A preliminary study on the effect of germination on saponin content and composition of lentils and chick peas

Phytochemical Profile and Composition of Chickpea (Cicer arietinum L.): Varietal Differences and Effect of Germination under Elicited Conditions

Germination is a simple process that improves the nutritional and medicinal values of seeds such as chickpeas. However, the detailed analysis of the phytochemical profile after chemical elicitation during chickpea germination is indispensable when making inferences about its biological properties. Therefore, an evaluation was made of the effect of the chemical inducers salicylic acid (SA, 1 and 2 mM), chitosan (CH, 3.3 and 7 μM), and hydrogen peroxide (H2O2, 20 and 30 mM) during germination at 25 °C with 70% RH for 4 days on the content of antinutritional and bioactive compounds, including phenolics, sterols, and saponins, in three Mexican chickpea varieties (Blanoro, Patron, and San Antonio) using UPLC-ELSD-ESI-QqQ-MS/MS, UPLC-DAD-ESI-QqQ-MS/MS, and HPLC-DAD-sQ-MS. The highest increase in phenolics and saponins was found in the Blanoro sprouts induced with SA 2 mM, whereas the highest phytosterol content was detected in San Antonio sprouts induced with CH 7 μM. In addition, significant increases in mono-, di-, and oligosaccharides and decreases in antinutritional contents were achieved after germination with most of the elicitation conditions. More importantly, we identified new compounds in chickpea sprouts, such as the lignans matairesinol and secoisolariciresinol, the phenolic compounds epicatechin gallate and methyl gallate, some phytosterols, and the saponin phaseoside 1, which further increased after chemical elicitation.

Proximate composition and anti-nutritional factors in Mucuna pruriens (velvet bean) seed flour as affected by several processing methods

Mucuna pruriens seed being an underutilized legume with antinutrients was processed to reduce antinutrients and improve nutritional quality. The seeds were cleaned, washed and subjected to single treatments of soaking (24 h, 48 h, 72 h), cooking (20 min, 40 min, 60 min, 80 min), roasting (10 min, 15 min, 20 min), germination (24 h, 48 h, 72 h) and fermentation (24 h, 48 h, 72 h). Combined treatments: soaking (72 h) + cooking (60 min); germination (48 h) + roasting (15 min); germination (48 h) + cooking (60 min); fermentation (72 h) + roasting (15 min) were also separately carried out. Proximate composition and antinutrients were evaluated. Crude protein ranged from 25.34 to 29.50%, ash 3.02-3.82% and crude fibre 0.70-4.69. Crude protein was increased by single and double treatments while ash content was increased by only single treatments. All the treatments reduced the crude fibre. For single and double treatments, phenol, L-3,4-dihydroxyphenylalanine and trypsin inhibitor were in the range of 0.69-3.49%, 0.01-6.83% and 0.00-12.58 TIU/mg protein respectively. This research indicated that the use of up to 72 h soaking, 80 min cooking, 20 min roasting, 72 h germination or 72 h fermentation (Rhizopus oligosporus) is not adequate to reduce phenol and L-3,4-dihydroxyphenylalanine in Mucuna pruriens seed flour to below the recommended safe limits of 0.003% and 0.1% respectively. The double treatment of 72 h fermentation +15 m roasting was the only treatment that reduced L-3,4-dihydroxyphenylalanine to safe limit of 0.01%.

Quality-controlled LC-ESI-MS food metabolomics of fenugreek (Trigonella foenum-graecum) sprouts: Insights into changes in primary and specialized metabolites

Fenugreek (Trigonella foenum-graecum L.) is an important food and spice with bioactive compounds against diabetes. In this study, fenugreek seeds germinating in darkness for 72 h were studied using quantification of trigonelline and 4-hydroxyisoleucine and an LC-ESI-MS/MS-based metabolomic approach capable of accurately estimating 237 features from various primary and specialized compound classes. During germination, the concentrations of trigonelline and 4-hydroxyisoleucine rose by 33.5% and 33.3%, respectively. At the same time, untargeted metabolomics revealed 9 putative flavonoids increasing 1.19- to 2.77-fold compared to the dormant seeds. A set of 19 steroid saponins rose by 1.08- to 31.86-fold. Primary metabolites however showed much more variability: abundance changes in amino acid derivatives, peptides and saccharides fell in the 0.09- to 22.25-fold, 0.93- to 478.79-fold and 0.36- to 941.58-fold ranges, respectively. To increase biosynthesis of specialized metabolites during germination, sprouts were exposed to 1-100 mM methyl jasmonate (MeJA) and methyl salicylate (MeSA). The hormone treatments affected normal metabolism: 67.1-83.1 % and 64.1-83.5 % of compounds showed a reduction compared to the controls in 100 mM MeJA and MeSA treatments at different sampling time points. Contrary to expectations, the abundance of flavonoids decreased, compared to the control sprouts (0.75- and 0.68-fold change medians, respectively). The same was observed for most, but not all steroid saponins. The quality-controlled untargeted metabolomics approach proved to yield excellent insight into the metabolic changes during germination of fenugreek. The results suggest that although fenugreek germination causes major shifts in plant metabolism, there are no major qualitative changes in bioactive specialized metabolites during the first three days. This stability likely translates into good bioactivity that is similar to that of the seeds. Because the large changes in the primary metabolites likely alter the nutritive value of the seed, further studies are warranted.

Reduction of pulse "antinutritional" content by optimizing pulse canning process is insufficient to improve fat-soluble vitamin bioavailability

Some bioactive compounds found in pulses (phytates, saponins, tannins) display antinutritional properties and interfere with fat-soluble vitamin bioavailability (i.e., bioaccessibility and intestinal uptake). As canned chickpeas are consumed widely, our aim was to optimize the chickpea canning process and assess whether this optimization influences fat-soluble vitamin bioavailability. Different conditions during soaking and blanching were studied, as was a step involving prior germination. Proteins, lipids, fibers, vitamin E, lutein, 5-methyl-tetrahydro-folate, magnesium, iron, phytates, saponins and tannins were quantified. Bioaccessibility and intestinal uptake of vitamin D and K were assessed using in vitro digestion and Caco-2 cells, respectively. Significant reductions of phytate, saponin and tannin contents (-16 to -44%), but also of folate content (up to -97%) were observed under optimized canning conditions compared with the control. However, bioaccessibility and cellular uptake of vitamin D and K remained unaffected after in vitro digestion of test meals containing control or optimized canned chickpeas.

Effect of Germination on Alfalfa and Buckwheat: Phytochemical Profiling by UHPLC-ESI-QTOF-MS/MS, Bioactive Compounds, and In-Vitro Studies of Their Diabetes and Obesity-Related Functions

Germination can be used to enhance nutritional value and health functions of edible seeds. Sprouts are considered healthier than raw seeds because they are richer in the basic nutritional components (carbohydrates, protein, vitamins, and minerals) and also contain more bioactive components responsible for various biological activities. The effect of sprouting on the antioxidant, antidiabetic, antiobesity activities, and metabolite profiles of alfalfa and buckwheat seeds was investigated in this study. DPPH radical scavenging activity was highest in buckwheat sprouts followed by alfalfa sprout, buckwheat seed, and alfalfa seed, respectively. ABTS radical scavenging potential showed a similar trend as DPPH with buckwheat sprouts exerting the best scavenging capacity. Alfalfa sprout and buckwheat seed exhibited the highest percentage inhibitory activity of α-glucosidase (96.6 and 96.5%, respectively). Alfalfa sprouts demonstrated the strongest inhibitory activity against pancreatic lipase (57.12%) while alfalfa seed showed the highest advanced glycation end products (AGEs) formation inhibitory potential (28.7%). Moreover, thirty-three (33) metabolites were characterized in the seed and sprout samples. Sprouts demonstrated a higher level of metabolites compared to raw seeds. Hence, depending on the type of seed and the target activity, sprouting is a good technique to alter the secondary metabolites and functional properties of edible seeds.

Comparison of saponin composition and content in wild soybean (Glycine soja Sieb. and Zucc.) before and after germination

Eight wild soybean accessions with different saponin phenotypes were used to examine saponin composition and relative saponin quantity in various tissues of mature seeds and two-week-old seedlings by LC-PDA/MS/MS. Saponin composition and content were varied according to tissues and accessions. The average total saponin concentration in 1 g mature dry seeds of wild soybean was 16.08 ± 3.13 μmol. In two-week-old seedlings, produced from 1 g mature seeds, it was 27.94 ± 6.52 μmol. Group A saponins were highly concentrated in seed hypocotyl (4.04 ± 0.71 μmol). High concentration of DDMP saponins (7.37 ± 5.22 μmol) and Sg-6 saponins (2.19 ± 0.59 μmol) was found in cotyledonary leaf. In seedlings, the amounts of group A and Sg-6 saponins reduced 2.3- and 1.3-folds, respectively, while DDMP + B + E saponins increased 2.5-fold than those of mature seeds. Our findings show that the group A and Sg-6 saponins in mature seeds were degraded and/or translocated by germination whereas DDMP saponins were newly synthesized.

Chromatographic determination of plant saponins

The methods used for saponin determination in plant materials are presented. It is emphasised that the biological and spectrophotomeric methods still being used for saponin determination provide, to some extent, valuable results on saponin concentrations in plant material. However, since they are sensitive to the structural variation of individual saponins they should be standardized with saponin mixtures isolated from the plant species in which the concentration is measured. However, one plant species may contain some saponins which can be determined with a biological test and others which cannot. That is why biological and colorimetric determinations do not provide accurate data and have to be recognized as approximate. Thin-layer chromatography on normal and reversed-phases (TLC, HPTLC, 2D-TLC) provides excellent qualitative information and in combination with on-line coupling of a computer with dual-wavelength flying-spot scanner and two-dimensional analytical software can be used for routine determination of saponins in plant material. The densitometry of saponins has been very sensitive, however, to plate quality, spraying technique and the heating time and therefore appropriate saponin standards have to be run in parallel with the sample. Gas-liquid chromatography has limited application for determination since saponins are quite big molecules and are not volatile compounds. Thus, there are only few applications of GC for determination of intact saponins. The method has been used for determination of TMS, acetyl or methyl derivatives of an aglycones released during saponin hydrolysis. However, structurally different saponins show different rates of hydrolysis and precise optimisation of hydrolysis conditions is essential. Besides, during hydrolysis a number of artefacts can be formed which can influence the final results. High performance liquid chromatography on reversed-phase columns remains the best technique for saponin determination and is the most-widely used method for this group of compounds. However, the lack of chromophores allowing detection in UV, limits the choice of gradient and detection method. The pre-column derivatisation with benzoyl chloride, coumarin or 4-bromophenacyl bromide has been used successfully in some cases allowing UV detection of separation. Standardisation and identification of the peaks in HPLC chromatograms has been based on comparison of the retention times with those observed for authentic standards. But new hyphenated techniques, combining HPLC with mass spectrometry and nuclear magnetic resonance are developing rapidly and allow on-line identification of separated saponins. Capillary electrophoresis has been applied for saponin determination only in a limited number of cases and this method is still being developed.