biostudies-literatureSantos-Ferreira NPortuguese Foundation for Science and TechnologyEuropean Regional Development Fund (ERDF), through Centro 2020 and COMPETE 2020, and Portuguese national funds via Fundação para a Ciência e a Tecnologia (FCT)41https://www.ebi.ac.uk/biostudies/studies/S-EPMC12945184biostudies-literatureUnknown11(2)Infectious diseases remain a major global health challenge, underscoring the need for safe and accessible antiviral therapies. Natural products, particularly marine macroalgae, are promising sources of bioactive compounds with antiviral properties. This study evaluated the antiviral activity of extracts from two red algae collected along the Portuguese coast: two life stages (tetrasporophyte and female gametophyte) of <i>Chondracanthus teedei</i> var. <i>lusitanicus</i> and the algae <i>Osmundea pinnatifida</i>. Antiviral effects were assessed against Coxsackievirus A12 (CVA12) and a lentivirus (LV) vector model. Extracts from both algae inhibited viral replication in vitro at non-cytotoxic concentrations. The tetrasporophyte extract of <i>C. teedei</i> exhibited virucidal activity againstTropical medicine and infectious diseaseIn Vitro Antiviral Activity of Red Algae Extracts from <i>Chondracanthus teedei</i> var. <i>lusitanicus</i> and <i>Osmundea pinnatifida</i> Against Coxsackievirus A12 and a Lentiviral Vector.PMC12945184UID/04539/2025, LA/P/0058/2020UID/MAR/04292/2013Nogueira CSantos-Ferreira NNobrega CGoncalves TPereira LMota MPereira de Almeida LfalseIn Vitro Antiviral Activity of Red Algae Extracts from <i>Chondracanthus teedei</i> var. <i>lusitanicus</i> and <i>Osmundea pinnatifida</i> Against Coxsackievirus A12 and a Lentiviral Vector.Infectious diseases remain a major global health challenge, underscoring the need for safe and accessible antiviral therapies. Natural products, particularly marine macroalgae, are promising sources of bioactive compounds with antiviral properties. This study evaluated the antiviral activity of extracts from two red algae collected along the Portuguese coast: two life stages (tetrasporophyte and female gametophyte) of <i>Chondracanthus teedei</i> var. <i>lusitanicus</i> and the algae <i>Osmundea pinnatifida</i>. Antiviral effects were assessed against Coxsackievirus A12 (CVA12) and a lentivirus (LV) vector model. Extracts from both algae inhibited viral replication in vitro at non-cytotoxic concentrations. The tetrasporophyte extract of <i>C. teedei</i> exhibited virucidal activity against2026-01-01T00:00:00Z2026 Jan2026-07-14T09:20:58.918Z2026-07-14T03:03:27.612ZS-EPMC129451844174601110.3390/tropicalmed11020041