In vitro Antioxidant Activity and Phytochemical Profiling of Methanolic Extract of Lemna minor

The present study investigated the in vitro antioxidant potential of methanolic extracts of Lemna minor and characterised its phenolic and flavonoid constituents using liquid chromatography-mass spectrometry (LC-MS) and high-performance liquid chromatography (HPLC). Antioxidant activity was evaluated using phosphomolybdenum total antioxidant capacity (TAC), Folin-Ciocalteu total phenolic content (TPC), ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical-scavenging assays, with L-ascorbic acid employed as the reference standard. The methanolic extract exhibited a total antioxidant capacity of 16.24 ± 6.00 mg AAE/g extract and a total phenolic content of 34.00 ± 5.43 mg GAE/g extract. The extract demonstrated strong free radical-scavenging activity, with EC50 values of 0.77 ± 0.04 mg/mL for the DPPH assay and 2.00 ± 0.08 mg/mL for the ABTS assay. LC-MS analysis identified several bioactive phenolic acids and flavonoids, including p-coumaric acid, ferulic acid, catechin and naringenin, which were subsequently confirmed by HPLC. The extract was characterised by low contents of antinutritional factors such as tannins and phytates. The presence of phenolic phytochemicals as well as the in vitro antioxidant activity indicate that L. minor may be considered a promising source of plant-based functional ingredients.