Unusual coumarin patterns of Pelargonium species forming the origin of thetraditional herbal medicine umckaloabo

The coumarin patterns of Pelargonium sidoides DC. and Pelargonium reniforme CURT., forming the origin of the herbal medicine "umckaloabo", were analys ed and compared for therapeutic equivalence. For both species, members of t ri- and tetraoxygenated coumarins almost exclusively were present in the re spective metabolic pools. However, the roots of P. sidoides and P. reniform e expressed conspicuously distinct coumarin variations, with umckalin, its 7-O-methyl ether, 7-acetoxy-5,6-dimethoxycoumarin, 6,8-dihydroxy-7-methoxyc oumarin, 6,8-dihydroxy-5,7-tetramethoxycoumarin, artelin and three unique c oumarin sulfates as uncommon metabolites of this class of secondary product s of P. sidoides. Furthermore, the highly oxygenated but known coumarins fr axinol, isofraxetin and fraxidin were associated with the new 8-hydroxy-5,6 ,7-trimethoxycoumarin as representatives of P. reniforme. Of the twelve ide ntified coumarins only the two species shared the ubiquitous scopoletin and the unique 6,7,8-trihydroxycoumarin. From the oxygenation patterns it is e vident that the majority of these Pelargonium coumarins match the recently established basic structural requirements for marked antibacterial activity i.e. the presence of a methoxy function at C-7 and an OH group at either t he C-6 or C-8 position. The current data on the coumarin profiles of each P elargonium species also indicate a previous erroneous identification of the plant material claimed to be P. reniforme. Absence and presence of umckali n and its 7-O-methyl ether defines P. reniforme and P. sidoides, respective ly.