Free Phenolic Acids Research Articles

Effects of different fermentation modes on tea leaves: Revealing the metabolites modification by quasi-targeted metabolomics

To investigate the effects of aerobic and anaerobic fermentation on tea leaves and to compare the differences between different fermentation modes, the metabolite profiles of pre-fermented tea, anaerobic-fermented tea, and aerobic-fermented tea from the same batch were comprehensively analyzed by quasi-targeted metabolomics. The results showed that the two fermentation modes altered tea metabolites significantly differently based on 1162 identified metabolites. A total of 611 differential metabolites were screened in different fermented teas, of which phenolics were the most critical compounds. Both fermentation modes reduced the levels of phenolic esters/glucosides in tea, accompanied by the accumulation of free phenolic. Notably, aerobic fermentation was more conducive for flavonoid glycosides and phenolic acid esters/glycosides reduction, while anaerobic fermentation better for free phenolic acids enhancement, especially gallic acid and its derivatives. Additionally, potential metabolic pathways of tea phenolics during fermentation were depicted, primarily involving the hydrolysis, methylation, and glycosylation of flavonoids, as well as the hydrolysis, esterification, degradation, and amination of phenolic acids. Furthermore, there were also some differences in the metabolism of amino acids, sugars, organic acids and lipids between the two fermentation modes. This study will advance our insights into the fermentation metabolism of post-fermented tea.

Interpopulation Variation of Leaf Polyphenol Content in Spiraea aquilegifolia (Rosaceae) from the Republic of Buryatia.

The composition and content of polyphenols in leaves was studied in Spiraea aquilegifolia Pall. plants from nine natural populations of the Republic of Buryatia (Western Transbaikalia) by high-performance liquid chromatography (HPLC). At least 24 compounds were detected in hydroethanolic extracts of S. aquilegifolia leaves by HPLC. Of these, three phenol carboxylic acids (chlorogenic, p-hydroxybenzoic, and p-coumaric acids) and six flavonols (hyperoside, isoquercitrin, avicularin, astragalin, quercetin, and kaempferol) were identified. Hyperoside (2.9-8.2 mg/g), avicularin (3.0-5.8 mg/g), and isoquercitrin (0.8-2.5 mg/g) were the main flavonols found in leaf hydroethanolic extracts. Plants from populations located at the northern distribution limit in Western Transbaikalia were found to have higher contents of phenol carboxylic acids (near the village Koma) and flavonols (near the village Klyuchi). Plants from populations located at the eastern limit (near the villages Kusoty and Zagan) showed the lowest concentration of the identified phenolic compounds. The contents of the identified free phenolic acids and flavonols were moderate or high in S. aquilegifolia leaves as compared to other Spiraea species examined, rendering it important to further study the composition of phenolic compounds in S. aquilegifolia.

Ferulic acid improved the yogurt stability through interaction with milk protein

Our previous study suggested that bound phenolic acids of rice bran were converted into free phenolic acids during fermentation and these free phenolic acids improved the yogurt stability. Thus, this work investigated the effect of adding ferulic acid, the major phenolic acid of rice bran, on the yogurt stability. It was observed that the syneresis of yogurt was reduced by adding 100 μg/mL ferulic acid before fermentation, which suggested that ferulic acid increased the yogurt stability. Accordingly, adding ferulic acid made the yogurt gel more compact. However, 100 μg/mL ferulic acid had no significant impact on the pH, viscosity, and viscoelasticity of yogurt. Thus, the interaction between ferulic acid and milk protein was investigated. It was observed that ferulic acid interacted with milk protein through the hydrogen bond and van der Waals force. Therefore, it was speculated that ferulic acid interacted with milk protein molecules and induced the more compact structure of yogurt, thus improving the yogurt stability. However, adding ferulic acid after fermentation had no significant impact on the yogurt stability, because the gelation of milk protein caused by fermentation hindered the interaction between ferulic acid and milk protein.

Impact of Germination on the Edible Quality and Nutritional Properties of Brown Rice Noodles.

Brown rice noodles are increasingly favored by consumers for their health benefits; however, their development is hindered by their poor edible qualities. The effect of germination on the cooking, textural, organoleptic and nutritional qualities of brown rice pasta was investigated. In comparison to ungerminated brown rice noodles, germination resulted in a shorter cooking time, reduced cooking losses, and decreased hardness and adhesion of noodles as well as reduced bitter taste. These changes can be attributed to germination altering the basic composition of brown rice. Meanwhile, the contents of γ-aminobutyric acid, free phenolic acid, and bound phenolic acid increased by 53.43%, 21.71%, and 7.14%, respectively, while the content of resistant starch de-creased by 21.55%. Sprouting is a promising strategy for improving the edible quality and nutritional properties of brown rice noodles.

MYB24, MYB144, and MYB168 positively regulate suberin biosynthesis at potato tuber wounds during healing.

The essence of wound healing is the accumulation of suberin at wounds, which is formed by suberin polyphenolic (SPP) and suberin polyaliphatic (SPA). The biosynthesis of SPP and SPA monomers is catalyzed by several enzyme classes related to phenylpropanoid metabolism and fatty acid metabolism, respectively. However, how suberin biosynthesis is regulated at the transcriptional level during potato (Solanum tuberosum) tuber wound healing remains largely unknown. Here, 6 target genes and 15 transcription factors related to suberin biosynthesis in tuber wound healing were identified by RNA-seq technology and qRT-PCR. Dual luciferase and yeast one-hybrid assays showed that StMYB168 activated the target genes StPAL, StOMT, and St4CL in phenylpropanoid metabolism. Meanwhile, StMYB24 and StMYB144 activated the target genes StLTP, StLACS, and StCYP in fatty acid metabolism, and StFHT involved in the assembly of SPP and SPA domains in both native and wound periderms. More importantly, virus-induced gene silencing in S. tuberosum and transient overexpression in Nicotiana benthamiana assays confirmed that StMYB168 regulates the biosynthesis of free phenolic acids, such as ferulic acid. Furthermore, StMYB24/144 regulated the accumulation of suberin monomers, such as ferulates, α, ω-diacids, and ω-hydroxy acids. In conclusion, StMYB24, StMYB144, and StMYB168 have an elaborate division of labor in regulating the synthesis of suberin during tuber wound healing.

Unveiling the distribution of free and bound phenolic acids, flavonoids, anthocyanins, and proanthocyanidins in pigmented and non-pigmented rice genotypes.

The total phenolic content, phenolic acid profile, anthocyanins, proanthocyanidins, flavonoids, and antioxidant capacity of the whole-grain and bran portion of sixteen distinct rice genotypes that correspond to three distinct pericarp bran colors-black, red, and non-pigmented (NP)-were examined. Ten free and bound phenolic acids, as well as two flavonoids, were analyzed using HPLC-PDA. The flavonoids included kaempferol and catechin hydrate, and the free phenolic acids included gallic acid, 2,5-dihydroxybenzoic acid, vanillic acid, syringic acid, p-coumaric acid, chlorogenic acid, trans-cinnamic acid, trans-ferulic acid, p-coumaric acid, and sinapic acid. Trans-ferulic acid (207.39 mg/kg), p-hydroxybenzoic acid (94.36 mg/kg), and p-coumaric acid (59.75 mg/kg) were the principal bound phenolic acids in pigmented rice genotypes, whereas in NP genotypes they were trans-ferulic acid (95.61 mg/kg) and p-hydroxybenzoic acid (58.32 mg/kg). The main free phenolic acid was syringic acid (120.43 mg/kg) in all genotypes. 2,5-dihydroxybenzoic acid was also detected in NP genotypes, mainly in the bound form (4.88 mg/kg). NP genotypes Basmati 386 and Punjab Basmati 7 also displayed high content of bran flavonoids (1001 and 1028 mg CE/100g). The bound form of phenolics had significant DPPH and ABTS + activity. This study found wide diversity in the phenolic acid profile, total phenolic constituents, and antioxidant activity in the bran and whole grain of pigmented and NP rice. The individual phenolic acids in free and bound forms in different fractions of the grain were found to exert their antioxidant activity differently. The results obtained will provide new opportunities to improve the nutritional quality of rice with enhanced levels of phytochemicals in the ongoing breeding programs. Black rice bran contains a high level of phytochemicals and thus has a potent pharmaceutical role. This information would enhance the use of whole-grain and bran of pigmented rice in food product development by food technologists. Further studies may be focused on clinical trials with respect to cancer and diabetes.

Carboxylic acid accumulation and secretion contribute to the alkali-stress tolerance of halophyte Leymus chinensis.

Leymus chinensis is a dominant halophytic grass in alkalized grasslands of Northeast China. To explore the alkali-tolerance mechanism of L. chinensis, we applied a widely targeted metabolomic approach to analyze metabolic responses of its root exudates, root tissues and leaves under alkali-stress conditions. L. chinensis extensively secreted organic acids, phenolic acids, free fatty acids and other substances having -COOH or phosphate groups when grown under alkali-stress conditions. The buffering capacity of these secreted substances promoted pH regulation in the rhizosphere during responses to alkali stress. L. chinensis leaves exhibited enhanced accumulations of free fatty acids, lipids, amino acids, organic acids, phenolic acids and alkaloids, which play important roles in maintaining cell membrane stability, regulating osmotic pressure and providing substrates for the alkali-stress responses of roots. The accumulations of numerous flavonoids, saccharides and alcohols were extensively enhanced in the roots of L. chinensis, but rarely enhanced in the leaves, under alkali-stress conditions. Enhanced accumulations of flavonoids, saccharides and alcohols increased the removal of reactive oxygen species and alleviated oxygen damage caused by alkali stress. In this study, we revealed the metabolic response mechanisms of L. chinensis under alkali-stress conditions, emphasizing important roles for the accumulation and secretion of organic acids, amino acids, fatty acids and other substances in alkali tolerance.

Steam explosion technology as a tool to alter the physicochemical properties of intermediate wheatgrass (Thinopyrum intermedium) bran

Products containing the perennial grain intermediate wheatgrass (IWG) have recently entered the market, but little is known about the effect of processing operations on its constituents. This study investigated the effect of steam explosion (SE) conditions, i.e., temperature (130, 150 or 170 °C) and residence time (5 or 10 min), spanning severity factors from 1.6 to 3.1, on physicochemical properties of IWG bran. Even the lowest temperature and shortest time combination (130 °C, 5 min), was sufficient to inactivate peroxidase, generally regarded as the most heat-stable enzyme in grains. Contents of free phenolic acids as well as water-extractable arabinoxylans significantly increased while phytic acid was reduced after SE. However, starch damage, free fatty acids as well as browning (all negatively affecting quality) increased with treatment severity. Thus, SE is a promising technology to reduce enzymatic activity, enhance phenolic and soluble fiber contents in IWG bran, but severity factors >2.5 may negatively affect quality.

Metabolite profiling and histochemical localization of alkaloids in Hippeastrum papilio (Ravena) van Scheepen

Hippeastrum papilio (Amaryllidaceae) is a promising new source of galanthamine - an alkaloid used for the cognitive treatment of Alzheimer's disease. The biosynthesis and accumulation of alkaloids are tissue - and organ-specific. In the present study, histochemical localization of alkaloids in H. papilio's plant organs with Dragendorff's reagent, revealed their presence in all studied samples. Alkaloids were observed in vascular bundles, vacuoles, and intracellular spaces, while in other plant tissues and structures depended on the plant organ. The leaf parenchyma and the vascular bundles were indicated as alkaloid-rich structures which together with the high proportion of alkaloids in the phloem sap (49.3% of the Total Ion Current – TIC, measured by GC-MS) indicates the green tissues as a possible site of galanthamine biosynthesis. The bulbs and roots showed higher alkaloid content compared to the leaf parts. The highest alkaloid content was found in the inner bulb part. GC-MS metabolite profiling of H. papilio's root, bulb, and leaves revealed about 82 metabolites (>0.01% of TIC) in the apolar, polar, and phenolic acid fractions, including organic acids, fatty acids, sterols, sugars, amino acids, free phenolic acids, and conjugated phenolic acids. The most of organic and fatty acids were in the peak part of the root, while the outermost leaf was enriched with sterols. The outer and middle parts of the bulb had the highest amount of saccharides, while the peak part of the middle leaf had most of the amino acids, free and conjugated phenolic acids.

Phenolic compounds in purple whole-wheat flour and bread: Comparative analysis

Whole-wheat flour of purple wheat varieties contains anthocyanins and other phenolic compounds with high antioxidant activity, which makes it a potential raw material for functional foods. The content and composition of phenolic compounds in whole-wheat flour depends on the genotype and weather conditions; in the bread, however, they also depend on the bread-making technology. This article offers a comparative analysis of phenolic compounds in purple whole-wheat flour and bread baked from this flour.
 The study featured purple soft spring wheat (Triticum aestivum L.) of two varieties, Nadira and Line 193, which were harvested in 2016 and 2017, and corresponding bread samples. The antioxidant activity and phenolic content were measured spectrophotometrically while the qualitative analysis relied on the method of high-performance liquid chromatography (HPLC). 
 In the hot and dry year of 2016, the content of bound phenolic acids reached 2.0–2.4 mg/g dry weight in the flour of both genotypes. In the cool and humid year of 2017, the content of anthocyanins in the Nadira flour increased by 2.7 times and amounted to 0.65 mg/g dry weight. However, the corresponding bread sample had a much lower phenolic content: soluble phenolics were halved, anthocyanins dropped by 3–4 times, and bound phenolic acids went down by 7–17 times. The content of bound phenolic acids in the flour correlated positively with the content of free phenolic acids in the bread. The HPLC analysis revealed an increase in the content of free hydroxycinnamic acids in the bread: p-coumaric acid was the most abundant and amounted to 0.14–0.22 mg/g dry weight.
 Conventional State Standard 27669-88 for bread making resulted in a total decrease in anthocyanins, bound phenolic acids, and most free phenolics. Therefore, this technology cannot be applied to functional bread. The results can help develop a breadmaking technology for purple wheat varieties.

The Content of Antioxidant Compounds and VOCs in Sorghum Grain Grown in Central and Eastern Europe

Sorghum is a plant belonging to the Poaceae family. It is drought-resistant and has low soil requirements. In the face of climate change, it is increasingly cultivated in Europe. Poland is a country with great agricultural potential; it is thus important to develop effective and economic methods of agricultural production, which is confirmed by the introduction of sorghum into cultivation. The aim of this study was to characterize the composition of bioactive compounds (i.e., phenolic acids, flavonoids, carotenoids, and phytosterols) and VOCs in sorghum grain of two varieties, i.e., white ‘Sweet Caroline’ and red ‘Sweet Susana’ grown in the temperate climate (Pętkowo, Poland (52°12′40″ N 17°15′31″ E)). The following tests were carried out: analysis of phenolic acids, flavonoids, carotenoids, phytosterols, antioxidant activity (ABTS), free phenolic acids (FPAs); elemental analysis; and water, fat and starch content analysis. Based on the conducted research, it was concluded that Poland has appropriate conditions for growing sorghum, as the content of bioactive (antioxidant) compounds was at a similar level to those grown in tropical and subtropical climates. Of the nine phenolic acids and seven flavonoids determined, the highest concentrations in both sorghum grain varieties were found for ferulic, p-coumaric and protocatechuic acids. The content of ferulic acid was three times higher in Sweet Caroline grains than in Sweet Susana grains. Differences in the content of these compounds may be the result of genetic differences between the Sweet Susana and Sweet Caroline varieties.

Heterologous expression and enzymatic characteristics of sulfatase from Lactobacillus plantarum dy-1.

Barley, rich in bioactive components including dietary fiber, polyphenolic compounds and functional proteins, exhibits health benefits such as regulating glucose and lipid metabolism. Previous studies have found that the content and composition of free phenolic acids in barley may be significantly changed by fermentation with the laboratory patented strain Lactobacillus plantarum dy-1 (L. p dy-1), but the mechanism of enzymatic release of phenolic acid remains to be elucidated. Based on this, this study aimed to identify the key enzyme in L. p dy-1 responsible for releasing the bound phenolic acid and to further analyze its enzymatic properties. The Carbohydrate-Active enZYmes database revealed that L. p dy-1 encodes 7 types of auxiliary enzymes, among which we have identified a membrane sulfatase. The enzyme gene LPMS05445 was heterologous to that expressed in E. coli, and a recombinant strain was induced to produce the target protein and purified. The molecular weight of the purified enzyme was about 59.9 kDa, with 578.21 U mg-1 enzyme activity. The optimal temperature and pH for LPMS05445 expression were 40 °C and 7.0, respectively. Furthermore, enzymatic hydrolysis by LPMS05445 can obviously change the surface microstructure of dietary fiber from barley bran and enhance the release of bound phenolic acid, thereby increasing the free phenolic acid content and improving its physiological function. In conclusion, sulfatase produced by Lactobacillus plantarum dy-1 plays a key role in releasing bound phenolic acids during the fermentation of barley.

Cytotoxicity of Sambucus nigra L. on Cancer Cell Line and In Vitro Antioxidant Properties

Objective: Essential oils, free fatty acids, flavonoids, glycosides, phenolic acids, carotenoids, vitamins, and minerals are found in significant quantities in the characteristic chemical composition of Sambucus nigra L. This study aimed to evaluate the antioxidant potential of Sambucus nigra L. Fructus and evaluate the cytotoxicity on the cancer cell line.
 Methods: The Sambucus nigra L. fruits were collected from Yalova Atatürk Horticultural Central Research Institute in September 2021. The ethanol extract was prepared. Antioxidant property of Sambucus nigra L. fruit extracts was evaluated with 2,2-diphenyl-1-picryl-hydrazyl- hydrate (DPPH) radical scavenging activity, Cupric Ion Reducing Antioxidant Capacity (CUPRAC). Also, total phenolic content, total flavonoid content, and total anthocyanin content were calculated. Liver hepatocellular carcinoma cell line (HepG2) was used for cytotoxicity assay and an 2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was applied.
 Results: The total phenolic, total flavonoid contents and total monomeric anthocyanins were 9.75±0.92 mg GAE/ mg fruit extract, 0.07437±0.004 mg quercetin/ mg fruit extract, respectively. 0.45±0.0014 mg catechin/gram of fruit extract and 2.08±0.025 mg Cyanidin-3 glucosides/g fruit extract. CUPRAC and DPPH results showed that Sambucus nigra L. extract has strong antioxidant activity. The results of the cytotoxicity assay indicated that while concentrations of the extract increased, the viability of HepG2 decreased.
 Conclusion: Our findings suggest that the Sambucus fruit extract is particularly rich in antioxidant components that are possibly modulating their beneficial use for hepatocellular malignancies, significantly reducing the number of viable cancer cells and inducing cell death.

Phenolic compounds and antimicrobial activity of leaves of the genus Sorbus species and natural hybrids

The identification of new sources of biologically active substances is an actual direction of research in recent years, in particular, the demand for antimicrobial compounds and natural preservatives of plant origin is growing. Plants of the genus Sorbus L. are known in folk medicine, but for the rational use of plant material, there is a lack of systematic study of the features of the secondary metabolites’ accumulation and the spectrum of biological activity of plants during vegetation in different environmental conditions. In the present work, the seasonal dynamics of the total content of polyphenols, flavonoids and free phenolic acids in the leaves of rowan plants natural to the flora of Ukraine and introduced in the steppe region were investigated. The highest accumulation of phenolic compounds was found in the leaves of S. domestica, S. latifolia, S. hybrida, S. torminalis and S. aucuparia in the first half of June, and in S. aria and S. intermedia in May, which will serve as a criterion for selecting the best plant material to obtain biologically active compounds. The seasonal dynamics of the content of flavonoids and phenolic acids in the leaves of plants had significant species differences, which require more in-depth studies of the phytocompounds component composition. Antimicrobial activity of leaf ethanol extracts of rowan plant was found to be high against gram-negative bacterial strain Klebsiella pneumoniae B920 (especially the activity of S. aria, S. intermedia and S. aucuparia extracts) and Pseudomonas aeruginosa B907 (especially the activity S. torminalis and S. domestica), clinical gram-positive strains of Staphylococcus epidermidis (the highest activity of S. aria, S. domestica and S. intermedia extracts), as well as against clinical strains of fluconazole-resistant fungus Candida albicans (especially the activity of extracts of S. latifolia S. torminalis and S. intermedia). A conclusion was made about the prospects of using leaf extracts of the genus Sorbus plants as an economical and affordable natural source of biologically active polyphenols with a wide spectrum of antimicrobial activity. Further research may be aimed at elucidating the component composition of rowan leaf extracts and establishing the relationship between individual phytocompounds and the antimicrobial effects of plant extracts.

Concentration of Phenolic Compounds and Phenolic Acids of Various Spelt Cultivars in Response to Growing Years

The aims of this study were to evaluate and compare the radical scavenging activities (DPPH), phenolic concentrations and concentrations of selected phenolic acids (PAs) of spelt cultivars and breeding lines with common wheat in a three-year controlled field experiment under conditions of organic farming. No significant variations were observed in the total and free DPPH of Altgold, Ebners Rotkorn, Ostro and PN-1-36 with common wheat. The total DPPH ranged from 52.13% to the lowest value of 44.01% in Franckenkorn. Total, free and bound phenolic concentrations were the highest for common wheat (1902.55 µg FAE g−1 DM of total), while all spelt cultivars achieved significantly lower values (from 1434.94 µg FAE g−1 DM in Franckenkorn to 1650.22 µg FAE g−1 DM in Ebners Rotkorn). Bound phenolic compounds represented 86.3% of the total ones. An extremely dry and warm ripening period had a negative impact on the synthesis of phenolic compounds. The highest concentration of total PAs was observed in spelt Ebners Rotkorn (681.75 µg g−1 DM) and the lowest in common wheat (396.05 µg g−1 DM). The total share of free and bound PAs was 5.7% and 74.8%, respectively. The extremely dry and very warm grain filling period had a more evident negative impact on the concentration of free PAs compared to bound forms. The dominant free PA was ferulic (70.48%), followed by syringic (9.30%), p-HBA (5.59%), sinapic acid (5.40%), salicylic (4.18%), p-coumaric acid (3.22%) and caffeic acid (1.93%). Spelt cultivar Ebners Rotkorn was distinguished by the highest concentration of free and bound forms of PAs.

Effect of electrohydrodynamic drying on bee pollen biochemical pathways

The mechanism of ionic wind and electric field of electrohydrodynamic (EHD) drying dehydration stress on the biochemical and molecular basis of bee pollen is still unclear. In this study, metabolomics and proteomics were employed to analyze the changes in biochemicals and small-molecule metabolic compounds of bee pollen during the drying process using needle-to-plate and plate-to-plate electrode system. The results show that ionic wind and electric field contributed 85.0% and 15.0% respectively to the dehydration characteristics, with the electric field having a greater effect on the quality parameters. As compared to ionic wind, the ribosome, the citric acid cycle (TCA cycle), and proteasome pathway played a positive role in regulating the abiotic and biochemical responses of electric field dehydration. Both ionic wind and electric field changed the expression of functional proteins related to amino acid metabolism pathways, resulting in a decrease in the expression of characteristic metabolites such as L-phenylalanine, L-aspartic acid, and L-pyroglutamic acid from 114.27 × 107, 5.31 × 107, and 142.55 × 107 in fresh rape bee pollen to 57.46 × 107, 3.32 × 107, and 57.46 × 107 in needle-to-plate (N-P) electrode treated and 61.25 × 107, 2.47 × 107, as well as 33.82 × 107 in plate-to-plate (P-P) electrode treated samples. Additionally, the differential expression of proteasome pathway and the destruction of the structural integrity of the cell wall storing phenolic compounds resulted in the further interaction of protein-phenolic supercomplexes, which in turn changed the content of free phenolic acids in rape bee pollen. These findings elucidated the biochemical regulation strategy and protein-phenolic compound interaction mechanism of rape bee pollen during EHD drying processing, and further emphasized the synergistic mechanism of ionic wind and electric field.

Interpopulation Variability of Polyphenol Concentration in the Leaves of <i>Spiraea aquilegifolia</i> (Rosaceae) from the Republic of Buryatia

Abstract—Composition and content of flavonoids and phenol carboxylic acids in the leaves of Spiraea aquilegifolia Pall. from natural populations of the Republic of Buryatia (Western Transbaikalia) are given in the article. Aqueous ethanol (40%) extracts from raw materials were used for chromatographic study of phenolic compounds. The analysis of phenolic compounds was carried out on an analytical High-Performance Liquid Chromatography (HPLC) system consisting of an Agilent 1200 liquid chromatograph (USA) with a diode array detector, an autosampler, and a system for collecting and processing chromatographic data ChemStation. At least 24 phenolic compounds were identified in aqueous ethanol extracts from Spiraea aquilegifolia Pall. leaves by HPLC. Three acids (chlorogenic, p-coumaric and p-hydroxybenzoic) and six flavonols (hyperoside, isoquercitrin, avicularin, astragalin, quercitrin and kaempferol) were identified among them. Flavonols hyperoside (2.9–8.2 mg/g), avicularin (3.0–5.8 mg/g) and isoquercitrin (0.8–2.5 mg/g) are the main substances in aqueous ethanol extracts from leaves. Plants from populations located at the northern distribution limit in the Western Transbaikalia have a higher content of phenol carboxylic acids (near the village Koma) and flavonols (near the village Klyuchi). Plants from populations located to the eastern limit (near villages Kusoty and Zagan) have the lowest concentration of identified phenolic compounds. A high and very high level of interpopulation variability of the studied biochemical parameters has been established. This can be explained by the functional significance of the identified compounds and their active participation in general metabolic processes in the plant. The content of identified free phenolic acids and flavonols in S. aquilegifolia was characterized by medium and high levels, compared to other studied Spiraea species. This confirms the prospects for further study of the composition of phenolic compounds of S. aquilegifolia.

Barley and Malt as Base Ingredients for the Production of New Bio-Functional Foods

This work aimed to evaluate the chemical composition, bioactive compounds (phenolics and γ-aminobutyric acid, GABA), and antioxidant properties of different barley varieties (Overture, Charles, Sinfonía, Montoya, and Andreia) and their malts to weigh up them as potential ingredients for producing new bio-functional foods. For this, five barleys and five malts obtained from them were studied. Regarding chemical composition, total starch was the main component (≈62%) of barleys followed by total dietary fiber (≈22.6%) and proteins (≈9.5%). Potassium and phosphorus were the most abundant elements, with mean values being 3746.1 and 3679.1 g 100g<sup>-1</sup>d.w., respectively. Regarding the free amino acid profile, the proportion of hydrophobic free amino acids was higher than that of branched-chain amino acids or sulfur-containing amino acids and the mean value of GABA was 8.8 mg 100g<sup>-1</sup>. Ferulic acid was the most abundant free phenolic acid detected in the different barleys, followed by coumaric acid. All barley extracts showed ABTS and DPPH inhibitory activities and ferric-reducing antioxidant power (FRAP). As expected, total starch, total dietary fiber, and crude fat contents of malts were lower than those found for barley. However, the malting process increased GABA, ferulic acid, hydrophobic free amino acids, branched-chain amino acids, and sulfur amino acid contents. Additionally, the antioxidant properties of malts were higher than those obtained for barleys. Barley flour could be successfully used as a bio-functional ingredient in many foods. Furthermore, given the high content of soluble solids (mainly carbohydrates, antioxidant compounds such as free phenolic acids and free amino acids, and GABA), malted flours would be novel ingredients for preparing beverages with bio-functional properties.

The Effect of Various Forms of Sulfur on Soil Organic Matter Fractions and Microorganisms in a Pot Experiment with Perennial Ryegrass (Lolium perenne L.).

This article focuses on the agronomic evaluation of the supplementation of mineral NPKMg fertilizers with elemental sulfur, magnesium, potassium, or ammonium sulfates in pot experiments with ryegrass growing in a sandy Arenosol with very low sulfur content. A benefit evaluation was carried out on the basis of biomass production, crop nutritional status, and changes in the content of soil organic matter fractions. Furthermore, the total number of bacteria, nitrogen-fixing bacteria, and fungi was estimated using the qPCR technique in soil samples after 60 days of ryegrass growth. The combined application of NPKMg and sulfur or sulfate fertilizers significantly increased the summary yield of three cuttings of fresh ryegrass biomass in the range of 32.3% to 82.7%. The application, especially in the form of sulfates, significantly decreased the content of free phenolic acids. Furthermore, compared to the control, i.e., soil with NPKMg applied alone, an increase in the content of glomalin-related proteins and a decrease in the amount of water-soluble organic carbon compounds were observed. Neither the number of DNA marker copy numbers of the total bacterial community nor the nitrogen-fixing bacteria were noticeably different. In turn, the total number of genetic markers for fungi was significantly higher in soils with potassium or ammonium sulfates compared to the control soil. The general results suggest that the application of sulfur fertilizers with NPKMg mineral fertilizer can benefit crops and support soil fertility due to the stabilization of aggregates and the decrease in water-soluble organic compounds.

Fermented corn bran: A by-product with improved total phenolic content and antioxidant activity

Corn bran is a milling by-product of the corn industry; however, it has been considered a potential source of phenolic compounds. This study was conducted to evaluate the potential of solid-state fermentation with Lactobacillus reuteri and Lactobacillus plantarum for improving the phenolic compounds and antioxidant activity of corn bran. The fermentation caused a significant increase in the total phenolic content (TPC) of fermented corn brans compared to the control sample. Highest TPC was obtained after 48 h of fermentation. The antioxidant activity, measured through different methodologies (DPPH, ABTS, ORAC assays), was higher in the fermented corn bran samples than in the control one. Fermentation increased the concentration of free phenolic acids, especially ferulic acid and p-coumaric acid, in the fermented samples. Fourier-transform infrared spectroscopy indicated that fermentation promoted the degradation of some ester bonds in the substrate structure, which could lead to the release of free phenolic acids. Meanwhile, scanning electron microscopy showed that the fermentation led to the formation of a loose surface structure in the fermented samples. The results revealed that solid-state fermentation was an effective method for the enhancement of phenolic compounds, suggesting that this bioprocessing technology may help improve the antioxidant activity of fermented corn bran.