Abstract:In order to understand the chemical constituents of Swietenia macrophylla King, thirteen compounds were isolated from its roots. On the basis of spectral data, they were identified as 1,5-dihydroxyxanthone (1), 1,6-dihydroxy-5-methoxyxanthone (2), euxanthone (3), 1,2-dimethoxyxanthone (4), (+) catechin (5), (+) sesamin (6), bis-(2-ethylhexyl) phthalate (7), 3-oxotirucalla-7,24-dien-21-oic acid (8), (20S)-3β-acetoxy-24-methylenedam-maran-20-ol (9), cycloeucalenol (10), β-sitosterol (11), 7-deacetoxy-7-oxogedunin (12) and 7-deacetoxy-7α-hydroxygedunin (13). Among them, compounds 1-4, 6-10 and 13 were isolated from the genus Swietenia for the first time. Moreover, compound 4exhibited inhibitory activity against acetylcholinesterase.