New tertiary alkaloids of Strychnos decussata

From the stem bark of Strychnos decussata (Pappe) Gilg (Loganiaceae), five tertiary indole alkaloids have been isolated and identified. Previously known alkaloids, but new to this plant, were: akagerine (1) and 17-O-methylakagerine (2), while alkaloids newly found in nature were 10-hydroxy-21-O-methylkribine (3a), 10-hydroxyepi-21-O-methylkribine (3b) and 10-hydroxy-17-O-methylakagerine (4). Structures have been ascribed to the new compounds on the basis of their spectral, particularly nmr, data. The pharmacological activity of the alkaloids is also discussed.