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).