title: Antineoplastic agents, 122. Constituents of Combretum caffrum.
abstract: An investigation of the South African tree Combretum caffrum (Combretaceae) for antineoplastic constituents was conducted by employing the astrocytoma bioassay (9ASK). By this approach and a combination of solvent partition, steric exclusion, and adsorption chromatographic procedures, a substance designated combretastatin [1a] was isolated and found to display significant (71-90% astrocyte reversal at 1-100 micrograms/ml dose levels) astrocyte reversal and murine P-388 lymphocytic leukemia (PS) cell growth inhibition (ED50 0.011 micrograms/ml). The structure of (-)-combretastatin was elucidated by X-ray crystal structure analysis and confirmed by total synthesis. The absolute configuration at C-10 was assigned the R-configuration on the basis of Horeau esterification techniques. Other prominent, albeit PS-inactive, constituents were found to be 3,3',4'-tri-O-methylellagic acid [2] and acacetin [3].
authors: Cancer Research Institute, Arizona State University, Tempe 85287.
authors: G R
authors: GR
authors: Pettit
authors: G M
authors: GM
authors: Cragg
authors: S B
authors: SB
authors: Singh
mesh_terms: D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000032:analysis*; D002942:Circular Dichroism; D007941:Leukemia P388 / Q000188:drug therapy; D051379:Mice; D010936:Plant Extracts / Q000032:analysis; D010946:Plants, Medicinal / Q000032:analysis*; D013019:South Africa
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D010936:Plant Extracts