Two novel prenylated kaempferol derivatives from fresh bud's fur of Platanus acerifolia and their anti-proliferative activities.

Two novel prenylated kaempferol derivatives (1, 2), together with seven known metabolites were isolated from ethanol extract of fresh Platanus acerifolia bud's fur by multistep chromatographic processing. Structure of compounds 1 and 2 was confirmed by 1D, 2D NMR spectra and HR-ESI-MS. In addition, compound 1 was further analysed by X-ray crystallography. Anti-proliferative activities in vitro against human breast carcinoma (MCF-7) and human hepatocellular carcinoma (Hep-G2) cell lines for compound 1, 2 and 8 were evaluated. Compound 1 exhibited cytotoxic activity towards MCF-7 and Hep-G2 cell lines with the IC50 values 38.2 and 39.5 μM, respectively. Moreover, compound 2 showed weak cytotoxic activities against the two cell lines.