title: New cytotoxic bicyclic hexapeptides, RA-XXIII and RA-XXIV, from Rubia cordifolia L.
abstract: Two new bicyclic hexapeptides, RA-XXIII and RA-XXIV, were isolated from the roots of Rubia cordifolia L. (Rubiaceae). Their structures were determined by the analysis of their 2D NMR spectra, chemical methods, and X-ray crystallography. The IC50 values of RA-XXIII and RA-XXIV against P-388 leukemia cells were 0.16 and 0.48 microg/ml, respectively.
authors.affiliation: School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, Japan.
authors.forename: Ji-Ean
authors.initials: JE
authors.lastname: Lee
authors.forename: Yukio
authors.initials: Y
authors.lastname: Hitotsuyanagi
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Fukaya
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Kondo
authors.forename: Koichi
authors.initials: K
authors.lastname: Takeya
mesh_terms: D000641:Ammonia / Q000737:chemistry; D000972:Antineoplastic Agents, Phytogenic / Q000302:isolation & purification* / Q000494:pharmacology*; D001966:Bromine / Q000737:chemistry; D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy; D008745:Methylation; D010456:Peptides, Cyclic / Q000302:isolation & purification / Q000494:pharmacology*; D018517:Plant Roots / Q000737:chemistry; D045470:Rubia / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D010456:Peptides, Cyclic; C529728:RA-XXIII; C529727:RA-XXIV; D000641:Ammonia; D001966:Bromine