Isatin derivatives and their anti-bacterial activities.

Bacterial infections are account for the majority of hospital-acquired and community-acquired infections. The emergency and widespread of drug-resistant pathogens has further worsened the situation. In recent years, various isatin derivatives have been screened for their anti-bacterial activities, and some of them demonstrated promising in vitro and in vivo potency. This review covers the recent advances of isatin derivatives including isatin-azole, isatin-quinoline/quinolone, isatin-furan/coumarin, isatin-hydrazone/(thio)semicarbazone, isatin dimers and isatin-indole hybrids as potential anti-bacterial agents. The enriched structure-activity relationship may pave the way for further rational development of isatin derivatives with broader spectrum, higher potency, lower toxicity and multiple mechanisms of action.

Dry and wet ozonation of denim: Degradation products, reaction mechanism, toxicity and cytotoxicity assessment.

The study aims to identify the denim ozonation by-products under different operating conditions and investigate the chemical toxicity of these compounds via the inhibitory effect of the sample on the light emission of bioluminescent bacteria (Vibriofischeri) and on human health using the HepG2 human hepatoma cell line. Various by-products in treated denim extract were detected w gas chromatography-mass spectrometry (GC-MS) analysis. The results revealed that the main oxidation by-product was isatin (1H-indole-2,3-dione), which formed in excess amounts on wet ozonated denim. It was observed that this compound showed more toxicity when high ozone concentrations were used, especially in the presence of moisture. It exhibited a considerable antibacterial activity. EC20 and EC50 average values of 5.55% and 13.47% were obtained with a wet ozonation rinse bath at 48 g/N·m3, which makes it hazardous to aquatic environments.

Synthesis and in vitro Bio-activity Evaluation of N4-benzyl Substituted 5-Chloroisatin-3-thiosemicarbazones as Urease and Glycation Inhibitors.

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).

Oestrogen receptor-mediated liposomal drug delivery for treating melanoma.

Function of steroid hormone oestrogen that transactivates oestrogen receptor (ER) is expressed in multiple organs. Except for malignancies of gynaecological organs, ER remains largely unutilised as a target to treat cancers of ER-expressing brain, prostate, skin etc. We have previously developed oestrogen targeting cationic lipid molecule (ES-C10), which showed targeted killing of ER + breast and skin cancer cells. In this study, we explored the targeting ability of ES-C10 as a ligand as well as its additive killing effect (if any), when incorporated in two different liposomes (DCME and DCDE), carrying two anticancer molecules MCIS3 and Docetaxel™, respectively. DCME and DCDE exhibited higher cytotoxicity in ER + cancer cells than in ER - cancer or in non-cancer cells. Both liposomes induced ER-mediated cytotoxicity and caspase 3-induced apoptosis in ER + melanoma cells. Further, decreased levels of pAkt, and increased levels of PTEN and p53 were also observed. Both the targeted liposomes were least haemolytic. These selectively delivered drug-cargoes to tumour mass over other vital organs and induced better anti-tumour effect, which led to increased survivability than their respective controls. In conclusion, we demonstrated the development of two independent liposomal drug-delivery systems associated with an anticancer, oestrogen-structure based ligand for efficient, ER-mediated anti-melanoma effect.

Synthesis and evaluation of in vivo antioxidant, in vitro antibacterial, MRSA and antifungal activity of novel substituted isatin N-(2,3,4,6-tetra-O-acetyl-ß-d-glucopyranosyl)thiosemicarbazones.

Some new isatin N-(2,3,4,6-tetra-O-acetyl-ß-d-glucopyranosyl)thiosemicarbazones 4a-t with different substituents at 1-, 5- and 7-positions of isatin ring have been synthesized by reaction of N-(2,3,4,6-tetra-O-acetyl-ß-d-glucopyranosyl)thiosemicarbazide 2 with corresponding isatins 3a-t. Compounds 4a-t were evaluated in vivo for antioxidant activity and in vitro for anti-microorganism activities. The MIC values were found for Gram positive bacteria (MIC = 1.56-6.25 µM), for Gram negative bacteria (MIC = 12.5 µM), and for fungi Aspergillus niger (MIC = 3.12-12.5 µM), Fusarium oxysporum (MIC = 6.25-12.5 µM) and Saccharomyces cerevisiae (MIC = 6.25-12.5 µM). Regarding the antioxidant activity, the SOD, GHS-Px and catalase activities of 4c-i and 4m-r were MIC = 10.57-10.85, 0.27-0.93 and 345.45-399.75 unit/mg protein, respectively. Compounds 4e-h had MIC values of 0.78, 1.56, and 3.12 µM for three clinical MRSA isolates. Compound 4e showed the selective cytotoxic effects against some cancer (LU-1, HepG2, MCF7, P338, SW480, KB) cell lines and normal fibroblast cell line NIH/3T3.

Synthesis, Biological Activity, and Docking Study of Novel Isatin Coupled Thiazolidin-4-one Derivatives as Anticonvulsants.

A series of 2-(substituted-phenyl)-3-(2-oxoindolin-3-ylidene)amino)-thiazolidin-4-one derivatives were designed and synthesized under microwave irradiation, using an eco-friendly, efficient, microwave-assisted synthetic protocol that involves cyclocondensation of 3-substituted benzylidine-hydrazono-indolin-2-one 3a-j with thioglycolic acid in dimethyl formamide (DMF) as solvent and anhydrous zinc chloride as a catalyst, keeping in view the structural requirement of the pharmacophore. The intermediate compounds 3a-j were obtained by condensation of the hydrazone of indoline-2,3-dione with aromatic aldehydes. The synthesized derivatives were evaluated for CNS depressant activity and anticonvulsant activity in mice using the maximal electroshock seizure (MES) and subcutaneous pentylenetetrazole (sc-PTZ) induced seizure tests. All the derivatives showed good CNS depressant activity and showed protection in the MES test, indicative of their ability to inhibit the seizure spread. A histopathological study was performed to evaluate liver toxicity caused by the synthesized compounds. The compounds were nontoxic. A computational study was performed, in which log P values were calculated experimentally. Virtual screening was performed by molecular docking of the designed compounds into the ATP binding sites of the NMDA and AMPA receptors, to predict if these compounds have analogous binding modes.

Synthesis and evaluation of the cytotoxic activities of some isatin derivatives.

A series of isatin derivatives, 1-butyl-5/7-chloro/fluoro-3-((4-methoxybenzyl)imino)indolin-2-ones (3a-d), 6-butyl-chloro/fluoro-6H-indolo[2,3-b]quinoxalines (4a-h), and 5/7-chloro/fluoro-3-((4-methoxybenzyl)imino)indolin-2-ones (5a-h) were synthesized and characterized by using Fourier transform (FT)-IR, (1)H- and (13)C-NMR spectroscopy, mass spectrometric and elemental analysis. The substances were further subjected to in vitro cytotoxicity evaluation against HeLa, SK-BR-3, and MCF-7 cells. The results showed that quinoxalines 4d, 4e, and 4g; and indolin-2-one 5f display significant in vitro cytotoxic activities against HeLa cells and further the compound 4d has resulted in highest cytotoxicity in the entire series studied. In addition, 5f was shown to display substantial activity against all the three cell lines used in the current study.

In vitro assessment of the cytotoxic, apoptotic, and mutagenic potentials of isatin.

Isatin (1H-indole-2,3-dione) is a chemical found in various medicinal plant species and responsible for a broad spectrum of pharmacological and biological properties that may be beneficial to human health, as an anticonvulsant, antibacterial, antifungal, antiviral, and anticancer agent. The aim of the present study was to determine in vitro the cytotoxic, mutagenic, and apoptotic effects of isatin on CHO-K1 and HeLa cells using the MTT viability assay (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide), micronucleus (MN) test, apoptosis index, and nuclear division index (NDI). The 5 isatin concentrations evaluated in the mutagenicity and apoptosis tests were 0.5, 1, 5, 10, and 50 µM, selected through a preliminary MTT assay. Positive (doxorubicin, DXR) and negative (phosphate buffered saline, PBS) control groups were also included in the analysis. Isatin did not exert a mutagenic effect on CHO-K1 after 3 and 24 h of treatment or on HeLa cells after 24 h. However, 10 and 50 µM concentrations inhibited cell proliferation and promoted apoptosis in both CHO-K1 and HeLa cells. Data indicate that the cytotoxic, apoptotic, and antiproliferative effects of isatin were concentration independent and cell line independent.

Synthesis and in vitro cytotoxic evaluation of N-alkylbromo and N-alkylphthalimido-isatins.

The manuscript pertains to the synthesis and in vitro cytotoxic evaluation of a series of N-alkylbromo and N-alkylphthalimido-isatins against four different human cancer cell lines namely Colon: HCT-15; Liver: Hep-2; Lung: A-549 and Leukemia: THP-1 at 10 and 100 µM concentrations. The active compounds based on preliminary studies were evaluated for their IC(50) value against six cell lines viz. Colo-205, HCT-15 (Colon), THP-1 (Leukemia), A-549 (Lung), PC-3 (Prostate) and HeLa (Cervix). The active analogue IS-4 exhibited IC(50) values of 4.57, 10.90, 11.75, 12.40 and 54.20 µM against HeLa, PC-3, HCT-15, THP-1 and Colo-205, respectively.

Mutagenicity and genotoxicity of isatin in mammalian cells in vivo.

Isatin (1H-indole-2,3-dione) is a synthetically versatile substrate used for the synthesis of heterocyclic compounds and as a raw material for drug synthesis. Isatin and its derivatives demonstrate anticonvulsant, antibacterial, antifungal, antiviral, and anticancer properties. We evaluated the genotoxic and mutagenic effects of acute (24h) and repeated (14d) exposure to isatin in vivo, using the comet assay and the micronucleus test. Three doses (50, 100, and 150mg/kgb.w.) were administered to mice via gavage. Doses were selected according to the LD(50) of isatin, estimated in a preliminary test to be 1g/kgb.w. To evaluate the results, parametric (ANOVA/Tukey) and non-parametric (Kruskal-Wallis/Dunn's post hoc test) tests were used, according to the nature of the data distribution. At all doses (50, 100 and 150mg/kgb.w.), after acute treatment with isatin, alterations in DNA migration (comet assay) were not observed and mutagenic effects were not seen (micronucleus test on peripheral blood cells). After repeated doses, only the highest dose of isatin (150mg/kgb.w.) induced alterations in the DNA that gave rise to micronuclei in the bone marrow and peripheral blood cells of the mice. Our results show that the mutagenic and genotoxic effects of isatin depend on dose and on period of exposure.

Synthesis and biological evaluation of some new N(4)-substituted isatin-3-thiosemicarbazones.

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.

Isatin, an endogenous monoamine oxidase inhibitor, triggers a dose- and time-dependent switch from apoptosis to necrosis in human neuroblastoma cells.

Isatin is an endogenous indole that is increased in stress, inhibits monoamine oxidase (MAO) B and improves bradykinesia and striatal dopamine levels in rat models of Parkinson's disease. Consequently, it has been suggested that isatin might be a possible treatment for Parkinson's disease although little is known about its effects on neural cell growth and survival. The aim of this study was to investigate the survival of dopaminergic human neuroblastoma (SH-SY5Y) cells following treatment with increasing concentrations of isatin. SH-SY5Y cells were exposed to isatin for defined time points, after which cell survival was determined by MTT assay. A combination of Annexin V binding and propidium iodide (PI) exclusion was used to distinguish apoptosis from necrosis in flow cytometry experiments and FACS profiles of permeabilised PI-labelled cells were employed for the assessment of cell cycle distribution. Isatin treatment (1-400 microM) for 24h induced a significant dose-dependent increase in MTT metabolism by SH-SY5Y cells in culture, but this was not due to an increase in cell division. At the higher concentrations (200-400 microm) isatin triggered cell death, although MTT metabolism was still increased in the culture, suggesting that surviving cells were hypermetabolic. Following a longer (48 h) exposure, isatin was found to cause cell death in a dose-dependent manner; at lower concentrations (50 microM), the predominant mode of cell death was apoptosis while at the highest concentration (400 microm) increasing numbers of necrotic cells were also evident. Thus, in dopaminergic SH-SY5Y cells isatin induces cell death in dose- and time-dependent manner. This death occurred as a continuum of survival, apoptosis and necrosis. Our results re-emphasise that caution should be exercised when considering high doses of isatin as a putative anti-Parkinson's disease therapeutic.

Anticonvulsant and sedative-hypnotic activities of N-substituted isatin semicarbazones.

A series of N-methyl/acetyl, 5-(un)-substituted isatin-3-semicarbazones were screened for anticonvulsant and sedative-hypnotic activities. The results revealed that protection was obtained in all the screens i.e., MES, scPTZ, and scSTY. Compounds 2, 4, 6, 10 but not 1 and 3 showed low neurotoxicity when compared to clinically used drugs. Compounds 5, 7, 8 and 9 were completely non-toxic. Compound 6 showed good activity in the rat oral MES screen. Among all the compounds, 3 and 6 emerged as the most active compounds as indicated by the protection they exhibit in MES, scSTY, and scPTZ screens. All the compounds showed significant sedativehypnotic activity.

Isatin, a putative anxiogenic endocoid, induces memory dysfunction in rats.

Isatin (2,3-dioxoindole), one of the components of tribulin, which has been postulated to function as an endogenous marker of stress and anxiety, was shown to induce a dose-related attenuation of learning acquisition in an active avoidance test and inhibition of learning retention, or memory, in a step-down passive avoidance paradigm and transfer latency in an elevated plus-maze, in rats. Earlier studies have indicated that isatin functions as a 5-hydroxytryptamine (5-HT)3 receptor agonist in its anxiogenic activity in rats and is an antagonist at mammalian atrial natriuretic peptide (ANP) receptors. Since 5-HT3 receptor antagonists and centrally administered ANP have been shown to facilitate learning and memory, the observed memory dysfunction induced by isatin can be attributed to its receptor activity at 5-HT3 and ANP receptors. The investigation also indicates that anxiogenic agents are likely to disrupt memory functions.

Targeted construction of temperature-sensitive mutations in vaccinia virus by replacing clustered charged residues with alanine.

The feasibility of using "clustered charge-to-alanine" mutagenesis (replacement by alanine of two or more charged residues clustered in a five- or six-amino acid sequence) to create temperature-sensitive, conditionally lethal mutations in vaccinia virus was examined by creating nine mutations in the vaccinia virus gene G2R. G2R was chosen for this analysis because mutations in this gene confer selectable phenotypes. Specifically, vaccinia viruses that contain a wild-type copy of G2R nare sensitive the effects of the anti-poxvirus drug isatin-beta-thiosemicarbazone (IBT), while mutations in G2R that completely abolish the function of the G2R protein product confer dependence upon IBT for growth. A previously isolated mutant carrying a temperature-sensitive mutation that maps to G2R (Cts56) is resistant to IBT at the permissive temperature and dependent upon IBT at the restrictive temperature. Nine clustered charge-to-alanine mutants were examined. Four of the these mutants (AS1, AS4, AS6, and AS9) display some degree of temperature sensitivity in the function of the G2R gene product. AS1 is temperature sensitive for growth in both a plaque assay and in a one-step growth experiment. AS6 and AS9 form small plaques at the nonpermissive temperature and are temperature sensitive for growth in a one-step growth experiment. AS4 manifests its temperature sensitivity as temperature-dependent IBT resistance. Five of the mutations (AS2, AS3, AS5, AS7, and AS8) appeared to confer phenotypes indistinguishable from that of wild-type vaccinia. These results demonstrate that temperature-sensitive conditionally lethal mutants can be created in vaccinia virus by altering the charge characteristics of essential viral proteins.

Chemical mutagenesis testing in Drosophila. IX. Results of 50 coded compounds tested for the National Toxicology Program.

Fifty chemicals were tested for mutagenic activity in post-meiotic and meiotic germ cells of male Drosophila melanogaster using the sex-linked recessive lethal (SLRL) assay. As in the previous studies in this series, feeding was chosen as the first route of administration. If the compound failed to induce mutations by this route, injection exposure was used. One gaseous chemical (1,3-butadiene) was tested only by inhalation. Those chemicals that were mutagenic in the sex-linked recessive lethal assay were further tested for the ability to induce reciprocal translocations. Eleven of the 50 chemicals tested were mutagenic in the SLRL assay. These included bis(2-chloroethyl) ether, 1,4-butanediol diglycidyl ether, 1-chloro-2-propanol, dimethyl methylphosphonate, dimethyl morpholinophosphoramidate, dimethyloldihydroxyethylene urea, 2,2-dimethyl vinyl chloride, hexamethylphosphoramide, isatin-5-sulfonic acid (Na salt), isopropyl glycidyl ether, and urethane. Five of these, including 1,4-butanediol diglycidyl ether, 2,2-dimethyl vinyl chloride, hexamethylphosphoramide, isopropyl glycidyl ether, and urethane, also induced reciprocal translocations.