LC–MS–MS and GC–MS analyses of biologically active extracts of Tunisian Fenugreek (Trigonella foenum-graecum L.) Seeds
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The objective of this study is to investigate the chemical composition of biologically active extracts from Fenugreek (Trigonella foenum-graecum L.) Seeds. A variety of in vitro models such as β-carotene-linoleic acid and 1,1-diphenyl-2-picryl hydrazyl (DPPH) were used to measure the antioxidant activity. Alpha-amylase inhibitory activity was evaluated by enzyme inhibition using in vitro assay. The hexane extract with a potent inhibition ability against linoleic acid (95.4%) as well as a powerful α-amylase inhibitory activity (IC50 = 26.9 µg/mL) was analyzed by gas chromatography coupled with mass spectrometry (GC–MS). A total of 20 compounds were identified, some of them being reported for the first time in fenugreek seeds [e.g. β-thujone (10.8%), (2E, 4E)-decadienal (7.8%), heptanal (6.7%), and (2E, 4E)-heptadienal (5.3%)]. On the other hand, methanol extract exhibited a strong DPPH radical-scavenging activity (IC50 = 19.0 µg/mL) compared to that of BHT as well as the highest alpha-amylase inhibitory activity (IC50 = 52.1 μg/mL). HPLC technique coupled with negative ion electrospray ionization mass spectrometry and diode array detection (HPLC-DAD–ESI/MS) was employed to identify polyphenols in the methanol extract. The obtained results allowed the detection of 3 flavonoids glycosides and one amino acid identified on the basis of their UV and MS spectra, and comparisons with standards when available, as well as with literature data. A systematic study of the obtained MS spectra and the observed fragmentation allowed identifying for known compounds: vicenin-2, 4-hydroxyisoleucine, isoschaftoside and isoorientin. These two last compounds were identified for the first time in Fenugreek Seeds.
KeywordsFenugreek Seeds GC/MS HPLC-DAD–ESI/MS Flavonoid C-glycosides Biological activities
The authors are grateful for the financial support of the Ministry of Higher Education and Scientific Research, Tunisia, granted to the Laboratory of Organic Chemistry, Natural Substances Team, Faculty of Sciences of Sfax, [Grant Number LR17ES08].
Compliance with ethical standards
Conflict of interest
The authors report that they have no conflicts of interest.
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