Optimization of Microwave-Assisted Extraction of Polysaccharides from Ulva pertusa and Evaluation of Their Antioxidant Activity

Abstract

The use of green marine seaweed Ulva spp. as foods, feed supplements, and functional ingredients has gained increasing interest. Microwave-assisted extraction technology was employed to improve the extraction yield and composition of Ulva pertusa polysaccharides. The antioxidant activity of ulvan was also evaluated. The impacts of four independent variables, i.e., extraction time (X1, 30 to 60 min), power (X2, 500 to 700 W), water-to-raw-material ratio (X3, 40 to 70), and pH (X4, 5 to 7) were evaluated. The chemical structure of different polysaccharides fractions was investigated via FT-IR and the determination of their antioxidant activities. A response surface methodology based on a Box–Behnken design (BBD) was used to optimize the extraction conditions as follows: extraction time of 43.63 min, power level of 600 W, water-to-raw-material ratio of 55.45, pH of 6.57, and maximum yield of 41.91%, with a desired value of 0.381. Ulvan exerted a strong antioxidant effect against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and showed reducing power in vitro. Ulvan protected RAW 264.7 cells against H2O2-induced oxidative stress by upregulating the expression and enhancing the activity of oxidative enzymes such as superoxide dismutase (SOD) and superoxide dismutase (CAT). The results suggest that the polysaccharides from U. pertusa might be promising bioactive compounds for commercial use.

Macroalgae as a Source of Valuable Antimicrobial Compounds: Extraction and Applications

“…This approach demonstrated to be a high-efficient and practical method for the bioactive compounds extraction from seaweeds [ 178 ]. Others seaweeds such as S. thunbergii , and red algae P. haitanensis [ 179 ]; G. lemaneiformis [ 180 ]; U. pertusa [ 181 ]; S. ceylonensis , U. lactuca , G. lemaneiformis and Durvillaea antarctica , [ 180 ] were also subject to MAE to obtain polysaccharides. Shuntaro Tsubaki et al [ 182 ] proved the efficacy of microwave-assisted hydrothermal extraction for the production of sulfated polysaccharides from U. meridionalis , U. ohnoi and M. latissimum [ 182 ].…”

Ulvan, a Polysaccharide from Macroalga Ulva sp.: A Review of Chemistry, Biological Activities and Potential for Food and Biomedical Applications

“…In addition, the major fraction of ulvans are distributed as a single polydispersed population on gel permeation chromatography. The polymolecularity was due to linear xyloglucan structure of ulvans [24,25]. Ulvan extracted from U. lactuca contains polysaccharides that can be used as natural fibers or matrix; they can also be modified for other purposes, including as part of a composite [26].…”

A Critical Review of the Abilities, Determinants, and Possible Molecular Mechanisms of Seaweed Polysaccharides Antioxidants

“…Generally, more than two assays are applied to measure the antioxidant ability ( Table 1 ). For example, the ulvan extracted from U. pertusa by the method of microwave-assisted extraction exerted a high antioxidant ability as evaluated by the radical-scavenging activity of DPPH and ABTS, and reducing power [ 94 ]. However, the results from different assays do not always agree, which may be attributed to the diverse mechanisms of the antioxidants.…”

“…For examples, the neoagaro-oligosaccharides (NAOs), acid hydrolyzed from agar, have been reported to benefit the antioxidative system of type 2 diabetes mellitus (T2DM) mice by upregulating the activity of GPx and SOD while significantly reducing the concentration of MDA [ 108 ]. Ulvan alleviated the damage of RAW264.7 murine macrophage cell lines induced by H 2 O 2 through the upregulation of levels of SOD and CAT [ 94 ]. Chen et al investigated the ROS scavenging ability of agaro-oligosaccharides in vitro through the DPPH assay, then further studied the attenuating effect of oligosaccharides on ROS production in human liver L-02 cells treated by the oxidative agents, H 2 O 2 and antimycin A [ 109 ].…”