Abstract

Lichens are natural products distributed in a variety of environments, including rocks, trees, soil, human structures, forests, mountains, and even in deserts and polar regions. In their quest to unravel the intricacies of lichen chemistry, most scientists have delved into the study of these organisms, finding a source of several distinctive and unique secondary metabolites, such as depsides, depsidones, dibenzofurans, anthraquinones and pulvinic acid derivatives. Hovewer, the fact that these organisms can also biosynthesise molecules such as terpenoids and sterols has been overlooked, since they are poorly studied in these organisms. To fill this knowledge gap, a comprehensive review of terpenoids and sterols reported up to 2023 has been carried out in the present study. A total of 177 lichen terpenoid compounds have been reported, and divided into 2 sesquiterpenes, 19 diterpenes, 5 sesterterpenes, 110 triterpenes, 8 rare terpenes and 33 sterols. These compounds have been described in different lichen species, where only a few compounds have been studied for their biological properties. Thus, we review lichen-derived terpenoids with an emphasis on their sources of origin to provide an impetus for future research.