Site of action of N,N'-bis(methylisatin-beta-thiosemicarbazone)-2-methylpiperazine in the vaccinia virus replication cycle

N,N'-Bis(methylisatin-beta-thiosemicarbazone)-2-methylpiperazine inhibits late function or synthesis of a late component in the replication cycle of vaccinia virus. The kinetics of formation of the component sensitive to the inhibition with N,N'-bis(methylisatin-beta-thiosemicarbazone)-2-methylpiperazine precedes that of appearance of infectious virus by 30 min. The finding is in accord with the site of action of unsubstituted isatin-beta-thiosemicarbazone.

2-Acetylpyridine thiosemicarbazones. 6.2-Acetylpyridine and 2-butyrylpyridine thiosemicarbazones as antileukemic agents

N4-Monosubstituted and N4,N4-disubstituted thiosemicarbazones derived from 2-acetylpyridine, 2-acetyl-6-methylpyridine and 2-butyrylpyridine, and N4,N4-disubstituted selenosemicarbazones derived from 2-acetylpyridine were evaluated against leukemia P388 in the mouse. Significant antitumor activity (T/C greater than 125%) was observed for members of each class. Enhancement of antitumor activity resulted from increasing the size of the N4-substituent of the thiosemicarbazone moiety. Selenosemicarbazones were less active than the corresponding thiosemicarbazones.

Arylidenepyruvic acid thiosemicarbazone and thiazoline derivatives as potential antimicrobial agents

Two novel series of arylidenepyruvic acid thiosemicarbazone and thiazoline derivatives were synthesized and evaluated as potential antimicrobial agents. These substances did not exhibit any significant antibacterial effects when tested against a variety of microorganisms.

Arylmethanol and thiosemicarbazone influence of plasmodial macromolecular synthesis and cell stability

The influence of mefloquine and additional antimalarial drugs on (3H)adenosine uptake, macromolecular synthesis, and cell stability was determined in rodent red cells parasitized with Plasmodium berghei. High arylmethanol to cell ratios induced lysis, whereas inhibition of macromolecular synthesis occurred at lower drug/cell ratios. A 2-acetylpyridine thiosemicarbazone rapidly suppressed (3H)adenosine uptake, and also blocked macromolecular synthesis by parasitized cells.

comparative analysis of cellular respiratory inhibition by substituted phenylglyoxal-bis-(4-methyl-3-thiosemicarbazone) zinc chelates

Fourteen para-substituted phenylglyoxal-bis-(4-methyl-3-thiosemicarbazone) zinc chelates have been synthesized as inhibitors of cellular respiration and therefore as potential antineoplastic agents. Each chelate has been evaluated as an inhibitor of Ehrlich ascites tumor cell and of rat liver slice respiration. The molar I50 values for respiratory inhibition have been subjected to computerized correlation to delineate quantitative relationships between biological activity and chemical structure. Activity against the tumor cell model is characterized by a positive lipophilic and a detrimental steric influence while activity against rat liver slice displays only a weak positive lipophilic effect. Quantitative comparative analysis suggests that selective action against the tumor cell system can be improved by substituents which are electron withdrawing and lipophilic in nature.

Thiosemicarbazones of 2-acetylpyridine, 2-acetylquinoline, 1- and 3-acetylisoquinoline and related compounds as inhibitors of clinically significant bacteria in vitro

Antibacterial activity of 64 thiosemicarbazones of 2-acetylpyridine, 2-acetylquinoline, 1- and 3-acetylisoquinoline and related compounds was determined by testing clinical isolates of ten bacterial genera, including some which were antibiotic resistant. Minimal inhibitory concentrations (MICs) of 0.016 to 0.125 microgram/ml were obtained with 26% of the compounds for Neisseria meningitidis and 0.002 to 0.25 microgram/ml with 19% of the compounds for N. gonorrhoeae. Staphylococcus aureus was inhibited in the MIC range of 0.062 to 0.5 microgram/ml by 34% of the thiosemicarbazones, whereas 26% inhibited Streptococcus faecalis with an MIC range of 0.25 to 1.0 microgram/ml. Less antibacterial activity was shown toward the Gram-negative bacilli, i.e., Pseudomonas, Klebsiella-Enterobacter, Shigella, Escherichia coli, Serratia marcescens and Proteus.

2-Acetylpyridine thiosemicarbazones. 5. 1-[1-(2-Pyridyl)ethyl]-3-thiosemicarbazides as potential antimalarial agents

Reduction of the azomethine bond of 2-acetylpyridine thio- and selenosemicarbazones with sodium borohydride readily afforded the corresponding thio- or selenosemicarbazides when they were N4,N4-disubstituted. This conversion failed, however, when the thio- or selenosemicarbazones were N4-substituted or unsubstituted. A more general route to the desired thio- or selenosemicarbazides consisted of reduction with sodium borohydride of methyl 3-[1-(2-pyridyl)ethylidene]hydrazinecarbodithioate to give the 2-pyridylethyl derivative. Displacement of methyl mercaptan from the thio ester moiety of the latter by amines produced 1-[1-(2-pyridyl)ethyl]-3-thiosemicarbazides. These compounds were somewhat more active as antimalarial agents in Plasmodium berghei infected mice than the corresponding thiosemicarbazones; however, the enhancement of activity was accompanied by an increase in toxicity. Compound 7, 3-azabicyclo[3.2.2]nonane-3-carbothioic acid 2-[1-(2-pyridyl)ethyl]hydrazide, is the most potent derivative of 2-acetylpyridine we have evaluated to date.

In vitro assessment of 2-acetylpyridine thiosemicarbazones against chloroquine-resistant Plasmodium falciparum

A series of 2-acylpyridine thiosemicarbazones was evaluated in vitro against a chloroquine-resistant Plasmodium falciparum strain. Antimalarial activity was assessed by the inhibition of uptake of [G-3H]hypoxanthine by the parasites. Among the mono- and disubstituted derivatives tested, 13 of 17 had 50% inhibitory doses of less than 10 ng/ml. Increasing the size of the ring at N4 from four to five, six, and seven members produced concomitant decreases in activity. Similarly, increasing the size of the aliphatic substituent on the azomethine carbon reduced activity. Selected compounds were also tested against a chloroquine-susceptible strain. The results suggested that the activities of these agents were not modified significantly by resistance to chloroquine. In general, in vitro activities correlate poorly with the in vivo activities in mice infected with Plasmodium berghei.

Morphologic alteration of Anaplasma marginale in calves treated with a dithiosemicarbazone

Blood and clotted blood samples from 3 calves with anaplasmosis were examined by light and electron microscopies before and after the calves were treated twice with alpha-ethoxyethylglyoxal dithiosemicarbazone (given IV). In the treated calves anaplasma bodies were swollen and irregularly shaped and had rough surfaces when viewed by light microscopy. Posttreatment electron microscopic examinations revealed swelling and vacuolation of initial bodies of anaplasma bodies, and ballooning of the vesicular membrane surrounding the anaplasma body. Other initial bodies were ameboid in shape this was or was not accompanied by rupture of the vesicular membrane of the anaplasma body. Necrotic, ameboid-shaped initial bodies also were seen. Some necrotic initial bodies were surrounded by complete vesicular membrane, and others were close to a broken, curled vesicular membrane.

2-Acetylpyridine thiosemicarbazones. 4. Complexes with transition metals as antimalarial and antileukemic agents

Reaction of the 2-acetylpyridine thiosemicarbazones, 3-azabicyclo[3.2.2]nonane-3-thiocarboxylic acid 2-[1-(2-pyridyl)ethylidene]hydrazide (IIIa), its selenium analogue (IIIb), 1H-hexahydroazepine-1-thiocarboxylic acid 2-[1-(2-pyridyl)ethylidene]hydrazide (IV), and 1H-octahydroazocine-1-thiocarboxylic acid 2-[1-(2-pyridyl)ethylidene]hydrazide (V) with Cu(II), Ni(II), Fe(III), and Mn(II) salts gave crystalline complexes. Relative to the free ligands, these complexes show reduced antimalarial activity in mice infected with Plasmodium berghei; however, antileukemic properties are enhanced by coordination with the above-mentioned metals.

[Effect of sodium valproate on the mediator amino acid content in the rat brain]

The effect of sodium valproate (200 mg/kg, intraperitoneally) on the content of transmitter amino acids in the large hemispheres, hippocamp and thalamus was studied in experiments on rats. Thirty minutes after the injection no appreciable shifts in the content of GABA or glutamate were recorded in homogenates of these structures. However, this does not exclude the effect of sodium valproate in the dose mentioned on the GABA system at the expense of changes in the compartmentation of GABA. The concentration of aspartate was found to be significantly decreased in all the brain structures under study. It is suggested that these changes in the aspartate system might be related to the realization of the tranquilizing effect of valproate since they coincided in time with the behavioral effects of the drug.

Correlations between structure and antimycobacterial activity in a series of 2-acetylpyridine thiosemicarbazones

The antimycobacterial activity of a new series of 2-acetylpyridine thiosemicarbazones was determined in vitro using Mycobacterium smegmatis ATCC 607. The resulting log minimal inhibitory concentration (mumol l-1) values were plotted against the partition coefficient (log P) values for each compound, and fell on a parabolic distribution curve having a log P opt of 3.0. Compounds having partition coefficients outside the range 2.0 to 4.0 were inactive against M. smegmatis. When similar assays were carried out using M. tuberculosis, M. kansasii, M. marinum, M. simiae, M. avium and M. intracellulare, a similar series of parabolic activity curves were obtained having log P opt values around 4.0. The significance of this shift in the log P opt value obtained using the slow-growing pathogenic mycobacteria compared to that observed with the rapid-growing M. smegmatis is discussed in relation to the structures of the variable substituents of these new 2-acetylpyridine thiosemicarbazone compounds.

Activity of 2-acetylpyridine and 2-acetylquinoline thiosemicarbazones tested in vitro in combination with other antituberculous drugs

Determinations of minimal inhibitory concentrations (MIC) were carried out using three new 2-acetylpyridine and two new 2-acetylquinoline thiosemicarbazones tested against Mycobacterium tuberculosis, M. kansasii, M. simiae, M. avium, and M. intracellulare. Two of the compounds (Compounds L and 3I) exhibited MIC less than or equal to 5 micrograms per ml for all of the test organisms, except for M. simiae, which was resistant to most antituberculous drugs. The other thiosemicarbazones (Compounds 3L, 2N, 3G, and 2H) were relatively inactive against the nontuberculous mycobacteria. Rifampin, amikacin, and clofazimine were active when tested singly or in combination with Compounds L and 3I. Addition of compound 3I to a mixture of rifampin, amikacin, and clofazimine resulted in combination MIC of less than 0.6 microgram/ml against all of the nontuberculous mycobacteria, suggesting that combinations of this type may be suitable for the treatment of infections caused by these highly drug-resistant organisms.

The influence of dithiosemicarbazone on the immunity of sheep to heartwater

Four out of 9 sheep, immune to heartwater and subsequently treated with gloxazone, showed a febrile reaction when they were challenged 6 months later, but the same number of untreated controls also developed this reaction. In a second group of treated immune animals challenged after 9 months, 8 out of 8 showed a febrile reaction, whereas only 3 out of 8 controls reacted. Furthermore, the blood of one of the 4 sheep that reacted to challenge at 6 months was infective to a susceptible sheep inoculated with it, whereas that of 4 out of the 8 challenged at 9 months was infective.

Antimycobacterial activity of 2-acetylpyridine thiosemicarbazones in relation to their antileprosy activity

Antimycobacterial assays were carried out on sixteen 2-acetylpyridine thiosemicarbazones using a number of culturable mycobacteria in vitro. The resulting MIC determinations were plotted against the lipophilicity (log P) values for the various test compounds. Plots of log MIC vs log P values conformed to a parabolic regression curve having a log Pmax of 4.0 for the slow-growing mycobacteria and 3.0 for the rapid grower, M. smegmatis. Ten thiosemicarbazone compounds covering a log P range of 1.0 to 4.5 were tested for their antileprosy activity in M. leprae-inoculated mouse foot pads. The resulting activity curve had a log Pmax of 2.0. The significance of these findings is discussed in terms of the role played by limiting diffusional factors within the tissue so far as the penetration of these thiosemicarbazones into the intracellular environment is concerned.

[Substances with antiviral activity. XX. Thiosemicarbazones of 1-substituted 3-formyl-2-ethoxycarbonyl(carboxy)indoles]

A series of 3-formyl-2-ethoxycarbonyl(carboxy)indole thiosemicarbazones 1-substituted were synthesized and evaluated for in vitro antiviral activity against vaccinia virus strain IHD. The thiosemicarbazone of 1-(m-chlorobenzoyl)-3-formyl-2-ethoxycarbonylindole [(II g); Table II] was the most active compound. Some structure activity relationships are discussed.