Simultaneous Assessment of the Efficacy and Toxicity of Marine Mollusc-Derived Brominated Indoles in an In Vivo Model for Early Stage Colon Cancer.

The acute apoptotic response to genotoxic carcinogens animal model has been extensively used to assess the ability of drugs and natural products like dietary components to promote apoptosis in the colon and protect against colorectal cancer (CRC). This work aimed to use this model to identify the main chemopreventative agent in extracts from an Australian mollusc Dicathais orbita, while simultaneously providing information on their potential in vivo toxicity. After 2 weeks of daily oral gavage with bioactive extracts and purified brominated indoles, mice were injected with the chemical carcinogen azoxymethane (AOM; 10 mg/kg) and then killed 6 hours later. Efficacy was evaluated using immunohistochemical and hematoxylin staining, and toxicity was assessed via hematology, blood biochemistry, and liver histopathology. Comparison of saline- and AOM-injected controls revealed that potential toxic side effects can be interpreted from blood biochemistry and hematology using this short-term model, although AOM negatively affected the ability to detect histopathological effects in the liver. Purified 6-bromoisatin was identified as the main cancer preventive agent in the Muricidae extract, significantly enhancing apoptosis and reducing cell proliferation in the colonic crypts at 0.05 mg/g. There was no evidence of liver toxicity associated with 6-bromoisatin, whereas 0.1 mg/g of the brominated indole tyrindoleninone led to elevated aspartate aminotransferase levels and a reduction in red blood cells. As tyrindoleninone is converted to 6-bromoisatin by oxidation, this information will assist in the optimization and quality control of a chemopreventative nutraceutical from Muricidae. In conclusion, preliminary data on in vivo safety can be simultaneously collected when testing the efficacy of new natural products, such as 6-bromoisatin from Muricidae molluscs for early stage prevention of colon cancer.

Biomimetic total synthesis of (-)-isatisine A.

The biomimetic total synthesis of (-)-isatisine A, a novel alkaloid with an unprecedented fused tetracyclic skeleton, was accomplished in 8 steps from indole and 4,6-O-isopropylidene-protected glucal. The synthesis features a convergent synthetic strategy which relies on nucleophilic addition and a biomimetic benzilic ester rearrangement as key reactions.

Marine compounds selectively induce apoptosis in female reproductive cancer cells but not in primary-derived human reproductive granulosa cells.

Anticancer properties of tyrindoleninone and 6-bromoisatin from Dicathais orbita were tested against physiologically normal primary human granulosa cells (HGC) and reproductive cancer cell lines. Tyrindoleninone reduced cancer cell viability with IC50 values of 39 µM (KGN; a tumour-derived granulosa cell line), 39 µM (JAr), and 156 µM (OVCAR-3), compared to 3516 µM in HGC. Apoptosis in HGC's occurred after 4 h at 391 µM tyrindoleninone compared to 20 µM in KGN cells. Differences in apoptosis between HGC and KGN cells were confirmed by TUNEL, with 66 and 31% apoptotic nuclei at 4 h in KGN and HGC, respectively. These marine compounds therefore have potential for development as treatments for female reproductive cancers.

Design and evaluation of a novel fluorescent CB2 ligand as probe for receptor visualization in immune cells.

Cannabinoid CB2 receptor has emerged as a very promising target over the last decades. We have synthesized and evaluated a new fluorescent probe designated NMP6 based on 6-methoxyisatin scaffold, which exhibited selectivity and K(i) value at hCB2 of 387 nM. We have demonstrated its ability to be an effective probe for visualization of CB2 receptor binding using confocal microscopy and a flow cytometry probe for the analysis of CB2 protein expression. Furthermore, NMP6 was easily obtained in two chemical steps from commercially available building blocks.

Inhibition of monoamine oxidase by C5-substituted phthalimide analogues.

Literature reports that isatin as well as C5- and C6-substituted isatin analogues are reversible inhibitors of human monoamine oxidase (MAO) A and B. In general, C5- and C6-substitution of isatin leads to enhanced binding affinity to both MAO isozymes compared to isatin and in most instances result in selective binding to the MAO-B isoform. Crystallographic and modeling studies suggest that the isatin ring binds to the substrate cavities of MAO-A and -B and is stabilized by hydrogen bond interactions between the NH and the C2 carbonyl oxygen of the dioxoindolyl moiety and water molecules present in the substrate cavities of MAO-A and -B. Based on these observations and the close structural resemblances between isatin and its phthalimide isomer, a series of phthalimide analogues were synthesized and evaluated as MAO inhibitors. While phthalimide and N-aryl-substituted phthalimides were found to be weak MAO inhibitors, phthalimide homologues containing C5 substituents were potent reversible inhibitors of recombinant human MAO-B with IC(50) values ranging from 0.007 to 2.5 µM and moderately potent reversible inhibitors of recombinant human MAO-A with IC(50) values ranging from 0.22 to 9.0 µM. By employing molecular docking the importance of hydrogen bonding between the active sites of MAO-A and -B and the phthalimide inhibitors are highlighted.

Vasodilatory activity of novel carbamate derivatives of isatin.

Isatin (1H-indole-2,3 dione) is an endogenous compound that may act as a physiological regulator of muscle contraction by reducing cGMP production by inhibition of guanylyl cyclase (GC) activity. Intracellular cGMP levels can regulate the contractile response of smooth muscle. Therefore, in the present study we investigated the effects of seven novel carbamate derivatives of isatin, namely C1-C7, on the contractility of aortic rings from Wistar rats. Carbamates C1 and C6 most effectively promoted endothelium-dependent relaxation of aortic rings pretreated with 10 micromol/L phenylephrine (PE) to induce contraction. The concentration of the C1 and C6 carbamates necessary to reduce PE-induced aortic contraction by 50% (IC(50)) was 5.6 +/- 1.0 and 48.4 +/- 3.4 micromol/L, respectively. Carbamate derivative-induced vasodilation required an intact endothelium, which is responsible for nitric oxide (NO) release. Pretreatment of rings with 100 micromol/L naloxone or 10 micromol/L atropine prevented the C1- and C6-mediated vascular relaxation, indicating that the vasodilatory activity was dependent on the activation of opioid or muscarinic receptors, respectively. The results of our studies provide insights into the role of novel carbamates in the regulation of vascular tone. Carbamates could stimulate NO synthesis, which induces vasodilation primarily by stimulation of GC and cGMP production. Taken together, our findings suggest that carbamate derivative-induced vasodilation may be considered an alternative treatment for primary and/or secondary hypertension.

Isatisine A, a novel alkaloid with an unprecedented skeleton from leaves of Isatis indigotica.

9alpha,13alpha-Dihydroxylisopropylidenylisatisine A (1), which was derived from isatisine A (2) and possessed an unprecedented fused pentacyclic skeleton, was isolated from the leaves of Isatis indigotica Fort. The structure and relative configuration were elucidated on the basis of extensive NMR analyses and finally determined by single-crystal X-ray diffraction. Compound 1 showed moderate anti-HIV-1 activity with EC50 = 37.8 microM and SI = 7.98.

Sedative-hypnotic profile of novel isatin ketals.

Isatin (1H-indol-2,3-dione) is an endogenous compound found in many tissues and fluids. Isatin and its derivatives exert pharmacological effects on the central nervous system, including anxiogenic, sedative and anticonvulsant activities. Two new groups of isatin derivatives were synthesized (nine dioxolane ketals and nine dioxane ketals) and studied for their sedative, hypnotic and anesthetic effects using pentobarbital-induced sleeping time, locomotor activity evaluation and intravenous infusion. The dioxolane ketals were more potent than dioxane ketals for inducing sedative-hypnotic states, causing up to a three-fold increase in pentobarbital hypnosis. The dioxolane ketals produced sedation, demonstrated by decreased spontaneous locomotor activity in an open field. Hypnosis and anesthesia were observed during intravenous infusion of 5'-chlorospiro-[1,3-dioxolane-2,3'-indolin]-2'-one (T3) in conscious Wistar rats. Complete recovery from hypnosis and anesthesia required 39.1+/-7.3 and 6.8+/-2.4 min, respectively. Changes in hemodynamic parameters after infusion of 5.0 mg/kg/min were minimal. These findings suggest that these new isatin derivatives represent potential candidates for the development of new drugs that act on the central nervous system and may lead to a new centrally acting anesthetic with no toxic effects on the cardiovascular or respiratory systems.

Synthesis and in-vitro cytotoxicity evaluation of gatifloxacin Mannich bases.

Mannich bases of gatifloxacin were synthesized by reacting them with formaldehyde and several isatin derivatives. Their chemical structures have been confirmed by means of their IR, 1H-NMR data and by elemental analysis. The compounds were tested in-vitro against a panel of 58 human tumour cell lines derived from nine neoplastic diseases. Among them compound 1-cyclopropyl-6-fluoro-8-methoxy-1,4-dihydro-4-oxo-7[[N4-(3'-sulphadoximino)-1'-(5-bromoisatinyl) methyl]-3-methyl N1-piperazinyl]-3-quinoline carboxylic acid (6) emerged as a potent anticancer agent being more active than standard DNA topoisomerase II inhibitor, etoposide against 30 cancer cell lines.

Synthesis, antitubercular activity and pharmacokinetic studies of some Schiff bases derived from 1-alkylisatin and isonicotinic acid hydrazide (INH).

N'-(1-alkyl-2,3-dihydro-2-oxo-1H-3-indolyliden)-4-pyridinecarboxylic acid hydrazide derivatives, 3(a-g), were synthesized in a trial to overcome the resistance developed with the therapeutic uses of isoniazid (INH). The lipophilicity of the synthesized derivatives supersedes that of the INH as expressed by Clog p values. The synthesized compounds and INH were tested against bovin, human sensitive and human resist strains of Mycobacterium tuberculosis. Compounds 3a, 3d, 3f and 3g with 1-unsubstituted, 1-propyl, 1-propynyl and 1-benzyl groups respectively exhibited equipotent growth inhibitory activity (MIC 10 micromol) against the tested strains as compared with INH however the later has no activity against human resist strain. Pharmacokinetic study revealed that the rate and extent of absorption of the tested derivatives (3d and 3f) significantly higher than that of INH (p < 0.05). The relative bioavailabilities (F(R)%) were 183.15 and 443.25 for 3f and 3d respectively as compared to INH. These results preliminary indicate the possible use of the prepared derivatives for treatment of tuberculosis infections in order to overcome the resistance developed with INH.

Synthesis and antibacterial screening of hydrazones, Schiff and Mannich bases of isatin derivatives.

Schiff bases and hydrazones of substituted isatins (1-28) were prepared by reacting isatin and aromatic primary amines/hydrazines. A new series of the corresponding N-Mannich base (29-35) was synthesised by reacting them with formaldehyde and diphenyl amine. The chemical structures were confirmed by means of 1H-NMR, IR spectral data and elemental analysis. The compounds were screened for antibacterial activity against seven Gram (+) and seven Gram (-) standard and pathological bacterial strains by the paper disc diffusion technique. The minimum inhibitory concentrations of the active compounds were determined. 1-Diphenyl amino-methyl-3-(4-bromo phenylimino)-1,3-dihydro-indol-3-one (30) and 3-(4-bromo phenylimino)-5-nitro-1,3-dihydro-indol-3-one (13) were found to be the most active compounds of the series. Mannich bases exhibited higher activity than the corresponding Schiff bases.

Glucosylation of isatin-3-oxime followed by 2D in situ NMR in plant cells at highest magnetic field without labelling.

The glucosylation of isatin-3-oxime (1) was monitored by in situ 2D 1H-13C inverse correlated gradient assisted NMR spectroscopy in plant cell suspension cultures of Rauvolfia serpentina without labelling. The applied high magnetic field of 800 MHz allowed measurements within 20 min at concentrations of 1 of 5.76 mM. Complete glucosylation of 1 occurs inside the cells within 72 hours. During this time isatin-3-oxime-glucoside (2) accumulates without further metabolism.

[The reaction of 3-(R-phenyl)-6-hydrazine pyridazines with substituted isatins (II)]. / La réaction de certaines 3-(R-phényle)-6-hydrazino-pyridazines avec des isatines substituées (II).

This paper presents the synthesis of six hydrazones from isatin and 1-morpholinomethyl-isatin and also of their six cooper's complex salts. Their structure was confirmed by the results of the quantitative elemental analysis and by IR, UV-VIS spectral analysis. The biological tests point out that cooper's complex salt of 3-(3'-phenyl-pyridazinylhydrazono)-5-methyl-indoline-2-one (1:2) (VI a) has the smallest toxicity (DMT over 800 mg/kg.w. p.o.), a remarkable anti-inflammatory activity (inhibition 57.1%, IAR 1.1) and also a gastroprotector coefficient of 43.3%. In the mean time, the cooper's complex salt of 3-(3'-p-anisyl-pyridazinyl-hydrazono)-5-methyl-ind oline-2-one (1:2) (VI b) has a gastroprotector coefficient of 76.3% and a lower anti-inflammatory activity than the first derivative (inhibition 36.9%).

[New isatin-derived hydrazones and Mannich bases with possible biological activity]. / Noi hidrazone si baze Mannich derivate de la isatina, cu eventuala activitate biologica.

The paper presents a synthesis of six new Mannich bases, five hydrazones derived from 1-piperidino-methyl-5-R-isatin and three copper complex compounds of 3-(3'-R-phenyl-pyridazinil-hydrazone)-indoline-2-ones (R=H, CH3, OCH3). The structure of the new compounds was confirmed by the results of the elementary and spectral analysis. Pharmacodynamic studies indicated that copper complex compounds present effective biological properties. Thus, it can be seen that the experimental carrageenan-induced inflammatory oedema was 58.3% inhibited by the complex V (R=CH3) after oral administration. Antimicrobial tests revealed that only compound V (R=OCH3) shows a moderate antimicrobial activity against the gram-positive and gram-negative bacteria, used in the test.

[The reaction of 3-(R-phenyl)-6-hydrazine pyridazine with 5-methylisatin and 1-morpholinomethyl-5-methylisatin]. / La réaction de la 3-(R-phényle)-6-hydrazino-pyridazine avec la 5-méthyl-isatine et la 1-morpholinométhyl-5-méthyl-isatine.

This paper presents the synthesis of six hydrazones obtained by treating 5-methyl-isatin or 1-morpholino methyl-5-methyl-isatin with 3-(R-phenyl)-6-hydrazino-pyridazine (R = OCH3, Cl, Br) and two complex combination with copper, derived from 3-(p-anisyl-pyridazinyl)-hydrazone-5-methyl-indoline-2- one. The structure of the new compounds was confirmed by the results of the quantitative elementary and IR, UV-VIS spectral analysis. The biological tests point out that product VI, in which a copper atom binds two molecules of 3-(p-anisyl-pyridazinyl)-hydrazono-5-methyl-indoline-2-one, has a considerable antiinflammatory activity, giving a inflammation inhibition of 39, 6%. All the synthetized compounds have a moderate antimicrobial activity against Candida albicans.

Antiviral, antibacterial, and antifungal activities of isatin N-Mannich bases.

Preliminary antiviral, antibacterial, and antifungal screening results of a series of isatin N-Mannich bases are provided.