Chemical constituents of Cinnamomum cebuense.

To investigate the chemical constituents of Cinnamomum cebuense, an endemic and critically endangered tree found only in Cebu, Philippines. The compounds were isolated by silica gel chromatography. The structures of the isolates were elucidated by NMR spectroscopy. The dichloromethane (DCM) extract of the bark of C. cebuense afforded a new monoterpene natural product 1 and a new sesquiterpene 2, along with the known compounds, 4-hydroxy-3-methoxycinnamaldehyde (3), 4-allyl-2-methoxyphenol (4), α-terpineol (5) and humulene (6). The DCM extract of the leaves of C. cebuense yielded 6, β-caryophyllene (7), squalene (8), and a mixture of α-amyrin (9), β-amyrin (10) and bauerenol (11). The structures of 1-7 were elucidated by extensive 1D and 2D NMR spectroscopy, while the structures of 8-11 were identified by comparison of their (13)C NMR data with those reported in the literature. The bark of C. cebuense afforded monoterpenes, sesquiterpenes and phenolics, while the leaves yielded sesquiterpenes and triterpenes.