Fucoidan Extracted From Sporophyll of Undaria pinnatifida Grown in Weihai, China - Chemical Composition and Comparison of Antioxidant Activity of Different Molecular Weight Fractions.

Jing Yu,Yu Zhao,Jun Lu,Jun Wu,Yang Liu,Shaoping Nie,Wei Zhu,Wei Tang,Shiping Yang,Xiaotong Yang,Qianqian Li,Amira Hassouna,William Lindsey White

doi:10.3389/fnut.2021.636930

Abstract

Fucoidan is a multifunctional marine carbohydrate polymer that differs in its chemical composition and bioactivity both between seaweed species and within species from different locations across the globe. In this study, fucoidan was extracted from the sporophyll of Undaria pinnatifida grown in Weihai, Shandong Province, China. Fucoidan fractions with molecular weight cutoffs (MWCO) of >300 kDa and <10 kDa were obtained via dialysis. The fucoidan standard from Sigma (Fstd, ≥95, CAS: 9072-19-9), fucoidan crude extract (WH), >300 kDa fraction (300k) and <10 kDa fraction (10k) were compared in terms of chemical composition and antioxidant capacity. Based on Fourier transform infrared spectroscopy (FT-IR) analysis, Fstd, WH, and 300k all showed strong bands around 830 cm−1, corresponding to the sulfate substituent in the molecule. The results showed that compared with WH and 300 k, the degree of sulfation at 10k was the lowest. From Nuclear magnetic resonance spectroscopy (NMR) result, the four fucoidan samples all contain α-L-fucose. The primary antioxidant ability of the 10k is significantly higher than that of the 300k, WH, and Fstd, but the secondary antioxidant capabilities of the 10k and 300k were similar, and both were higher than that of the butylated hydroxyanisole (BHA). The ferric reducing antioxidant ability was higher in the 300k and WH fractions. This demonstrates that fucoidan extracted from U. pinnatifida grown in Weihai, China should be a useful nutraceutical resource.

Highlights

Oxidative stress is a condition of imbalance between the intracellular reactive oxygen species (ROS, produced during the aerobic metabolism) production, and scavenging by the antioxidant defense system (1)
Fucoidan and its fractions extracted from Weihai U. pinnatifida have good antioxidant capacity
The results show that the low molecular weight fucoidan fraction contains lower sulfate and uronic acid content compared with the high molecular weight fraction and the crude fucoidan

Summary

Introduction

Oxidative stress is a condition of imbalance between the intracellular reactive oxygen species (ROS, produced during the aerobic metabolism) production, and scavenging by the antioxidant defense system (1). An excess of ROS has a damaging effect on cellular organelles as well as biomacromolecules, including proteins, lipids, and nucleic acids (2). The increased intracellular damage eventually leads to cell dysfunction and various diseases may occur (3). Discovering non-toxic compounds with strong antioxidant activity is beneficial for the prevention and treatment of diseases caused by oxidative stress. There is increased research in isolating bioactive compounds from terrestrial and marine organisms (1). Seaweeds contain high amounts of polysaccharides with many bioactivities, including antioxidant, anti-inflammation, anti-diabetes, anticoagulant, anti-hypertension, and anti-cancer activities

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Results

Conclusion