Platachromone A-D: Cytotoxic 2-styrylchromones from the bark of Platanus x acerifolia (Aiton) Willd.

Four novel 2-styrylchromones,4',5,7-trihydroxy-6-isopentene-2-styrylchromone (1), 4',5,7-trihydroxy-8-isopentene-2-styrylchromone (2), 4',5,7-trihydroxy-6-(2-hydroxy-3-methylbut-3-enyl)-2-styrylchromone (3) and 4',5,7-trihydroxy-8-(2-hydroxy-3-methylbut-3-enyl)-2-styrylchromone (4), were isolated from shed bark of Platanus x acerifolia (Aiton) Willd., as well as four known compounds, 4',5,7-trihydroxy-2-styrylchromone (5), scutellarein (6), 4',5,7-trihydroxy-6-prenylflavone (7), and 4',5,7-trihydroxy-8-prenylflavone (8). The structures of compounds 1-4 were established by direct interpretation of their spectral data, mainly high resolution electrospray ionization mass spectrometry (HR-ESI-MS), 1D and 2D NMR (H-1-H-1 COSY, HSQC and HMBC). The cytotoxicity of the compounds 1-8 was evaluated in four human carcinoma cell lines, including HepG2, SMMC-7721, MDA-MB-231, and KB. Compounds 1-4 exhibited significantly cytotoxic activity toward HepG2 and KB cells, with IC50 values ranging from 3.0 to 9.7 mu M. (C) 2013 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.