Lignans from the rhizomes of Iris tectorum

Abstract

Chemical examination of the ethanol extract of rhizomes of Iris tectorum led to the isolation and characterization of three new lignans, (7R,7'R,8S,8'S)-5'-methoxy-neo-olivil (1a), (7S,7'S,8R,8'R) -5'-methoxy-neo-olivil (1b), (7S,7'R,8S,8'S)-neo-olivil (2a), (7R,7'S,8R,8'R)-neo-olivil (2b), (7R,7'R,8S,8'S,7''S,8''S)-threo-neo-olivil-4'-O-8-guaiacylglycerol ether (3), together with six known ones (4-9). Among them, compounds 1 and 2 were found to be racemic mixtures, respectively, which were verified by chiral HPLC analysis, compound 3 was a new sesquineolignan. The structures were elucidated on the basis of extensive spectroscopic analysis. To our knowledge, this is the first report of lignan constituents isolated from I. tectorum. All compounds were evaluated for their cytotoxicity against five human tumor cell lines and none of them displayed significant toxicity in tested cell lines at a concentration of 10 μM.

Keywords: Cytotoxicity; Iris tectorum; Lignans; Racemic mixtures; Sesquineolignan.