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 Undaria pinnatifida, 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 (Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) 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.
Highlights
To recover a fraction of U. pinnatifida enriched in phlorotannins, while promoting a circular economy approach to the fractions thereby obtained, a preliminary series of sequential solid–liquid extractions (SLE) and liquid–liquid extractions (LLE) was designed and performed (a comprehensive flowchart is presented in Supplementary Materials (S1))
When ethanolic and 50% EtOH extracts of Sargassum muticum, obtained at three different temperatures were compared, the highest content of phenolics was detected in EtOH extracts, while the lowest was found in water extracts [79]. This way, the results presented here do not agree with Machu et al [80] findings, that reported that water is the best solvent for phenolics extraction from Eisenia bicyclis, Sargassum fusiforme, Saccharina japonica, and U. pinnatifida in comparison to the aqueous MeOH and Acetone extracts, neither the results from Leyton et al [75], where the optimal conditions for the extraction of phlorotannins were pretreatment with hexane, followed by extraction with water
This work presents an overview of the available innovative solutions to obtain, explore, and exploit seaweed compounds to apply in the biomedical field, since, new wound healing products with antimicrobial and anti-inflammatory activity are needed
Summary
The biodiversity that characterizes the marine environment has contributed to the bioprospection of unique compounds in the last years, culminating in an unprecedented development of blue biotechnology [1]. A major part of the research in this field has focused on seaweeds, as they are recognized potential sources of biotechnologically relevant extracts and/or compounds for a myriad of applications [2]. Brown seaweeds are the most economically valuable due to the application of their bioactive compounds, namely alginate, in the food and beverage industry, with a market valued at USD 706.9 million in 2019 [3]. Other valuable bioactive compounds in brown seaweeds are sulphated polysaccharides, carotenoids, polyphenols, and phytosterols [5,6]. The polyphenolic compounds of brown seaweed are a group of molecules exclusively produced by these organisms, known as phlorotannins
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