Unmasking the Aliphatic Repertoire: New Polyunsaturated Metabolites in Bupleurum falcatum sensu lato Provide Chemotaxonomic Insights
Journal
Plants
Date Issued
2025-05-10
Author(s)
Nešić, Milica D.
Nešić, Milan S.
Raca, Irena Lj.
Radulović, Niko S.
DOI
10.3390/plants14101432
Abstract
Bupleurum falcatum (Apiaceae) sensu lato includes multiple infraspecific taxa with longstanding taxonomic ambiguities, often resulting from incomplete morphological and chemical characterizations. Herein, diethyl ether extracts were analyzed from four Balkan populations that were tentatively identified as B. falcatum subsp. falcatum (syn. B. falcatum) and B. falcatum subsp. cernuum (syn. B. sibthorpianum). Comprehensive chro-matography and spectroscopic techniques (GC-MS and 1D/2D NMR) enabled the iso-lation of several newly identified aliphatic polyunsaturated esters, including com-pounds bearing uncommon conjugated tetraene and triyne backbones. These novel structures differ from canonical falcarinol derivatives by lacking the usual 3-hydroxylation, suggesting a divergent branch in the crepenynate pathway. The chemical profiles of each sample correlated closely with leaf morphology and infra-specific designations: for example, the Galičica Mt. population of B. falcatum featured a unique newly detected heptadecadientriyne, while the populations from Šar Planina and Suva Planina displayed distinct polyunsaturated repertoires. Extracts from B. sibthorpianum likewise contained stereoisomeric compounds that highlight metabolic divergence. Collectively, these findings demonstrate significant chemotypic variation within the Bupleurum falcatum complex and provide the first account of less-polar sec-ondary metabolites, including newly discovered polyunsaturated metabolites. Future research integrating molecular markers and bioactivity assays may elucidate how these specialized metabolites contribute to both the taxonomy and pharmacological potential of these understudied taxa.