Sea aster (Aster tripolium L.) and searocket (Cakile maritima Scop.), potential ingredients in the New Nordic Diet, were analyzed by high-resolution radical scavenging and high-resolution α-glucosidase inhibition assays. Results from the two bioactivity profiles were used to guide subsequent structural analysis toward constituents with potential health-promoting effects. Structural analysis was performed by high-performance liquid chromatography-high-resolution mass spectrometry-solid-phase extraction and automated tube transfer nuclear magnetic resonance spectroscopy, that is, HPLC-HRMS-SPE-ttNMR. High-resolution mass spectrometry together with detailed analysis of one- and two-dimensional proton detected NMR experiments enabled unambiguous assignment of the targeted analytes. This revealed a series of caffeoyl esters (1, 2, 5), flavonoid glycosides (3, 4, 6, 11-15), flavonoids (7-9), sinapate esters (10, 16, 17), and sinapinic acid (18) associated with radical scavenging and/or α-glucosidase inhibition. In vitro assays implemented in this study showed that sea aster holds potential as a future functional food ingredient for lowering postprandial blood glucose level for diabetics, but further investigations are needed to prove the effect in vivo.
ABSTRACT. The ethanol extract of the kernel of the endemic plant Moringa stenopetala after silica gel column chromatography led to the isolation of 4-(α-L-rhamnopyranosyloxy)benzyl glucosinolate (1) and sucrose. The oil obtained by Soxhlet extraction with petrol was trans-esterified with BF3-MeOH and analyzed by GC-MS. The results showed the presence of diverse fatty acids namely palmitic (11%), palmitoleic (1.2%), stearic (11%), oleic (63%), linoleic (1.2%), arachidic (6%) and the rare behenic acids (6%). The white glossy seed husk which comprises 25% of the whole seed yielded two compounds namely 4-(σ-L-rhamnosyloxy)benzyl alcohol (2) and allantoin (3). To the best of our knowledge this is the first report of compound 2 as a natural product. Allantoin is reported here for the first time from the genus Moringa.
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