Evaluation of antioxidant properties of Brown Seaweed Polysaccharides (BSP) for prebiotic studies

Abstract

Introduction: Human gut microbiota plays a magnificent role in balancing the condition of health and diseases. Globally, gut microbiota mediated immune system are gaining attention nowadays for the treatment of several health ailments such as diabetes, cancer and malnourishment. Bioactive compounds such as polysaccharides are found beneficial for enhancing the activity of gut microbes due to the stable existence of worthy dietary fibres. Marine macroalgae or seaweeds are the appropriate bioresources to be explored for its biotherapeutic properties of dietary fibres. Methods: This study aimed to investigate the extraction efficiency of polysaccharides from the brown seaweeds which were earlier collected from the southeast coast of India, Tuticorin [8.81°N; 78.16°E]. Four edible Indian brown seaweeds such as Sargassum wightii, Spatoglossum asperum, Calpomenia sinuosa and Padina tetrastromatica were screened to explore the potential uses as prebiotic food ingredients. Four different extraction methods such as conventional solvent based extraction (SBE), microwave assisted extraction (MAE), ultrasonication based extraction (UBE) and enzyme assisted extraction (EAE) were attempted in the present study. Results: The extraction efficiency was calculated based on percentage yield and found to be 30-40% for SBE, 40-60% for MAE and UBE and 55-70% for EAE methods. The present study revealed that processing time as the important factor for extraction process which should be further optimized. UBE (20 KHz, 30 min) and MAE (2.5GHz, 15 min) require minimum time and found to be thermoeffective with improved efficiency of 5-25% while compared to SBE (24 h). The inclusion of particular enzymes αamylase, protease, amyloglucosidase improved extraction efficiency with meagre impact on total sugar yield, while compared with the SBE method. Discussion: Carbohydrates are released by thermal hydrolysis in SBE method, while MAE and UBE rupture the cell wall with increased porosity by dielectric heating, compression and rarefaction respectively. This porous nature further enhanced the release of carbohydrates. EAE resulted in higher extraction efficiency could be due to complete breakdown of cell wall, linkage bonds, and interior complex storage materials