Solvent-Dependent Phenolic Profiling and Bioactivities of Medicago marina L.: An Ultrasound-Assisted Extraction Approach

Abstract

Despite previous phytochemical investigations of Medicago marina L., comparative information on the phenolic composition and multifunctional bioactivities of extracts obtained with different solvents remains limited. This study compared water and methanol extracts prepared by ultrasound-assisted extraction using targeted liquid chromatography–tandem mass spectrometry (LC-MS/MS), antioxidant assays, and enzyme inhibitory assays. The extracts had comparable total phenolic contents, whereas the methanol extract was richer in flavonoids. LC-MS/MS profiling showed distinct phenolic compositions between the investigated extraction batches: the water extract contained higher levels of ferulic acid, apigenin, and several hydroxybenzoic acid derivatives, whereas the methanol extract was enriched in hyperoside, hesperidin, chlorogenic acid, and other flavonoid derivatives. On an extract-mass basis, the water extract showed higher 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical-scavenging activity, ferric reducing antioxidant power (FRAP), and phosphomolybdenum antioxidant capacity, whereas the methanol extract showed higher ferrous ion-chelating and enzyme inhibitory activity values. Yield normalization to the initial dry plant material altered the relative performance of the two extraction batches in several assays because of the higher water extraction yield. These findings show that extract-level enrichment and yield-normalized activity provide complementary perspectives on the phytochemical and biological characteristics of the specific M. marina extraction batches investigated.