Diterpenoids with Schistosomula-Killing and Anti-Fibrosis Activities In Vitro from the Leaves of Croton tiglium

The leaves of C. tiglium have been comprehensively researched for their structurally novel bioactive natural compounds, especially those with anti-schistosomiasis liver fibrosis activity, because ethyl acetate extract, which can be extracted from the leaves of C. tiglium, has good anti-schistosomiasis liver fibrosis effects. One new tigliane-type diterpene, 20-acetyl-13-O-(2-metyl)butyryl-phorbol (1), and nine known (2-10) analogues were isolated from the leaves of C. tiglium. Their structures were elucidated on the basis of spectroscopic analysis and ECD analysis. All diterpenoids had a stronger insecticidal effect on schistosomula, and compounds 2, 4, and 10 had good anti-liver-fibrosis effects. Furthermore, compared with the model group, compound 2 significantly downregulated the protein and mRNA expression of COL-I, COL-III, alpha-SMA, and TGF-beta 1 on TGF-beta 1-induced liver fibrosis in LX-2 cells. Meanwhile, compound 2 also regulated the expression of TGF-beta/Smad-pathway-related proteins. The results suggest that diterpenoids from C. tiglium may serve as potential schistosomula-killing and anti-liver-fibrosis agents in the future.