Quaternary ammonium compounds are cationic detergent, as well as disinfectants and are commonly used to emulsify and remove organic material.
They are also known to be effective against fungi, amoebas and enveloped viruses. Quaternary ammonium compounds are believed to act by disrupting the cell membrane or viral envelope and are lethal to a wide variety of organisms.
Excerpt from an article “How we know disinfectants should kill the COVID-19 coronavirus”, by Kerri Jansen March 13, 2020, in Chemical & Engineering News (C&EN):
“Alcohol-based products disintegrate the protective lipids. Quaternary ammonium disinfectants, commonly used in healthcare and food-service industries, attack protein and lipid structures, thwarting the pathogen’s typical mode of infection. The novel virus is one of the easiest virus types to deactivate, though SARS-CoV-2–specific data are lacking”.
In her article, Jansen further reports that “Enveloped viruses like SARS-CoV-2, the virus that causes COVID-19, which rely on a protective lipid coating—are the easiest type to deactivate. In contrast with many gastrointestinal viruses like norovirus which have a tough protein shell called a capsid, viruses with this fatty wrapping are relatively vulnerable”.
Virologist Seema Lakdawala of the University of Pittsburgh describes it thus: “It’s much more sensitive. It’s sort of a wimpy protective shell”.
There are a few ways to burst this flimsy shell – and the bactericidal action of the quaternaries has been attributed to the inactivation of energy-producing enzymes, denaturation of essential cell proteins and disruption of the cell.
If you’d like to read more, here’s the link: