Antimicrobial properties of Fomitopsis officinalis in the light of its bioactive metabolites: a review

Fomitopsis officinalis, also known as Laricifomes officinalis, is a medicinal polypore used for millennia (Agarikon) to contrast several diseases, particularly the pulmonary ones. A rich literature has dealt with its ethno-mycological aspects, but isolation and chemical characterisation of single compounds has only recently significantly developed, as well as in vitro tests for bioactivity. According to several reports there is evidence of a broad-spectrum antibacterial and antiviral activity by F. officinalis, including pathogens like Mycobacterium tuberculosis, Yersinia pseudotuberculosis and Staphylococcus aureus, as well as Ortopox virus. Chlorinated coumarins from mycelia and lanostane triterpenoids from basidiomes have been demonstrated to be directly responsible for antiviral-antibacterial and trypanocidal activity, respectively. A wider literature deals instead with crude extracts including an undetermined mixture of metabolites, whose efficacy in vitro is yet far from being standardised as extraction and treatment methodology are highly variable. Nevertheless, in vivo tests on bees provided promising results in order to develop sustainable solutions against the pathogens responsible for colony collapse disorders. Despite increasing attention has been paid to other medicinal aspects of this polypore, such as immune-tropic or antitumor, this review rationally reports and critically analyses the available knowledge by focusing on aspects of antimicrobial properties.