Objective: To isolate alkaloids from Tabernaemontana divaricata. Method: The air-dried powdered leaves of T. divaricata were extracted with CH3OH at room temperature. The CH3CH2OH extract was partitioned between ethyl acetate and 2 mol · L-1 H2SO4

and the acidic aqueous phase was basified with NaOH to pH 9-10 and the alkaloids were extracted with CHCl3.The crude alkaloids were subjected to silica gel chromatography

MCI chromatography

and Sephadex LH-20 column to isolate alkaloids

and their structures were established on the basis of spectroscopic methods. including NMR and mass spectrometry and comparison with literature. Cytotoxicity of the compounds was evaluated by the MTT method. Result: Six monoterpenoid indole alkaloids were isolated and their structures were elucidated as ervaramine-type: ervatamine (1)

20-epiervatamine (3)；vobasine-type: tabernaemontanine (2)

dregamine (4)

and aspidosperma-type: (-)-mehranine (5) and tetrahydroalstonine (6). Conclusion: Compounds 4 and 6 were isolated from T. divaricata for the first time. All the alkaloids were assessed for their cytotoxicity against five human tumour lines (HL-60

SMMC-7721

A-549

MCF-7 and SW-480)

and the result showed that none had activity.