Rearranged Jatrophane Diterpenoids from Euphorbia helioscopia with 5/6/6/4 and 5/6/6/5 Fused Skeletons and Potent Anti-ZIKV Activity.

Three rearranged jatrophane diterpenoids, eupheilosnoids A-C (1-3), were isolated from Euphorbia helioscopia. Compound 1 possesses a fused 5/6/6/4 tetracyclic carbon skeleton, whereas compounds 2 and 3 feature a 5/6/6/5 ring system. Compounds 1-3 were evaluated for anti-ZIKV activity. Among them, compound 2 exhibited potent anti-ZIKV activity with an EC50 of 2.09 μM, which was significantly superior to that of the positive control ribavirin (RBV). Further studies revealed that compound 2 significantly inhibited the expression of ZIKV envelope protein (ZIKV-E).