Chemistry of the Coccoidea. IV. Polyhydroxyanthraquinones and their glucosides from Eriococcus coriaceus (Hemiptera: Insecta)

Abstract

A group of seven polyhydroxyanthraquinones based on emodin and the new 2-acetylemodin has been isolated from the eriococcid Eriococcus coriaceus Maskell. Their structures have been established by chemical interconversion, spectroscopic analysis and comparison with known substances. They occur in the living insects as O-glucosides, four of which were isolated pure. Glucosylation has been shown to involve the oxygen substituent at position 8 by a convenient p.m.r. spectroscopic procedure developed for the purpose. Aqueous extracts of E. coriaceus show glucosidase activity towards aryl substrates.