Isolation, characterization, and biological activity of naphthoquinones from Calceolaria andina L.

Abstract

Two compounds recognized as responsible for the insecticidal activity of extracts of Calceolaria andina L. (Scrophulariaceae) have been isolated and characterized as 2-(1,1-dimethylprop-2-enyl)3-hydroxy-1,4-naphthoquinone and the corresponding acetate, 2-acetoxy-3-(1,1-dimethylprop-2-enyl)-1,4- naphthoquinone. Their activities against 29 pest species and 9 beneficial species of arthropod from a total of 11 orders have been determined. Activities against homopteran and acarine species are of the same order as those of established pesticides, and, significantly, no cross-resistance is observed for strains resistant to established classes of insecticide. Mammalian toxicities are low.