Constituents of the higher fungi. Part VIII. The blueing of Boletus species. Variegatic acid, a hydroxytetronic acid from Boletus species and a reassessment of the structure of boletol

Abstract

Four species of Boletus contain a new tetronic acid, variegatic acid, which has been identified as 3,3′,4,4′-tetrahydroxypulvinic acid. The compound is responsible for the blueing reaction in these species.