A Biorefinery Approach to the Biomass of the Seaweed Undaria pinnatifida (Harvey Suringar, 1873): Obtaining Phlorotannins-Enriched Extracts for Wound Healing

Abstract

Brown seaweeds are recognized sources of compounds with a wide range of properties and applications. Within these compounds, phlorotannins are known to possess several bioactivities (e.g., antioxidant, anti-inflammatory, and antimicrobial) with potential to improve wound healing. To obtain phlorotannins enriched extracts from <i>Undaria pinnatifida</i>, a biorefinery was set using low-cost industry-friendly methodologies, such as sequential solid-liquid extraction and liquid-liquid extraction. The obtained extracts were screened for their antioxidant and antimicrobial activity against five common wound pathogens and for their anti-inflammatory potential. The ethanolic wash fraction (wE100) had the highest antioxidant activity (114.61 ± 10.04 mmol·mg^-1 extract by Diphenyl-1-picrylhydrazyl (DPPH) and 6.56 ± 1.13 mM eq. Fe II·mg^-1 extract by and Ferric Reducing Antioxidant Power (FRAP)), acting efficiently against Gram-negative (<i>Pseudomonas aeruginosa</i>) and Gram-positive (<i>Staphylococcus aureus</i>) bacteria, and showing a nitric oxide production inhibition over 47% when used at 0.01 µg·mL^-1. NMR and FTIR chemical characterization suggested that phlorotannins are present. Obtained fraction wE100 proved to be a promising candidate for further inclusion as wound healing agents, while the remaining fractions analyzed are potential sources for other biotechnological applications, giving emphasis to a biorefinery and circular economy framework to add value to this seaweed and the industry.