Brown Seaweed From Moroccan Coasts Shows Potent Antioxidant and Antidiabetic Power

A common brown seaweed that carpets the rocky shores of Morocco’s Mediterranean and Atlantic coastlines is emerging as one of the most intriguing marine candidates in the search for natural compounds that could help fight oxidative stress and type 2 diabetes. In a study published in Plant Biosystems, a research team led by Youssra Aalilou of Mohammed V University in Rabat, working alongside collaborators in Morocco, Turkey and Saudi Arabia, carried out an unusually complete investigation of Halopteris scoparia, a perennial brown alga long noted in the phycological literature but rarely subjected to such a systematic, multi-solvent chemical and pharmacological workup. The study bridges classical phytochemistry with modern computational biology, moving from crude extracts to individual molecules and, ultimately, to molecular docking and molecular dynamics simulations against two enzymes central to glucose metabolism.

The central question the researchers posed was deceptively simple: does the solvent used to extract a seaweed’s chemistry matter? The answer, emphatically, is yes. The team prepared five distinct extracts of H. scoparia using solvents of increasing polarity, n-hexane, dichloromethane, ethanol, methanol and water, and then quantified the total polyphenol, flavonoid and tannin content of each using standardized colorimetric assays. This gradient approach is grounded in a well-established principle of natural products chemistry: polar solvents tend to pull phenolic acids, flavonoid glycosides and tannins out of plant and algal tissue, while nonpolar solvents preferentially dissolve lipids, pigments and terpenoid compounds. By comparing the same biomass extracted five ways, the researchers could effectively partition the alga’s chemical inventory into discrete fractions, each with its own biological signature.

The results confirmed the polarity principle with striking clarity. The aqueous extract, the most polar of the five, registered the highest total polyphenol and tannin contents, and it translated that chemical richness into biological performance, topping the ferric reducing antioxidant power (FRAP) assay, the ABTS radical scavenging assay and the metal-chelating assay. These three tests probe complementary antioxidant mechanisms: FRAP measures the capacity to reduce ferric ions, a proxy for electron-donating ability; ABTS tracks the neutralization of a stable synthetic radical cation; and metal chelation assesses the ability to bind transition metals such as iron and copper that catalyze the formation of destructive hydroxyl radicals through Fenton chemistry. Tannins, with their dense arrays of hydroxyl groups, are particularly effective metal chelators, which helps explain why the tannin-rich aqueous fraction dominated that particular assay.

The methanolic extract told a different but equally instructive story. It achieved the strongest performance in the DPPH assay, which measures scavenging of a lipophilic synthetic radical, and in the CUPRAC assay, which evaluates the reduction of cupric ions. Meanwhile, the dichloromethane extract, the least polar fraction apart from hexane, showed the greatest activity in the phosphomolybdenum assay, a measure of total antioxidant capacity based on the reduction of molybdenum(VI) to molybdenum(V). The fact that no single extract won every contest is not a contradiction but a feature of antioxidant chemistry: different assays respond to different mechanisms, solubilities and reaction kinetics, and a compound that excels at quenching one radical may be mediocre at reducing a metal ion. For bioprospectors, this means the choice of extraction solvent is effectively a choice of which biological activity to prioritize.

Antioxidant capacity was only half of the pharmacological picture. The team also evaluated the extracts’ ability to inhibit two digestive enzymes, alpha-amylase and alpha-glucosidase, that sit at the heart of post-meal glucose spikes. Alpha-amylase cleaves long starch molecules into shorter oligosaccharides in the mouth and small intestine, and alpha-glucosidase then trims those fragments down to absorbable glucose at the intestinal brush border. Drugs that blunt both enzymes, such as acarbose, are standard adjuncts in the management of type 2 diabetes, but they come with gastrointestinal side effects, which has fueled a sustained hunt for gentler plant- and algae-derived inhibitors. Here the ethanolic and dichloromethane extracts stood out, exhibiting dual inhibitory activity against both enzymatic targets, a result the authors highlight as evidence that H. scoparia’s antidiabetic potential is distributed across chemically distinct fractions rather than confined to a single polar class of compounds.

To move beyond crude extracts, the researchers turned to high-performance liquid chromatography (HPLC), which allowed them to tentatively identify individual bioactive compounds within the extracts. Among the molecules flagged by this profiling were sophocarpine, a quinolizidine alkaloid tentatively identified here as an isomer of monocrotaline, and a structurally elaborate phenanthrene carboxylic acid, formally named 1,4a-dimethyl-9-oxo-7-propan-2-yl-3,4,10,10a-tetrahydro-2H-phenanthrene-1-carboxylic acid. The word tentatively matters: HPLC-based identification without full isolation and nuclear magnetic resonance confirmation remains provisional, and the authors are careful to frame their assignments accordingly. Even so, the presence of sophocarpine is particularly noteworthy, because this alkaloid has previously attracted attention in the diabetes literature for its effects on PPAR-gamma-regulated gene expression, a key transcriptional axis in glucose and lipid metabolism.

The study’s most technically ambitious phase was computational. Using molecular docking, the team positioned the tentatively identified compounds inside the three-dimensional active sites of alpha-amylase and alpha-glucosidase, calculating binding affinities and mapping the specific amino acid residues that anchor each ligand. Docking, however, offers only a static snapshot, so the researchers followed up with molecular dynamics simulations, which allow the protein-ligand complexes to flex and breathe in a simulated aqueous environment over time. A ligand that looks perfect in a static dock can fall apart once the enzyme’s loops and side chains begin to move; sustained stability across a dynamics trajectory is therefore a much stronger signal of genuine binding potential. By this combined criterion, sophocarpine and the phenanthrene carboxylic acid emerged as the most promising compounds toward both enzymatic targets, suggesting that the alga’s antidiabetic activity may ultimately trace back to these specific molecules rather than to a diffuse collective effect.

The findings land in a research landscape that has been warming to marine macroalgae as pharmaceutical feedstocks. Previous work on H. scoparia has documented apoptosis-inducing activity in cancer cell lines, antimicrobial effects, antiprotozoal potential and a rich inventory of sulfated polysaccharides, fucoxanthins and mycosporine-like amino acids. A 2024 in vivo study in alloxan-induced diabetic mice had already hinted at the alga’s antihyperglycemic promise. What the new study adds is a rigorous, solvent-resolved map of which chemical fractions carry which activities, plus a computational shortlist of candidate molecules that can now be prioritized for isolation, synthesis and wet-lab validation. It also situates H. scoparia alongside related brown algae, such as Halopithys incurva and Cladostephus spongiosus, that the same Moroccan-Turkish collaboration has recently profiled, building a comparative framework for the region’s phlorotannin-rich seaweed flora.

Significant caveats remain before any of this reaches a pharmacy shelf. In vitro enzyme inhibition does not guarantee clinical efficacy, since intestinal absorption, metabolism and off-target toxicity all intervene between a docking score and a therapeutic effect. The tentative compound identifications require confirmation by isolation and structural elucidation, and the most active extracts will need to be tested in animal models of diabetes and subjected to standard safety pharmacology. Nonetheless, the study makes a persuasive case that a seaweed most people walk past on the beach is a chemically layered resource whose polar fractions deliver antioxidant firepower while its mid-polarity fractions carry dual enzyme-inhibitory activity. As the global burden of type 2 diabetes continues to climb and the search for safer, food-derived enzyme inhibitors intensifies, Halopteris scoparia has earned a place on the shortlist of marine organisms worth watching, and the pipeline from Moroccan tide pools to computational drug design has rarely looked more productive.

Subject of Research: Phytochemical characterization and antioxidant and antidiabetic evaluation of Halopteris scoparia brown alga extracts

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

Article References: Aalilou, Y., Zengin, G., Karim, E. M., Hassoun, M., El karfi, W., Moussa, H., Mortada, S., Ak, G., Chtita, S., Ullah, R., Alotaibi, A., Meddah, B., Bouyahya, A., & Faouzi, M. E. A. (2026). Exploration of Halopteris scoparia extracts and their bioactive compounds: from phytochemical characterization to in silico investigations. Plant Biosystems, 160(4), Article 234. https://doi.org/10.1007/s44473-026-00237-y

Image Credits: AI Generated

DOI: 10.1007/s44473-026-00237-y

Keywords: Halopteris scoparia, brown algae, antioxidant, antidiabetic, alpha-amylase, alpha-glucosidase, polyphenols, tannins, sophocarpine, molecular docking, molecular dynamics, marine natural products