Antiinflammatory activity of natural triterpenes—An overview from 2006 to 2021

Terpenes are one of the most abundant classes of secondary metabolites produced by plants and can be divided based on the number of isoprene units (C₅ ) in monoterpenes (2 units-C₁₀ ), sesquiterpenes (3 units-C₁₅ ), diterpenes (4 units-C₂₀ ), triterpenes (6 units-C₃₀ ), etc. Chemically, triterpenes are classified based on their structural skeleton including lanostanes, euphanes, cycloartanes, ursanes, oleananes, lupanes, tirucallanes, cucurbitanes, dammaranes, baccharanes, friedelanes, hopanes, serratanes etc. Additionally, glycosylated (saponins) or highly oxidated/degraded (limonoids) triterpenes could be found in nature. The antiinflammatory effect and action as immunomodulators of these secondary metabolites have been demonstrated in different studies. This review reports an overview of articles published in the last 15 years (from 2006 to 2021 using PubMed and SciFinder database) describing the antiinflammatory effects of different triterpenes with their presumed mechanism of action, suggesting that triterpenes could be appointed as natural products with future pharmaceutical applicability.