Klaudia Michalska

Steroidal saponins from the genus Allium

Steroidal saponins are widely distributed among monocots, including the Amaryllidaceae family to which the Allium genus is currently classified. Apart from sulfur compounds, these are important biologically active molecules that are considered to be responsible for the observed activity of Allium species, including antifungal, cytotoxic, enzyme-inhibitory, and other. In this paper, literature data concerning chemistry and biological activity of steroidal saponins from the Allium genus has been reviewed.

Root tubers of Lactuca tuberosa as a source of antioxidant phenolic compounds and new furofuran lignans.

From the root tubers of Lactuca tuberosa, a wild edible plant species, nine phenolic compounds were isolated, including two new furofuran lignan glucosides, named lactuberin A and lactuberin B. Their structures were elucidated by spectroscopic methods, especially HRESIMS and 2D NMR techniques. This is the first time that compounds belonging to the epi series of 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane type furofuran lignans have been found in Lactuca species. The total phenolic content of the root tuber extract was evaluated and its major phenolic constituents, caffeic acid, chlorogenic acid and 3,5 dicaffeoylquinic acid, known to possess antioxidant activity, were quantified. Additionally, the root tuber extract showed DPPH radical scavenging activity implying its potential as functional food.

Sesquiterpenoids and phenolics from roots of Taraxacum udum

From roots of Taraxacum udum, two new and four known sesquiterpene lactones were isolated, together with five known phenolic compounds. The new compounds were characterized as 11beta, 13-dihydrotaraxinic acid and taraxinic acid 6-O-acetyl-beta-glucopyranosyl ester by spectroscopic methods, especially 1D and 2D NMR, and by comparison with structurally related compounds. The plant material was shown to be a good source of taraxinic acid derivatives.

Lignans and sesquiterpenoids from Lactuca sibirica

From aerial parts of Lactuca sibirica, two new and one known furofuran lignans were isolated, together with four known lactucin-like guaianolides. On the basis of spectral data, the new lignans were characterized as acylated glucopyranosides of 4alpha, 8alpha-dihydroxypinoresinol.

Root constituents of Cichorium pumilum and rearrangements of some lactucin-like guaianolides.

Abstract Two eudesmanolides, eight lactucin-like guaianolides and five phenolic compounds were isolated for the first time from roots of Cichorium pumilum, along with two previously reported eudesmane-type sesquiterpene lactones. Rearrangements of some lactucin-like guaianolides during isolation procedures were also discussed.

A guaianolide alloside and other constituents from Picris kamtschatica.

From Picris kamtschatica two new guaianolide glycosides, including a beta-allopyranosyl analogue of ixerin F, were isolated, in addition to ten known sesquiterpene lactones and six phenolic compounds. This is the first time a sesquiterpene lactone alloside has been described from plants. The compounds were characterized based on mass, 1D and 2D NMR spectral data.

Structure elucidation and complete NMR spectral assignments of two new sesquiterpene lactone xylosides from Lactuca triangulata

Two new sesquiterpene lactone xylosides, derivatives of the guaianolides 9α‐hydroxyleucodin and 9α‐hydroxy‐11,13‐dehydroleucodin, were isolated from roots of Lactuca triangulata. Their structures were established on the basis of 1H and 13C NMR spectra, 2D NMR (HMQC, HMBC, COSY, NOESY) techniques and comparison with the literature data. The compounds represent the first example of sesquiterpene lactone xylosides. Copyright

Structural analysis of 1l-chiro-inositol diester from Taraxacum udum.

1l-1,5-Di-O-p-hydroxyphenylacetyl-chiro-inositol was isolated from the leaves of Taraxacumudum, along with seven other secondary metabolites. Identification of the inositol derivative, based on extensive spectroscopic analyses ((1)H, (13)C and 2D NMR) in two solvents, allowed the correction of previously published data and conformational studies. This is the second report on the presence of inositol esters with p-hydroxyphenylacetic acid in plants.

Sesquiterpenoids and Phenolics from Crepis conyzifolia

Abstract From the roots of Crepis conyzifolia, two new and two known guaianolides were isolated together with three known phenylpropanoids. Structures of the new compounds were established as 8β-hydroxy-4β, 15-dihydrozaluzanin C and 4β, 15, 11β, 13-tetrahydrozaluzanin C-3-O-β-glucopyranoside by spectral methods. The identity of 8 -epiisolippidiol and dentalactone was also discussed.

Sesquiterpene lactones from Lactuca canadensis and their chemotaxonomic significance

A total of 19 sesquiterpene lactones were isolated from roots of Lactuca canadensis L., of which 10 were reported for the first time from Lactuca species and two were unknown. This is also the first report on the co-occurrence of three pairs of zaluzanin C-type guaianolides, epimeric at C-3, and on the presence of six eudesmanolides, oxygenated at C-1 and C-3, in Lactuca species. The new compounds were characterized as 3-epizaluzanin C-3-O-β-glucopyranoside and 11,13-dehydrolactuside C using 1D and 2D NMR and high resolution mass spectroscopy. The sesquiterpene lactone profile of this species is dominated by zaluzanin C-type guaianolides (9 compounds) and eudesmanolides (8 compounds). The dissimilarity of this profile compared to that of other taxa of the genus is discussed.