Isolation of Premyrsinane, Myrsinane, and Tigliane Diterpenoids from Euphorbia pithyusa Using a Chikungunya Virus Cell-Based Assay and Analogue Annotation by Molecular Networking

Six new premyrsinol esters (1-6) and one new myrsinol ester (8) were isolated from an aerial parts extract of Euphorbia pithyusa, together with a known premyrsinol (7) and two known dideoxyphorbol esters (9 and 10), following a bioactivity-guided purification procedure using a chikungunya virus (CHIKV) tell-based assay. The structures of the new diterpene,esters (1-6 and 8) were elucidated by MS and NMR. spectroscopic data interpretation. Compounds. 1-10 were evaluated against CHIKV replication, and results showed that the 4 beta-dideoxyphorbol ester 10 was the most active compound, with an EC50 value of 4:0 +/- 0.3 mu M and a selectivity index of 10.6. To gain more insight into the structural diversity of diterpenoids produced by E. pithyusa, the initial extract and chromatographic fractions were analyzed by LC-MS/MS. The generated data were procedure and revealed that dozens of unknown premyrsinane, myrsinane, and tigliane analogues were present. annotated using a molecular networking