International Journal of Biological Macromolecules 34 (2004) 63–71 Anti-herpes simplex virus activity of sulfated galactans from the red seaweeds Gymnogongrus griffithsiae and Cryptonemia crenulata Laura B. Talarico a,† , Rosiane G.M. Zibetti b,† , Paula C.S. Faria b,† , Luis A. Scolaro a , Maria E.R. Duarte b , Miguel D. Noseda b , Carlos A. Pujol a , Elsa B. Damonte a,∗ a Laboratorio de Virolog´ıa, Departamento de Qu´ımica Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, 1428 Buenos Aires, Argentina b Departamento de Bioqu´ımica e Biologia Molecular, Universidade Federal do Paraná, P.O. Box 19046, CEP 81531-990 Curitiba, Paraná, Brazil Abstract This study presents the chemical composition and antiviral activity against herpes simplex virus type 1 (HSV-1) and 2 (HSV-2) of sulfated galactan crude extracts and main fractions obtained from two red seaweeds collected in Brazil, Gymnogongrus griffithsiae and Cryptonemia crenulata. Most of the eighteen tested products, including homogeneous kappa/iota/nu carrageenan and dl-galactan hybrid, exhibited antiherpetic activity with inhibitory concentration 50% (IC 50 ) values in the range 0.5–5.6 g/ml, as determined in a virus plaque reduction assay in Vero cells. The galactans lacked cytotoxic effects and showed a broad spectrum of antiviral activity against HSV-1 and HSV-2. No direct virus inactivation was observed after virion treatment with the galactans. The mode of action of these compounds could be mainly ascribed to an inhibitory effect on virus adsorption. Most importantly, a significant protection against a murine vaginal infection with HSV-2 was afforded by topical treatment with the sulfated galactans. © 2004 Elsevier B.V. All rights reserved. Keywords: Herpes simplex virus; Antiviral activity; Sulfated polysaccharide; Kappa/iota/nu carrageenan; d,l-Galactan hybrid; Red seaweed 1. Introduction Sulfated polysaccharides are known to present a broad range of biological activities comprising antiviral and anti- tumoral action, variable effects on the immune system and anticoagulant activity. In particular, the antiviral effect of naturally occurring and chemically synthesized polysulfates against a variety of enveloped viruses, such as herpes sim- plex virus type 1 (HSV-1) and 2 (HSV-2), human immunod- eficiency virus (HIV), human cytomegalovirus, respiratory syncytial virus and influenza virus, has been reported [1,2]. At present, the availability of safe and potent antiviral agents against herpesviruses is far from ideal. Acyclovir (ACV) is the compound of choice for clinical use against HSV-1 and HSV-2, in systemic or topical therapy [3]. Other ACV-related nucleoside analogs, all targeted against viral DNA synthesis, have been more recently licensed for human use [4]. However, the emergence of viral resistant variants ∗ Corresponding author. Fax: +54-11-4576-3342. E-mail address: edamonte@qb.fcen.uba.ar (E.B. Damonte). † LBT, RGMZ and PCSF contributed equally to this paper. after prolonged treatment in immunocompromised patients is one of the main reasons for the continuous search of novel antiherpetic agents. In this context, the mentioned sulfated polysaccharides represent an interesting type of compounds to pursue as promising virus inhibitors. Red seaweeds contain large amounts of polysaccha- rides, and sulfated galactans represent the main matrix polysaccharide. They consist of linear chains of alternat- ing 3-linked -d-galactopyranosyl residues (A units) and 4-linked -galactopyranosyl (or 3,6-anhydrogalactosyl) residues (B units). The latter residues are from the d-series in the case of carrageenans and l-series for agarans, and with d- and l-galactose interspersed on the same molecule in the dl-galactan hybrids [5,6]. These structures are usu- ally substituted with sulfate esters, pyruvic acid ketals, methoxyl groups and may have different degrees and kinds of branching [5]. Previous reports have described the effective inhibitory action of this type of natural polysulfates against HSV-1, HSV-2 and HIV [7–14]. This study presents the chemical composition and in vitro and in vivo antiherpetic properties of sulfated galac- 0141-8130/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.ijbiomac.2004.03.002