Antiviral potential of extracts from <i>Myriogloea major</i> against herpes simplex type 1, 2 and bovine coronavirus

SUMMARY Fucose‐rich sulfated polysaccharides such as fucoidans are primarily found in brown algae. These compounds possess interesting pharmacological perspectives for antiviral and antioxidant drug development. The brown alga Myriogloea major (Chordariaceae, Ectocarpales) is an endemic brown alga from Argentine Patagonia similar to other members of the Chordariaceae family used as a commercial source of fucoidans. In the present study, M. major was extracted with diluted hydrochloric acid (pH 2) solution in a protocol usually utilized for obtaining fucoidans. The dry weight from two extracts at different extraction stages (E1 and E2) represented 42% of the extracted dried biomass. Chemical analysis showed that the extracts contained between 15% (E2) and 20% (E1) of sulfate esters and approximately 80% of fucose constituents on their polysaccharides. The total phenolic content was lower than 1% (gallic acid equivalents). We analyzed the antioxidant activity of these extracts against the anti‐herpes simplex virus (HSV)‐1, HSV‐2 and bovine coronavirus. The antioxidant activity was lower than 50% at a concentration of 1 mg mL −1 in both extracts. Our findings demonstrate that, in the presence of these extracts, the viral adsorption and internalization were reduced by up to 75%. By applying its antiviral action to block the viral infection, the progeny virus released from host cells was significantly restricted, without affecting cell‐to‐cell spread of virus or virus viability.