Plant origin of Indonesian propolis : New compounds and their antibacterial activity

We revealed that the plant origin of the propolis from Lombok, Indonesia is Calophyllum inophyllum by observing stingless bee (Tetragonula fuscobalteata) behavior and LC-MS analysis of the ethanol extracts of the propolis and C. inophyllum resin. To the best of our knowledge, there are no reports that determined the plant origin of propolis as Calophyllum spp. Further new chromanone derivative, 1 was isolated from the resin of the stem bark of C. inophyllum. The structure of 1 was elucidated by a combination method based on its IR, UV, HRESIMS, 1D and 2D NMR data. Part of the absolute structure of 1 was determined by electronic circular dichroism (ECD) supported by time-dependent density functional theory ECD calculation. C. inophyllum resin and 1 showed significant antibacterial activity against Staphylococcus aureus and Escherechia coli. The MIC of 1 against S. aureus and E. coli were 30 and 15 µM, respectively. The results suggested that C. inophyllum resin and Indonesian propolis can be used as functional materials.
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