[Alkaloids of Pausinystalia macroceras].

A study of the alkaloidal content of trunk-barks of Pausinystalia macroceras (K. Schum.) Pierre, Rubiaceae, resulted in the isolation of six alkaloids, five of which are indole alkaloids that belong to the yohimbane and heteroyohimbane groups; among them, yohimbine was found in major amount. Moreover, the levorotatory isomer of calycanthine, a quinoline dimeric tryptophane derived base, has been isolated for the first time. The phytochemical significance of calycanthine and related alkaloids is discussed.