Sulfated polysaccharides from common smooth hound: Extraction and assessment of anti-ACE, antioxidant and antibacterial activities

•Sulfated polysaccharides (SPs) were extracted from smooth hound viscera.•SPs displayed high antioxidant activities, particularly with SP1.•SPs were found to be potential antibacterial agents.•Anion exchange chromatography showed various carbohydrate fractions.•Both SPs showed the presence of GalA and GlcNAc in large amounts. The present study investigates biological activities of sulfated polysaccharides (SPs) isolated from smooth hound by precipitation with cetylpyridinium chloride (SP1) or ethanol (SP2). SP1 showed the highest amounts of sulfated groups (10.2%) and proteins (7.84%) and high molecular weight sugars. Infrared spectroscopic analysis showed typical peaks of sulfated polysaccharides, particularly for the SP1 that was characterized by the presence of O=S=O groups and acetyl groups. Interestingly, SPs displayed important angiotensin I converting enzyme (ACE) inhibitory (IC50=1.04 and 0.75mg/ml for SP1 and SP2, respectively), antibacterial (Gram+ and Gram−) and antioxidant activities (reducing power, metal chelating activity, β-carotene bleaching inhibition and DNA nicking assay). Moreover, SPs fractionation by DEAE-cellulose column chromatography showed one peak during the buffer elution phase and three major fractions during the linear gradient of NaCl. The overall data suggested that SPs could be used as natural antioxidant, antimicrobial and anti-ACE ingredient to formulate functional foods.