mitoguazone and diminazene-aceturate

Polyamines are essential for cell growth and differentiation and therefore, S-adenosylmethionine decarboxylase (SAMDC), a key regulatory enzyme of the polyamine biosynthesis, is considered as a potentially important target for chemotherapy of filarial infections. Recombinant Onchocerca volvulus SAMDC was expressed in Escherichia coli and characterised. The enzyme activity was found to be stimulated 15-fold by addition of 1 mM putrescine. The Km-value for S-adenosylmethionine was determined to be 36 microM. Furthermore, the efficiencies of SAMDC inhibitors were analysed: Berenil inhibits the enzyme activity competitively with a Ki-value of 0.1 microM. MDL 73811 acts as an irreversible inhibitor with a Ki-value of 1.4 microM. Recently synthesised aromatic methylglyoxal bis(guanylhydrazone) analogues demonstrated high efficacy as inhibitors of the SAMDCs. Some of these analogues exhibited Ki-values of 5 and 14 nM for the Onchocerca enzyme, a result which shows an up to 100-fold increase in specificity compared to the value of 0.47 microM for methylglyoxal bis(guanylhydrazone). These inhibitors might have potential as drug candidates against filarial worms.

Topics: Adenosylmethionine Decarboxylase; Animals; Cloning, Molecular; Deoxyadenosines; Diminazene; Enzyme Inhibitors; Escherichia coli; Filaricides; Filarioidea; Genetic Vectors; Helminth Proteins; Humans; Mitoguazone; Onchocerca volvulus; Organic Chemicals; Polyamines; Recombinant Proteins

Leishmania donovani S-adenosyl-L-methionine (AdoMet) decarboxylase was found to show a growth related pattern. Methylglyoxal bis (guanylhydrazone) (MGBG) and Berenil inhibited the growth of Leishmania donovani promastigotes (strain UR6) in a dose dependent manner. The concentrations of MGBG and Berenil required for 50% inhibition of rate of growth were 67 and 47 microM, respectively. The growth inhibition of MGBG was partially reversed by spermidine (100 microM) and spermine (100 microM). Berenil inhibition of promastigote growth was partially reversed by 100 microM spermidine whereas 100 microM spermine did not result in any reversal of growth. The reduction in parasitemia in vitro by these inhibitors was accompanied by inhibition of AdoMet decarboxylase activity and spermidine levels.

Topics: Adenosylmethionine Decarboxylase; Animals; Antiprotozoal Agents; Diminazene; Dose-Response Relationship, Drug; Kinetics; Leishmania donovani; Mitoguazone; Polyamines; Probability; Time Factors

Trypanosoma brucei E164 and a dyskinetoplastic derivative, Dysk164, were injected into mice that were treated subsequently with methylglyoxal-bis-guanylhydrazone, berenil, ethidium bromide, and acriflavine. Additionally, parasites were photoaffinity labeled with ethidium monoazide to effect covalent drug attachment prior to injection into animals. In all cases, killing of animals with E164 was blocked by the drug treatment, whereas killing due to Dysk164 was not. These findings are consistent with the view that the intact kinetoplast plays an essential role in the action of these drugs.

Topics: Acriflavine; Animals; Azides; Diminazene; Dose-Response Relationship, Drug; Drug Resistance; Ethidium; Female; Light; Mice; Mitochondria; Mitoguazone; Mutation; Parasitemia; Trypanocidal Agents; Trypanosoma brucei brucei; Trypanosomiasis, African

Methylglyoxal bis(guanyl hydrazone) (MGBG) and the related diamidine compounds berenil and pentamidine inhibited multiplication of A. culbertsoni. The growth inhibition by MGBG (2.5 mM) in the peptone medium was accompanied by the disappearance of spermidine and a marked reduction in the level of diaminopropane. MGBG and berenil completely inhibited growth in a chemically defined medium at 1 mM and 1-2 microM concentration, respectively. However, there was no decrease in the polyamine levels in the early stages of growth inhibition by these agents. Uptake of putrescine, spermidine and spermine by A. culbertsoni has been demonstrated but addition of exogenous polyamines did not reverse the growth inhibitory action of MGBG and berenil. Inhibition of S-adenosylmethionine decarboxylase and decrease in polyamine synthesis do not seem to be the primary targets for the antiamoebic action of MGBG and berenil.

Topics: Acanthamoeba; Animals; Antiprotozoal Agents; Diminazene; Mitoguazone; Polyamines

Putrescine-dependent S-adenosylmethionine decarboxylase (EC 4.1.1.50) was demonstrated in Ascaris suum and Onchocerca volvulus; activation was found to be about fourfold by putrescine. Mg2+ did not affect the enzyme activity. A. suum was taken as a model nematode and its S-adenosylmethionine decarboxylase was partially purified and characterized. The molecular weight was estimated to be 220,000. The apparent Km-value for adenosylmethionine was determined to be 17 microM. Methylglyoxal bis(guanylhydrazone) and berenil competitively inhibited the enzyme activity; the apparent Ki-values were found to be 0.24 microM and 0.11 microM, respectively. The dependence of filarial worms on uptake and interconversion of putrescine and polyamines as well as properties of the S-adenosylmethionine decarboxylase, different from the host enzyme, points to the polyamine metabolisms as a useful target for chemotherapy.

Topics: Adenosylmethionine Decarboxylase; Animals; Ascaris; Carboxy-Lyases; Chromatography, Gel; Diminazene; Enzyme Activation; Female; Magnesium; Male; Mitoguazone; Onchocerca; Pentamidine; Polyethylene Glycols; Putrescine

Acanthamoeba culbertsoni, the free living pathogenic amoeba responsible for fatal meningoencephalitis, contains an S-adenosylmethionine decarboxylase (EC 4.1.1.50) which is strongly activated by putrescine and to a lesser extent by cadaverine; spermidine, spermine, diaminopropane and 1,6-diaminohexane are inactive. Methylglyoxal bis-(guanylhydrazone) competitively inhibited the enzyme with a Ki value of 123 microM. The enzyme was strongly inhibited by berenil (Ki = 0.5 microM) and to a lesser extent by pentamidine. The putrescine-activated enzyme is inhibited by MgCl2. The apparent molecular weight of 110,000 and its enzymatic properties indicate that the enzyme has characteristics intermediate between the bacterial and eukaryotic S-adenosylmethionine decarboxylases.

Topics: Adenosylmethionine Decarboxylase; Amoeba; Animals; Carboxy-Lyases; Cell-Free System; Diminazene; Enzyme Activation; Kinetics; Metals; Mitoguazone; Molecular Weight; Pentamidine; Putrescine

Trypanosoma brucei brucei S-adenosyl-L-methionine (AdoMet) decarboxylase was found to be relatively insensitive to activation by putrescine as compared with the mammalian enzyme, being stimulated by only 50% over a 10,000-fold range of putrescine concentrations. The enzyme was not stimulated by up to 10 mM-Mg2+. The Km for AdoMet was 30 microM, similar to that of other eukaryotic AdoMet decarboxylases. T.b. brucei AdoMet decarboxylase activity was apparently irreversibly inhibited in vitro by Berenil and reversibly by pentamidine and methylglyoxal bis(guanylhydrazone). Berenil also inhibited trypanosomal AdoMet decarboxylase by 70% within 4 h after administration to infected rats and markedly increased the concentration of putrescine in trypanosomes that were exposed to the drug in vivo. Spermidine and spermine blocked the curative effect of Berenil on model mouse T.b. brucei infections. This effect of the polyamines was probably not due to reversal of Berenil's inhibitory effects on the AdoMet decarboxylase.

Topics: Adenosylmethionine Decarboxylase; Amidines; Animals; Carboxy-Lyases; Diminazene; Male; Mitoguazone; Pentamidine; Putrescine; Rats; Rats, Inbred Strains; Spermidine; Spermine; Trypanocidal Agents; Trypanosoma brucei brucei