delta-Cadinene, Calarene and delta-4-Carene from Kadsura heteroclita Essential Oil as Novel Larvicides Against Malaria, Dengue and Filariasis Mosquitoes

Mosquitoes (Diptera: Culicidae) are major vectors of extremely dangerous pathogens and parasites. Malaria, dengue fever, yellow fever, filariasis, schistosomiasis, Japanese encephalitis and Zika virus represent important public health challenges. Mosquito control is being problematic due to the development of strains resistant to synthetic mosquitocides currently marketed and concerns for the environment and human health. Plant species employed in traditional Asian medicine may be alternative sources of newer and effective mosquitocides. Here we evaluated the larvicid al potential of the essential oil (EO) extracted from the Kadsura heteroclita leaves. Furthermore, we identified its main EO chemical constituents (delta-Cadinene, Calarene and delta-4-Carene) and we tested them on larvae of Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus. The chemical composition of the EO was analyzed by gas chromatography-mass spectroscopy. GC-MS showed that the essential oil of K. heteroclita contained 33 compounds. Main chemical constituents were delta-Cadinene (18.3%), Calarene (14.8%) and delta-4-Carene (12.5%). The EO was toxic on An. stephensi, Ae. aegypti and Cx. quinquefasciatus larvae, LC50 were 102.86, 111.79 and 121.97 mu g/mL. delta-Cadinene, Calarene and delta-4-Carene appeared highly effective against An. stephensi (LC50 = 8.23, 12.34 and 16.37 mu g/mL, respectively) followed by Ae. aegypti (LC50 = 9.03, 13.33 and 17.91 mu g/mL), and Cx. quinquefasciatus (LC50 = 9.86, 14.49 and 19.50 mu g/mL). Overall, this study adds basic information to develop effective larvicides against malaria, dengue and filariasis mosquitoes.