Antimitotic effects of usnic acid on different biological systems.

Usnic acid is a biosynthesis product characteristic of several epiphytic lichens such as Evernia, Cladonia and Parmelia. Usnic acid has several interesting biological properties. It is an antibiotic and it also seems to exert an antimitotic action. It has even been postulated that usnic acid can play a role as an environmental indicator, since its concentration varies according to the presence of toxic agents. A series of tests have been run on different biological systems such as fungi, yeasts, plant cells and neoplastic human cell cultures in order to make a general evaluation of the properties of usnic acid and to highlight any analogy between its effects on phylogenetically distant organisms. The results obtained confirm some of the already known properties of usnic acid and identify concentration ranges that are active against cells from different organisms. Furthermore, at low concentrations, the acid displays a capacity to stimulate cell metabolism in some of the biological systems tested.