It says, "involving chewing gum made from lablab beans (bean gum)".

https://en.wikipedia.org/wiki/Lablab --

Taiwanese researchers found that a carbohydrate-binding protein (i.e. a legume lectin) from lablab beans effectively blocks the infections of influenza viruses and SARS-CoV-2.[60] Researchers from Finland and USA found that extracts from chewing gum manufactured from lablab bean seeds had broad-spectrum anti-viral properties, likely due to the binding action of Flt3 Receptor Interacting Lectin (FRIL) on viruses; the anti-viral effect was similar to that of purified FRIL

Hunh I always assumed it was just some kind of modified natural rubber but it’s literally plastic (PVAc, PIB) that release microplastics into the saliva.