New Cytotoxic Bicyclic Hexapeptides, RA-XXIII and RA-XXIV, from Rubia cordifolia L.

New Cytotoxic Bicyclic Hexapeptides, RA-XXIII and RA-XXIV, from Rubia cordifolia L. Structures of cytotoxic bicyclic hexapeptides, RA-XIX, -XX, -XXI, and -XXII, from Rubia cordifolia L. A novel bicyclic hexapeptide, RA-XVIII, from Rubia cordifolia: Structure, semi-synthesis, and cytotoxicity A novel bicyclic hexapeptide, RA-XVIII, from Rubia cordifolia: Structure, semi-synthesis, and cytotoxicity New antitumor bicyclic hexapeptides, RA-XI, -XII, -XIII and -XIV from Rubia cordifolia. Two antitumour bicyclic hexapeptides from Rubia cordifolia Studies on antitumor cyclic hexapeptides RA obtained from Rubiae Radix, Rubiaceae. VI Minor antitumor constituents. Isolation and antitumor activity of cyclic hexapeptides isolated from Rubiae radix. Isolation, structural elucidation, and synthesis of RA-XVII, a novel bicyclic hexapeptide from Rubia cordifolia, and the effect of side chain at residue 1 upon the conformation and cytotoxic activity RA-dimer A, a novel dimeric antitumor bicyclic hexapeptide from Rubia cordifolia L.