Striking Diversification of Exudate Profiles in Selected Primula Lineages

Abstract

In continuation of previous studies on glandular exudates of Primula, we analyzed eleven so far unstudied species and several populations for exudate composition. Unsubstituted flavone and unusually substituted flavones, normally predominant in Primula exudates, were not detected in all of the analyzed samples. Instead, some species exhibited regular substituted flavonoids, and in some cases, no flavonoids could be detected at all. The detection of a diterpene (1) in P. minima exudates is new to Primula. On basis of MS and NMR, 1 was structurally characterized as ent-kaur-16-en-19-oic acid. Comparative profiling of exudates as performed by HPLC and TLC against authentic markers indicated further the presence of the benzoquinone primin and derivatives in some exudates. Thus, exudates of newly studied species contrast markedly with those analyzed so far. The significance of observed exudate diversification is discussed in view of the phylogeny of derived lineages in European alpine regions.

Exudate Compounds of Origanum Species

“…Exudate flavonoids and their distribution among the plant kingdom have been comprehensive studied by Prof. Eckhard Wollenweber and the followers of this approach for analysis [1][2][3][4][5][6][7]. In addition to being taxonomically important, these compounds have important ecological functions due to their location on the surface on plant.…”

New Primula-type Flavones from Exudates of Selected Dionysia spp. (Primulaceae)

“…Corresponding to Primula species, the majority of compounds are unsubstituted flavone and 7-deoxy-flavones with unusual substitution patterns. As the biosynthesis of these compounds is still obscure, and occurrence appears to be typical of this Primula assemblage, these structures were earlier named Primula-type compounds [2]. However, some species of Dionysia, as well as some of the phylogenetically derived Primula groups, were shown to accumulate flavonoids which are derived from the known classical biosynthetic pathways, in addition or in a mutually exclusive way [2].…”

“…As the biosynthesis of these compounds is still obscure, and occurrence appears to be typical of this Primula assemblage, these structures were earlier named Primula-type compounds [2]. However, some species of Dionysia, as well as some of the phylogenetically derived Primula groups, were shown to accumulate flavonoids which are derived from the known classical biosynthetic pathways, in addition or in a mutually exclusive way [2]. Furthermore, several unusual chalcones were recently described from Dionysia species [3], and (E)-chalcone was reported as essential oil constituent of D. oreodoxa and D. diapensifolia, respectively [4,5].…”

“…New accessions of earlier studied species (D. bryoides, D. balsamea, D. bornmuelleri) and of hitherto unstudied D. leucotricha and D. denticulata were analyzed for exudate composition. Structural characterization of three flavones (1)(2)(3), as new for Dionysia is reported. Based upon comparative HPLC profiling, existing exudate samples from earlier studies were re-analyzed [1] for occurrence of these new compounds within closely related taxonomic units of Dionysia.…”

“…Exudates of analyzed populations of D. bryoides showed the presence of three flavonoid compounds that did not match with any of the other Primula or Dionysia flavonoids from our HPLC database. Three flavone derivatives could be separated and identified as 2'-hydroxy-3'-methoxyflavone (1), 2',3'dimethoxyflavone (2), and 3',5'-dimethoxyflavone (3), respectively ( Figure 1). These compounds are new for Dionysia; their presence in Primula spp.…”