New bioactive dihydrofuranocoumarins from the roots of the Tunisian Ferula lutea (Poir.) Maire

A phytochemical investigation of the roots of Ferula lutea (Poir.) Maire led to the isolation of new dihydrofuranocoumarins as two inseparable isomers, (?)-5-hydroxyprantschimgin 1 and (?)-5-hydroxydeltoin 2, together with eight known compounds, (?)-prantschimgin 3, (?)-deltoin 4, psoralen 5, xanthotoxin 6, umbelliferone 7, caffeic acid 8, β-sitosterol 9 and stigmasterol 10. Their structures were elucidated on the basis of extensive spectroscopic methods, including 1D and 2D NMR experiments and mass spectroscopy analysis, as well as by comparison with literature data. The anti-acetylcholinesterase and cytotoxic effects of the isolates and antioxidant activities of the mixture (1+2) were also evaluated in this work. Results showed that the mixture (1+2) has the most cytotoxic activity with IC₅₀ values 0.29 ± 0.05 and 1.61 ± 0.57 μM against the cell lines HT-29 and HCT 116, respectively. The greatest acetylcholinesterase inhibitory activity (IC₅₀ = 0.76 ± 0.03) was exhibited by the xanthotoxin 6. In addition, the mixture (1+2) was investigated for its antioxidant activity and showed IC₅₀ values 18.56, 13.06, 7.59, and 4.81 μM towards DPPH free radical scavenging, ABTS radical monocation, singlet oxygen and hydrogen peroxide, respectively.