Larvicidal activity of isoflavonoids from Muellera frutescens extracts against Aedes aegypti

The biological activity of extracts from the leaves, bark and roots of Muellera frutescens, an Amazonian ichtyotoxic plant, were evaluated to find new environmentally safe insecticides. The n-hexane extracts of bark, leaf, and root showed a strong toxic activity against Aedes aegypti mosquito larvae. Bioguided fractionation of the bark extract led to the isolation of seven isoflavonoids (12a-hydroxyelliptone, elliptone, (-)-variabilin, rotenone, rotenolone, tephrosin and deguelin). Rotenone and deguelin are responsible for the larvicidal activity of the plant. M frutescens leaves contain up to 0.6%, w/w, deguelin. These results justify the traditional ichtyotoxic use of M frutescens. The leaves contain a relatively high proportion of deguelin and, therefore, can be considered as a renewable source of this environmentally friendly insecticidal isoflavonoid.