New Sesquiterpene Lactones from Illicium floridanum

In continuation of our phytochemical investigation of Illicium floridanum Ellis (American star anise, star bush), three new sesquiterpene lactones possessing the anisatin−type carbon skeleton (8,9-seco-prezizaane skeleton), 14-acetoxy-3-oxofloridanolide (1), 13-acetoxy-14-(n-butyryloxy)floridanolide (2), and 3β-acetoxy-14-n-butyryloxy-10-deoxyfloridanolide (3), were isolated from fruits of this plant. Their structures were elucidated by 1D and 2D NMR measurements. The molecular structure of 1 was obtained by single crystal X-ray diffraction. The 11,3-δ-lactone structure of the compound previously described as debenzoyldunnianin in our previous communication, on grounds of NMR spectral evidence and X-ray crystallographic analysis is revised to a δ-lactone closed between C-11 and C-7 (compound 4). The neurotoxic sesquiterpene lactone anisatin (5) and its isomer 2α-hydroxyneoanisatin (3-deoxy-2α-hydroxyanisatin, 6) were also isolated and identified by spectroscopic means. The presence of the neurotoxin 5 in relatively high amounts in the fruits and leaves confirms and explains early reports on the toxicity of this plant.