A new Corynanthe-type indole alkaloid, (-)-9-methoxymitralactonine (1), having a highly conjugated system was isolated from the young leaves of Mitragyna speciosa in Malaysia, and its structure was first deduced by spectroscopic analysis and then confirmed by chiral-total synthesis starting from optically pure epoxy-ketone and 5-methoxy-3,4-dihydro-beta-carboline. The chiral HPLC analysis demonstrated that the natural 9-methoxymitralactonine contained predominantly the (-)-enantiomer over the (+)-enantiomer in the ratio of 62:38. (C) 2000 Elsevier Science Ltd. All rights reserved.