Valorization of coastal seagrass biomass: Enzyme-assisted extraction of bioactive compounds from Posidonia oceanica

in this study, we focus on the enzyme-assisted extraction (EAE) of bioactive compounds from Posidonia oceanica, a Mediterranean seagrass of ecological importance that is often treated as waste. Increasing evidence highlights its beneficial properties, making it a promising source of compounds for the production of value-added compounds. A Taguchi experimental design was employed to optimize the EAE, using the cellulolytic commercial enzyme preparation Cellic CTec3® HS. The effects of key parameters, namely extraction time, solid-to-liquid ratio, and enzyme loading, were evaluated for total phenolic content (TPC) and total flavonoid content (TFC). Optimization was achieved using “the larger-the-better” approach, and under optimal conditions (solid-to-liquid ratio 1% w/v, enzyme loading 200 U/g, and extraction time 6 h), TPC and TFC reached 27.54 ± 0.84 mg GAE/g DW and 9.22 ± 0.84 mg CAE/g DW, respectively, representing approximately a ten-fold and more than five-fold increase compared to conventional ethanol:water extraction. An additional hemicellulolytic enzyme preparation, Viscoferm® was evaluated under the optimized conditions, and EAE with Cellic CTec3® HS yielded higher TPC and TFC. The optimized extracts obtained with Cellic CTec3® HS and Viscoferm® were further assessed for their antioxidant activity, anti-aging activity (inhibition of tyrosinase activity), anti-diabetic activity (inhibition of amylase and α-glucosidase activity), and antibacterial activity (inhibition of E. coli growth). The Cellic CTec3® HS extract yielded highest antioxidant activity (IC50 =203.72 ± 23.99 µL extract/mL) and antibacterial activity (21.37 ± 2.00 %), whereas the Viscoferm® extracts demonstrated stronger antidiabetic activity with IC50 values of IC50 = 38.42 ± 2.45 mg/mL (α-amylase) and 43.84 ± 1.29 mg/mL (a-glucosidase). Both extracts showed relatively low tyrosinase inhibition; at 200 mg/mL, Cellic CTec3® HS and Viscoferm® exhibited 41.62 ± 0.10% and 18.69 ± 0.57% inhibition, respectively. These findings confirm the potential of Posidonia oceanica as a sustainable source of bioactive compounds with promising applications.