A novel antitumor bicyclic hexapeptide dimer, RA-dimer A (3), was isolated
from the roots of Rubia cordifolia L. The structure of 3 was determined by
analysis of spectroscopic data and chemical correlations. Peptide 3 is the
first example of the RA congeners having a dimeric structure. (C) 2000 Else
vier Science Ltd. All rights reserved.