Secondary mould metabolites. Part 15. Structure elucidation of rubellins A and B, two novel anthraquinone metabolites from Mycosphaerella rubella

Abstract

The structure of rubellins A (1) and B (2), two novel anthraquinone metabolites isolated from Mycosphaerella rubella, have been assigned by detailed analysis of their ¹H and ¹³C n.m.r. spectra and chemical evidence. Their relative configuration and conformation were deduced from the observed ¹H–{¹H} nuclear Overhauser effects (n.O.e.s) and the value of ¹H–¹H coupling constants.