Siamfuranones A-C, three novel furanone derivatives from the flowers of Uvaria siamensis and their biological activities.

Three previously undescribed furanone derivatives named siamfuranones A-C ( 1 - 3 ), together with 11 known compounds ( 4 - 14 ), were isolated from the flowers of Uvaria siamensis . Their planar structures were determined through analysis of spectrometric and spectroscopic evidence, while electronic circular dichroism (ECD) calculations were used to determine their absolute configurations. In addition, gauge-including atomic orbitals (GIAO) NMR chemical shift calculation, supported by the advanced statistical method DP4 plus, was used to confirm the relative configuration of siamfuranone B ( 2 ). All the isolated compounds were evaluated against two cancer cell lines (A549 and Hela), and screened for antibacterial activities. Furthermore, they were assessed for cytotoxicity against a normal cell line ( Vero cell).