We revealed the plant origin of propolis from Lombok, Indonesia; its plant origin was Calophyllum inophyllum Linn. This was confirmed by observing the behavior of stingless bees and from the LC-MS analysis of the 70% ethanol extracts of the propolis and C. inophyllum resin. Furthermore, a new chromanone derivative, calophylloidic acid A (1), was isolated from the stem bark resin of C. inophyllum. The structure of 1 was elucidated using a combination method based on the IR, UV, HRESIMS, and 1D and 2D NMR analyses. The absolute structure of C-2 and C-3 positions of 1 was determined by electronic circular dichroism (ECD). This determination was supported by the time-dependent density functional theory (TD-DFT) and ECD calculations. Additionally, the C. inophyllum resin, propolis, and 1 exhibited significant antibacterial activity against Staphylococcus aureus and Escherichia coli.
- Calophylloidic acid A
- Calophyllum inophyllum