ORIGINAL ARTICLE Immunomodulatory and Antioxidant Activities of Sulfated Polysaccharides from Laminaria ochroleuca, Porphyra umbilicalis, and Gelidium corneum Roberto T. Abdala Díaz 1 & V. Casas Arrojo 1 & M. A. Arrojo Agudo 1 & C. Cárdenas 2 & S. Dobretsov 3,4 & F. L. Figueroa 1 Received: 12 November 2018 /Accepted: 8 May 2019 # Springer Science+Business Media, LLC, part of Springer Nature 2019 Abstract Seaweeds of the genera Laminaria, Gelidium, and Porphyra have been used in both food and non-food industries due to their unique properties and characteristic biological activity. This study assesses the antioxidant activity and immunomodulatory properties of the acidic polysaccharides extracted from Laminaria ochroleuca, Porphyra umbilicalis, and Gelidium corneum collected in the Atlantic coast of Tarifa (Cadiz, Spain). The proliferation of murine cell line RAW 264 decreased with increasing concentration of polysaccharides of the three algal species. The highest both antioxidant (25.69 μmol TE g -1 DW) and immu- nomodulatory activities were observed in the sulfated polysaccharides of L. ochroleuca compared to that of P. umbilicalis and G. corneum. Sulfated polysaccharides of L. ochroleuca presented high potential anticancer activity in cell lines of human colon cancer HTC-116 (IC 50 = 0.44 mg mL -1 ), human malignant melanoma G-361 (IC 50 = 5.42 mg mL -1 ), breast adenocarcinoma human MCF-7 (IC 50 = 8.32 mg mL -1 ), and human leukemia U-937 (IC 50 = 3.72 mg mL -1 ). It is concluded that metabolites of L. ochroleuca can offer significant advantages for the pharmaceutical industry, particularly when macrophage activation is required. Keywords Antioxidant activity . Immunomodulator . Macroalgae . Seaweeds . Sulfated polysaccharides Introduction Algae are widely recognized for their nutritional value and commonly used as component of the diet in certain areas, such as East Asia (Tiwari and Troy 2015; Wells et al. 2017). For decades, seaweeds have been an important source of second- ary metabolites (agar and carrageenan, for example, are com- monly used as texturing agents in the food industry). Different species of Laminaria and Porphyra genus are particularly appreciated both for their flavor and their properties in cos- metics and food industries (Kim 2012). Sulfated polysaccha- rides from marine algae offer a broad scope of physiological properties, finding diverse applications as anticoagulant, antihyperlipidemic, antiviral, and antitumor agents (Jiao et al. 2011; Abdala-Díaz et al. 2011). Some authors have re- ported that sulfated polysaccharides in brown algae are bound to play a significant role in the future of cosmetic industry (Thomas and Kim 2013). Algal polysaccharides are free radical scavengers and therefore have antioxidant effect and prevent oxidative dam- age in living organisms (Rupérez et al. 2002). Until recently, algal sulfated polysaccharides were largely ignored as a valu- able source of antioxidants (Rocha de Souza et al. 2007). Algal fucan fractions have also shown significant antioxidant properties in superoxide radical and hydroxyl radical scaveng- ing assays (Stengel and Connan 2015). Superoxide radical scavenging activity correlated positively with the sulfate con- tent of the polysaccharide fractions (Wang et al. 2010). Antioxidant activity in carrageenans (Rocha de Souza et al. 2007) and ulvans (Qi et al. 2005) also appeared to correlate * Roberto T. Abdala Díaz abdala@uma.es 1 Ecology Department, Faculty of Sciences, Malaga University, Campus de Teatinos s/n, CP 29071 Malaga, Spain 2 Biochemistry Department, Faculty of Sciences, Malaga University, Campus de Teatinos s/n, CP 29071 Malaga, Spain 3 Department of Marine Science and Fisheries, College of Agricultural and Marine Sciences, Sultan Qaboos University, PO Box 34, 123 Al Khoud, Muscat, Oman 4 Center of Excellence in Marine Biotechnology, Sultan Qaboos University, PO Box 50, 123 Al Khoud, Muscat, Oman Marine Biotechnology https://doi.org/10.1007/s10126-019-09905-x