Optimizing phlorotannins extraction from Fucus vesiculosus using Box-Behnken design: Unveiling techniques for enhanced antioxidant activity and metabolic enzyme inhibition

Phlorotannins, phenolic compounds found in brown macroalgae, exhibit potential bioactive effects. This study evaluated the extraction of phlorotannins from Fucus vesiculosus using conventional and ultrasound-assisted extraction (UAE) methods, focusing on solvent-material ratio, solvent concentration, extraction time, and sonication power for UAE. The experiments, designed using a Box-Behnken design, measured total phlorotannin content (TPhC), DPPH, FRAP, and ABTS. The conventional method, under optimal conditions, produced TPhC, DPPH, FRAP, and ABTS values of 512.25 ± 14.26 mg PGE/100 g, 29.70 ± 1.40 mg TE/100 g, 589.57 ± 15.06 mg TE/100 g, and 332.73 ± 31.03 mg TE/100 g, respectively. The UAE method, under its optimal conditions, yielded higher values: 954.00 ± 33.65 mg PGE/100 g, 146.35 ± 3.30 mg TE/100 g, 1037.61 ± 32.93 mg TE/100 g, and 809.95 ± 46.58 mg TE/100 g. The extracts were tested for inhibitory effects on α-amylase and α-glucosidase, with the purified UAE extract showing greater inhibition of α-amylase (IC₅₀ = 7.06 ± 0.67 μg/mL) compared to acarbose (IC₅₀ = 14.63 ± 0.28 μg/mL). For α-glucosidase, acarbose had higher activity (IC₅₀ = 11.54 ± 0.04 μg/mL) than the UAE purified extract (IC₅₀ = 15.04 ± 0.07 μg/mL). UHPLC-qTOF-MS analysis identified various phlorotannin derivatives, with Tetrafucotetraphlorethol (m/z 993) only in the UAE purified extract. This study concludes that purified phlorotannin extract from UAE can potentially regulate α-amylase and α-glucosidase, enzymes linked to metabolic disorders like diabetes and obesity.