Research progress on the main bioactive components and their corresponding biosynthetic enzymes in Cyclocarya paliurus

Cyclocarya paliurus (Batalin) Iljinsk., a medicinal and edible plant widely utilized in China, is a rich source of triterpenoids and flavonoids, which are recognized for their hypoglycemic, hypolipidemic, antioxidant, and antitumor properties. However, recent comprehensive summaries of its bioactive constituents and associated biosynthetic mechanisms remain limited. In this review, we systematically categorized the principal bioactive compounds isolated from C. paliurus, classifying triterpenoids into seven structural groups and flavonoids into four, based on their core skeletal frameworks. Notably, C-11 glycosylation was identified as a distinctive structural feature specific to C. paliurus triterpenoids. Furthermore, we summarized the key enzymes involved in the biosynthesis of these triterpenoids and flavonoids and, for the first time, proposed putative biosynthetic pathways by integrating current biochemical and genomic evidence. This review provides a comprehensive overview of the bioactive constituents and their associated biosynthetic enzymes in C. paliurus, offering valuable insights into the molecular basis of these natural products and establishing a foundation for future in vitro biosynthesis efforts.