Microbial O-Demethylation, Hydroxylation, Sulfation, and Ribosylation of a Xanthone Derivative from Halenia elliptica

1-Hydroxy-2,3,5-trimethoxyxanthone (1), one of the major xanthone derivatives isolated from Halenia elliptica, was biotransformed by two fungi, Trichothecium roseum and Paecilomyces marquandii. Transformation of 1 by T. roseumgave 1,5-dihydroxy-2,3-dimethoxyxanthone (2), 5-O-sulfate-1-hydroxy-2,3-dimethoxyxanthone (3), 5-O-sulfate-1-hydroxy-2,3,7-trimethoxyxanthone (4), 5-O-beta-ribofuranosyl-1-hydroxy-2,3-dimethoxyxanthone (5), and 1,5,6-trihydroxy-2,3-dimethoxyxanthone (6). Compound 2 was also formed by P. marquandii. The structures of the isolated compounds were elucidated by spectroscopic analyses. Among the five microbial-converted compounds, 3, 4, 5, and 6 are new compounds.