| Abstract
| - An extensive phytochemical analysis of the saponin content has been undertaken on leek, Alliumporrum L., sown and collected at different seasons. As a result of this investigation, eight saponins(1−8) have been isolated, four of them (5−8) being novel compounds. Compounds 5 and 6, possessingthe same tetrasaccharide moiety of compounds 1 and 3, display very unusual spirostane aglycones,12-ketoporrigenin and 2,12-diketoporrigenin (named porrigenin C), respectively, recently isolatedfor the first time as free sapogenin in the same plant. Compounds 7 and 8 are rare cholestanebidesmosides possessing a di- and trisaccharide residues linked to a polyhydroxycholesterol aglycone,respectively. The structures of the isolated compounds have been determined by nondegradativespectroscopic analysis, mainly based on NMR. All the eight saponins isolated from leek were testedfor their cytotoxic activity against two different cell lines in vitro, and compounds 1, 2, and 6 resultedparticularly active. Keywords: Allium porrum L.; Liliaceae; saponins; NMR; cytotoxic activity
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