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Larvicidal efficacies of plants from Midwestern Brazil: melianodiol from Guarea kunthiana as a potential biopesticide against Aedes aegypti
Sarmento, Ulana Chaves; Miguita, Carlos Henrique; Almeida, Luís Henrique de Oliveira; Gaban, Cleusa Rocha Garcia; da Silva, Lilliam May Grespan Estodutto; de Souza, Albert Schiaveto; Garcez, Walmir Silva & Garcez, Fernanda Rodrigues
Abstract
A total of 36 ethanol extracts from different anatomical parts of 27 plant species (18 families), native to the Pantanal
and Cerrado biomes in Midwest Brazil, was assessed for their effect against Ae. aegypti larvae, the vector
of dengue, hemorrhagic dengue, Zika and chikungunya fevers. Only the extract obtained from seeds of Guarea kunthiana
(Meliaceae) proved active (LC50 = 169.93 μg/mL). A bioassay-guided investigation of this extract led to the
isolation and identification of melianodiol, a protolimonoid, as the active constituent (LC50 = 14.44 mg/mL). Meliantriol,
which was also obtained from the bioactive fraction, was nevertheless devoid of any larval toxicity, even at the
highest concentration tested (LC50 > 100.0 mg/mL). These results indicate that the larvicidal activity of melianodiol
stems from the presence of the carbonyl moiety at C-3 in the 21,23-epoxy-21,24,25-trihydroxy-tirucall-7-ene-type
skeleton. The structures of both protolimonoids were established on the basis of spectral methods (1H and 13C NMR
and MS). This is the first report on the toxicity of melianodiol against Ae. aegypti larvae. Based on the results, melianodiol
can be regarded as a potential candidate for use as an ecologically sound biocontrol agent for reducing
the larval population of this vector.
Keywords
Guarea kunthiana; mosquito control; dengue; Zika; chikungunya; protolimonoid
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