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PubMed1989

2,2'-Dicarbomethoxyamino-5,5'-dibenzimidazolyl ketone--a new antifilarial agent.

The activity of 2,2'-dicarbomethoxyamino-5,5'-dibenzimidazolyl ketone (II, C.D.R.I. Comp. 82/437) has been evaluated for its micro- and macro-filaricidal efficacy against Litomosoides carinii in rodents. A dose of 3 mg/kg (i.p.) and 50 mg/kg (oral) x 5 days of Comp. 82/437 was found to eliminate almost 100% of adult worms and microfilariae of L. carinii in cotton rat. It also killed 100% and 97% of adult worms and microfilariae of Dipetalonema viteae and Brugia malayi in Mastomys natalensis respectively, at 150 and 200 mg/kg x 5 days orally. The compound also exhibited marked chemoprophylactic and in vitro activity against L. carinii.

Administration, Oral↗
PubMed1990

Antibodies against the cuticlin of Ascaris suum cross-react with epicuticular structures of filarial parasites.

The insoluble cuticlin from the cortical zone of the cuticle of adult Ascaris suum was purified and used to raise antibodies in C57/bl mice. The specificity of the antibodies for the external cortical layer was shown in the indirect immunofluorescence antibody test and by immunoelectronmicroscopy. A very high specificity for the external cortical layer was found. Some cross-reactions with cuticular collagens occurred, and increased after booster immunizations. The anti-cuticlin antibody cross-reacted with the electron-dense layers of the cortical zones of adult Acanthocheilonema viteae and Brugia pahangi. A very weak reaction was found in the cortical zone of adult Onchocerca volvulus. In the cuticles of third stage larvae of all three species mainly epitopes in the cortical zones were labelled. In no case did the anti-cuticlin antibody interact with the outermost surface of the cuticle.

Animals↗
PubMed1992

Activity, mechanism of action and pharmacokinetics of 2-tert-butylbenzothiazole and CGP 6140 (amocarzine) antifilarial drugs.

A variety of recently developed drugs, designed to be used in antifilarial chemotherapy, contain a thiocarbonylamide group as a common structural element. One group of these compounds is based on a 2-tert-butylbenzothiazole ring in which the carbonylamide linkage is present as an isothiocyanate, dithiocarbamic acid ester or thiourea derivative. The single representative of another series is an N-methylpiperazine adduct of amoscanate (CGP 6140 or amocarzine). CGP 6140 is currently undergoing clinical trials in patients suffering from onchocercosis. All of the drugs with antifilarial activity affect the motility of filarial worms in vitro. The primary site of action of most of these compounds is the mitochondrion. The drugs result in the swelling of this organelle and also the inhibition of respiration and other associated metabolic functions. The dithiocarbamic acid esters (e.g., CGP 20376) are devoid of intrinsic antifilarial activity. Activity of these compounds requires conversion to the corresponding isothiocyanates. This occurs spontaneously in aqueous solution at physiological pH. The thiourea compounds were found to inhibit acetylcholinesterase activity by competing with its substrate. There is also evidence that the latter drugs are metabolized by a host-derived enzyme to their isothiocyanate analogs. CGP 6140 affects both mitochondrial function and acetylcholinesterase activity. The biochemical effects of the antifilarial compounds were not found to be significantly different between mammalian and parasite test systems. Biochemical and pharmacokinetic studies suggest that the selective toxicity of the new series of drugs towards filarial parasites is most likely preferential drug uptake by the pathogen. The lack of a unique target for these compounds in the parasite may explain the side-effects seen upon their administration to humans.

Animals↗
PubMed1992

Chemical composition of Litomosoides carinii microfilarial sheaths.

Litomosoides carinii microfilariae were exsheathed by freezing and thawing, and the sheaths were separated by filtration. Samples of pure sheaths thus obtained were hydrolyzed, methanolyzed or oxidized with nitric acid under pressure at 300 degrees C, respectively, and were analyzed for amino acids, sugars, fatty acids or for metal ions and phosphorus. Almost 75% of the sheath dry weight could thus be accounted for. Amino acids (55 weight %) were the major constituents, and amongst these glutamine and proline (approximately 11% each). The detection of 2% cysteine/cystine indicated the possible presence of disulfide crosslinks. Besides amino acids, approximately 8% of sugars--roughly equimolar amounts of (N-acetyl)galactosamine and uronic acids--1.5% of monovalent cations (Na+ and K+) and 9.5% of phosphate were detected. No appreciable amounts of fatty acids, neutral sugars, neuraminic acid, or (N-acetyl)glucosamine (i.e. no chitin) were found.

Amino Acids↗
PubMed1994

Chemotherapy of experimental filariasis: enhancement of activity profile of ivermectin with immunomodulators.

The effect of certain immunopotentiators (Freund's complete adjuvant, picroliv, tuftsin and CDRI Compound 86/448) was evaluated on exertion of antifilarial activity of ivermectin at different dose levels in cotton rats experimentally infected with Litomosoides carinii. Ivermectin alone (up to 250 micrograms/kg p.o. x 5 days) caused sterilization of most of the surviving female parasites, but had no lethal effect on adult worms. In combination with immunomodulators, ivermectin brought about significant lethal effect on adult parasites even at a dose of 1 microgram/kg x 5 days. Nevertheless, in animals receiving FCA alone, sterility was caused in > 50% of female parasites. Other immunomodulators used alone had a suppressive effect on microfilaraemia only. Immunomodulators alone or in combination with ivermectin also caused enhanced filaria-specific antibody response.

Adjuvants, Immunologic↗
PubMed1976

The Dirofilaria parasite in the orbit.

A 51-year-old white man had proptosis, pain, and inflammation of the left orbit and later developed diplopia. Treatment with antibiotics relieved most of the symptoms but a localized painful mass persisted in the left orbit. On biopsy a Dirofilaria worm was found. The patient was treated with corticosteroids and the residual nodule subsided. The patient was seen regularly for five months after surgery and the lesion has not recurred.

Conjunctivitis↗
PubMed1990

Quinone mediated ATP production in the filarial parasite Setaria digitata.

The cattle filarial parasite Setaria digitata, a facultative anaerobe which is reported to be cyanide insensitive, lacks cytochromes and presents many unique characters. Experiments showed the occurrence of two lower quinones Q6 and Q8 and its rapid synthesis is revealed by a [14C] acetate incorporation study. A schematic quinone mediated hydrogen peroxide production with the generation of ATP through oxidation of substrates has been proposed. Search for specific blockers at the level of quinone might prove to be an effective measure for the control of filarial parasites and thereby filariasis.

Acetates↗
PubMed1991

Quinone mediated electron transport system in the filarial parasite Setaria digitata.

Setaria digitata, a cattle filarial parasite, is known to have peculiarities such as hydrogen peroxide (H2O2) production, cyanide insensitivity, absence of cytochromes and presence of quinones. Estimation of mitochondrial H2O2 with different substrates and inhibitors showed that salicylhydroxamic acid (SHAM), the alternative oxidase inhibitor, inhibited the H2O2 production maximally. Based on the inhibitory studies with rotenone, antimycin A, o-hydroxydiphenyl, SHAM and 2 thenoyltrifluoroacetone, a mechanism for the electron transport is proposed. Quinone Q8 seems to have a central role, hence inhibitors at the level of quinones might prove to be effective in designing drugs for filariasis.

Animals↗
PubMed1991

Oxidative phosphorylation coupled to electron transfer in the filarial parasite Setaria digitata.

The filarial parasite of Bos indicus, Setaria digitata is reported to have many unique characteristics such as cyanide insensitivity and mitochondrial hydrogen peroxide production. The latter is more sensitive to the alternative oxidase inhibitor salicylhydroxamic acid (SHAM). Studies on the generation of ATP molecules through mitochondriae in the presence of different substrates and inhibitors showed that the oxidative phosphorylation coupled to electron transport occurs mainly at site I and involves the participation of quinone Q8. Based on the data, a scheme for the filarial electron transport system is proposed in which the quinones have a central role. Hence inhibitors at the quinone level might prove to be effective targets for chemotherapy.

Animals↗
PubMed1992

Quinone dependent NADH dehydrogenation in mitochondria-like particles from Setaria digitata, a filarial parasite.

In the cattle filarial parasite, Setaria digitata, the mitochondria-like particles have been shown to possess site I associated oxidative phosphorylation and rotenone sensitive and insensitive pathways for the dehydrogenation of NADH. Quinone depleted mitochondria-like particles show a loss of activity of these NADH dehydrogenases and also a complete loss of fumarate reductase activity. Reconstitution with quinone restores both NADH linked oxygen uptake and fumarate reductase activity. Thus activities of complex I and fumarate reductase are linked to quinone. Hence an inhibitor at the level of quinone can simultaneously block both aerobic and anaerobic pathways which drive ATP production and may prove useful in the effective control of filariasis.

Animals↗
PubMed1992

Fumarate reductase system of filarial parasite Setaria digitata.

In the cattle filarial parasite Setaria digitata the mitochondria like particles have been shown to possess NADH dependent fumarate reduction coupled with site I electron transport associated phosphorylation. This reduction is catalysed by the fumarate reductase system. The Km for fumarate is 1.47 mM and that for NADH is 0.33 mM. This activity is sensitive to rotenone, antimycin A and o-Hydroxy diphenyl. One ATP is produced for each pair of electrons transferred to fumarate. The fumarate reductase system consisting of NADH-coenzyme Q reductase, cytochrome b like component(s) and succinate dehydrogenase/fumarate reductase is thus very important and hence specific inhibitors of the system may prove useful in the effective control of filariasis.

Animals↗