Robustaquinones, novel anthraquinones from an elicited Cinchona robusta suspension culture

A suspension culture of Cinchona robusta which under normal culture conditi ons does not produce anthraquinones, produces a range of these anthraquinon es after elicitation. Eight new anthraquinones were identified, robustaquin ones A-H, in addition to two known anthraquinones, 1,3,8-trihydroxy-2-metho xyanthraquinone and copareolatin 6-methyl ether. Their oxygenation pattern, characterized by a 6,7-disubstitution in the A-ring, is rare and raises qu estions about their biogenetic origin. They might be derived from phenylpro panoids and not from o-succinylbenzoic acid. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.