Chemical composition and antioxidant properties of selected mangrove species from the Sine Saloum Delta (Senegal) using UHPLC-MS/MS and molecular networking.

Mangrove ecosystems are important sources of secondary metabolites with significant pharmacological potential. However, the chemical diversity of West African mangroves remains largely unexplored. This study investigated the phytochemical composition and antioxidant activity of aqueous and hydroethanolic extracts from Avicennia germinans, Laguncularia racemosa, and Conocarpus erectus leaves, harvested from the Sine Saloum Delta Biosphere Reserve (Senegal). Metabolic profiling was performed by UHPLC-MS/MS combined with Feature-Based Molecular Networking (FBMN) for metabolite annotation. Antioxidant activity was assessed by off-line and on-line DPPH and ABTS assays, while the total phenolic content (TPC) was determined by the Folin-Ciocalteu method. A total of 153 metabolites were tentatively annotated, primarily phenolic acids, flavonoids, hydrolysable tannins and terpenoids. L. racemosa and C. erectus exhibited the highest TPC and the strongest antioxidant activities, while A. germinans showed limited free radical scavenging activity despite its high triterpenoid content. On-line UHPLC-DPPH/ABTS-MS/MS analysis enabled the rapid identification of the main antioxidant metabolites such as ellagic acid, myricetin and quercetin glycosides. This metabolomics approach highlights the chemical richness and antioxidant potential of L. racemosa and C. erectus. This study contributes to the chemical characterization and valorization of Senegalese mangroves as promising sources of bioactive natural products.