Sesquiterpenoids from Brachylaena hutchinsii

The MeOH extract from the bark of Brachylaena hutchinsii yielded two ketoaldehyde sesquiterpenes, 8-ketocopaenal [1] and 8-ketoylangenal [2], which are also known as brachylaenalones A and B, respectively. In addition to the above-mentioned aldehydes, the corresponding ketoalcohols 8-ketocopaenol [3] and 8-ketoylangenol [4] were also isolated from the same plant, along with a fifth non-ketonic compound, ylangenol [5]. Although the ketoaldehydes 1 and 2 have already been described in the literature, their structures have not been completely established. We describe the isolation, identification, and antibacterial activity of five sesquiterpenes from Bra. hutchinsii and propose new structures for brachylaenalones A and B based on their spectral data.