Formation and secretion of a unique quinone by hairy root cultures of Lithospermum erythrorhizon

A unique colorless quinone. named rhizonone, showing strong antifungal acti vity against spore germination of Cladosporium fulvum was isolated from the hairy root cultures of Lithospermum erythrorhizon in MS medium. The struct ure was elucidated as 5a-methyl-5a,6,10b, 10c-tetrahydro-2H-anthra[9,1-bc]f uran-7,10-dione mainly on the basis of spectroscopic data. This unique carb on skeleton, not previously known among the compounds isolated from this pl ant species, might be derived from geranylhydroquinone, an important interm ediate of shikonin biosynthesis. Rhizonone was secreted into the medium whi le shikonin derivatives accumulated on the surface of the hairy roots and t heir debris, (C) 1999 Elsevier Science Ltd. All rights reserved.