Releasing Bioactive Compounds from Brown Seaweed with Novel Cold-Adapted Alginate Lyase and Alcalase

The brown algae: Sargassum binderi sonder shows a potential nephroprotective activity in in-vivo experimental model

OBJECTIVES

This study aimed to investigate the protective activity of brown seaweed, the ethanolic and water extracts of Sargassum binderi (S. binderi) were examined. Anticancer drug, cisplatin is normally used for the treatment of solid tumors that cause acute kidney damage after assemblage in the renal tubules.

MATERIAL AND METHODS

It was an acute nephrotoxicity study, animals were divided into several groups randomly, cisplatin (7mg/kg i.p.) and normal saline were used as positive and negative control respectively. The S. bindari ethanolic and water extract were given orally in a dose of 200mg/kg for 5days. Various biomarkers were assessed to observe the nephroprotective potential, while antioxidant activities were investigated using reduced glutathione, catalase and malondialdehyde as oxidative stress. GCMS was performed to validate the presence of important therapeutic moieties.

RESULTS

The current result justified that pretreatment with S. binderi inhibited the elevation of antioxidant parameters and also showed protection against lipid peroxidation, induced by cisplatin challenge. The overall impact was the nephroprotection, which has been revealed from the results. GCMS evaluation of hexanes fraction revealed the presence of therapeutically important compounds including heptasiloxane, 3,7,11,15-tetramethyl-2-hexadecen-1-ol, hexadecamethyl, cyclooctasiloxane, and hexadecamethyl. These compounds have been reported for their antioxidant, antibacterial, anticancer, and antifungal activities.

CONCLUSION

S. binderi showed reno-protective effect by checking their well-known biochemical parameters probably due to the antioxidant activity as confirmed by the presence of compounds.

Direct Preparation of Alginate Oligosaccharides from Brown Algae by an Algae-Decomposing Alginate Lyase AlyP18 from the Marine Bacterium Pseudoalteromonas agarivorans A3

Alginate oligosaccharides (AOs), derived from alginate degradation, exhibit diverse biological activities and hold significant promise in various fields. The enzymatic preparation of AOs relies on alginate lyases, which offers distinct advantages. In contrast to the conventional use of sodium alginate derived from brown algae as the substrate for the enzymatic preparation of AOs, AO preparation directly from brown algae is more appealing due to its time and energy efficiency. Thus, the identification of potent alginate lyases and cost-effective brown algae substrates is crucial for optimizing AO production. Herein, we identified and characterized an alginate lyase, AlyP18, capable of efficiently decomposing algae, from a marine bacterium Pseudoalteromonas agarivorans A3 based on secretome analysis. AlyP18 is a mesothermal, endo-type and bifunctional alginate lyase with high enzymatic activity. Two brown algae substrates, Laminaria japonica roots and Macrocystis pyrifera, were used for the AO preparation by AlyP18. Upon optimization of AlyP18 hydrolysis parameters, the substrate degradation efficiency and AO production reached 53% and ~32% for L. japonica roots, respectively, and 77% and ~46.5% for M. pyrifera. The generated AOs primarily consisted of dimers to pentamers, with trimers and tetramers being dominant. This study provides an efficient alginate lyase and alternative brown algal feedstock for the bioconversion of high-value AOs from brown algae.

Degradation of Natural Undaria pinnatifida into Unsaturated Guluronic Acid Oligosaccharides by a Single Alginate Lyase

Here, we report on a bifunctional alginate lyase (Vnalg7) expressed in Pichia pastoris, which can degrade natural Undaria pinnatifida into unsaturated guluronic acid di- and trisaccharide without pretreatment. The enzyme activity of Vnalg7 (3620.00 U/mL-culture) was 15.81-fold higher than that of the original alg (228.90 U/mL-culture), following engineering modification. The degradation rate reached 52.75%, and reducing sugar reached 30.30 mg/mL after combining Vnalg7 (200.00 U/mL-culture) and 14% (w/v) U. pinnatifida for 6 h. Analysis of the action mode indicated that Vnalg7 could degrade many substrates to produce a variety of unsaturated alginate oligosaccharides (AOSs), and the minimal substrate was tetrasaccharide. Site-directed mutagenesis showed that Glu238, Glu241, Glu312, Arg236, His307, Lys414, and Tyr418 are essential catalytic sites, while Glu334, Glu344, and Asp311 play auxiliary roles. Mechanism analysis revealed the enzymatic degradation pattern of Vnalg7, which mainly recognizes and attacks the third glycosidic linkage from the reducing end of oligosaccharide substrate. Our findings provide a novel alginate lyase tool and a sustainable and commercial production strategy for value-added biomolecules using seaweeds.

High-level production of a novel alginate lyase (FsAly7) from Flammeovirga sp. for efficient production of low viscosity soluble dietary fiber from sodium alginate

Sodium alginate is one of the most abundant sustainable gum source for dietary fiber production. However, the preparation efficiencies of low viscosity soluble dietary fiber from sodium alginate remain low. Here, a novel alginate lyase gene (FsAly7) from Flammeovirga sp. was identified and high-level expressed in Pichia pastoris for low viscosity soluble dietary fiber production. The highest enzyme production of 3050 U mL-1 was achieved, which is by far the highest yield ever reported. FsAly7 was used for low viscosity soluble dietary fiber production from sodium alginate, and the highest degradation rate of 85.5 % was achieved under a high substrate content of 20 % (w/v). The molecular weight of obtained soluble dietary fiber converged to 10.75 kDa. FsAly7 catalyzed the cleavage of glycosidic bonds in alginate chains with formation of unsaturated non-reducing ends simultaneously in the degradation process, thus altered the chemical structures of hydrolysates. The soluble dietary fiber exhibited excellent properties, including low viscosity, high oil adsorption capacity activity (2.20 ± 0.03 g g-1) and high emulsifying activity (60.05 ± 2.96 mL/100 mL). This investigation may provide a novel alginate lyase catalyst as well as a solution for the efficient production of low viscosity soluble dietary fiber from sodium alginate.