Bioactive daphnane diterpenes from the flower buds of Daphne genkwa (Thymelaeaceae)

Four diterpenes of the daphnane type were isolated from a methanol extract of the flower buds of Daphne genkwa, the two of them were new structures named genkwadanes J (1) and K (2). Their structures were determined based on analysis of their 1D- and 2D-NMR, HRESIMS and ECD calculations. Among the isolates, the cytotoxicity was assessed via the MTT method using the K562, MCF-7 and HeLa cancer cell lines, the positive control was taxol. Compounds 1 and 3 exhibited appreciable cytotoxic activity against the K562 cancer cell line with IC₅₀ values between 6.58 and 5.33 μM. Compounds 2 and 4 showed noteworthy inhibitory effects against the MCF-7 cell line with IC₅₀ values of 3.25 and 2.56 μM, respectively. All compounds showed weak cytotoxicities to the Hela cell line with IC₅₀ values in the range of 20.19-55.23 μM.