Urticalean Rosids Clade (Rosales): Deciphering the Riddle From a Chemical Point of View

Cannabaceae, Moraceae, Ulmaceae and Urticaceae are members of the Urticalean rosids clade (Rosales). Their infrafamilial and infrageneric relationships remain poorly understood. The aim of this study was to assess chemical similarities and differences between families of the Urticalean rosids clade based on aromatic phenolic compounds. Analysis of the structural variability of these compounds may help to understand the taxonomic relationships of the clade. Data on the occurrence and type of aromatic phenolic compounds were obtained from the SciFinder database. Parameters of phenolic protection, oxidation and skeletal specialisation were calculated. Multivariate statistical analyses were performed. Flavones and flavonols were found to be chemosystematic markers of the clade. Moraceae showed aromatic phenolic compounds with more specialised skeletons, while Cannabaceae, Ulmaceae and Urticaceae showed regular skeletons. Phenolic protection mechanisms are more specialised in Moraceae (O-prenylation and O-methylation), while O-glycosylation predominated in the other families. Distinct evolutionary trends in structural types and oxidation patterns distinguish Moraceae, suggesting metabolic differences within the clade.