Publicação on-line; 25 ref.; 4 tables; 4 illus.; Summaries (En, Pt)

ABSTRACT:

The present study was carried out with the objective of assessing the acute toxicity
of four essential plant oils against the brine shrimp lethality bioassay. The essential oils were
dissolved in dimethyl sulfoxide (DMSO) at 1 % and concentrations at 0.01; 0.05; 0.25; 1.25;
6.25 and 31.25 µg/ml were prepared which were added in microcells of 96 dishes containing
from 10 to 15 nauplii of Artemia salina in saline solution with a total volume of 150 µL. Each
concentration was replicated 8 times. Two controls were used, one with saline water solution
containing 38 g of coarse salt/l and the other with DMSO 1 % solvent dissolved in the saline
solution. Samples were maintained with light and at environmental temperature. Larvae death
on exposing them to contact for 24 h was counted. The Lethal Concentration 50 (LC50) was
determined by the Probit method using the statistical package SPSS, version 22. All essential
oils tested manifested a high acute toxicity at low dosages. These showed high lethality and
its results followed by order of toxicity were: Cymbopogon citratus (LC50= 1.212 µg/ml) >Lippia
rotundifolia (LC50= 1.256 µg/ml) >Lippia origanoides (LC50= 1.267 µg/ml) >Cymbopogon citratus
Lemon-Grass© (LC50= 1.284 µg/ml). It is concluded that given the lethality exhibited by the
essential oils of Cympogogon citratus Lemon-Grass©, C.citratus, Lippia origanoides and
Lippia rotundifolia against the Artemia salina micro-crustaceous can be considered promissory
essential oils for its use for the control of harmful organisms. Other more specific studies are
recommended for demonstrating its biological activity.

Key words: essential oils, toxicity, LC50, Artemia salina

RESUMO -

Efeito toxicológico de óleos essenciais das plantas contra Artemia salina. O
presente estudo foi realizado com o objetivo de avaliar a toxicidade aguda de óleos essenciais
frente á Artemia salina. Os óleos essenciais foram dissolvidos em dimetilsulfóxido (DMSO) a
1% e em concentrações de 0,01; 0,05; 0,25; 1,25; 6,25 e 31,25 µg/ml e foram adicionados em
microplacas de 96 poços contendo de 10 a 15 náuplios de Artemia salina em solução salina
totalizando um volume de 150 µl, sendo que o ensaio com cada concentração foi repetido 8
vezes. Os controles foram com solução salina (38 g/l) e o outro com DMSO (1%). As amostras
foram mantidas com luz e à temperatura ambiente e a mortalidade das larvas avaliada após 24h.
A concentração letal 50 (CL50) foi determinada pelo método Probit utilizando o pacote estatístico
SPSS, versão 22. Todos os óleos essenciais testados manifestaram uma toxicidade aguda
elevada a baixas dosagens. Os óleos que apresentaram alta letalidade foram o Cymbopogon
citratus (CL50= 1.212 µg/ml) >Lippia rotundifolia (CL50= 1.256 µg/ml) >Lippia origanoides (CL50=
1.267 µg/ml) >Cymbopogon citratus Lemon-Grass© (CL50= 1.284 µg/ml). Conclui-se que, dada
a letalidade exibida pelos óleos essenciais de Cympogogon citratus Lemon-Grass©, C. citratus,
Lippia origanoides e Lippia rotundifolia frente aos microcrustáceos, Artemia salina, esses óleos
essenciais podem ser considerados eficientes para serem utilizados no controlo de organismos
nocivos. Estudos mais específicos são recomendados para demonstrar a sua atividade biológica.

Palavras-chave: óleos essenciais, toxicidade, CL50, Artemia salina