Anacardic Acid: Molluscicide in Cashew Nut Shell Liquid

Abstract

The components of anacardic acid, (a mixture of 6-n-C₁₅ alkylsalicylic acids whose side chains vary in degrees of unsaturation) have been isolated by high pressure liquid chromatography from a crude extract of cashew nut shell, Anacardium occidentale, and tested for toxicity to fresh water snails, Biomphalaria glabrata. The triene component is the most toxic form (LC₅₀ 0.35 ppm), the diene and monoene components are less toxic (LC₅₀ 0.9 and 1.4 ppm), and the saturated component is relatively nontoxic (LC₅₀ > 5 ppm). Since decarboxylated anacardic acid (cardanol) and salicylic acid do not kill snails at concentrations up to 5 ppm, it appears that both, carboxyl group and unsaturated side chain are absolutely required for molluscicidal activity. The mechanism of toxicity of anacardic acid to snails is unknown.