22ND INTERNATIONAL SEAWEED SYMPOSIUM, COPENHAGEN Antiherpetic (HSV-1) activity of carrageenans from the red seaweed Solieria chordalis (Rhodophyta, Gigartinales) extracted by microwave-assisted extraction (MAE) Romain Boulho 1 & Christel Marty 1 & Yolanda Freile-Pelegrín 2 & Daniel Robledo 2 & Nathalie Bourgougnon 1 & Gilles Bedoux 1 Received: 28 November 2016 /Revised and accepted: 1 June 2017 # Springer Science+Business Media B.V. 2017 Abstract Carrageenan yield, physicochemical properties, and antiviral activity of the carrageenan from Solieria chordalis (Rhodophyceae, Solieriaceae) harvested at the Brittany coast (France) were investigated. S. chordalis carra- geenan was extracted by conventional and the microwave- assisted extraction (MAE) methods. The effect of different parameters during MAE extraction such as alkali concentra- tion (0, 0.5 and 1% KOH), extraction time (10, 20, and 25 min) and temperature (90 and 105 °C) were evaluated. Native carrageenan extracted by MAE had the highest yield (29.3%) after 10 min at 90 °C. After alkali treatment, carra- geenan yield ranged from 10.7 to 18.4%. No significant dif- ferences in the carrageenan yield were observed between MAE and conventional method under alkaline conditions. Chemical analysis and FTIR spectra revealed the presence of a predominant iota-carrageenan. Evaluation of the antiviral activity of S. chordalis carrageenan against HSV-1 (Herpes simplex virus type 1) showed a EC 50 of the iota- carrageenans fractions in the range of 3.2 to 54.4 μg mL -1 (MOI 0.01 ID 50 mL -1 ) without cytotoxicity in that range of concentrations. Keywords Solieria chordalis . Rhodophyta . Carrageenan . MAE . Antiherpetic activity . HSV-1 . Extraction Introduction Carrageenans are a family of linear sulfated galactans extract- ed mainly from red seaweed of the order Gigartinaceae. They are widely used for their gelling, thickening, and stabilizing properties in food, cosmetic, or pharmaceutical industries. Carrageenans are mainly obtained from certain species of Rhodophyta: Chondrus, Eucheuma, Gigartina, and Hypnea (Campo et al. 2009; Li et al. 2014). They are composed of alternating 3-linked-D-galactopyranose (G-units) and 4- linked D-galactopyranose (D-units) or 4-linked 3,6-anhydro- D-galactopyranose (DA-units), forming the disaccharide re- peating units of carrageenans. They are classified according to the presence of the 3,6-anhydro-bridge on the 4-linked ga- lactose residue and the position and number of sulfate groups. These polysaccharides can also be traditionally identified as kappa (κ-; G4S-DA), iota (ι-; G4S-DA2S), and lambda (λ-; G2S-D2S,6S) (Knutsen et al. 1994). The precursors of κ- and ι- respectively named mu (μ-) and nu (ν-) present sulfate groups in carbon 6, coded as D6S, and under alkaline treat- ment this group is converted in DA units. Polysaccharides extracted from Rhodophyta have been shown to exhibit antiviral activity against a wide spectrum of viruses including important human pathogenic agents such as human immunodeficiency virus (HIV), Herpes simplex virus (HSV), Vesicular stomatitis virus (VSV), and Cytomegalovirus (CMV) (Baba et al. 1988; Harden et al. 2009; Bouhlal et al. 2011; Serive et al. 2012). An example of these antiviral properties against anti-HIV is the gel named BCarraguard^, a carrageenan-based formu- lation used as vaginal microbicide that blocks HIV and other STD (sexually transmitted diseases) (Béress et al. 1993). Moreover, other red seaweed polysaccharides ex- tracted from the Dumontiaceae are available in capsules as a food supplement prescribed as an antiviral agent after * Romain Boulho romain.boulho@univ-ubs.fr 1 Laboratoire de Biotechnologie et Chimie Marines, EA3884, UBS, IUEM, F-56000 Vannes, France 2 Departamento de Recursos del Mar, Cinvestav - Unidad Merida, A.P. 73, Cordemex, 97310 Merida, Yucatan, Mexico J Appl Phycol DOI 10.1007/s10811-017-1192-5