Abstract #662

# 662
Chemical modification of EPS to improve its health functionalities.
Siqian Li1, Nagendra Shah*1, 1The University of Hong Kong, Pokfulam Road, Hong Kong.

Exopolysaccharides (EPS) from S. thermophilus ASCC 1275 (ST1275) were isolated, purified and lyophilized and sulfated using SO3·pyridine complex and FT-IR was used to identify the characteristic bands in EPS and sulfated EPS. Changes in antioxidant activities after sulfate modification were examined by measuring FRAP, DPPH, superoxide anion and hydroxyl radical scavenging activities. Antibacterial activities and MIC tests of EPS and sulfated EPS were investigated against S. aureus, E. coli and L. monocytogenes by cylinder-plate diffusion method. Changes in anti-proliferative activities after sulfate modification were also examined on HepG2 and Caco-2 cells by MTT method, while changes in anti-inflammatory activities were examined in RAW264.7 macrophages. LPS was used to induce inflammation in RAW264.7 macrophages. The results revealed that the sulfate modification of EPS was achieved and the degree of sulfate modification, which was identified as the average number of oxygen-sulfate groups per residue in EPS, was 0.31. Additionally, bands in FT-IR spectra indicated that sulfate group was at the C6 position of the galactose skeleton in sulfated EPS. The results also revealed that the antioxidant activities of sulfated EPS were significantly (P < 0.05) improved compared with those of unmodified EPS in all the 4 antioxidant activities assays. Sulfated EPS had larger inhibition zone on S. aureus, E. coli and L. monocytogenes compared with those of unmodified EPS which indicated that the antibacterial activities of EPS were significantly (P < 0.05) improved after sulfate modification. Furthermore, sulfated EPS had lower MIC for S. aureus, E. coli and L. monocytogenes, which also suggested that the antibacterial activities of EPS improved after sulfate modification. Sulfated EPS had higher anti-proliferative activities on both HepG2 and Caco-2 cells. Also, pro-/anti-inflammatory (IL-6/IL-10; TNF-α/IL-10) cytokine secretion ratios of LPS-stimulated RAW264.7 macrophage were significantly (P < 0.05) decreased after sulfated EPS treatments at non-cytotoxic doses. In conclusion, our results indicated that antioxidant, antibacterial, anti-proliferative and anti-inflammatory activities of ST1275 EPS were improved after sulfate modification

Key Words: EPS, sulfate modification, antimicrobial activity

Speaker Bio
Nagendra P. Shah is currently a Professor of Food Science and Technology at the University of Hong Kong. He worked at Victoria University, Melbourne, Australia from January 1991 to December 2012 at various capacities including Associate Lecturer, Lecturer, Senior Lecturer, Associate Professor and Full Professor.  
Prof. Shah has a long and intensive research history in probiotics, prebiotics and functional foods that has led to a distinguished international reputation in this area. He has published 235 research papers, 27 book chapters, and 205 conference abstracts. Additionally, he has edited 2 books on Dairy Products and Quality Control, and Probiotic and Prebiotic. He has also edited 2 special issues of the International Dairy Journal. His work has been highly cited in peer-reviewed journals. His citation numbers and h-index are one among the highest in the world in the area of food science.
Prof. Shah’s work has been internationally recognized and has received several prestigious international awards for his contributions to research including the 1999 American Dairy Science Association Foundation Scholar Award, the 2003 Marschall Rhodia International Dairy Science Award, the 2008 Dairy Industry Association of Australia Loftus Hill award, the 2009 California Dairy Research Foundation William Haines International Dairy Science Award, the 2011 Australian Institute of Food Science and Technology (AIFST) Keith Farrer Award of merit, the 2013 American Dairy Science Association Distinguished Service Award. He is Fellow of the Australian Institute of Food Science and Technology and American Dairy Science Association.
He has served as the editor of the Journal of Food Science and Technology and ASEAN Food Journal and has been serving as editor of International Journal of Food and Nutrition and Advances in Chemical Science and associate editor of Journal of Food Science. Additionally, he is on the editorial board of several journals including International Dairy Journal and Journal of Dairy Science.