Two bicyclic hexapeptides, allo-RA-V (4) and neo-RA-V (5), and one cyclic hexapeptide, O-seco-RA-V (6), were isolated from the roots of Rubia cordifolia L. Their gross structures were elucidated on the basis of spectroscopic analysis and X-ray crystallography of compound 5. The absolute stereochemistry of compounds 4 and 5 were established by their total syntheses, and the absolute stereochemistry of compound 6 by chemical correlation with deoxybouvardin (3). Comparison of the 3D structures of highly active RA-VII (1) with less-active compounds 4 and 5 suggests that the orientation of the Tyr-5 and/or Tyr-6 phenyl rings plays a significant role in their biological activity. The isolation of peptides 4–6, along with compound 3, and the comparison of their structures seem to indicate that peptide 6 may be the common precursor to bicyclic peptides 3–5 in the plant.

Six new sesquiterpene lactone esters, daucoguaianolactones A–F (1–6), and one new sesquiterpene lactone, daucoeudesmanolactone A (7) were isolated from the leaves and stems of Daucus glaber (Forssk.) Thell., along with the known sesquiterpene lactones talasins A and B and badkhysin. The structures of 1–6 were established on the basis of extensive 1D- and 2D-NMR spectroscopic studies and that of 7 by X-ray crystallography. Compounds 4, 7, and talasins A and B showed moderate cytotoxicity against P-388 leukemia cells.