Mosquito larvicidal and ovicidal activity of puffer fish extracts against Anopheles stephensi, Culex quinquefasciatus and Aedes aegypti (Diptera: Culicidae)

The extracts of liver (LE), ovary (OE), skin (SE) and muscle (ME) tissues of four species of puffer fishes viz., Arothron hispidus, Lagocephalus inermis, Lagocephalus scleratus and Chelonodon patoca were evaluated against larvae and eggs of three mosquito vectors, Anopheles stephensi, Culex quinquefasciatus and Aedes aegypti. The LC50 values were 1194.26, 1382.73 (LE); 1421.42, 1982.73 (OE); 7116.86, 15038.98 (ME) and 10817.8 ppm (SE) for An. stephensi and Cx. quinquefasciatus respectively for A. hispidus. In the case of L. inermis, the LC50 values were 1163.83, 1556.1 and 2426.38 (LE); 1653.53, 2734.74 (OE); 6067.47 (ME) and 10283.04 ppm (SE) for An. stephensi, Cx. quinquefasciatus and Ae. aegypti respectively. The LC50 values were 1509.98, 1608.69 (LE) and 1414.9, 2278.69 ppm (OE) for An. stephensi and Cx. quinquefasciatus respectively for the extracts of L. scleratus. In the case C. patoca extracts the LC50 values were 1182.29, 1543.00, 2441.03 (LE) and 1076.13, 2582.11 ppm (OE) for An. stephensi, Cx. quinquefasciatus and Ae. aegypti respectively. OE and LE of all puffer fishes exhibited zero percent egg hatchability from 600 to 1000 ppm against eggs of An. stephensi and Cx. quinquefasciatus. This study shows that puffer toxins are effective in killing the larvae and eggs of mosquitoes.

Mosquito attractant blends to trap host seeking Aedes aegypti

Aedes aegypti is the key vector of three important arboviral diseases -dengue, yellow fever and chikungunya. To identify volatile chemicals which could be used in odour based traps for Aedes mosquito surveillance, a few synthetic compounds and compound blends have been evaluated in an indigenously designed olfactometer. A total of 24 compounds and seven compound blends were screened against unfed adult female Ae. aegypti mosquitoes for attraction and compared with control group. The attractancy or repellency index of the test material to mosquitoes was calculated and rated them as class-1, class-2 and class-3 with rating values ranging 1-15, 16-33 and 34-100 respectively. Out of the 24 compounds tested, six were showing significant attractancy (P < 0.05) and among that 1-octene-3-ol showed maximum attractancy with a rating value of 57.81. Sixteen compounds showed significant repellency (P < 0.05) and among that with a rating value of 72.47, 1-hexene-3-ol showed strong repellent action against Ae. aegypti. All the seven blends showed significant mosquito attractancy (P < 0.05) and among that with a rating of 62.08 Myristic acid, Lactic acid and CO(2) blend exhibited first-rate mosquito attractancy.

Development of a controlled release formulation of an indigenous insect growth regulator, DPE-28, a substituted diphenylether, for controlling the breeding of Culex quinquefasciatus

BACKGROUND & OBJECTIVES

DPE-28, a substituted diphenyl ether (2,6-ditertiarybutyl phenyl-2',4'-dinitro phenyl ether) was reported to exhibit promising insect growth regulating activity against Culex quinquefasciatus, the vector of lymphatic filariasis. A controlled release formulation (CRF) of DPE-28 has been developed to control Cx. quinquefasciatus in its breeding habitats. Toxicity of DPE-28, safety to non-target mosquito predators and the release profile of the CRF of DPE-28 are studied and discussed.

METHODS

The acute oral and dermal toxicity was tested in male and female Wistar rats as per the Organization for Economic Cooperation and Development (OECD) guidelines 425 and 402 respectively. The toxicity of DPE-28 to non-target predators was tested as per the reported procedure from this laboratory. The CRF of DPE-28 was prepared by following the reported procedure developed at this laboratory earlier. The concentration of DPE-28 released from the CRF was monitored by HPLC by constructing a calibration graph by plotting the peak area in the Y-axis and the concentration of DPE-28 in the X-axis.

RESULTS

DPE-28 has been tested for acute oral toxicity and found to be moderately toxic with LD 50 value of 1098 mg/kg body weight (b.w). The results of the acute dermal toxicity and skin irritation studies reveal that DPE-28 is safe and non-irritant. DPE-28 when tested at 0.4 mg/litre against non-target mosquito predators did not produce any mortality. The release profile of the active ingredient DPE-28 from the CRF by HPLC technique showed that the average daily release (ADR) of DPE-28 ranged from 0.07 to 5.0 mg/litre during first four weeks. Thereafter the matrix started eroding and the ADR ranged from 5 to 11 mg/litre during the remaining 5 wk. The cumulative release of active ingredient showed that > 90 per cent of the active ingredient was released from the matrix.

INTERPRETATION & CONCLUSIONS

The controlled release matrix of DPE-28 was thus found to inhibit the adult emergence (>80%) of Cx. quinquefasciatus for a period of nine weeks. The CRF of DPE-28 may play a useful role in field and may be recommended for mosquito control programme after evaluating the same under field conditions.

Biochemical studies on glutathione S-transferase from the bovine filarial worm Setaria digitata

Setaria digitata is a filarial worm of the cattle used as a model system for antifilarial drug screening, due to its similarity to the human filarial parasites Wuchereria bancrofti and Brugia malayi. Since filarial glutathione S-transferase (GST) is a good biochemical target for antifilarial drug development, a study has been undertaken for the biochemical characterization of GST from S. digitata. Cytosolic fraction was separated from the crude S.digitata worm homogenate by ultracentrifugation at 100,000 g and subjected to ammonium sulfate precipitation followed by affinity chromatography using GSH-agarose column. The kinetic parameters K (m) and V (max) values with respect to GSH were 0.45 mM and 0.105 μmol min(-1) mL(-1) respectively. With respect to 1-chloro-2,4-dinitrobenzene, the K (m) and V (max) values were 1.21 and 0.117 μmol min(-1) mL(-1) respectively. The effect of temperature and pH on GST enzyme activity was studied. The protein retained its enzyme activity between 0°C and 40°C, beyond which it showed a decreasing tendency, and at 80°C, the activity was lost completely. The enzyme activity was varying with change in pH, and the maximum GST activity was observed at pH 7.5. Gel filtration chromatographic studies indicated that the protein has a native molecular mass of about 54 kDa. The single band of GST subunit appeared in sodium dodecyl sulfate polyacrylamide gel electrophoresis was found to have molecular mass of ∼27 kDa. This shows that cytosolic S. digitata GST protein is homodimeric in nature.

Utility of Topiramate for the Treatment of Patients with Chronic Migraine in the Presence or Absence of Acute Medication Overuse

Chronic migraine has been linked to the excessive use of acute headache medications. Medication overuse (MO) is commonly considered the most significant risk factor for the progression of migraine from an episodic to a chronic condition. Managing MO is a challenge. Discontinuation of the acute medication can result in withdrawal headache, nausea, vomiting and sleep disturbances. This review summarizes the results from two similarly designed, randomized, placebo- controlled, multicentre studies of chronic migraine conducted in the USA and European Union. Both studies demonstrate the efficacy and safety of the migraine preventive medication, topiramate, for the treatment of chronic migraine in patient populations both with and without MO. These studies may have important implications for the future of chronic migraine management, suggesting that detoxification prior to initiating prophylactic therapy may not be required in all patients if MO is present.

Protective effect of vitamin E against carbendazim-induced testicular toxicity–histopathological evidences and reduced residue levels in testis and serum

The fungicide Carbendazim Methyl-2-benzimidazole carbamate (MBC) is known to produce male reproductive toxicity. The present study has been undertaken to investigate the impact of vitamin E, an antioxidant against the testicular toxicity induced by MBC. HPLC analysis showed that the amount of MBC in testis and serum was 57.40 +/- 3.38 nmol/g and 14.10 +/- 0.84 nmol/ml, respectively, in rats treated with carbendazim + vitamin-E, which were significantly lower than that of rats treated with carbendazim alone (240 +/- 15.60 nmol/g and 318.70 +/- 22.52 nmol/ml, respectively). MBC treatment significantly decreased the testicular weight while co-administration of vitamin-E registered normal testicular weight. Histomorphometric analysis revealed a significant decrease (P < 0.05) in the diameter of the seminiferous tubules and lumen in MBC-treated rats compared to control whereas they remained normal in vitamin E + MBC-treated rats. Leydig cells appeared dispersed and hypertrophic after MBC treatment. Various histopathological changes were observed in testis of rats treated with MBC whereas these changes were absent in vitamin-E + MBC-treated rat testis. In conclusion protection against MBC-induced toxicity was observed with co-administration of vitamin E with MBC.

N,N-diethyl phenylacetamide (DEPA): A safe and effective repellent for personal protection against hematophagous arthropods

Repellents play an important role in protecting humans from the bites of insect pests. An effective and safe repellent will be useful in reducing human-vector contact and thereby help in the interruption of vector borne disease transmission. Because of the unavailability of m-toluic acid in India for the manufacture of N,N-diethyl m-toluamide (DEET), there is a need to develop an alternate effective and safe insect repellent. In total, 120 substituted amides were synthesized and tested for repellency at 1.0 mg/cm2 under laboratory conditions. Among these amides, N,N-diethyl phenylacetamide (DEPA), applied at 1.0 mg/cm2 in different oil bases, was found to exhibit promising repellency (6-8 h) in the laboratory when tested against Aedes aegypti (L.) The repellent DEPA was evaluated on army personnel in comparison with dimethylphthalate (DMP) and DEET against mosquitoes, black flies, and land leeches under field condition in the North-East Frontier area of India. Both DEPA and DEET displayed broad-spectrum repellency. DEPA was more effective than DMP against all test organisms. However, no significant difference was noticed between DEPA and DEET for repellency at 0.25 and 0.5 mg/cm2 against black flies and mosquitoes. DMP was the least effective among the three compounds in the field studies. The relative potency of DEPA in comparison with DEET and DMP for repellency against Phlebotomine sand flies also was determined. At 0.1 mg/cm2, both DEPA and DEET were found to be equally effective with a protection time from 4.37 +/- 0.08 to 4.45 +/- 0.15 h. Both compounds were significantly more effective than DMP. At 0.2 mg/cm2, DEPA and DEET provided protection times of 6.52 +/- 0.08 and 7.15 +/- 0.15 h, respectively. DEPA was formulated into a vanishing cream, a pharmacologically safe polymer-based liquid, and a liposphere lotion. The vanishing cream and the two-polymer liquid formulations enhanced protection times from 4.4 to 6.5 and 7.13 h, respectively, compared with an alcohol solution applied at 0.5 mg/cm2 on the forearm of human volunteers. Formulations of DEPA and DEET applied at 0.5 mg/cm2 on rabbits exposed to Ae. aegypti enhanced protection times compared with an alcohol solution and the liposphere lotion from 4.0 to 6.0 h and 4.0 to 5.0 h, respectively. Comparison of mean protection times of DEET and DEPA applied at a rate of 0.3 mg/cm2 to human volunteers exposed to Cx. quinque-fasciatus under field conditions indicated that the lotion formulations of DEET and DEPA provided significantly (Duncan's multiple-range test, P < 0.05) higher protection times than did alcohol solutions. Toxicological studies revealed that DEPA is safe.

Optimization of media composition for the production of cyclosporin A by Tolypocladium species

BACKGROUND & OBJECTIVE

Cyclosporins are produced by certain species of the filamentous fungi, belonging to the genus Tolypocladium. While there are numerous reports on the use of cyclosporins in clinical studies, reports on the various aspects of their production have been very limited. Therefore, this study was carried to optimize the medium composition for the production of cyclosporin A, produced by a strain of the filamentous fungus, Tolypocladium species by static fermentation.

METHODS

The effect of different nutrients on the production of cyclosporin A, produced by Tolypocladium species in stationary culture was studied by growing the fungus for 21 days at 25 +/- 2 degrees C under different media composition. Cyclosporin A was extracted by homogenizing the fungal cells with methanol and the cyclosporin A level was analyzed by high performance liquid chromatography (HPLC).

RESULTS

Among the six different media studied for the production of cyclosporin A, medium 'f' containing glucose (8%), casein acid hydrolysate (3%), malt extract (2%), peptone (1%) and DL- alpha-amino butyric acid (0.5%) favoured the maximum production (2.22 +/- 0.02 g/l medium or 5.85 +/- 0.35 g/kg biomass).

INTERPRETATION & CONCLUSION

This study showed that by optimizing the composition of fermentation media enhanced production of cyclosporin A was obtained. Since the strain Tolypocladium (VCRC F21 NRRL No.18950) produces a high level of cyclosporin A in the identified fermentation medium, it could be exploited for industrial production.

Focus on trial endpoints of clinical relevance and the use of almotriptan for the acute treatment of migraine

Almotriptan is a 5-HT(1B/1D) receptor agonist, or triptan, indicated for the acute treatment of migraine. It has been shown to be effective and well tolerated for the treatment of acute migraine in approximately 5000 patients enrolled in short-term placebo- and active-controlled trials and long-term open-label trials. A recent meta-analysis reported that almotriptan has the highest sustained pain-free (SPF) rate and lowest adverse-event (AE) rate of all oral triptans. Sustained pain free is a composite endpoint of pain freedom at 2 h, no recurrence of moderate-to-severe headache and no use of rescue medication from 2 to 24 h after dosing. Patient surveys have indicated that migraine sufferers consider complete pain relief, no recurrence, rapid onset and no side-effects to be the most important attributes of their acute treatment. Composite endpoints such as SPF and SPF with no AEs (SNAE) contain the attributes that migraine sufferers express as being the most important elements of an acute migraine therapy, and their use in future clinical trials should aid in the selection of agents that can offer patients the highest likelihood of consistent treatment success.

Structure of glutathione S-transferase of the filarial parasite Wuchereria bancrofti: a target for drug development against adult worm

A three dimensional structural model of Glutathione-S-transferase (GST) of the lymphatic filarial parasite Wuchereria bancrofti (wb) was constructed by homology modeling. The three dimensional X-ray crystal structure of porcine pi-class GST with PDB ID: 2gsr-A chain protein with 42% sequential and functional homology was used as the template. The model of wbGST built by MODELLER6v2 was analyzed by the PROCHECK programs. Ramachandran plot analysis showed that 93.5% of the residues are in the core region followed by 5.4 and 1.1% residues in the allowed and generously allowed regions, respectively. None of the non-glycine residues is in disallowed regions. The PROSA II z-score and the energy graph for the final model further confirmed the quality of the modeled structure. The computationally modeled three-dimensional (3D) structure of wbGST has been submitted to the Protein Data Bank (PDB) (PDB ID: 1SFM and RCSB ID: RCSB021668). 1SFM was used for docking with GST inhibitors by Hex4.2 macromolecular docking using spherical polar Fourier correlations.

Development of biodegradable aluminium carboxymethylcellulose matrices for mosquito larvicides

The use of ecofriendly biodegradable controlled-release formulations of mosquito larvicides could reduce the frequency of application and losses due to degradation of the insecticide compared with conventional formulations. Among the 20 matrices developed by entrapping the organophosphorus mosquito larvicide, fenthion, in carboxymethylcellulose ionotropically cross-linked with aluminium ions which were studied for release profiles, two matrices, CRF3b and CRF5b, were found to be stable for 16 and 14 weeks under simulated field conditions. The average concentration of fenthion released per week ranged from 0.06 to 3.5 mg litre(-1) for CRF3b and 0.09 to 2.72 mg litre(-1) for CRF5b. Of these two formulations, CRF3b was the more stable, maintaining the concentration of the active ingredient at the level required to effect mosquito control. The cumulative release of fenthion per pellet was 80% from CRF3b and 72% from CRF5b. Based on the study with fenthion, two similar matrices for triflumuron, a benzoylphenylurea insect growth regulator, STAR3b and STAR5b were developed. These matrices were stable up to 16 weeks with the average concentration of triflumuron released per week ranging from 0.05 to 3.44 mg litre(-1) for STAR3b and 0.07 to 2.71 mg litre(-1) for STARSb. The cumulative release of triflumuron per pellet was 75% from STAR3b and 76% from STAR5b. From the results of this study under simulated conditions, it is estimated that the application of four pellets of either fenthion or triflumuron per square metre of the breeding surface may play a useful role in controlling Culex quinquefasciatus Say in larval habitats for about 4 months.

Trans --> cis isomerization of trans-[(dppm)2Ru(H)(L)][BF4] (L = P(OR)3) complexes: preparation of cis-[(dppm)2Ru(eta2-H2)(L)][BF4]2

A series of new dicationic dihydrogen complexes of ruthenium of the type cis-[(dppm)(2)Ru(eta(2)-H(2))(L)][BF(4)](2) (dppm = Ph(2)PCH(2)PPh(2); L = P(OMe)(3), P(OEt)(3), PF(O(i)Pr)(2)) have been prepared by protonating the precursor hydride complexes cis-[(dppm)(2)Ru(H)(L)][BF(4)] (L = P(OMe)(3), P(OEt)(3), P(O(i)Pr)(3)) using HBF(4).Et(2)O. The cis-[(dppm)(2)Ru(H)(L)][BF(4)] complexes were obtained from the trans hydrides via an isomerization reaction that is acid-accelerated. This isomerization reaction gives mixtures of cis and trans hydride complexes, the ratios of which depend on the cone angles of the phosphite ligands: the greater the cone angle, the greater is the amount of the cis isomer. The eta(2)-H(2) ligand in the dihydrogen complexes is labile, and the loss of H(2) was found to be reversible. The protonation reactions of the starting hydrides with trans PMe(3) or PMe(2)Ph yield mixtures of the cis and the trans hydride complexes; further addition of the acid, however, give trans-[(dppm)(2)Ru(BF(4))Cl]. The roles of the bite angles of the dppm ligand as well as the steric and the electronic properties of the monodentate phosphorus ligands in this series of complexes are discussed. X-ray crystal structures of trans-[(dppm)(2)Ru(H)(P(OMe)(3))][BF(4)], cis-[(dppm)(2)Ru(H)(P(OMe)(3))][BF(4)], and cis-[(dppm)(2)Ru(H)(P(O(i)Pr)(3))][BF(4)] complexes have been determined.