Seco-Tetracyclic and Seco-Pentacyclic Triterpenoids from Nature: Phytochemistry, Biological Activity: A Review

Seco-tetracyclic and seco-pentacyclic triterpenoids are a special class of triterpenoids with ring/rings cleaved on the original skeleton structures. A class of important triterpene derivatives, secotetracyclic and seco-pentacyclic triterpenoids, have long stimulated the interest and attention of botanists and natural products chemists. There is no systematic and comprehensive review for them. This review is focused on the phytochemical investigations and biological activities of seco-tetracyclic and seco-pentacyclic triterpenoids from nature, covering the literature from 2000-2019. This review describes 310 seco-tetracyclic and 139 seco-pentacyclic triterpenoids discovered from 154 species belong to 97 genera, which cover the chemical structures, types, sources, and bioactivities of compounds. The literature from 2000-2019 is reviewed and 208 references are cited.