4-Alkyl-5,7-dihydroxycoumarins from the flowering buds of Mesua ferrea

Abstract

Five new 4-alkyl-5,7-dihydroxycoumarins, Mesuaferol G–K (1–5), together with four known 4-alkyl-5,7-dihydroxycoumarins (6–9) were isolated from the methanol extraction of the flowering buds of Mesua ferrea by flash extraction. Their structures were established on the basis of extensive analyses of HR-ESI-MS, UV, IR and NMR methods, the absolute configurations were confirmed by the Mosher's method and circular dichroism (CD) measurement and theoretical calculation (ECD) methods. Additionally, a putative biogenetic relationship of these compounds was also proposed. The cytotoxicity of all these isolates against HepG2, MCF-7 and Hela cancer cell lines was evaluated. In MCF-7 and Hela cell lines, all compounds exhibited strong activity (IC50 in the range of 3.21–13.54 μM and 4.69–14.47 μM, respectively), while almost all compounds showed moderate cytotoxic activities against HepG2 cell lines.