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Inhibition of amino acyl tRNA synthetase activity by copper complexes of two metal binding ligands. N-Methyl isatin beta-thiosemicarbazone and 8-hydroxyquinoline.

Copper complexes of N-methyl isatin beta-thiosemicarbazone, 1-formyl isoquinoline thiosemicarbazone and thiosemicarbazide inhibit amino acyl tRNA synthetase activity. Copper complexes of 8-hydroxyquinoline and 8-mercaptoquinoline also inhibit. The 1 : 1 ligand-metal complex is significantly more active than the 2 : 1 complex. The free ligand alone and copper sulfate alone have little, if any, effect. These complexes have no effect on the ATP-PPi exchange reaction and do not cause deacylation of amino acyl tRNAs. This indicates that the process inhibited by these complexes is the amino acylation reaction. This is the first report that these copper binding ligands can inhibit enzymatic processes which involve nucleic acids but which are not viral, bacterial or mammalian cell polymerases.

Amino Acyl-tRNA Synthetases↗

In vitro and in vivo evaluation of isatin-beta-thiosemicarbazone and marboran against vaccinia and cowpox virus infections.

It has been reported previously that some thiosemicarbazone compounds have prophylactic activity against smallpox disease and therapeutic activity against vaccinia virus (VV) infections. In these studies, isatin-beta-thiosemicarbazone (IBT) and marboran were administered once daily by intraperitoneal (ip) injection to mice using 30, 10 or 3 mg/kg for 5 days beginning 24, 48 or 72 h after inoculation with VV or cowpox virus (CV). Both compounds were highly effective (p < 0.01) at preventing mortality due to VV even when treatment was delayed up to 72 h postinfection. In CV-infected mice, neither IBT nor Marboran were effective in preventing mortality at any dosage tested when administered at 24 h postinoculation. Viral replication in liver, spleen and kidney was delayed or reduced by 100-to 10,000-fold by 10 mg/kg of marboran, but not IBT, in VV infections. Neither compound was effective against CV infection. Neither IBT nor marboran treatment of mice cutaneously infected with VV or CV reduced viral replication or clinical disease. These results suggest that this class of compound has little therapeutic potential for orthopoxvirus infections since the in vivo activity against CV, a surrogate virus for variola, is lacking.

Animals↗

Complexes of 2-thiophenecarbonyl and isonicotinoyl hydrazones of 3-(N-methyl)isatin. A study of their antimicrobial activity.

Cobalt(II), nickel(II), copper(II) and zinc(II) complexes of 2-thiophenecarbonyl and isonicotinoyl hydrazones of 3-(N-methyl)isatin (HL(1) and HL(2), respectively) were synthesized and characterized, being the crystal structures of HL(1), HL(2) and [Ni(L(1))(2)].2CHCl(3) elucidated by X-ray diffraction techniques. The in vitro antimicrobial activity of all these compounds was tested against several bacteria and fungi. HL(1)and its complexes exhibited a strong inhibition of the growth of Haemophilus influenzae (MIC 0.15-1.50microg/mL) and good antibacterial properties towards Bacillus subtilis (MIC 3-25microg/mL). The minimal inhibitory concentration (MIC) was defined as the lowest concentration of compound inhibiting the growth of each strain. The antibacterial effectiveness was confirmed against a number of Gram positive bacteria, including methicillin-resistant Staphylococcus aureus. Yeasts and moulds showed a low susceptibility, except the dermatophyte mould Epidermophyton floccosum that is inhibited at concentrations ranging from 6 to 50microg/mL. In general, the antimicrobial activity of the thiophene derivatives was greater than that of the isonicotinic analogues.

Anti-Bacterial Agents↗

Spectroscopic approach in the characterization of the copper(II) complexes of isatin-3,2'-quinolyl-hydrazones and their adducts.

Copper(II) complexes of isatin-3,2'-quinolyl-hydrazones of the type [Cu(L)X] (where X=Cl(-), Br(-), NO(3)(-), CH(3)COO(-) and ClO(4)(-)] and their adducts Cu(L)X.2Y [where Y=pyridine or dioxane and X=Cl(-), Br(-), NO(3)(-) and ClO(4)(-)] have been synthesized under controlled experimental conditions and characterized by using the modern spectroscopic and physicochemical techniques viz. IR, electronic, EPR, elemental analysis, magnetic moment susceptibility measurements and molar conductance, etc. On the basis of spectral studies a four coordinated square planer geometry is assigned for Cu(L)X type complexes whereas the adducts (Cu(L)X.2Y were found to have a six coordinated octahedral geometry.

Buffers↗

Binding of N-methyl isatin beta-thiosemicarbazone-copper complexes to proteins and nucleic acids.

N-Methyl isatin beta-thiosemicarbazone-copper complexes interact with nucleic acids and proteins as shown by ultraviolet (UV) and visible spectroscopy and Sephadex exclusion chromatography. The Cu++ ions are most effective; Co++ ions have less albeit significant activity. Chelating agents, such as Tris and histidine, high NaCl concentration, and dimethyl sulfoxide reduce the binding of the drug-metal complex. The binding constant of the drug-copper complex to calf-thymus DNA was calculated to range between 6.9 x 10(4) and 2.7 x 10(5) M-1.

Chelating Agents↗

Dipeptide-catalyzed asymmetric aldol condensation of acetone with (N-alkylated) isatins.

[reaction: see text] The aldol condensation of acetone with several isatins is described. The desired compound was obtained in quantitative yield and with good enantioselectivities up to 77%. The best results were obtained with 10 mol % H-D-Pro-L-beta3-hPhg-OBn as a catalyst, resulting in the preferential formation of the (R)-enantiomer. The absolute configuration of the newly formed chiral center has been assigned by an X-ray diffraction study and CD spectra analysis of the molecules.

Journal Article↗

Efficient entry to diversely functionalized spirocyclic oxindoles from isatins through carbonyl-addition/cyclization reaction sequences.

A novel approach to diversely functionalized spirocyclic oxindoles has been developed by using different metal-mediated carbonyl-addition/cyclization reaction sequences. Spirocyclization precursors, 2-indolinone-tethered homoallylic alcohols, (buta-1,3-dien-2-yl)methanols, and alpha-allenols have been obtained by regioselective addition of stabilized organoindium reagents to isatins in aqueous environment. Ruthenium-, silver-, and palladium-catalyzed reactions of the above unsaturated alcohol derivatives provided oxaspiro oxindoles.

Journal Article↗

Synthesis of vaccinia virus polypeptides in the presence of isatin-beta-thiosemicarbazone.

Isatin-beta-thiosemicarbazone (IBT) at a concentration of 14 muM inhibited the multiplication of vaccinia virus in HeLa cells. For the first 3 h after infection, viral deoxyribonucleic acid (DNA) was synthesized in the presence of IBT at the same rate as in the control culture; the replication rate declined at a later stage. The DNA failed to be coated with proteins and to become resistant to deoxyribonuclease unless IBT was removed. "Early" and "late" viral polypeptides were formed in the presence of IBT, as revealed by polyacrylamide gel electrophoresis. The formation from precursor of a core polypeptide, a reaction blocked by rifampin, was not affected by IBT. Therefore, it is suggested that a maturation step later than the one blocked by rifampin is involved in the inhibition of vaccinia virus by IBT.

DNA, Viral↗

Synthesis, anti-HIV and antitubercular activities of isatin derivatives.

HIV is the most significant risk factor for many opportunistic infections like tuberculosis. In this study, we designed an isatinimino lead compound as a novel non-nucleoside reverse transcriptase inhibitor with antimycobacterial properties for the effective treatment of AIDS and AIDS-related tuberculosis. Among the compounds sythesized, 1-cyclopropyl-6-fluoro-8-methoxy-1,4-dihydro-4-oxo-7[[N4-[3'-[(4,6-dimethylpyrimidin-2-yl)benzenesulfonamido-4-yl]imino-1'-(5-fluoroisatinyl)]methyl]-3-methyl N1-piperazinyl]-3-quinoline carboxylic acid (9) emerged as the most potent broad-spectrum chemotherapeutic agent active against HIV (EC50: 12.1 microg/ml), and Mycobacterium tuberculosis (MIC: 1.22 microg/ml).

Anti-HIV Agents↗