title: Three types of cytotoxic natural caged-scaffolds: pure enantiomers or partial racemates.
abstract: Two rare new natural products, the neocaged-xanthone pruniflorone T (1) and the rearranged caged-xanthone pruniflorone U (3), and the known caged-xanthone cochinchinone C (2) were isolated from the roots of Cratoxylum formosum ssp. pruniflorum. The unique structures of 1-3 were determined by analysis of NMR and X-ray diffraction data. The X-ray data of 1-3 revealed that they all exist with both enantiomers in their crystal packing. Separation of 1-3 by chiral HPLC led to the isolation of three pairs of enantiomers, (-)-1/(+)-1, (-)-2/(+)-2, and (-)-3/(+)-3, and their absolute configurations were determined by analysis of single-crystal X-ray diffraction and ECD spectroscopic data. A 1:1 mixture of 1 and 3 showed potent in vitro cytotoxicity against an MCF-7 human breast cancer cell line with an IC50 value of 0.11 μg/mL.
authors.affiliation: Faculty of Traditional Thai Medicine, Prince of Songkla University , Hat-Yai, Songkhla 90112, Thailand.
authors.forename: Nawong
authors.initials: N
authors.lastname: Boonnak
authors.forename: Suchada
authors.initials: S
authors.lastname: Chantrapromma
authors.forename: Hoong-Kun
authors.initials: HK
authors.lastname: Fun
authors.forename: Supreeya
authors.initials: S
authors.lastname: Yuenyongsawad
authors.forename: Brian O
authors.initials: BO
authors.lastname: Patrick
authors.forename: Wisanu
authors.initials: W
authors.lastname: Maneerat
authors.forename: David E
authors.initials: DE
authors.lastname: Williams
authors.forename: Raymond J
authors.initials: RJ
authors.lastname: Andersen
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D002166:Camptothecin / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D028084:Clusiaceae / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004354:Drug Screening Assays, Antitumor; D005260:Female; D006801:Humans; D020128:Inhibitory Concentration 50; D008968:Molecular Conformation; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D018517:Plant Roots / Q000737:chemistry; D013237:Stereoisomerism; D013785:Thailand; D044004:Xanthones / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D044004:Xanthones; C000591554:cochinchinone C; C000591552:pruniflorone T; C000591553:pruniflorone U; D002166:Camptothecin