title: Rhuschalcones II-VI, five new bichalcones from the root bark of Rhus pyroides.
abstract: Biflavonoids detected in trace amounts in an earlier investigation of the twigs of Rhus pyroides have now been found in the root bark of this species. These new flavonoids belong to a rare bichalcone class and have been identified as 2',4',4' ',2' ",4' "-pentahydroxy-4-O-5' "-bichalcone (rhuschalcone II, 2), 2',4',4' ',2' "-tetrahydroxy-4' "-methoxy-4-O-5' "-bichalcone (rhuschalcone III, 3), 4,2',4' ',2' "-tetrahydroxy-4' "-methoxy-4'-O-5' "-bichalcone (rhuschalcone IV, 4), 4,2',4',4' ',2' ",4' "-hexahydroxy-3,5' "-dihydrochalcone-chalcone (rhuschalcone V, 5), and 4,2',4',4' ',2' ",4' "-hexahydroxy-3,5' "-bichalcone (rhuschalcone VI, 6), repectively. Also obtained was the known compound rhuschalcone I (1). Their structures were determined by spectroscopic and chemical methods, and for 1-3 by total synthesis. All the bichalcones (1-6) tested exhibited selective cytotoxic activity against the HT29 and HCT-116 colon tumor cell lines.
authors.affiliation: Department of Chemistry, University of Botswana, Private Bag 00704, Gaborone, Botswana.
authors.forename: Ladislaus K
authors.initials: LK
authors.lastname: Mdee
authors.forename: Samuel O
authors.initials: SO
authors.lastname: Yeboah
authors.forename: Berhanu M
authors.initials: BM
authors.lastname: Abegaz
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D001902:Botswana; D002599:Chalcone / Q000031:analogs & derivatives / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D003110:Colonic Neoplasms; D004354:Drug Screening Assays, Antitumor; D005419:Flavonoids; D008545:Melanoma; D015394:Molecular Structure; D024301:Plant Bark / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry; D010946:Plants, Medicinal / Q000737:chemistry*; D029045:Rhus / Q000737:chemistry*; D014407:Tumor Cells, Cultured / Q000187:drug effects
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D005419:Flavonoids; D002599:Chalcone