Current knowledge on the extraction, purification, identification, and validation of bioactive peptides from seaweed

Abstract

Current knowledge on the extraction, purification, identification, and validation of bioactive peptides from seaweed Seaweed (macroalgae) is considered as a sustainable bioresource rich in high-quality nutrients such as protein. Seaweed protein can be used as an alternative to other protein sources. Furthermore, these proteins are natural reservoirs of bioactive peptides (BAPs) associated with various health benefits such as antioxidant, antihypertensive, and antidiabetic activities. However, seaweed-derived BAPs remain underexploited due to challenges that arise during protein extraction from algal biomass. Coupled with this, limited proteomic information exists regarding certain seaweed species. This review highlights the current state of the art of seaweed protein extraction techniques, e.g., liquid, ultrasound, microwave, pulsed electric field, and high hydrostatic pressure assisted extraction. The review also focuses on the enzymatic hydrolysis of seaweed proteins and characterization of the resultant hydrolysates/peptides using electrophoretic and chromatographic techniques. This includes reference to methods employed for separation, fractionation, and purification of seaweed BAPs, as well as the methodologies used for identification, e.g., analysis by mass spectrometry. Furthermore, a bioinformatics or in silico approach to aid discovery of seaweed BAPs is discussed herein. Based on the information available to date, it is suggested that further research is required in this area for the development of seaweed BAPs for nutraceutical applications.

Proteomic characterization of pilot scale hot-water extracts from the industrial carrageenan red seaweedEucheuma denticulatum

“…Low protein yields using simple aqueous extraction from E. denticulatum has previously been reported in literature (Bjarnadóttir et al, 2018; Fleurence, Le Coeur, Mabeau, Maurice, & Landrein, 1995). This, in turn, implies that there is still a significant potential for protein extraction from the seaweed and other approaches such as for instance pressurized and supercritical fluid extraction (Herrero, Sánchez-Camargo, Cifuentes, & Ibáñez, 2015), addition of cofactors (Harnedy & FitzGerald, 2013a; Maehre, Edvinsen, Eilertsen, & Elvevoll, 2016), microwave-assisted extraction (Magnusson et al, 2019), ultrasound-assisted extraction (Bleakley & Hayes, 2017), or any combination thereof (Cermeño, Kleekayai, Amigo-Benavent, Harnedy-Rothwell, & FitzGerald, 2020), may be more suitable. Enzyme assisted extraction (EAE) is an emerging technology for seaweed protein extraction, showing great potential (Hardouin et al, 2016; Naseri, Marinho, Holdt, Bartela, & Jacobsen, 2020; Terme et al, 2020; Vásquez, Martínez, & Bernal, 2019).…”

Algal proteins: Production strategies and nutritional and functional properties

“…Moreover, the physical disruption of cells prevents chemical contamination of the algal preparation, while preserving a good percentage of the internal cell components (Show et al, 2015). When physical methods are used, the protein yield has a range between 41 and 90 % for microalgae and 15-80% for macroalgae (Cermeño et al, 2020;Safi et al, 2014). The maximum protein yield found for microalgae, using only physical methods, was on Porphyridium cruentum (90%) under high-pressure conditions, where a 2.2 kW disruptor was applied in two passes at 2700 bar to a freeze-dried sample at a concentration of 2% of dry weight (Safi et al, 2014).…”

“…There are various actuation mechanisms involved but, generally, they operate by destroying the cell wall of algae through the use of enzymes, solvents, osmotic pressure or by precipitating cell wall proteins. These methods can result in a protein yield ranging between 15.8 and 73.5% for microalgae and 25 to 42% for macroalgae (Cermeño et al, 2020;Hardouin et al, 2016;Safi et al, 2014). Similarly to physical methods, the maximum protein yield found for microalgae using only nonphysical methods was attained with Porphyridium cuentrum (57.3 ± 3.84% dw) by means of a chemical treatment with pH changes and successive centrifugation steps.…”

“…Thus, some enzymes (e.g., cellulase, xylanase, viscozyme, and lysozyme) can be used to break these complex molecules and increase cell disruption efficacy, allowing higher protein yields. However, this technique requires knowledge about the composition and complexity of each algal cell wall in order to select the most reliable enzyme to break specific macromolecules, which could affect the efficiency of the process (Cermeño et al, 2020). On the other hand, enzymatic hydrolysis can be used as an alternative to chemical extraction because it is performed in an ecologically friendly and non-hazardous manner and is a low-energy procedure (Soto-Sierra et al, 2018).…”

“…Among the chemical extraction methods (e.g., acids, bases, and surfactants), alkaline extraction (e.g., using NaOH) is the most common and it has been established as an effective method for solubilization of hydrophobic proteins by the degradation of chemical bonds (Cermeño et al, 2020). The disruption efficiency is strongly dependent on the choice of solvent because it will define the type and selectivity of interactions with the cell wall.…”