Green Extraction of Fucoxanthin with Promising Nutraceutical Applications

Sargassum muticum is an invasive brown macroalga in Galicia (Spain). Thus, exploitation of this biomass for the extraction of bioactive compounds could be an interesting strategy to add value to food supplements and functional foods. Among these compounds, fucoxanthin (Fx) has been gaining attention for its promising biological activities, such as its antioxidant, antimicrobial, anticancer, antihypertensive, anti-inflammatory, anti-diabetic, anti-obesity, neuroprotective, anti-angiogenic and photoprotective properties. Fucoxanthin is the most abundant and characteristic pigment in brown algae, accounting for approximately 10% of the total carotenoids in nature. The aim of this study was to optimize the extraction yield (grams extract per 100 g of macroalgae dried weight, g E/100 g Ma dw) and Fx content (mg Fx/g E) from Sargassum muticum using ultrasound-assisted extraction (UAE). For this purpose, a response surface methodology (RSM) study with a five-level circumscribed central composite design (28 independent experiments) was applied to optimize three main UAE variables: ethanol concentration (S, 35–100%), time (t, 5–55 min) and power (p, 100–500 W). A second-order polynomial model was used to fit the experimental data (obtained in triplicate). Based on the model prediction (R2 = 0.965), the optimal conditions that individually maximized extraction yield were 29.98 ± 1.03 g E/100 g Ma dw at a t-value of 45.00 ± 3.35 min, an S-value of 37.50 ± 3.06% and a p-value of 409.46 ± 10.12 W. Meanwhile, for maximizing the Fx content (R2 = 0.8199), the response was optimal at 0.93 ± 0.10 mg Fx/g Ma dw at a t-value of 45.00 ± 3.35 min, an S-value of 84.22 ± 4.59% and a p-value of 339.73 ± 9.22 W.