ABSTRACT
Mosquitoes are important vectors responsible for spreading a number of diseases affecting both humans and animals. Many diseases as dengue, chikungunya, yellow fever, malaria, filariasis and Japanese encephalitis are spread by mosquitoes. There are many reports of plant extracts and their active constituents showing anti-mosquito activities as larvicidal, pupicidal, ovicidal and adulticidal activities. Persea americana Mill. (Lauraceae), known as avocado, has been reported to show many pharmacological and antimicrobial activities. In this communication, the mosquito larvicidal activities of the three-active constituents, avocadene, avocadyne and avocadenol-A, from the methanolic extract of the unripe fruit peel are presented. The three mosquito species studied were Aedes aegypti, Culex quinquefasciatus and Anopheles stephensi. All three compounds showed the highest larvicidal activity against An. stephensi, LC50 values being 2.80ppm for avocadene, 2.33ppm for avocadyne and 2.07ppm for avocadenol-A. Avocadene showed larvicidal activity of 3.73ppm against Ae. aegypti and 5.96ppm against Cx. quinquefasciatus. The LC50 value of avocadyne was 5.35ppm against Ae. aegypti and 3.98ppm against Cx. quinquefasciatus. Similarly, avocadenol-A showed 6.56ppm against Ae. aegypti and 2.35ppm against Cx. quinquefasciatus. The active constituents were isolated by bioactivity-guided fractionation by silica gel column chromatography and RP HPLC. The compounds were identified by physical and spectroscopic data and compared with literature values already reported.
