Distribution of Bioactive Polyphenolics and Carbohydrate Polymers in a Brown Alga: Macrocystis pyrifera

Author: Unnati Aum Dave

Dave, Unnati Aum, 2023 Distribution of Bioactive Polyphenolics and Carbohydrate Polymers in a Brown Alga: Macrocystis pyrifera, Flinders University, College of Medicine and Public Health

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Marine algae have served as an excellent source of bioactive compounds such as phenolics and polysaccharides, which have been utilised in complementary therapies of several diseases. Additionally, algal polysaccharides have also been used for modifying the consistency of food in food industries across the world due to their excellent rheological properties. This study aims to uncover the content of bioactive polyphenolics and polysaccharides in different tissues (leaf, stem, bladder and roots) of Macrocystis pyrifera, one of the most abundant brown algae in south-eastern Australia. The results will guide manufacturers to efficiently extract and utilise different bioactive compounds from M. pyrifera, which could enhance their applications in food and pharmaceutical industries.

In this study, one crude phenolic fraction (CPF) and three different polysaccharide fractions were extracted and separated by sequential solvent extraction. The total phenolic content of CPF was measured using Folin-Ciocalteu method, while the monosaccharide composition and carbohydrate content of all CPF and polysaccharide fractions was analysed by 1-phenyl-3-methyl-5-pyrazolone (PMP) derivatization and high-performance liquid chromatography (HPLC) method. The antioxidant activities of these fractions were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. In different algal tissues, CPF and a water insoluble polysaccharide fraction (WISF) seems to be more abundant with higher yield during extraction compared to the water-soluble polysaccharide fraction (WSF) and the alginate fraction (ALGF). Furthermore, the total phenolic and carbohydrate content varies in different algal tissues, although they have very similar monosaccharide composition. Root contains the highest amount of phenolics and total carbohydrates, while bladder shows the lowest amount. This is positively correlated to the results of DPPH assays, revealing highest antioxidant activity in roots followed by leaf, stem and bladder.

In conclusion, this study was successful in fulfilling the goal of estimating the proportion of polyphenolics and polysaccharides in M. pyrifera. This species proves to be an excellent source of compounds with potent antioxidant activity having potential applications in pharmaceuticals and cosmetic industries. Furthermore, these properties are beneficial to health industries to develop healthy foods

Keywords: Brown seaweeds, Macrocystis pyrifera, extraction, polysaccharides, polyphenols, monosaccharide analysis, distribution of bioactives.

Subject: Medical Biotechnology thesis

Thesis type: Masters
Completed: 2023
School: College of Medicine and Public Health
Supervisor: Vincent Bulone