Structure-activity relationships of eugenol derivatives against Aedes aegypti (Diptera: Culicidae) larvae.

BACKGROUND

Dengue fever is a severe public health problem for several countries. In order to find effective larvicides to aid control programs, the structure-activity relationships of eugenol derivatives against Aedes aegypti (Diptera: Culicidae) larvae were evaluated. Additionally, the composition and larvicidal activity of Syzygium aromaticum essential oil was assessed.

RESULTS

Four compounds representing 99.05% of S. aromaticum essential oil have been identified. The essential oil was active against Ae. aegypti larvae (LC(50) = 62.3 and 77.0 ppm, field-collected and Rockefeller larvae respectively). The larvicidal activity of eugenol, the major compound of the essential oil, was further evaluated (LC(50) = 93.3 and 71.9 ppm, field-collected and Rockefeller larvae respectively). The larvicidal activity and structure-activity relationships of synthetic derivatives of eugenol were also assessed. The larvicidal activity of the derivatives varied between 62.3 and 1614.9 ppm. Oxidation of eugenol allylic bond to a primary alcohol and removal of the phenolic proton resulted in decreased potency. However, oxidation of the same double bond in 1-benzoate-2-methoxy-4-(2-propen-1-yl)-phenol resulted in increased potency.

CONCLUSIONS

Structural characteristics were identified that may contribute to the understanding of the larvicidal activity of phenylpropanoids. The present approach may help future work in the search for larvicidal compounds.