The Biochemical of Tetradium,Euodia and Melicope and their significance in the Rutaceae

From the stem and root barks of Tetradium glabrifolium (Rutaceae) benzophenanthridine alkaloids have been isolated together with furoquinoline alkaloids, coumarins and limonoids. The occurrence of the l-benzyltetrahydroisoquinolinederived benzophenanthridines adds Tetradium to the small group of rutaceous genera (Fagaropsis, Phellodendron, Toddalia, Zanthoxylum) known to produce alkaloids of this type. These findings support Hartley's decision to reassign taxa from Euodia (sensu Engler) into the three genera Tetradium, Euodia s. s. and Melicope and his contention that Tetradium is closely allied to Zanthoxylum and Phellodendron, with which it shares several unusual chemical characters. Hartley's re-alignment of Tetradium, which cuts across Engler's sub-families Rutoideae and Toddalioideae, is therefore sustained by the known distribution of secondary metabolites, whilst available information suggests a wide disparity between the chemical profiles of Tetradium and Melicope. The chemosystematic significance of the addition of Tetradium to the 1-benzyltetrahydroisoquinoline producing genera and the potential of these taxa to have acted as a starting point for biochemical evolution within the Rutaceae is discussed.