Ovicidal, repellent, adulticidal and field evaluations of plant extract against dengue, malaria and filarial vectors

Mosquitoes are insect vectors responsible for the transmission of parasitic and viral infections to millions of people worldwide, with substantial morbidity and mortality. Infections transmitted by mosquitoes include malaria, yellow fever, chikungunya, filariasis and other arboviruses. Insecticides of botanical origin may serve as suitable alternative biocontrol techniques in the future. The adulticidal activities of crude hexane, benzene, ethyl acetate, acetone and methanol leaf extracts of Acalypha alnifolia were assayed for their toxicity against three important vector mosquitoes, viz., Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus. The adult mortality was observed after 24 h of exposure. All extracts showed moderate adulticide effects; however, the highest adult mortality was found in methanol extract were observed. The LC₅₀ values of A. alnifolia leaf extracts against adulticidal activity of (hexane, benzene, ethyl acetate, acetone and methanol) A. aegypti, A. stephensi and C. quinquefasciatus were the following: A. aegypti values were 371.87, 342.97, 320.17, 300.86 and 279.75 ppm; A. stephensi values were 358.35, 336.64, 306.10, 293.01 and 274.76 ppm; C. quinquefasciatus values were 383.59, 354.13, 327.74, 314.33 and 291.71 ppm. The results of the repellent activity of hexane, benzene, ethyl acetate, acetone and methanol extract of A. alnifolia plant at three different concentrations of 1.0, 3.0, and 5.0 mg/cm² were applied on skin of forearm in man and exposed against adult female mosquitoes. In this observation, this plant crude extracts gave protection against mosquito bites without any allergic reaction to the test person, and also, the repellent activity is dependent on the strength of the plant extracts. Mean percent hatchability of the ovicidal activity was observed 48 h post-treatment. The percent hatchability was inversely proportional to the concentration of extract and directly proportional to the eggs. Mortality of 100 % with methanol extract of A. alnifolia was exerted at 125 and 300 ppm. The larval density was decreased after the treatment of plant extracts at the breeding sites (water bodies system) of vector mosquitoes, and hence, these plant extracts are suitable alternatives of synthetic insecticides for mosquito vector management.These results suggest that the leaf solvent plant extracts have the potential to be used as an ideal eco-friendly approach for the control of mosquitoes. This study provides first report on the mosquito ovicidal, repellent and adulticidal activities of these plant extracts against mosquito vector species from India.     

Mosquito larvicidal and pupicidal activity of Euphorbia hirta Linn. (Family: Euphorbiaceae) and Bacillus sphaericus against Anopheles stephensi Liston. (Diptera: Culicidae)

ObjectiveTo explore the larvicidal and pupicidal activity of Euphorbia hirta (E. hirta) leaf extract and Bacillus sphaericus (B. sphaericus) against the malarial vector, Anopheles stephensi (An. stephensi).MethodsThe larvicidal and pupicidal activity was assayed against An. stephensi at various concentrations ranging from (75-375 ppm) under the laboratory as well as field conditions. The LC₅₀ and LC₉₀ value of the E. hirta leaf extract was determined by probit analysis.ResultsThe plant extract showed larvicidal effects after 24 h of exposure; however, the highest larval mortality was found in the methanol extract of E. hirta against the first to fourth instars larvae and pupae of values LC₅₀= 137.40, 172.65, 217.81, 269.37 and 332.39 ppm; B. sphaericus against the first to fourth instars larvae and pupae of values LC₅₀= 44.29, 55.83, 68.51, 82.19 and 95.55 ppm, respectively. Moreover, combined treatment of values of LC₅₀= 79.13, 80.42, 86.01, 93.00 and 98.12 ppm, respectively. No mortality was observed in the control.ConclusionsThese results suggest methanol leaf extracts of E. hirta and B. sphaericus have potential to be used as an ideal eco-friendly approach for the control of the malarial vector, An. stephensi as target species of vector control programs. This study provides the first report on the combined mosquito larvicidal and pupicidal activity of this plant crude extract and bacterial toxin against An. stephensi mosquitoes.     

Synthesis of silver nanoparticles using leaves of Catharanthus roseus Linn. G. Don and their antiplasmodial activities

Objective

To develop a novel approach for the green synthesis of silver nanoparticles using aqueous leaves extracts of Catharanthus roseus (C. roseus) Linn. G. Don which has been proven active against malaria parasite Plasmodium falciparum (P. falciparum).

Methods

Characterizations were determined by using ultraviolet-visible (UV-Vis) spectrophotometry, scanning electron microscopy (SEM), energy dispersive X-ray and X-ray diffraction.

Results

SEM showed the formation of silver nanoparticles with an average size of 35–55 nm. X-ray diffraction analysis showed that the particles were crystalline in nature with face centred cubic structure of the bulk silver with the broad peaks at 32.4, 46.4 and 28.0.

Conclusions

It can be concluded that the leaves of C. roseus can be good source for synthesis of silver nanoparticle which shows antiplasmodial activity against P. falciparum. The important outcome of the study will be the development of value added products from medicinal plants C. roseus for biomedical and nanotechnology based industries.     

Mosquitocidal properties of Calotropis gigantea (Family: Asclepiadaceae) leaf extract and bacterial insecticide, Bacillus thuringiensis, against the mosquito vectors

Calotropis gigantea leaf extract and Bacillus thuringiensis were tested first to fourth-instar larvae and pupae of Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus. The medicinal plants were collected from the area around Bharathiar University, Coimbatore, India. Calotropis gigantea leaf was washed with tap water and shade-dried at room temperature. An electrical blender powdered the dried plant materials (leaves). The powder 500 g of the leaf was extracted with 1.5 L of organic solvents of methanol for 8 h using a Soxhlet apparatus and filtered. The crude leaf extracts were evaporated to dryness in a rotary vacuum evaporator. The plant extract showed larvicidal and pupicidal effects after 24 h of exposure; no mortality was observed in the control group. For Calotropis gigantea, the median lethal concentration values (LC(50)) observed for the larvicidal and pupicidal activities against mosquito vector species Anopheles stephensi I to IV larval instars and pupae were 73.77, 89.64, 121.69, 155.49, and 213.79 ppm; Aedes aegypti values were 92.27, 106.60, 136.48, 164.01, and 202.56 ppm; and Culex quinquefasciatus values were 104.66, 127.71, 173.75, 251.65, and 314.70 ppm, respectively. For B. thuringiensis, the LC(50) values of I to IV larval instars and pupae of Anopheles stephensi were 37.24, 45.41, 57.82, 80.09, and 98.34 ppm; Aedes aegypti values were 42.38, 51.90, 71.02, 96.17, and 121.59 ppm; and Culex quinquefasciatus values were 55.85, 68.07, 94.11, 113.35, and 133.87 ppm, respectively. The study proved that the methanol leaf extract of Calotropis gigantea and bacterial insecticide B. thuringiensis has mosquitocidal property and was evaluated as target species of mosquito vectors. This is an ideal ecofriendly approach for the control of vector control programs.     

Laboratory and field evaluation of medicinal plant extracts against filarial vector, Culex quinquefasciatus Say (Diptera: Culicidae)

The present study explored the effects of Jatropha curcas, Hyptis suaveolens, Abutilon indicum, and Leucas aspera tested against third instar larvae of filarial vector, Culex quinquefasciatus. The dried plant materials were powdered by an electrical blender. From each sample, 500 g powder was macerated with 1.5 L of hexane, chloroform, ethyl acetate, and methanol 8h, using Soxhlet apparatus, and filtered. The extracts were concentrated at reduced temperature on a rotary evaporator and stored at a temperature of 4°C. The yield of crude extract was 11.4, 12.2, 10.6, and 13.5 g in hexane, chloroform, ethyl acetate, and methanol, respectively. The hexane, chloroform, ethyl acetate, and methanol extract of J. curcas with LC(50) values of 230.32, 212.85, 192.07, and 113.23 ppm; H. suaveolens with LC(50) values of 213.09, 217.64, 167.59, and 86.93 ppm; A. indicum with LC(50) values of 204.18, 155.53, 166.32, and 111.58 ppm; and L. aspera with LC(50) values of 152.18, 118.29, 111.43, and 107.73 ppm, respectively, against third instar larvae of C. quinquefasciatus. The larval mortality was observed after 24 h of exposure. Maximum larvicidal activity was observed in the methanolic extract followed by ethyl acetate, chloroform, and hexane extract. No mortality was observed in the control. The observed mortality were statistically significant at P?相似文献   

Effect of zinc on regulation of insulin-like growth factor signaling in human androgen-independent prostate cancer cells

BackgroundProstate cancer is one of the most frequently diagnosed cancers in men. Progression of these tumors is facilitated by growth factors that activate critical signaling cascades thereby promote prostate cancer cell growth, survival, and migration. Among these, insulin-like growth factors (IGFs) signaling pathway contributes a major role. In this study, we examined the effect of zinc on insulin-like growth factors signaling in prostate cancer cells.MethodsHuman androgen-independent prostatic carcinoma (PC-3) cells were treated with different concentrations of zinc (20–100 µmol/l) for 24 and 48 h. Cell viability was performed by 3[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. Insulin-like growth factor binding protein-3 (IGFBP-3), insulin-like growth factor-I receptor (IGF-IR), insulin receptor substrate-1 (IRS-1) and IRS-2, phosphatidylinositol-3 kinase (PI-3 K), protein kinase B or Akt, phosphorylated Akt (p-Akt), extracellular regulated kinase 1/2 (ERK1/2), phosphorylated ERK1/2 (p-ERK1/2), and cyclin D1 protein levels were assessed by Western blot analysis. Apoptosis was confirmed by 4′,6′-diaminido-2-phenylindole dihydrochloride (DAPI) staining, and mitochondrial membrane potential was performed using rhodamine-123 staining method.ResultsZinc significantly reduces the cell viability of PC-3 cells. It decreases the protein levels of IGF-IR, IRS-1, and IRS-2 and increases the level of IGFBP-3. Zinc reduces the levels of PI-3 K, Akt, ERK1/2, and cyclin Dl. Loss of mitochondrial membrane potential and apoptotic cell death were also observed in zinc-treated cells.ConclusionThis study suggests that zinc decreases the survival of androgen-independent prostate cancer cells by modulating the expression of IGF system components and its signaling molecules. Thus, zinc may be qualified as a potential agent for the treatment of prostate cancer.     

Chemoprevention of rat prostate carcinogenesis by diallyl disulfide, an organosulfur compound of garlic

Diallyl disulfide (DADS), an important component of garlic (Allium sativam) has been demonstrated to exert a potential chemopreventive activity against human cancers. DADS inhibits proliferation of both androgen dependent and independent prostate cancer cells in vitro. However there is no report available on the role of DADS on prostate cancer initiation in in vivo model. So the present chemoprevention study was conducted to evaluate the activity of diallyl disulfide as an anticancer agent in prostate carcinogenesis of male Sprague-Dawley rats. Testosterone and N-Methyl N-Nitroso Urea (MNU) were used to induce prostate carcinogenesis that involves a multi step process like, hyperplasia, dysplasia and prostatic intraepithelial neoplasia (PIN). The rats were induced prostate carcinogenesis by injection of testosterone and single dose of MNU and again the testosterone was continued throughout the experimental period. Forty percentage of animals carried PIN in dorsolateral prostate, while dysplasia and hyperplasia (55 to 65%) were common in ventral as well as dorsolateral prostates of the hormone and carcinogen treated rats. Rats treated with hormone and carcinogen along with DADS developed PIN at incidence of 10% in the ventral and dorsolateral prostates about 20 to 10%. Dysplasia and hyperplasia were less common in these rats. The results of this study provide evidence that DADS may have chemopreventive activity in rat prostate carcinogenesis.