Antifilarial activity of Caesalpinia bonducella against experimental filarial infections.

BACKGROUND & OBJECTIVE: Lymphatic filariasis is a disabling disease that continues to cripple population in tropical countries. Currently available antifilarial drugs are not able to control the disease. Therefore, a better antifilarial is urgently required for proper management of the disease. We undertook this study to assess the antifilarial activity of Caesalpinia bonducella-seed kernel against rodent filarial parasite in experimental model. METHODS: Microfilaraemic cotton rats and Mastomys coucha harbouring Litomosoides sigmodontis and Brugia malayi respectively, were treated with crude extract or fractions of the seed kernel C. bonducella through oral route for 5 consecutive days. Microfilaricidal, macrofilaricidal and female worm sterilizing efficacy was assessed. RESULTS: Crude extract showed gradual fall in microfilariae (mf) count in L. sigmodontis-cotton rat model from day 8 post-treatment attaining more than 95 per cent fall by the end of observation period. It also exhibited 96 per cent macrofilaricidal and 100 per cent female sterilizing efficacy. The butanol fraction F018 caused 73.7 per cent reduction in mf count and 82.5 per cent mortality in adult worms with 100 per cent female sterilization. The aqueous fraction F019 exerted more than 90 per cent microfilaricidal activity and 100 per cent worm sterilization. Two chromatographic fractions, F024 and F025 of hexane soluble fraction exhibited 64 and 95 per cent macrofilaricidal activity, respectively. Both the fractions caused gradual fall in microfilaraemia and 100 per cent worm sterilization. In B. malayi-M. coucha model F025 showed gradual reduction in microfilaraemia and caused 80 per cent sterilization of female parasites INTERPRETATION & CONCLUSION: In conclusion, C. bonducella- seed kernel extract and fractions showed microfilaricidal, macrofilaricidal and female-sterilizing efficacy against L. sigmodontis and microfilaricidal and female-sterilizing efficacy against B. malayi in animal models, indicating the potential of this plant in providing a lead for new antifilarial drug development.

In vitro antifilarial activity of Sencio nudicaulis Buch. Ham. Effect on Setaria cervi (Nematoda Filarioidea).

The effect on aqueous and alcoholic extracts of the leaves of Sencio nudicaulis Buch. Ham. was studied on the spontaneous movements of the whole worm and nerve-muscle preparation of Setaria cervi and on the survival of micro-filariae in vitro. Aqueous as well as alcoholic extracts caused inhibition of spontaneous motility of the whole worm and nerve-muscle preparation of S. cervi characterized by decreased amplitude, rate and tone of contractions. The concentration required to inhibit the movements of n.m. preparation was 1/3rd for aqueous and 1/20th for alcoholic extract suggesting a cuticular permeability barrier. The effect of S nudicaulis extracts was different than that produced by calcium channel blocker nifedipine on the whole worm and n.m. preparation. While nifedipine blocks the stimulant effect of Ach the extracts of S. nudicaulis fails to do so. While the response bears similarity with DEC which also does not block Ach response. Both aqueous and alcoholic extracts exhibited microfilaricidal action in vitro LC50 and LC90 being 10 and 15 ng/ml for aqueous extract, 5 and 12 ng/ml for alcoholic extract.

Regulation of cholinomimetic action of pyrantel pamoate by calcium channels in Setaria cervi.

Nerve muscle preparation of Setaria cervi (Nematoda:Filarioidea) exhibits spontaneous rhythmical movements when suspended in isolated organ bath containing modified Ringer's solution. Pyrantel pamoate (50 ng/ml) when applied caused initial short lasting stimulation followed by irreversible paralysis. When suspended in calcium free bathing fluid the movements of n.m. preparation showed a gradual decrease both in amplitude and rate of contraction til the movements ceased completely. The effect was similar when EDTA was added to the bath fluid. The stimulant effect of Pyrantel pamoate was blocked in calcium free solution and in bath applied EDTA. Calcium channel blocker Nifedipine in a concentration of 500 ng/ml blocked the effect of Pyrantel pamoate (50 ng/ml). Neither stimulation nor depression of movements was evident with higher concentration of PP (250 mg/ml) the stimulant effect of Pyrantel pamoate was blocked while the depressant effect characterized by decrease in amplitude of calcium is essential for the stimulant effect of Pyrantel pamoate and its response on n.m. preparation is similar to Acetylcholine.

Carboline antifilarials: effects on carbohydrate metabolising enzymes in Litomosoides carinii female.

Two antifilarial compounds, viz., 90/55 (7-oxo-1-phenyl-8, 14-dihydropyrido (3,4-b) imidazo (1,2-c) quinazolo (4,5-g) and 87/639 (6-Nitro-1-phenyl-9H-pyrido (3,4-b) indole at 0.5 and 2.0 micron concentrations substantially inhibited glucose uptake and increased lactate production by L. carinii during in vitro incubation for 2 hr. The treated parasites, showed increased activities of glycogen phosphorylase, phosphofructokinase and pyruvate kinase. Hexokinase and fumarate reductase activities level in the worms were significantly lowered. Therefore it appears that both the compounds kill adult L. carinii by interfering with its carbohydrate metabolism.

Evaluation of vanillic acid analogues as a new class of antifilarial agents.

A number of vanillic acid analogues (1-14) have been synthesised and evaluated against experimental filarial infections using cotton rats (Sigmodon hispidus) infected with Litomosoides carinii, a primary screening model, at a dose of 30 mg/kg, ip for 5 days. Of the 8 compounds tested, 4 (5,7, 11 and 12) exhibited high micro- and macro-filaricidal activity with sterilization of surviving female worms. Compounds 5, 7, 12 showed remarkable adulticidal action (> 80%). Sterilization of the female worms by compounds 11 and 12 was highly significant (80-100%).

Antifilarial activity of Centratherum anthelminticum seed extracts on Setaria cervi.

Effect of aqueous and alcoholic extract of C. anthelminticum was studied on the spontaneous movements of the whole worm and nerve-muscle preparation of S. cervi. Ethylacetate, acetone and methanol extract showed similar effect, of causing inhibition of spontaneous motility of the nerve-muscle preparation of S. cervi characterized by decreased amplitude and frequency of contractions. The inhibitory effect on the motility was reversible. Further, the extracts did not involve the blockade of cholinergic receptors as evidenced by the presence of unaltered stimulant response of acetylcholine in the presence of drug in bathing fluid.

Effect of diethyl carbamazine on neurotransmitter amino acids, biogenic amines and certain related enzymes in Setaria digitata.

Effect of diethyl carbamazine (DEC) on the levels of neurotransmitter amino acids and on the activities of related enzymes of S. digitata have been studied. When the worms were incubated in DEC, substances known to have neurotransmitter effect were found increased except glycine. Among the amines the level of serotonin, dihydroxy phenyl alanine and epinephrine were increased and that of histamine remained the same. DEC inhibited activities of monoamine oxidase, aspartate amino transferase and alanine amino transferase and enhanced those of cathepsin and glutamate dehydrogenase. The effect of DEC on the activities of the enzymes appear to account for the increased level of amino acids and amines. Results indicate that the reversible paralysis caused by DEC is due to the accumulation of neurostimulants and associated decrease in the concentration of inhibitors.

Effect of anthelmintics and phenothiazines on adenosine 5'-triphosphatases of filarial parasite Setaria cervi.

S. cervi showed particulate bound Ca2+ ATPase and Na+,K(+)-ATPase activities while Mg2+ ATPase was detected in traces. ATPase of S. cervi was also differentiated from the nonspecific p-nitrophenyl phosphatase activity. Female parasite and microfilariae exhibited higher Ca2+ ATPase and Na+,K(+)-ATPase activities than the male adults and the enzyme Na+,K(+)-ATPase was mainly concentrated in the gastrointestinal tract of the filarial parasite. Na+,K(+)-ATPase of the filariid was ouabain-sensitive while Ca2(+)-ATPase activity was regulated by concentration of Ca2+ ions and inhibited by EGTA. Phenothiazines, viz. trifluoperazine, promethazine and chlorpromazine caused significant inhibition of Ca2+ ATPase and Na+,K(+)-ATPase. Diethylcarbamazine was a potent inhibitor of these ATPases. Mebendazole, levamisole and centperazine also caused significant inhibition of the ATPases indicating this enzyme system as a common target for the action of anthelmintic drugs.

Glycosaminoglycan (GAG) level and activities of certain enzymes of GAG metabolism in Culex quinquefasciatus and Setaria digitata.

Significant differences were observed in GAG metabolism of S. digitata and one of its intermediate vectors, C. quinquefasciatus. Distribution of different components such as hyaluronic acid, heparin-sulphate, chondroitin-4-sulphate, chondroitin-6-sulphate, dermatan sulphate and heparin was comparable in both. However, there were quantitative differences; the difference was marked in the activity of enzymes of GAG metabolism in presence and absence of diethylcarbamazine (DEC) a known antifilarial drug. While the activities of beta-galactosidase and beta-N-acetyl glucosaminidase of S. digitata systems showed an inhibition of 96.5 and 92.6% respectively, in the Culex systems they showed an inhibition of 93.3% and an activation of 18% respectively. The differences clearly indicate the existence of basic differences in GAG metabolism of vector and parasite.

Effect of diethylcarbamazine on Setaria cervi in vitro.

Diethylcarbamazine (DEC) produced an initial stimulation followed by depression of the movements of the intact worm and nerve-muscle preparation of Setaria cervi. The effective concentration of DEC was reduced to one hundredth in the nerve-muscle preparation as compared to the whole worm, suggesting that the cuticular barrier is highly effective in preventing the penetration of the drugs. The depressant effect of DEC was concentration dependent and was not reversed even after repeated changes of the bath fluid. The worms consumed 7.7 mg +/- 0.2 glucose/g wet weight/hr. The consumption of glucose was directly proportional to its motor activity; it increased during the stimulant phase with low doses of DEC and decreased during the depressant phase.