Lignans in seeds of Linum species
Lignans in seeds of Linum species
Year: 2012
Authors: Schmidt, T.J. Klaes, M. Sendker, J.
Publication Name: Phytochemistry
Publication Details: Volume 82; Pages 89 – 99.
Abstract:
Mature seeds of 20 Linum species were analyzed for their content of lignans. The seeds of common flax (Linum usitatissimum L.) are known to contain as characteristic lignan sesoisolariciresinol diglucoside (SDG), whose presence in seeds of some other Linum species has also been reported. In order to investigate the material for the presence of such very polar lignans as well as for less polar non glycosidic lignans as frequently found in aerial parts ofLinum species, polar and non-polar extracts of each sample were analyzed by HPLC/ESI-MSMS. SDG was detected in 15 of 16 investigated seed samples of taxa representing sections Linum and Dasylinum. None of eight samples of taxa from sections Syllinum and Linopsis contained detectable amounts of SDG. Quite interestingly, most of the SDG positive samples contained the 8R, 80R isomer exclusively while only three (including L. usitatissimum ) contained the 8S, 80S stereoisomer as the predominant form. As a most noteworthy finding, the dichloromethane extracts obtained from seeds of several Linum species were found to contain significant concentrations of non-polar cyclolignans of the arylnaphthalene dihydronaphthalene
lactone type or, alternatively of the aryltetralin lactone type. Thus, seeds of Linum perenne L. as well as those of several other representatives of sections Linum and Dasylinum were found to contain significant concentrations of the arylnaphthalene justicidin B along with further compounds of this type and some aryldihydronaphthalene -type lignans. On the other hand, seeds of Linum flavum and further representatives of section Syllinum were found to contain aryltetralin type lignans, mainly in the form of esters with aliphatic carboxylic acids, such as 6 methoxypodophyllotoxin7 On hexanoate, whose occurrence in L. flavum seeds has very recently been reported by us for the first time. Various chemosystematic and biogenetic aspects are discussed in the light of these results. (Authors abstract)
Lignans are a large group of dimeric phenylpropanoids widely distributed in higher plants. They show antibacterial, antiviral and antifungal actions and possess anti-inflammatory, anti-oxidative as well as cytotoxic and antitumor effects.The seeds of Linum usitatissimum L. (flaxseeds) are known to be a rich source of the polar glycosidic dibenzylbutanediol type lignan secoisolariciresinol diglucoside (SDG). This study provides a survey of the lignan content in seeds of species from the major taxonomic sections of flaxseed, taking into account polar lignans as well as less polar cyclolignans. The authors report the presence of less polar cyclolignans of the AT and AN/AND types. L. usitatissimum aerial parts have been shown to contain a rich variety of DBBL-type lignans that were demonstrated to be R, R configured. The formation of these lignans essentially requires the formation of R, R SECO. Leaves and stems of the aerial parts expressed exclusively LuPLR2, also in agreement with the observed presence of only R configured lignans. It appears that changes in the expression levels of these key enzymes with opposite enantiospecificity must occur during the development from seed/embryo to mature plant. Further investigations on the course of lignan formation as a function of ontogenetic development of L. usitatissimum and further Linum species is underway. These findings show that the genus Linum is a very interesting taxon to study the chemodiversity of biologically and pharmacologically relevant lignans. (Editors comments)
