Trypanosoma cruzi: Carboxylesterase activity in intact epimastigotes

1. 1. Carboxylesterase activity corresponding to types A and B has been demonstrated in intact T. cruzi epimastigotes as shown by the hydrolysis of several esters of p-nitrophenol and the effect of suitable inhibitors. 2. 2. The in situ carboxylesterase activity was described by the Michaelis-Menten kinetic approach. The apparent Vmax for the acetate and butyrate esters were 66.5 and 165.3 nmol hydrolysed per min and mg of protein respectively. 3. 3. An Arrhenius plot of the temperature dependent activity showed two sharp linear regions with a transition temperature of 31.6°C and energies of activation of 6.2 and 14.1 kcal/mol. 4. 4. The in situ carboxylesterase activity was inhibited 26% by paraoxon and 56% by N-ethylmaleimide, but not by p-chloromercuribenzoate. © 1983

Effects of some β-carboline alkaloids on intact Trypanosoma cruzi epimastigotes

Several β-carboline (9H-pyrido-[3,4-b]-indole) alkaloids were evaluated for in vitro trypanosomicidal activity against Trypanosoma cruzi epimastigotes belonging to two different strains (Tulahuen and LQ) showing different sensitivity to nifurtimox. Important differences were observed in the susceptibility of the parasites to these natural substances, with the relatively nifurtimox-resistant LQ strain showing greater sensitivity to the β-carbolines. Respiratory chain inhibition appears to be a possible determinant of the trypanosomicidal activity of these compounds

Glutathione and trypanothione in several strains of Trypanosoma cruzi: Effect of drugs

Glutathione (GSH), trypanothione (T(SH)2) and glutathionyl spermidine (GSH-SP) concentrations were determined in the Tulahuen and LQ strains and the DM 28c clone of Trypanosoma cruzi. The concentrations of GSH, T(SH)2 and GSH-SP, expressed as nmol of GSH per g of parasite fresh weight, were 60.1, 397.8 and 103.9, respectively, for the Tulahuen strain. For the DM 28c clone, the values were 113.9, 677.9 and 164.1, respectively, and for the LQ strain they were 199.1, 1100.5 and 55.3, respectively. When the parasites were treated with 10 μM nifurtimox or 50 μM benznidazole for 2 h, the concentrations of all three reduced thiols decreased strongly. The total amount of T(SH)2 decreased by more than 50%. Treatment of the parasites with 5 mM buthionine sulfoximine, an inhibitor of GSH synthesis, for 6 h diminished the concentrations of the reduced thiols by between 27% and 53% with respect to the controls. Cyclohexylamine, an inhibitor of spermidine synthesis, decreased the concentrations of

Electrophoretic characterization of soluble proteins from dental tissues (polyphyodonts and diphyodonts species)

The developmental processes related to odontogenesis are similar in all vertebrates and they occur during embryogenesis. The dental papilla can exercises directive morphogenetic role on epithelia of different phylogenetic origin. In our laboratory we have previously shown that cultured heterologous tissue recombinations between adult lizards dental papillae and quail epithelia were capable of producing odontogenesis and amelogenesis. Employing sodium dodecyl‐sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) according to Laemmli ('70, Nature, 227:680–685.) and two‐dimensional polyacrylamide gel electrophoresis (2‐D PAGE) (O'Farrell, '75, J. Biol. Chem., 250:4007–4021.), we have examined the distribution of soluble proteins with respect to isoelectric point and molecular weight of dental papillae isolated from tooth germs at bell stage of adult lizard Liolaemus tenuis tenuis (polyphyodont species) and dog fetuses Canis familiaris (diphyodont species). A comparison was also made wit

Trypanosoma cruzi: A possible control of transfusion-induced Chagas' disease by phenolic antioxidants

The following phenolic antioxidant food additives were evaluated against Trypanosoma cruzi epimastigotes: BHT, BHA, gallic acid and its methyl, propyl, octyl, and lauryl esters, 2,4-di-tert-butyl-6-(4-methoxybenzyl)-phenol, 4,4′-isopropilidenediphenol, and protocatechuic acid and its ethyl ester. The inhibition of the respiration; the changes in motility, shape, and lysis of the parasites; and the human blood hemolysis caused by these chemicals were studied. Human blood samples experimentally contaminated with 2000 or 150,000 trypomastigotes per milliliter were freed of parasites after treatment for 24 hr at 4 °C with 5 or 10 mM BHT (2,6-di-tert-butyl-4-hydroxytoluene), respectively. Consequently, BHT and other phenolic compounds deserve further study to determine their role in preventing the transmission of Chagas' disease by blood transfusion. © 1990

Synthesis of indazol-4,7-dione derivatives as potential trypanocidal agents

The synthesis of new indazol-4,7-dione derivatives via 1,3-dipolar cycloaddition of diazomethane with 2,3-dimethyl-1,4-benzoquinone (2) and 1,4-naphthoquinone (7) followed by N-alkylation of the pyrazol nitrogen atom of the corresponding quinones (3) and (8) with methyl chloroacetate is described. A series of amides from esters (5) and (10) were also obtained. These compounds were tested in vitro as potential antitrypanosomal agents. Compounds (4) and (8) were found to have significant activity

Two casein kinase 1 isoforms are differentially expressed in Trypanosoma cruzi

The cDNAs for two casein kinase 1 (CK1) homologues, TcCK1.1 and TcCK1.2, have been isolated from Trypanosoma cruzi. Both isoforms showed strong identity with other known CK1s. Their corresponding genes encode proteins of 312- and 330-amino acid residues with apparent molecular weights of 16 and 37 kDa, respectively. TcCK1.1 is a two-copy gene while TcCK1.2 is tandemly repeated, an arrangement not yet found in any other CK1. TcCK1.1 has been overexpressed in Escherichia coli and the recombinant protein exhibited properties characteristic of the CK1 family. Northern blot indicated that both TcCK1s are expressed differentially during the life stages of the parasite: the isoform TcCK1.1 shows low levels of mRNA expression in epimastigotes and increased expression in trypomastigotes while TcCK1.2 presents an augmented expression in amastigotes as compared with the other two life stages of the parasite. The CK1-like activity of amastigotes and trypomastigotes is significantly higher than th

Nitro aryl 1,4-dihydropyridine derivatives: Effects of Trypanosoma cruzi

A series of nitro aryl 1,4-dihydropyridine derivatives produced inhibition of both cell growth and oxygen consumption on Tulahuen and LQ strains, and clone Dm 28c of epimastigotes of Trypanosoma cruzi. Nicardipine was found to be the most potent derivative in both growth cell (I50 = 70 μM) and oxygen uptake (I50 = 26 μM in intact parasites, I50 = 325 μM in situ mitochondria). A correlation between the inhibitory effects on the growth cell and the apparent first order kinetic for the uptake of the 1,4-dihypyridine derivatives by T. cruzi epimastigotes was found. Thus, nicardipine, the most potent derivative, exhibited the highest apparent rate constant, k(u), (0.043 min-1). On the other hand, no susceptibility differences by strains and clone Dm 28c to the action of these drugs were found