 3j and 3 k displayed moderate (40 %) antifungal activity against one or two fungal strains i.e. A. flavus and/or M. canis. In phytotoxicity assay, all the synthesized compounds, including the reference point 2m showed weak-to-moderate (15–70 %) activity at the highest tested concentration (500 μg/mL). In urease inhibition assay, compounds 3f, 3g and 3j proved to be the most potent inhibitors, demonstrating relatively a higher degree of enzymatic inhibition with IC50 values ranging from 37.7 to 47.3 μM.

A novel method for the synthesis of tetracyclic fused-ring heterocycles, closely related to circumdatin alkaloids, is developed via regioselective reaction of heterocyclic ketene aminals (HKA) with 3-formylchromones.

A series of twenty one N4-aryl substituted 5-trifluoromethoxyisatin-3-thiosemicarbazones 3a-3u was synthesized by the reaction of trifluoromethoxyisatin 1 with different arylthiosemicarbazides 2 in aqueous ethanol (50%), containing a few drops of acetic acid. Their structures were established on the basis of analytical (CHN) and spectral (IR, 1H-NMR, EIMS) data. All the synthesized compounds were evaluated for their toxicity potential by a brine shrimp lethality bioassay. Ten compounds i.e., 3a, 3e, 3i-3l and 3n-3q proved to be active in this assay, displaying promising toxicity (LD50 = 1.11 × 10−5 M − 1.80 × 10−4 M). Amongst these, 3k, 3n and 3o were found to be the most active ones (LD50 = 1.11 × 10−5 M − 1.43 × 10−5 M). Compound 3k showed the highest activity with a LD50 value of 1.11 × 10−5 M and can, therefore, be used as a lead for further studies. Structure-activity relationship (SAR) studies revealed that the presence of strong inductively electron-attracting trifluoromethoxy substituent at position-5 of the isatin moiety played an important role in inducing or enhancing toxic potentiality of some of the synthesized compounds.

A series of 5-nitroisatin-3-thiosemicarbazones 2a–2l was synthesised and evaluated for selected biological activities. The brine shrimp lethality bioassay was carried out to study their in vitro cytotoxicity potential and besides, their antifungal, phytotoxic and urease inhibitory effects were also investigated. Only compound 2j proved to be active in the brine shrimp assay exhibiting LD50 value 1.16 × 10−3 M. Compounds 2a and 2d displayed moderate antifungal activity (50 and 40%, respectively) against M. canis. Similarly, compound 2l exhibited moderate activity (40%) against the fungal strain, A.flavus. In phytotoxicity assay, all the synthesised compounds including the reference point 2m showed weak to moderate (20–60%) activity at the highest tested concentrations (1,000 μg and 500 μg/ml, respectively). In urease inhibition assay, compounds 2a, 2i and 2k proved to be potent inhibitors demonstrating pronounced inhibition with IC50 values 0.440, 0.901 and 27.880 μM, respectively. These compounds may act as leads for further studies.

4 -substituted 5-nitroisatin-3-thiosemicarbazones 2a-2q has been synthesized and screened for in vitro urease inhibitory activities. Compounds 2a-2d, 2g, 2i, 2j and 2q were found to be potent inhibitors of the enzyme. Of these, 2c exhibited a potent inhibitory activity with IC50 value 16.4 � M and may act as a lead molecule for further studies. Structure-activity relationship studies revealed that electronic effects of the substituents play an important role in the urease inhibitory potential of the synthetic compounds. ery program (15-21), we have recently synthesized a number of N 4 - substituted isatin-3-thiosemicarbazones as urease inhibitors with non toxic nature (22, 23). These findings form a solid basis for further research on such compounds to develop more potent, safe and useful urease inhibitors. Furthermore, structure-activity rela- tionship (SAR) studies revealed that the type and position of the substituents on phenyl ring, substituted at N 4 of the thiosemicarba- zone moiety, play an important role in the urease inhibitory poten- tial of these compounds. To further enhance the activity of new antiurease compounds, the study of the combination of substitution at position-5 of the isatin scaffold with attachment of different aryl groups (having one or two substituents about the phenyl ring) at N 4 of the thiosemicarbazone moiety was considered worth pursuing. The present work therefore deals with the synthesis and evaluation of urease inhibitory potential of a series of seventeen N 4 - arylsubstituted 5-nitroisatin-3-thiosemicarbazones. We describe here the effects of the nature of aryl groups at N 4 (modified by placement of one or two substituents about the phenyl ring) and the presence of nitro function at position-5 of the isatin scaffold on the urease inhibitory potential of these compounds.

A new series of 12 N(4)-substituted isatin-3-thiosemicarbazones 2a-l has been synthesized, characterized and screened for in vitro cytotoxic, phytotoxic and urease inhibitory effects. All the compounds proved to be active in the brine shrimp bioassay; 2a, 2b, 2d, 2f and 2h-l exhibited a high degree of cytotoxic activity (LD(50) = 1.10 x 10(- 5) M-3.10 x 10(- 5) M). In urease-inhibition assay, compounds 2a, 2b, 2e, 2f, 2h-j and 2l proved to be potent inhibitors displaying relatively much greater inhibition of the enzyme with IC(50) values ranging from 20.6 microM to 50.6 microM. Amongst these, 2a and 2f were found to be the most potent ones exhibiting pronounced inhibition with IC(50) value 20.6 microM. All the synthetic compounds showed weak to moderate (10-40%) phytotoxicity at the highest tested concentration (500 microg/mL) indicating their usefulness as inhibitors of soil ureases.

This study was aimed at determination of pharmacokinetic parameters of copper (II) acetylsalicylate (CAS). Ten volunteers received a 60-mg dose of CAS. Blood samples were collected just before and after 0.25, 0.5, 0.75, 1.0, 1.5, 2.5, 3.0, 3.5, 4.0, 4.5, 5.5, 7.0, 10, and 12.0 h of administration of the drug. The plasma samples were analyzed for CAS and its metabolites by a validated high-performance liquid chromatography method having a suitable lower limit of quantification. The dose of 60 mg was well tolerated without any adverse effect. The maximum plasma concentration of CAS was found to be 0.38 mg L(-1) with t (max) of 0.72 h. The plasma half-life, clearance, and volume of distribution of CAS were 8.67 h, 66.30 L h(-1) and 829 L kg(-1), respectively. The elimination of CAS, acetylsalicylic acid, copper salicylate, and salicylic acid follows the first order kinetics with r (2) 0.979, 0.880, 0.991, and 0.998, respectively. The study provided for the first time the pharmacokinetic data for CAS after oral administration of CAS. The data were found to be useful in understanding the claimed enhanced anti-inflammatory activity of the drug as compared with that of acetylsalicylic acid.

A novel fused isocoumarin skeleton has been synthesized through selective domino multicyclizations by mixing homothallic acid and 2,3-diphenylacryloyl chloride at 200 °C under catalyst and solvent free reaction conditions. Six fused rings with two stereogenic centers were assembled in a convenient one-pot operation in good yield. The resulting hexacyclic fused isocoumarin skeleton and its stereochemistry was fully characterized and unambiguously confirmed by X-ray diffraction analysis.

International audience; An exciting isatin-thiazoline hybrid molecule 2 having -C=N-N=C- linkage has been synthesized in 88% yield by the reaction of 5-fluoroisatin with N-(4-fluorophenyl)hydrazinecarbothioamide followed by condensation of the resultant isatin-thiosemicarbazone intermediate with p-chlorophenacyl bromide. The solid state self-assembly of this hybrid molecule was studied by X-ray crystallographic technique. A layered assembly composed of 1D-chains with methanol molecules encapsulated between every two chains is obtained, making a bi-chain sandwich like structure. The supramolecular forces involved in the stabilization of this structure are importantly fluorine-mediated interactions (C-H···F, F···S and F···π) along with others i.e. N-H···O, O-H···O, C-H···O, Cl···π, C-H···π and π···π interactions. To the best of our knowledge, this is the first example of solid state fluorine-mediated C-H···F, F···S and F···π interactions found in a family of isatin-based compounds

A series of Co (II), Cu (II), Ni (II) and Zn (II) complexes of mercaptothiadiazole-derived furanyl, thienyl, pyrrorlyl, salicylyl and pyridinyl Schiff bases were synthesized, characterized and screened for their in vitro antibacterial activity against four Gram-negative, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi and Shigella fexneri, and two Gram-positive; Bacillus subtilis and Staphylococcus aureous bacterial strains. The results of these studies show the metal complexes to be more antibacterial as compared to the prepared un-complexed Schiff bases.

Artemisinin (ARMN) is a potent antimalarial drug, which is effective against multidrug resistant strains of Plasmodium falciparum and produces rapid recovery even in patients with cerebral malaria. Being poorly soluble in water, artemisinin is incompletely absorbed after oral intake due to poor dissolution characteristics in the intestinal fluids. To enhance these properties, solid dispersions of artemisinin with succinic acid (SUC) were prepared using drug-carrier ratios 1 : 1, 1 : 4, 1 : 6, 1 : 8 and 1 : 10 by solvent evaporation and freeze drying methods. These solid dispersions were characterized by differential scanning calorimetery (DSC), Fourier transform infrared spectroscopy (FTIR), x-ray diffraction patterns (XRD), phase solubility and dissolution kinetics evaluated by applying zero order, first order, Higuchi, and Korsmeyer-Peppas models. Physical mixtures produced significantly higher aqueous solubility and rate of dissolution as compared to artemisinin alone. The dissolution profiles of all formulations followed Higuchi model and exhibited diffusion-controlled release of drug. Solvent evaporation method (SLVPs) exhibited improved solubility and freeze dried solid dispersions (FDSDs) produced highest solubility but stability constant was opposite. ARMN and SUC both were found completely crystalline as shown by their XRD patterns. Physical mixtures (PMs) showed reduced intensity in their XRD patterns while solid dispersions by SLVPs exhibited twice reduced intensity and much displaced angles, whereas FDSDs showed synergistic effects in some of ARMN and SUC peaks. DSC thermograms of FDSDs at drug-carrier ratios 1 : 1-1 : 4 showed lower melting temperature and enthalpy change (deltaH) values than respective SLVPs, whereas at higher ratios, a reverse was true. SLVPs showed displaced methyl stretching bands at lower drug-carrier ratios and exhibited O-H stretching characteristic bands of SUC at higher drug-carrier ratios. In addition, carbonyl group and C-O stretching vibrations characteristic of SUC (1307 cm(-1)) appeared prominently compared to PMs, whereas C-O stretching characteristic bands of ARMN disappeared at higher ratios. FDSDs exhibited distinct nature of bonding compared to respective SLVPs and PMs.

Organometallic-based, 1,1'-diacetylferrocene-derived antibacterial and antifungal thiocarbohydrazone, carbohydrazone, thiosemicarbazone and semicarbazone have been prepared by condensing equimolar amount of 1,1'-diacetylferrocene with thiocarbohydrazide, carbohydrazide thiosemicarbazide and semicarbazide, respectively. These were used as ligands for the preparation of their cobalt (II), copper (II), nickel (II) and zinc (II) metal complexes. All the synthesized ligands and their complexes were characterized by IR, NMR, elemental analyses, molar conductances, magnetic moments and electronic spectral data. These synthesized compounds were screened for their antibacterial activity against Escherichia coli, Bacillus subtillis, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi, and for antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata using the agar-well diffusion method. All the compounds showed good antibacterial and antifungal activity which increased on coordination with the metal ions thus, introducing a novel class of organometallic-based antibacterial and antifungal agents.

A series of isatins incorporating thiazole, thiadiazole, benzothiazole and p-toluene sulfonyl hydrazide moieties, along with their cobalt(II), copper(II), nickel(II) and zinc(II) metal complexes have been synthesized and characterized by elemental analyses, molar conductances, magnetic moments, IR, NMR and electronic spectral data. These compounds have been screened for antibacterial activity against Escherichia coli, Bacillus subtillis, Shigella flexneri, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi, and for antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata using the agar-well diffusion method. All the synthesized compounds have shown good affinity as antibacterial and/or antifungal agents which increased in most of the cases on complexation with the metal ions.

A new series of antibacterial and antifungal triazine-derived mono- and di-substituted (symmetrical and unsymmetrical) Schiff-bases and their cobalt(II), copper(II), nickel(II) and zinc(II) metal complexes have been synthesized and characterized by their elemental analyses, molar conductances, magnetic moments and IR and electronic spectral measurements. IR spectra indicated the ligands to act as tridentate towards divalent metal ions via a trazine-N, the azomethine-N and, indole-NH and deprotonated-O of salicylaldehyde. The magnetic moments and electronic spectral data suggest octahedral geometry for the Co(II), Ni(II) and Zn(II)complexes and square-pyramid for Cu(II) complexes. NMR spectral data of the ligands and their diamagnetic zinc(II) complexes well-define their proposed structures/geometries. Elemental analyses data of the ligands and metal complexes agree with their proposed structures/geometries. The synthesized ligands, along with their metal complexes were screened for their antibacterial activity against Escherichia coli, Bacillus subtillis, Shigella flexneri, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi and for antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata. The results of these studies show the metal complexes to be more antibacterial/ antifungal against two or more species as compared to the uncomplexed Schiff-base ligands.

Acylhydrazine derived pyrrolyl ligands and their metal [Co(II), Cu(II), Ni(II), and Zn(II)] complexes have been prepared and characterized on the basis of elemental analyses, magnetic moments, molar conductances and spectroscopic (electronic, IR, 1H and 13C NMR) data. All of these compounds function as tridentate ligands, with their deprotonated enolic form being preferred in the coordination to the metal ions. The title synthesized ligands and their metal(II) complexes have been screened for bactericidal activity against the pathogenic bacterial species Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa, and it is shown that the metal complexes act as more active antibacterial agents than the uncomplexed ligands from which they derive.

A condensation reaction of 2-amino-1,3,4-thiadiazole with 2-pyrrolecarboxaldehyde to form tridentate NNN donor Schiff base has been performed. The prepared Schiff base was further used for the formation of metal complexes having stoichiometry [M(L)2]Xn , where M=Cu(II) or Zn(II), L=N-(2-pyrrolylmethylene)-2-amino-1,3,4-thiadiazole, X=SO42− , NO3− , C2O42− or CH3CO2− and n=1 or 2. The new compounds described here have been characterized by their physical, spectral and analytical data, and have been screened against several bacterial strains such as Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The antibacterial potency of the Schiff base increased upon chelation/complexation, having the same metal ion (cation) but different anions opening up a novel approach in finding new ways to fight against antibiotic resistant strains.

2-Amino-1,3,4-thiadiazole undergoes a condensation reaction with furane-, thiophene- and pyrrole-2-carboxaldehyde to form tridentate NNO, NNS and NNN donor Schiff bases. These Schiff bases were further used to obtain complexes of the type [M(L)2]X, where M = Co(II), Cu(II), Ni(II) or Zn(II), L = L1, L2 or L3 and X = Cl2. The new compounds described here have been characterized by their physical, spectral and analytical data, and have been screened for antibacterial activity against several bacterial strains such as Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The antibacterial potency of the Schiff bases increased upon chelation/complexation in comparison to the uncomplexed Schiff bases against the tested bacterial species thus, opening new approaches to find new ways in the fight against antibiotic-resistant strains.

A series of 29 previously reported N(4)-substituted 5-nitroisatin-3-thiosemicarbazones 2-30 has been screened for leishmanicidal potential. Compounds 2-4, 7, 8, 10-13, 15-19, 21, 23, 24, 26, 28 and 30 exhibited good to excellent antileishmanial activities with IC50 values ranging from 0.44 ± 0.02 to 32.38 ± 0.66 µg/mL. Of these, 5, 7, 19 and 28 proved to be the most active antileishmanial agents, displaying activities with IC50 values 1.78 ± 0.35, 0.44 ± 0.02, 1.91 ± 0.04 and 4.28 ± 0.75 µg/mL, respectively, which were even better than the standard drug, pentamidine (IC50 = 5.09 ± 0.04 µg/mL). This study presents the first example of exhibition of leishmanicidal potential by isatin-thiosemicarbazones and as such furnishes a solid basis for further research on these compounds to develop more potent antileishmanial agents.

A simple protocol is developed for the reaction of heterocyclic ketene aminals with 3-formylchromones to give tetracyclic heterocycles.

Artemisinin (ARMN) is a drug of choice against drug-resistant malaria especially due to Plasmodium falciparum. Being poorly soluble in water, its solid dispersions with nicotinamide (NA) were prepared at various drug-carrier ratios (1:1, 1:4, 1:6, 1:8, 1:10) by solvent evaporation and freeze drying methods. These solid dispersions were characterized by differential scanning calorimetery (DSC), fourier transform infrared spectroscopy (FTIR), X-ray diffraction patterns (XRD), phase solubility and dissolution studies. Artemisinin and nicotinamide both were found completely crystalline as shown by their XRD patterns. Physical mixtures (PMs) showed decreased intensity in their XRD patterns while solid dispersions by solvent evaporation method (SLVPs) exhibited displaced angles and decreased intensity whereas freeze dried solid dispersions (FDSDs) showed least number of peaks having low intensity and maximum displaced angles. DSC thermograms of drug-carrier ratios at 1:1-1:4 showed lower melting temperature than artemisinin and nicotinamide in all preparations. Endothermic temperature of artemisinin in PMs and SLVPs increased with rise of nicotinamide content upto 1:6 ratio followed by decline. All samples showed crystallization temperature below the artemisinin except drug-carrier ratio 1:6 of PMs while δH value was minimum at this ratio. FDSDs produced lowest endothermic temperature than corresponding PMs and SLVPs. SLVPs exhibited band shifting in both functional and fingerprint region compared to respective PMs as exhibited by their FTIR spectra. FDSDs and SLVPs showed different nature of bonding among artemisinin and nicotinamide. FDSDs produced strongest CONH(2) bonding followed by SLVPs and PMs respectively. PMs produced significantly higher aqueous solubility and rate of dissolution as compared to artemisinin alone. SLVPs exhibited improved solubility and dissolution profile corresponding to PMs. FDSDs showed highest release rate and aqueous solubility followed by SLVPs and PMs at all ratios. PMs and SLVPs showed their highest dissolution profile at 1:6 drug-carrier ratio followed by gradual decrease while FDSDs progressed in dissolution rate with increase of nicotinamide content successively upto maximum at 1:10 ratio.

A new series of sixteen N4-aryl substituted 5-chloroisatin-3-thiosemicarbazones 2a-2p has been synthesized, characterized and tested for selected biological activities i.e. cytotoxicity, phytotoxicity and urease inhibition. In the brine shrimp bioassay, all the synthesized compounds gave LD50 values >2.30 X 10-4 M - 2.79 X 10-4 M and were, therefore, found to be almost inactive, whereas in phytotoxicity assay, regardless of the nature of aryl substituents, they displayed weak to moderate (5-40%) phytotoxic activity at the highest tested concentrations (500 or 1000 μg/mL). In urease inhibition bioassay, compounds 2a, 2c, 2e, 2f, 2k and 2m exhibited relatively a higher degree of urease inhibition with IC50 values ranging from 38.91 μM to 76.65 μM and thus proved to be potent inhibitors of the enzyme. Of these, 2f and 2m displayed pronounced inhibition with IC50 values 38.91 μM and 39.50 μM, respectively, and may act as lead compounds for further studies. Structure-activity relationship (SAR) studies revealed that electronic effects of the substituents about the phenyl ring at N4 of the thiosemicarbazone moiety played an important role in enhancing the urease inhibitory potential of some of the synthesized compounds.

New biologically active tridentate pyrazine-derived NNO, NNS and NNN Schiff base ligands (I, II and III) and their nickel(II), copper(II) and zinc(II) complexes 1–9. have been synthesised and characterised on the basis of conductance and magnetic measurements, elemental analyses, and 1H-NMR, IR and electronic-spectral data. The synthesised ligands and their complexes have been evaluated for antibacterial activity against Esoherichi a colt- Pseudomonas aeruginosa and Klebsiella pneumoniae The activity data show the metal complexes to be more antibacterial than the ligands against one or more bacterial species.

In the title compound, C17H10F6N4O2S, an intramolecular N—H...N hydrogen bonds forms an S(5) ring whereas N—H...O and C—H...S interactions complete S(6) ring motifs. The dihedral angle between the fused ring system and the phenyl ring is 6.68 (8)°. In the crystal, the molecules are dimerized due to N—H...O interactions. π–π interactions are present between the benzene rings [centroid–centroid distance = 3.6913 (15) Å] and between the five membered ring and the trifluoromethyl)phenyl ring [centroids–centroid distance = 3.7827 (16) Å]. One of the trifluoromethoxy F atoms is disordered over two sites with occupancy ratio of 0.76 (3):0.24 (3). The F atoms of the p-trifluoromethyl substituent are disordered over three sets of sites with an occupancy ratio of 0.70 (2):0.152 (11):0.147 (13).