O. Simon confirmed the statements of Knop and Schnedermann, finding cetraric acid in the plant in a free state.

[2][3] Rao and colleagues published the ultraviolet and infrared spectra of some lichen depsidones, including protocetraric acid, in 1967.

Protocetraric acid has broad spectrum antimicrobial properties against some pathogenic microbes such as Salmonella typhi.

[6] It also has weak activity against SARS-CoV-2 3C-like protease (Ki of 3.95 μM), as does the related depsidone salazinic acid, and therefore it is being studied as a scaffold for the potential discovery of more potent drugs for the treatment of COVID-19.

[9] Some authors have explicitly named protocetraric acid in the specific epithets of their published lichen species, thereby acknowledging the presence of this compound as an important taxonomic characteristic.