New Anti‐HIV Agents Isolated From Two Euphorbia Species

Four previously unreported tigliane diterpenes ( 1 , 2 , 4 , and 6 ), along with two known tiglianes ( 3 and 5 ), were isolated from the latex of Euphorbia palustris and Euphorbia lucida . The structures of the isolated compounds were elucidated by spectroscopic techniques. Antiviral activity assays for compounds 1 ‒ 4 and 6 against HIV‐1 and HIV‐2 replication were performed on a CD4 + T cell line, MT‐4 cells. The compounds were tested for their ability to inhibit infection by the HIV‐1 strain NL4.3 and the HIV‐2 strain ROD. Compound 6 showed no activity against either strain, while compound 4 was only slightly active against HIV‐2 (EC 50 = 12.778 µM). Compounds 1 , 2 , and 3 were able to inhibit both HIV‐1 and HIV‐2 infections. Among them, compound 2 was the most potent, with EC 50 values of 0.069 µM for HIV‐1 NL4.3 and 0.023 µM for HIV‐2 ROD. The PBMC toxicity profile for compound 2 is also more favorable compared with MT‐4 cells with CC 50 = 50 μM.