The white colour of the cyst wall of the metacercaria of Microphallus sp., even in the presence of dihydroxy phenol and phenoloxidase, is due to proteins generated through a possible quinone methide interaction. The quinone methide isomerase converts the phenoloxidase mediated quinone into β-hydroxy catechol. Formation of catechol from quinone by cyst extracts was observed spectrophotometrically and chromatographically. This enzyme is involved in detoxification of excess quinone and β-sclerotization of the cyst wall.
