New Insights into Antiviral Natural Formulations: Biopolymeric Films for the Prevention and Treatment of a Wide Gamma of Viral Infections

Viral infections remain a major concern, as existing treatments often yield inadequate responses or lead to the development of antiviral resistance in some cases. Fucoidan extracted from <i>Undaria pinnatifida</i> (F) is a natural sulphated polysaccharide that exhibits antiviral action. Despite its potential, the biomedical application of F is limited due to its difficult administration through trans-mucosal, skin, or oral ingestion. The most effective way to solve these problems is to propose novel methods of administration aiming to ensure better contact between the biopolymers and pathogens, leading to their inactivation. In this work, the synthesis of films based on chitosan (Ch)-coupled F is reported, aiming to generate a synergic effect between both biopolymers in terms of their antiviral and antioxidant capability. Biocomposites were prepared by a sonochemical method. They were characterized to infer structural properties, functionality, and possible F-Ch interactions by using Zeta potential, FTIR, and XRD techniques. The biocomposites showed excellent film-forming ability. They also exhibited improved antioxidant activity with respect to F and Ch individually and proved to be non-cytotoxic. These results demonstrate, for the first time, the antiviral activity of F:Ch biocomposites against bovine coronavirus and human viruses (adenovirus, poliovirus, herpes simplex, and respiratory syncytial virus), which could be applied in film form to prevent or treat viral infections.