Exploration of Halopteris scoparia extracts and their bioactive compounds: from phytochemical characterization to in silico investigations

Halopteris scoparia is a perennial brown alga widely distributed along both the Moroccan Mediterranean and Atlantic coasts and recognized for its diverse biological activities. This study investigated the influence of solvent polarity on the phytochemical composition, antioxidant capacity, and antidiabetic potential of five extracts (n-hexane, dichloromethane, ethanol, methanol, and water). Total polyphenol, flavonoid, and tannin contents were quantified using colorimetric assays, while HPLC analysis enabled the tentative identification of bioactive compounds. Antioxidant activity was assessed using six complementary in vitro assays, and antidiabetic potential was evaluated through both in vitro and in silico inhibition studies against α-amylase and α-glucosidase. The aqueous extract exhibited the highest total polyphenol and tannin contents and showed the strongest activity in FRAP, ABTS, and metal-chelating assays. The methanolic extract demonstrated the highest activity in DPPH and CUPRAC assays, whereas the dichloromethane extract showed the strongest phosphomolybdenum activity. Ethanolic and dichloromethane extracts exhibited dual inhibitory activity against both α-amylase and α-glucosidase. Molecular docking and molecular dynamics simulations identified sophocarpine, a tentatively identified monocrotaline isomer, and 1,4a-dimethyl-9-oxo-7-propan-2-yl-3,4,10,10a-tetrahydro-2H-phenanthrene-1-carboxylic acid as the most promising compounds toward both enzymatic targets. These findings highlight H. scoparia as a valuable marine source of antioxidant and antidiabetic agents and support its potential for future pharmacological applications.