New compound from the plant origin of propolis from Lombok, Indonesia and its antibacterial activity

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.

Automated summary

We identified the plant origin of propolis from Lombok, Indonesia as Calophyllum inophyllum Linn by observing the behavior of stingless bees and conducting LC-MS analysis. We also isolated a new chromanone derivative, calophylloidic acid A, from the resin of C. inophyllum and determined its structure using various analytical techniques. Furthermore, we found that the resin, propolis, and calophylloidic acid A exhibited significant antibacterial activity against Staphylococcus aureus and Escherichia coli.