Review of natural plant-derived seco-triterpenoids and derived saponins from 2020 to 2023: new compounds, distributions, diverse activities and structure–activity relationships

Seco-triterpenoids are a unique class of triterpenoids possessing distinct structural features. Based on the differences in their parent nucleus, they can be divided into two categories: tetracyclic triterpenes and pentacyclic triterpenes, which are widely distributed across various plant species. Previous studies indicate that natural seco-triterpenoids have diverse chemical structures and exhibit extensive biological activities, including anti-tumor, anti-inflammatory, hypoglycemic, and neuroprotective effects. This review comprehensively summarizes recent research (2020–2023) on seco-triterpenoids and derived saponins, encompassing their chemical structures, plant distributions, pharmacological activities, structure–activity relationships, and future development trends. Furthermore, we utilized the latest bibliometric tool, VOSviewer, to conduct a keyword cluster analysis, enabling us to identify current research hotspots and patterns. Besides, we have cataloged and analyzed 351 compounds, inclusive of 298 tetracyclic triterpenoids and 53 pentacyclic triterpenoids, in order to provide valuable references for activity mining and structural modification of seco-triterpenoids, facilitating further clinical applications and developments. Collectively, seco-triterpenoids represent an important class of natural products with significant potential for pharmacological use. By summarizing recent research achievements, this review provides a beneficial resource for scientists in the field, promoting the exploration and development of seco-triterpenoid-based drugs.