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Asian Pacific Journal of Tropical Biomedicine ; (12): 273-278, 2018.
Article in Chinese | WPRIM | ID: wpr-700126


Objective: To evaluate the larvicidal efficacy of crude and fractionated extracts of Dracaena loureiri endocarp against Aedes aegypti, Aedes albopictus, Culex quinquefasciatus, and Anopheles minimus mosquitos. Methods: Larvicidal activity was tested according to World Health Organization standard protocol.The third-stage larvae of each mosquito species were exposed to various concentrations of Dracaena loureiri crude extract and six groups of Dracaena loureiri fractionated extracts (RC-DT 009–014). Larval mortality rates were observed after 24 h and 48 h of exposure.Then, a computerized probit analysis of the mortality data was performed to determine lethal concentration 50 (LC50) and lethal concentration 90 values. Results: Anopheles minimus larvae (24-h LC5077.88 mg/L) had the highest susceptibility to crude extract, whereas others (Aedes aegypti, 24-h LC50224.73 mg/L; Aedes albopictus, 24-h LC50261.75 mg/L; and Culex quinquefasciatus, 24-h LC50282.86 mg/L) were significantly less susceptible. The most effective groups of fractionated extracts were RC-DT 012 and RC-DT 013. The mosquito species most susceptible to fractionated extracts was Culex quinquefasciatus, with 24-h LC50 values of 0.66 and 0.94 mg/L for RC-DT 012 and RC-DT 013, respectively. Conclusions: The larvicidal activity of fractionated extracts is more effective than that of crude extract against all tested mosquito species. For the most effective alternative larvicide, purification and a phytochemical constituent analysis must be performed.

Asian Pacific Journal of Tropical Biomedicine ; (12): 222-226, 2017.
Article in Chinese | WPRIM | ID: wpr-511488


Objective: To evaluate the larvicidal activity of the ethanolic and aqueous extracts of the endocarp and seeds of Dracaena loureiri (D. loureiri) against the dengue mosquito vector, Aedes aegypti. Methods: Bioassays were performed by exposing late third-stage to early fourth-stage larvae of Aedes aegypti to various concentrations of the extracts from D. loureiri. The larval mortality was observed after 24-and 48-h exposure. Results: The larvicidal bioassay in this study demonstrated that the ethanolic endocarp extract was the most effective with the LC50 value of 84.00 mg/L after 24 h exposure and< 50 mg/L after 48 h exposure. Extracts from the other parts of the plant were signifi-cantly less effective as a larvicide. Conclusions: The ethanolic endocarp extract of D. loureiri demonstrated effective lar-vicidal activity. It is an alternative source for developing a novel larvicide for controlling this mosquito species.

Asian Pacific Journal of Tropical Biomedicine ; (12): 428-431, 2017.
Article in Chinese | WPRIM | ID: wpr-609702


Objective:To investigate the prevalence of Candida spp.and the virulence factors of Candida albicans (C.albicans) isolated from external surfaces of blow flies collected from Mae Sot,Tak Province,Thailand,Methods:The blow flies were collected by sterile sweep nets from three areas in Mae Sot.Yeast isolation was first performed on Sabouraud dextrose agar (SDA) supplemented with chloramphenicol and cycloheximide.The yeast isolates were then identified by using chromogenic agar,a yeast identification test kit,a germ tube formation test and a carbohydrate utilization test.The β-hemolysis was determined on 7% sheep blood agar,while phospholipase activity was measured on SDA agar supplemented with 10% egg yolk suspension.Antifungal susceptibility testing was determined by broth micro-dilution testing against ketoconazole and amphotericin B.Results:The prevalence rate of Candida spp.on the external surfaces of the blow flies was 78.1%.All C.albicans isolated from the blow fly demonstrated β-hemolysin and potent phospholipase activities and 47.1% of C.albicans were resistant to ketoconazole with MIC values 128 μg/mL.Conclusions:The result s indicate that blow flies could play an essential role in the transmission of potentially pathogenic and antifungal resistant C.albicans into the environment.Further investigation on other virulence factors and genetic relatedness among isolates from the blow flies,the environment and clinical specimens is required to confirm this role.