Abstract
Scrophularia aestivalis Griseb. is a Balkan endemic species whose phytochemical composition and medicinal properties have not been previously investigated. The therapeutic potential of Scrophularia species has attracted considerable attention, resulting in extensive studies on their chemical and pharmacological properties, with over 200 secondary metabolites identified to date. The present study aimed to explore the phytochemical composition of Bulgarian-origin S. aestivalis, including isolation and characterization of individual secondary metabolites. From methanol extract of the plant's aerial parts, aucubin, harpagide, 8-O-acetylharpagide, cis- and trans-harpagoside, 6-O-methyl catalpol, acylated derivatives of catalpol, and linarin were isolated and identified. The anti-obesity activity of the extract and primary fractions was evaluated in a Caenorhabditis elegans model of obesity. Significant lipid-reducing activity was demonstrated in four fractions, indicating promising anti-obesogenic properties. Following chemical profiling and quantitative analysis, the main components of the most active fractions were identified, namely the cis- and trans-harpagoside isomers. Subsequent experiments demonstrated that treatment with harpagoside reduced lipid accumulation and improved mitochondrial function in glucose-supplemented worms, with the data suggesting potential involvement of the SKN-1 signaling pathway.