Abstract: The chemical constituents of semi-mangrove Excoecaria agallocha L. collected at Hainan island,China were isolated by silica gel column chromatography and preparative HPLC.Fifteen compounds were finally obtained from the EtOAc extract of E.agallocha L.On the basis of modern spectral data,they were identified as (±)-syringaresinol (1), (+)-medioresinol (2), (±)-buddlenol C (3), threo-buddlenol C (4),(±)-ficusesquilignan A (5),(-)-(7R,7′R,7′′S,8S,8′S,8′′S)-4′,4′′-dihydroxy-3,3′,3′′,5,5′,5′′-hexamethoxy-7,9′:7′,9-diepoxy-4,8′′-oxy-8,8′- sesquineolignan-7′′,9′′-diol(6),salicifoliol (7),cleomiscosin C (8),curcasinlignan A (9),scopoletin (10),fraxidin (11),iso-fraxidin (12),aurantiamide (13),aurantiamide acetate (14),syringaldehyde (15).Compounds 2-15 were isolated from this plant for the first time.

Key words: semi-mangroves, Excoecaria agallocha L., chemical constituent, lignan