Sargassum muticum is an invasive brown macroalga that has rapidly expanded along the Moroccan Atlantic coast, posing ecological challenges while representing an abundant marine biomass with potential biotechnological value. This study investigated the biochemical composition and metabolic properties of Moroccan S. muticum through compositional analysis, in vivo metabolic evaluation, and molecular docking. Proximate analysis revealed a carbohydrate-rich composition with moderate protein content, together with photosynthetic pigments and nutritionally relevant minerals. In a cafeteria diet-induced rat model, dietary supplementation with S. muticum significantly attenuated body weight gain, improved adiposity-related indices, reduced serum total cholesterol, triglycerides, LDL cholesterol, and C-reactive protein levels, and increased HDL cholesterol. To obtain mechanistic insight, molecular docking analysis was performed using representative phlorotannins reported from Sargassum species. Among the compounds evaluated, dieckol showed the highest docking scores toward key metabolic targets, including AMP-activated protein kinase and peroxisome proliferator-activated receptor gamma. Although these in silico findings do not demonstrate biological activation, they provide preliminary mechanistic support for the observed in vivo effects. Overall, the results highlight the potential of S. muticum for sustainable valorization as a functional marine bioresource.

Obesity is a chronic systemic disorder frequently associated with multiorgan complications of inflammatory and metabolic origin. This study aimed to evaluate the histoprotective effects of Sargassum muticum, an invasive brown seaweed harvested from the Moroccan Atlantic coast, in cafeteria diet-induced obese rats. Thirty-five Wistar rats were divided into five groups: standard control, obese control (cafeteria diet), two obese groups treated with Sargassum muticum at 10% and 20%, and one group treated with orlistat at 30 mg/kg. After eight weeks, tissue samples were collected for a histopathological analysis. In untreated obese rats, histological examination revealed multiple abnormalities, including submucosal edema, vascular congestion, gastric inflammatory infiltration, pulmonary hemorrhage and lipid vacuoles, as well as hepatic, cardiac, pancreatic, and testicular lesions. Treatment with S. muticum, particularly at 20%, markedly improved these alterations, characterized by a significant reduction in inflammatory infiltration, vascular congestion, lipid vacuolization, and tissue degeneration, together with improved preservation of tissue architecture. These effects were superior to those observed with orlistat. The anti-inflammatory, antioxidant, and metabolic properties of S. muticum are likely due to its richness in bioactive compounds, notably phlorotannins, fucoxanthin, and sulfated polysaccharides. These findings confirm the therapeutic potential of S. muticum in preventing histopathological complications of obesity and pave the way for translational studies and potential nutraceutical applications in human obesity management.