Anal Bioanal Chem (2016) 408:8065–8078 DOI 10.1007/s00216-016-9910-4 RESEARCH PAPER Metabolite profiling in Trigonella seeds via UPLC-MS and GC-MS analyzed using multivariate data analyses Mohamed A. Farag1 & Dalia M. Rasheed 2 & Matthias Kropf3 & Andreas G. Heiss4,5 Received: 2 July 2016 /Revised: 14 August 2016 /Accepted: 26 August 2016 /Published online: 10 September 2016 # Springer-Verlag Berlin Heidelberg 2016 Abstract Trigonella foenum-graecum is a plant of consider- supervised orthogonal projection to latent structures- able value for its nutritive composition as well as medicinal discriminant analysis (OPLS-DA). A distinct separation effects. This study aims to examine Trigonella seeds using a among the investigated Trigonella species was revealed, with metabolome-based ultra-performance liquid chromatography- T. foenum-graecum samples found most enriched in apigenin- mass spectrometry (UPLC-MS) in parallel to gas chromatog- C-glycosides, viz. vicenins 1/3 and 2, compared to the other raphy-mass spectrometry (GC-MS) coupled with multivariate two species. In contrast to UPLC-MS, GC-MS was less effi- data analyses. The metabolomic differences of seeds derived cient to classify specimens, with differences among specimens from three Trigonella species, i.e., T. caerulea, T. corniculata, mostly attributed to fatty acyl esters. GC-MS analysis of and T. foenum-graecum, were assessed. Under specified con- Trigonella seed extracts led to the identification of 91 metab- ditions, we were able to identify 93 metabolites including 5 olites belonging mostly to fatty acyl esters, free fatty acids peptides, 2 phenolic acids, 22 C/O-flavonoid conjugates, 26 followed by organic acids, sugars, and amino acids. This study saponins, and 9 fatty acids using UPLC-MS. Several novel presents the first report on primary and secondary metabolite dipeptides, saponins, and flavonoids were found in Trigonella compositional differences among Trigonella seeds via a meta- herein for the first time. Samples were classified via unsuper- bolomics approach and reveals that, among the species exam- vised principal component analysis (PCA) followed by ined, the official T. foenum-graecum presents a better source of Trigonella secondary bioactive metabolites. Electronic supplementary material The online version of this article Keywords Trigonella . Metabolomics . C-flavonoids . (doi:10.1007/s00216-016-9910-4) contains supplementary material, . which is available to authorized users. Chemometrics UPLC-MS GC-MS * Mohamed A. Farag [email protected] Introduction Culinary tradition of consuming Trigonella (fenugreek, 1 Pharmacognosy Department, College of Pharmacy, Cairo University, Kasr el Aini St, Cairo 11562, Egypt Fabaceae) in Southwest Asia and Mediterranean regions may well date back to the Neolithic era [1, 2]. The earliest discovery 2 Pharmacognosy Department, Faculty of Pharmacy, October 6 University, Central axis, Part 1/1, Sixth of October City 12566, Giza, of wild Trigonella species in settlements, from the ninth/tenth Egypt millennia B.C. in northern Syria, even pre-dating recorded agri- 3 Institute of Integrative Nature Conservation Research (INF), cultural history [3]. One of the more prominent finds of University of Natural Resources and Life Sciences (BOKU), Gregor T. foenum-graecum were the desiccated seeds in the tomb of Mendel-Strasse 33, 1180 Vienna, Austria Tutankhamun, dating to ca. 1323 B.C. [4]. The genus name 4 Institute of Botany, University for Natural Resources and Life Trigonella, is derived from the Latin diminutive of the word Sciences (BOKU), Gregor Mendel-Strasse 33, 1180 Vienna, Austria Btrigonon^ meaning triangle, which refers to the triangular shape 5 Vienna Institute for Archaeological Science (VIAS), University of of its flower [5]. The genus comprises ca. 55 species [6]with Vienna, Franz-Klein-Gasse 1/III, 1190 Vienna, Austria partly conflicting phylogenetic evidence on the relationships 8066 M.A. Farag et al. among intrageneric lineages [6]. Plants of the genus Trigonella, Materials and methods just as many other herbaceous members of the Fabaceae, are mostly used as forage and or green manure [7, 8]. Currently, Plant material the world’s principal producer of T. foenum-graecum is India, followed by Mediterranean countries viz. Egypt and Morocco Seeds for the present analyses were obtained via seed ex- [9, 10]. In spite of its important role in many regional cuisines change from the botanical gardens of Vienna, Siena, and [5], today, T. foenum-graecum is probably best known as a major Hohenheim. Two accessions of Trigonella caerulea (HOH, component in most curry mixtures [11]. IS 2001; HBV, IS 1992, No. 463) were analyzed as well as Apart from serving as a condiment and fodder, mem- single accession of T. corniculata (SIENA, IS 1993, No. 604) bers of the genus Trigonella, in different forms viz. seeds, and T. foenum-graecum (HOH: IS 1990, No. 877), germinated seeds, or fresh herbs, play an important role in respectively. the folk medicine of many regions [7, 12], and indeed, the pharmacological efficacy of Trigonella has been exten- Chemicals sively reported. Nursing women in the Middle East, casu- ally use fenugreek seeds decoction as a galactagogue to Chromoband C18 (500 mg, 3 mL) cartridge was obtained augment milk production [13, 14]. Fenugreek seeds and from Macherey & Nagel (Düren, Germany). All solvents used extracts exhibit an apparent hypocholesterolemic effect were of LC-MS grade purchased from J. T. Baker and are known to lower serum triglycerides and low- (The Netherlands). Vitexin, isovitexin, diosgenin, orientin, density lipoprotein in vivo [15–17]. The C27 steroidal and isoorientin were purchased from Chromadex (Wesel, sapogenin, diosgenin enriched in the seed is regarded as Germany). one of the main reasons for its pharmacological effects [18]. The well-known antidiabetic action of fenugreek Seeds extraction procedure for UPLC-MS and GC-MS was rationalized by a number of mechanisms [19–23] analysis mostly via its seed dietary fiber content that can hinder the rate of postprandial glucose absorption in type 2 dia- Air dried seeds were ground with a pestle in a mortar using betic subjects [24]. Moreover, it is the pyridine alkaloid liquid nitrogen. The powder (30 mg) was then homogenized trigonelline that exerts the antidiabetic activity via a direct with 2.5 mL 100 % MeOH containing 5 μg/mL umbelliferone action on β cells, promoting insulin secretion as well as (an internal standard for relative quantification) using a Turrax inhibition of intestinal α-amylase activity [25–27]. mixer (11000 RPM) for five 20-s periods, with intermittent Trigonelline was also recently discovered in Balanites recession of 1-min period to avoid excessive heating during egyptiaca date fruit extracts imparting the fruits its char- mixing. Extracts were then vortexed vigorously and centri- acteristic acrid taste and verifying its appreciable hypo- fuged at 3000g for 30 min to remove any plant debris. glycemic effect [28]. Additional to the aforementioned Aliquots of 500 μL were placed on a (500 mg) C18 cartridge data, fenugreek encompass a myriad of other natural prod- preconditioned with methanol and water, eluted with 3 mL uct classes that warrant other vast pharmacological actions 70%MeOHand3mL100%MeOH,andevaporatedunder viz. flavonoids, isoflavonoids, and other polyphenols a nitrogen stream, and the obtained dry residue was re- known to exhibit antioxidant, anticancer, anti-inflammato- suspended in 500 μLMeOH. ry, antinociceptive, and estrogenic activities [13, 29–33]. Polysaccharides, triterpenoids, and nicotinic acid have al- High-resolution UPLC-MS analysis so been reported in Trigonella [34–36]. Metabolomic evaluation based investigations allowed High-resolution UPLC-MS analysis conditions adopted were for biomarkers discovery inferring chemotaxonomical previously described in [37]. Chromatographic separation was variations between closely related plant genera or species performed on an Acquity UPLC system (Waters) equipped [37–40]. The goal of this study was to investigate with a HSS T3 column (100 × 1.0 mm, particle size 1.8 μm; Trigonella global metabolome in the context of different Waters). The analysis was carried out using a binary gradient phylogenetic lineages, represented by three species (i.e., elution system at a flow rate of 150 μL/min: 0 to 1 min, T. caerulea, T. corniculata,andT. foenum-graecum). The isocratic 95 % A (water/formic acid, 99.9/0.1 [v/v]), 5 % B approaches utilized focused on chromatographic hyphen- (acetonitrile/formic acid, 99.9/0.1 [v/v]); 1 to 16 min, linear ated ultra-performance liquid chromatography coupled to from 5 to 95 % B; 16 to 18 min then isocratic 95 % B; 18 to mass spectrometry (UPLC-MS) and gas chromatography 20 min, and finally, isocratic 5 % B. Full loop injection vol- coupled to mass spectrometry (GC-MS) combined with ume (3.1 μL) was used. Detection range of eluted compounds multivariate data analyses to reveal for differences among was from m/z 100 to 1000 mainly in negative ion mode, ob- individual species-specific samples. tained using the following instrument settings: nebulizer gas, Metabolites profiling in Trigonella seeds via UPLC-MS and GC-MS 8067 nitrogen, 1.6 bar; dry gas, nitrogen, 6 L/min, 190 °C; capillary, respectively. The HP quadrupole mass spectrometer was −5500 V; in-source CID energy, 0 V; hexapole RF, 100 Vpp; operated in the electron ionization mode at 70 eV and with quadrupole ion energy, 5 eV; collision gas, argon; collision a scan range of 50–650 m/z. Silylated components were energy, 10 eV; collision RF 200/400 Vpp (timing 50/50); identified using the procedure described in [37], and transfer time, 70 μs; prepulse storage, 5 μs; pulser frequency, peaks were first deconvoluted using AMDIS software 10 kHz; spectra rate, 3 Hz. Internal mass calibration was per- (www.amdis.net) and identified by its retention indices formed by infusion of 20 μL 10 mM lithium formate in (RI) relative to n-alkanes (C8–C40), mass spectrum isopropanol: water, 1:1 (v/v), at a gradient time of 18 min matching to NIST, WILEY library database, and with au- using a diverter valve.