Novel oligomeric caffeoyl derivatives and acylated flavone glycosides from Satureja nervosa Desf.: Chemical characterisation, structure-activity relationships, and multi-target bioactivity in Caenorhabditis elegans disease models

Satureja nervosa Desf. (Lamiaceae) contains structurally complex phenolic compounds, yet comprehensive chemical characterisation and mechanisms of bioactivity remain unexplored. This investigation identified and characterized bioactive constituents from eighteen wild Tunisian populations using water and ethanol extraction, established structure-activity relationships through systematic correlation analysis, and validated multi-target biological activities using in vivo disease models. HPLC-DAD-MS analysis with authentication against 13 commercial standards identified 49 phenolic compounds, including eleven previously unreported hydroxycinnamic acid-acylated flavone O-glycosides representing the first comprehensive report of such structures in Satureja, alongside multiple bioactive oligomeric caffeoyl derivatives (lithospermic acids, salvianolic acids, clinopodic acids). Water extracts demonstrated superior chemical diversity (31 vs 25 compounds) and phenolic content (97-1843 vs 2-161 mg/100 g DW) compared to ethanol extracts. Structure-activity correlation analysis identified specific oligomeric depsides as principal bioactive constituents: lithospermic acid-2 (R = 0.682, P < 0.01) for acetylcholinesterase inhibition and clinopodic acid K (R = 0.624, P < 0.01) for α-amylase inhibition. Elite water extracts demonstrated exceptional in vivo efficacy at 4 mg/mL in three Caenorhabditis elegans disease models: 63-64% increased survival against juglone-induced oxidative stress (wild-type N2), 75-78% metabolic rescue in daf-2(e1370) insulin-signalling mutants, and 62-75% neuroprotection against amyloid-β paralysis in the GMC101 Alzheimer's model, significantly outperforming ethanol extracts. The superior bioactivity of structurally complex oligomeric and acylated compounds compared to simple phenolic acids (rosmarinic acid constituting 58-83% of ethanol extracts) demonstrates multi-mechanistic effects beyond predictable phenolic antioxidant activity, establishing S. nervosa oligomeric phenolic derivatives as pharmacologically distinct bioactive natural products with validated multi-target therapeutic potential in vivo disease-relevant models.