Toxicity of Usnic Acid from Cladonia substellata (Lichen) to embryos and adults of Biomphalaria glabrata

Abstract

This study reports the molluscicidal activity of usnic acid isolated from Cladonia substellata Vanio (lichen) on embryos at various stages of development and in adult mollusks of Biomphalaria glabrata. The toxicity of usnic acid was also evaluated through Artemia salina larvae mortality. Usnic acid was extracted with diethyl ether, isolated, purified, and its structure confirmed by analyzing the spectra of proton nuclear magnetic resonance. LC₉₀ for 24 h of exposure were 1.62, 4.45, 5.36, and 4.49 μg mL^-1 for blastula, gastrula, trocophore, and veliger embryonic stages, respectively, and 3.45 μg mL^-1 for adult snails; LC₅₀ of usnic acid against A. salina was 2.46 μg mL^-1. LC₉₀ assessed 7 days after exposure was 2.56 μg mL^-1 for adult mollusks. In conclusion, these findings demonstrate that under laboratory conditions usnic acid has teratogenic and molluscicide potential to control the aquatic snail B. glabrata and may prove to be a promising candidate in the search for new molluscicide agents, but further detailed studies on its molluscicidal effect and possible environmental effects are needed.

Keywords: Biomphalaria glabrata; Embriotoxicity; Environmental toxicity; Molluscicidal activity; Natural product of lichen; Neglected diseases.