Two xanthones and two rotameric (3→8) biflavonoids from the Cameroonian medicinal plant Allanblackia floribunda Oliv. (Guttiferae)

[摘要] Two xanthones, 2-(3-hydroxy-3,3-dimethyldihydroallyl)-dihydro-6-deoxyisojacareubin (1) and dihydro- 6-deoxyjacareubin (2), and two 3 -> 8 rotameric biflavonoids, (2R,3S)-volkensiflavone-7-O-beta-acetylglu-copyranoside (3) and (2S,35)-morelloflavone-7-O-beta-acetylgiucopyranoside (4), together with fifteen known compounds, were isolated from a dichloromethane/methanol (1:1, v/v) extract of the bark of the plant Allanblackia floribunda. The structures of the new compounds were elucidated by NMR spectroscopy and mass spectroscopic techniques and those of the known ones were deduced by comparison with data reported in the literature. The isolated biflavonoids were obtained as mixtures of conformers exhibiting duplicate NMR signals in solution at 25 degrees C and their respective absolute configurations were assigned using circular dichroism spectroscopy. Selected isolated compounds were assessed for their antibacterial and antioxidant properties. (C) 2018 Elsevier Ltd. All rights reserved.

[发布日期] 2018-12-26

[关键词] Allanblackia floribunda;Guttiferae;Xanthones;Rotameric biflavonoids;Circular dichroism;Antioxidant;Antibacterial