Phytochemical and pharmacological investigation of oxidized secoiridoids from Ligustrum lucidum

In the pursuit of alternative plant sources rich in the secoiridoid glycosides oleuropein and ligstroside, our research focused on Ligustrum lucidum (Oleaceae) [ 1 ]. Preliminary analysis of its leaves led to the isolation of two novel oxidized analogues, oleuropeinic and ligstrosidic acid. These compounds were further investigated due to their significant pharmacological interest. The study aimed to comparatively evaluate various parts of L. lucidum, Fraxinus angustifolia, and Ligustrum vulgare , all Oleaceae family species, focusing on the content of the two acids and their overall metabolic profiles using HPTLC, HPLC-DAD, and UHPLC-HRMS/MS. Seasonal variation and drying methods of the plant material were also evaluated. The acids were efficiently isolated through a refined workflow incorporating CPC and semi-preparative HPLC. Their structures were confirmed by NMR and UHPLC-HRMS/MS, and optical rotation values were determined [ 2 ]. In total, 141 secondary metabolites were identified across all extracts. Comparative phytochemical analyses revealed notable variations in acid content based on species, plant part, and extraction conditions. To explore potential biological response, hepatoprotective activity was evaluated for ligstroside, oleuropein, ligstrosidic and oleuropeinic acid, respectively [ 3 ]. Notably, ligstrosidic acid demonstrated remarkable hepatoprotective effects compared to the positive control, oleuropein, suggesting the oxidized analogues may possess enhanced biological activity. These findings not only establish L. lucidum as a promising source of bioactive oxidized secoiridoids but also highlight the importance of extraction parameters and species selection in optimizing yield and bioactivity of plant-derived metabolites. Acknowledgments This work was supported by the “GreenCosmIn” project (HORIZON-MSCA-2022-SE-01, project code: 101131346) Publication History Article published online: 05 March 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany