Résumé
4-Methyl-7-hydroxy coumarin is considered as a lead molecule as a biopesticide. Its mono bromo and tribromo derivatives were synthesized. Two more derivatives were synthesized by acylation. Compound 1 (3,6,8-tribromo-7-hydroxy-4-methyl-chromen-2-one) was found to be the most potent against IVth instar larvae of C. quinquefasciatus and A. aegypti the LC50 being 1.49 and 2.23 ppm respectively. It showed 100% larval mortality at 25 ppm against A. aegypti and at 10 ppm against C. quinquefasciatus. Compounds 1 and 2 (3,6,8-tribromo-7-hydroxy-4-methyl-chromen-2'-oxo-2H-chromen-7-yl acetate) showed remarkable ovicidal activity. Significant reduction of 80-85% hatching of eggs of both mosquito species was observed at the highest dose of 100 ppm. The hatched larvae showed 100% mortality in the successive instars. Compounds 3 and 4 (3-bromo-7-hydroxy-4-methyl-chromen-2-one and 3-bromo-4-methyl-2'-oxo-2H-chromen-7-yl acetate) showed moderate activity against both mosquito species.
Sujets)
Aedes/effets des médicaments et des substances chimiques , Animaux , Dosage biologique , Chimie pharmaceutique/méthodes , Culex/effets des médicaments et des substances chimiques , Conception de médicament , Évaluation préclinique de médicament , Hymécromone/administration et posologie , Résistance aux insecticides/effets des médicaments et des substances chimiques , Insecticides/pharmacologie , Larve/effets des médicaments et des substances chimiques , Spectroscopie par résonance magnétique , Modèles chimiques , Lutte contre les moustiques , Pesticides/composition chimiqueRésumé
The larvicidal activity of ethanol, chloroform and hexane soxhlet extracts obtained from S. guttata seeds was investigated against the IVth instar larvae of Dengue fever vector, Aedes aegypti and filarial vector, Culex quinquefasciatus. All extracts including fractions of ethanol extract exhibited 100% larval kill within 24 hr exposure period at 500 ppm concentration. Fraction A1 of ethanol was found to be most promising; its LC50 was 21.552 and 35.520 ppm against C. quinquefasciatus and A. aegypti respectively. Naturally occurring S. guttata seed derived fractions merit further study as potential mosquito larval control agents or lead compounds.
Sujets)
Animaux , Culicidae/effets des médicaments et des substances chimiques , Insecticides/isolement et purification , Larve/effets des médicaments et des substances chimiques , Extraits de plantes/toxicité , Graines/composition chimique , Sterculia/composition chimiqueRésumé
Extracts and purified extracts of seeds of two plant species, Madhuca latifolia and Calophyllum inophyllum when evaluated against the 2nd instar larvae of Helicoverpa armigera reared on synthetic diet, exhibited high larval mortality, prolongation of developmental period, morphological deformities and highly significant reduction in adult emergence. The reduction in larval weights in the treatments was also highly significant.