Aglycone Content Research Articles

Comparison in Bioactive Compounds and Antioxidant Activity of Cheonggukjang Containing Mountain-Cultivated Ginseng Using Two Bacillus Genus.

In this study, the nutrients, phytochemicals (including isoflavone and ginsenoside derivatives), and antioxidant activities of cheonggukjang with different ratios (0%, 2.5%, 5%, and 10%) of mountain-cultivated ginseng (MCG) were compared and analyzed using microorganisms isolated from traditional cheonggukjang. The IDCK 30 and IDCK 40 strains were confirmed as Bacillus licheniformis and Bacillus subtilis, respectively, based on morphological, biological, biochemical, and molecular genetic identification, as well as cell wall fatty acid composition. The contents of amino acids and fatty acids showed no significant difference in relation to the ratio of MCG. After fermentation, isoflavone glycoside (such as daidzin, glycitin, and genistin) contents decreased, while aglycone (daidzein, glycitein, and genistein) contents increased. However, total ginsenoside contents were higher according to the ratio of MCG. After fermentation, ginsenoside Rg2, F2, and protopanaxadiol contents of cheonggukjang decreased. Conversely, ginsenoside Rg3 (2.5%: 56.51 → 89.43 μg/g, 5.0%: 65.56 → 94.71 μg/g, and 10%: 96.05 → 166.90 μg/g) and compound K (2.5%: 28.54 → 69.43 μg/g, 5.0%: 41.63 → 150.72 μg/g, and 10%: 96.23 → 231.33 μg/g) increased. The total phenolic and total flavonoid contents were higher with increasing ratios of MCG and fermentation (fermented cheonggukjang with 10% MCG: 13.60 GAE and 1.87 RE mg/g). Additionally, radical scavenging activities and ferric reducing/antioxidant power were significantly increased in fermented cheonggukjang. This study demonstrates that the quality of cheonggukjang improved, and cheonggukjang with MCG as natural antioxidants may be useful in food and pharmaceutical applications.

Antioxidant and anti-glycation activities of Mandevilla velutina extract and effect on parasitemia levels in Trypanosoma cruzi experimental infection: in vivo, in vitro and in silico approaches

Ethnopharmacological relevanceMandevilla velutina (Mart. Ex Stadelm.) Woodson, known in Brazil as "infalível" and "jalapa", is a medicinal plant native from the Cerrado region (Brazilian Savannah). The underground organ (xylopodium) of this species is prepared as ethanolic extract or infusion and it is commonly used in traditional medicine to treat snake venom. Although, locals and indigenous populations from Cerrado have used M. velutina for the treatment of infection by Trypanosoma cruzi (Chagas’ disease). Aim of the studyThis study aimed to evaluate the in vitro antioxidant and anti-glycation activities of the crude hydroethanolic extract of M. velutina xylopodium. Besides, it aimed to evaluate its effect on parasitemia levels in in vivo T. cruzi experimental infection. In addition, this study aimed to determine possible interactions between the main compound of the extract and molecular targets associated with survival and virulence of T. cruzi in in silico approaches. Materials and MethodsDetermination of total polyphenols, flavonoids and steroidal aglycones content were performed. In addition, high performance liquid chromatography (HPLC) was carried out to identify main compounds of the extract. Antioxidant activity was determined by DPPH radical scavenging, ferric ion reducing power (FRAP), Thiobarbituric acid reactive species (TBARS) and Oxygen Radical Absorbance Capacity (ORAC) methods. Anti-glycation activity was demonstrated through relative mobility in electrophoresis (RME), determination of free amino groups and inhibition of AGEs formation. Determination of the action of extract in parasitemia levels was performed by T. cruzi experimental infection of mice and nitrite levels were measured in the serum of animals evaluated in this study. Molecular docking analyses of the main compound (Velutinol A) with DNA and molecular targets associated with survival and virulence of T. cruzi. ResultsPhytoconstituents evaluation exhibited the presence polyphenols, flavonoids and steroidal aglycone, and HPLC identified the major presence of Velutinol A. Antioxidant and anti-glycation evaluations showed that the extract present significant activity in all methods evaluated. In addition, extract reduced the number of trypomastigotes and increased the survival of treated animals. The treatment using extract showed an interference in the synthesis of physiological nitric oxide as an immune response to infection. In silico assays demonstrated interaction between Velutinol A and DNA and molecular targets of T. cruzi. ConclusionsThe results showed that the hydroethanolic extract of M. velutina xylopodium contains bioactive compounds including polyphenols, flavonoids and steroidal aglycones (mainly Velutinol A) of which may be responsible for the antioxidant, anti-glycation and anti-parasitic activity against T. cruzi. Trypanocidal activity of M. velutina compounds may be linked to their influence on NO synthesis during infection and/or their capacity to bind and inhibit molecules associated to virulence and survival of T. cruzi.

Long-term stability of extra virgin olive oil: effects of filtration and refrigeration storage on the Kolovi variety.

The composition of extra virgin olive oil (EVOO) defines its sensory, nutritional, and human health benefits, and distinguishes it as a key component of the Mediterranean diet. Nevertheless, EVOO constituents are susceptible to degradation during processing and storage, which reduces the olive oil's quality and limits its shelf life. The present study investigated the effect of molecular filtration before storage and the effect of cool storage at 4 °C on the stability of 'Kolovi' EVOO, a variety originating from the Greek island of Lesvos, over a 24 month period. Storing EVOO at 4 °C positively affected free acidity, peroxide value, K268, fruity qualities, and concentrations of hydroxytyrosol, tyrosol, ligstroside aglycone, lutein, and squalene, in comparison with the control sample stored at room temperature, particularly after 1 year. Molecular filtration significantly affected the ratio of unsaturated fatty acids to saturated fatty acids (UFAs/SFAs). Optimal preservation of parameters such as acidity value and lutein content was achieved by combining molecular filtration with refrigeration. The present study recommends storing EVOO in the refrigerator for up to 18 months. Based on the regulatory limits of the quality characteristics of acidity, peroxide value, K232 value and fruity sensory attributes, the shelf-life of the protected geographical indication (PGI) 'Kolovi' EVOO can reach 2 years under cool storage (4 °C) and with molecular filtration before storage. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Characterization of a novel multifunctional β-glucosidase/xylanase/feruloyl esterase and its effects on improving the quality of Longjing tea

Herein, a novel multifunctional enzyme β-glucosidase/xylanase/feruloyl esterase (GXF) was constructed by fusion of β-glucosidase and bifunctional xylanase/feruloyl esterase. The activities of β-glucosidase, xylanase, feruloyl esterase and acetyl xylan esterase displayed by GXF were 67.18 %, 49.54 %, 38.92 % and 23.54 %, respectively, higher than that of the corresponding single functional enzymes. Moreover, the GXF performed better in enhancing aroma and quality of Longjing tea than the single functional enzymes and their mixtures. After treatment with GXF, the grassy and floral odors of tea infusion were significantly improved. Moreover, GXF treatment could improve concentrations of flavonoid aglycones of myricetin, kaempferol and quercetin by 68.1-, 81.42- and 77.39-fold, respectively. In addition, GXF could accelerate the release of reducing sugars, ferulic acid and xylo-oligosaccharides by 9.48-, 8.25- and 4.11-fold, respectively. This multifunctional enzyme may have potential applications in other fields such as food production and biomass degradation.

Techno-functional properties of whole okara flour hydrolyzed with a carbohydrase complex

Okara flour, a by-product of the manufacture of soy milk, is nutritionally rich, with a high protein and fiber content, and contains minerals and bioactive compounds, such as phenolic compounds. Okara can be used to enrich various food products. However, the high content of insoluble components, such as fiber and proteins, limits its applicability in bakery products, sauces, and beverages. Thus, enzymatic hydrolysis with carbohydrase can be an effective strategy to overcome technological bottlenecks. Studying techno-functional and biological properties is vital to understanding hydrolyzed okara flour's possible impacts and potential applications. Hydrolysis with Viscozyme®L reduced insoluble fibers and increased soluble fibers by 33% and 110%, respectively, using 4% of the enzyme (v/w) at pH 6, 53 °C for 3 h. This modification caused an impact on the techno-functional properties of hydrolyzed okara flour, such as reduced emulsification capacity and increased foaming capacity. Enzymatic hydrolysis also caused changes in the isoflavone profile, increasing the content of aglycones. Regarding antioxidant capacity, an improvement was verified by the ABTS method.

Influence of malting procedure on the isoflavonoid content of soybeans

The goal of this study was to analyse, whether malting technique (consisting of seed hydration, germination and drying) can be used to modify concentration of various isoflavonoids in soybean seeds. Seeds of three soybean varieties were germinated by different lengths of time (from 24 to 120 h) and dried by two different methods, typically used to produce so-called ‘light’ and ‘caramel’ malts. It was determined, that malting decreases concentration of 7-O-β-D-glucosides such as daidzin, genisitin and glycitin, while at the same time increasing concentration of aglycones (daidzein, genistein and glycitein). Increasing time of the germination period increased concentration of aglycones. ‘Caramel’ type malts were characterised with higher concentration of most of the isoflavonoids (daidzin, daidzein, genistin, genistein and glycitein) than ‘light’ type malts. Results of this study suggest that soybean malts can be an interesting substrate in the production of various food products with increased aglycone content.

Protective effect of soy germ-fermented postbiotics derived from Lacticaseibacillus paracasei DCF0429 (SGPB-DCF0429) in human reconstituted skin

Postbiotics are non-viable microorganisms and their components that provide health benefits to their hosts. At this time, the potential effects of food-based postbiotics have not been reported. This study was designed to isolate lactic acid bacteria (LAB) from traditional Korean fermented foods and to evaluate the beneficial properties of soy germ-fermented postbiotics produced using LAB in a reconstructed epidermis model. Among the LABs isolated from traditional Korean fermented foods, Lacticaseibacillus paracasei DCF0429 showed the highest antioxidant and β-glucosidase activities without any harmful enzyme activities. Additionally, L. paracasei DCF0429 increased the isoflavone aglycone content and antioxidant activity of soy germ during postbiotic production. Finally, the soy germ-fermented postbiotic DCF0429 (SGPB-DCF0429) was investigated for its skin barrier properties. SGPB-DCF0429 protected epidermis tissue against oxidative stress by increasing the cell viability and regulating pro-inflammatory cytokines. These results suggest that SGPB-DCF0429 could serve as a promising protective effect in oxidative stress-induced epidermis tissue.

Characterization and stabilization of GluLm and its application to deglycosylate dietary flavonoids and lignans

This study describes the characterization of the recombinant GH3 aryl-β-glucosidase “GluLm” from Limosilactobacillus mucosae INIA P508, followed by its immobilization on an agarose support with the aim of developing an efficient application to increase the availability and concentration of flavonoid and lignan aglycones in a vegetal beverage. In previous studies, heterologous GluLm-producing strains demonstrated a great capacity to deglycosylate flavonoids. Nevertheless, the physicochemical properties and substrate spectrum of the enzyme remained unknown up to now. A high production of purified GluLm was achieved (14 mg L−1). GluLm exhibited optimal activity at broad ranges of pH (5.0–8.0) and temperature (25–60°C), as well as high affinity (Km of 0.10 mmol L−1) and specific constant (86554.0 mmol L−1 s−1) against p-nitrophenyl-β-D-glucopyranoside. Similar to other GH3 β-glucosidases described in lactic acid bacteria, GluLm exhibited β-xylosidase, β-galactosidase, and β-fucosidase activities. However, this study has revealed for the first time that a GH3 β-glucosidase is capable to hydrolyze different families of glycosylated phenolics such as flavonoids and secoiridoids. Although it exhibited low thermal stability, immobilization of GluLm improved its thermostability and allowed the development of a beverage based on soybeans and flaxseed extract with high concentration of bioactive isoflavone (daidzein, genistein), lignan (secoisolariciresinol, pinoresinol, and matairesinol), and other flavonoid aglycones.Key points• Limosilactobacillus mucosae INIA P508 GluLm was purified and biochemically characterized• Immobilized GluLm efficiently deglycosylated flavonoids and lignans from a vegetal beverage• A viable application to produce vegetal beverages with a high content of aglycones is described

Isoflavone aglycone contents of commercial fermented soybean products in Korea and the isoflavone aglycone-producing ability of <i>Bacillus subtilis</i> isolated from the products

Isoflavone aglycone contents of commercial fermented soybean products in Korea and the isoflavone aglycone-producing ability of <i>Bacillus subtilis</i> isolated from the products

Effect of Storage Conditions on Physical Properties, Lipid Oxidation, Isoflavones and Antioxidant Capacity of Flour Prepared from Soy Milk By-Product

During the production of soy milk, a by-product is produced, which is typically treated as a waste material. This by-product has significant levels of dietary fibre, proteins, isoflavones and antioxidant capacity. As such, it has been recommended as an effective functional ingredient when milled to a flour after drying at 100 °C. The shelf-life stability of this dried by-product is relatively unknown when stored under different storage conditions (2 °C, 20 °C and 40 °C) and initial moisture content (9%, 12% and 14%), both packaged and exposed to immediate environments. This study investigated the impact of storage over ten weeks on the physical properties, lipid oxidation, antioxidant capacity and stability of isoflavones of this functional ingredient. The results showed that exposure significantly affected the stability of flour, especially on moisture content, water activity, isoflavone concentration and lipid oxidation. Different initial moisture contents significantly affected the initial and final colour, alongside final moisture and water activity when stored covered at 2 °C and 20 °C. Different storage temperatures were found to affect the moisture content, water activity, lipid oxidation, conversion of isoflavones and antioxidant capacity, with all tested initial moisture contents. Of note, higher conversion rates of malonyl isoflavones to β-glucosides were observed at high temperatures and longer times, while a minimum change in aglycone content occurred. In conclusion, the stability of this flour is least influenced by the initial moisture content but is more affected by high storage temperature and unpackaged conditions.

Effect of microbial fermentation on the quality of soybean meal

SummarySoybean meal is an important and inexpensive source of protein in food and animal feed, and contains anti‐nutritional factors such as trypsin inhibitors, antigenic proteins, oligosaccharides, phytic acids and lectins, which limit its application. Microbial fermentation has the capability to improve the nutritional value and biological activities of soybean meal by changing its natural composition. Fermentation results in the degradation of anti‐nutritional factors in soybean meal, an increased amount of small molecular protein peptides and improved content of isoflavone aglycone. However, the nutritional composition and biological activities of the resulting fermented products differ due to the different microbial species and conditions used for fermentation. Compared to soybean meal, fermented soybean meal has several beneficial effects such as digestibility, antioxidant and hypoallergenicity. The objective of this review is to discuss the fermentation processes of soybean meal, as well as outlines some biological activities associated with it. Furthermore, the current application of fermented soybean meal is also summarised.

Combined acid hydrolysis and fermentation improves bioactivity of citrus flavonoids in vitro and in vivo

Many bioactive plant compounds, known as phytochemicals, have the potential to improve health. Unfortunately, the bioavailability and bioactivity of phytochemicals such as polyphenolic flavonoids are reduced due to conjugation with sugar moieties. Here, we combine acid hydrolysis and tailored fermentation by lactic acid bacteria (Lactiplantibacillus plantarum) to convert the biologically less active flavonoid glycosides hesperidin and naringin into the more active aglycones hesperetin and naringenin. Using a comprehensive approach, we identify the most effective hydrolysis and fermentation conditions to increase the concentration of the aglycones in citrus extracts. The higher cellular transport and bioactivity of the biotransformed citrus extract are also demonstrated in vitro and in vivo. Superior antioxidant, anti-inflammatory and cell migration activities in vitro, as well as intestinal barrier protecting and antioxidant activities in Drosophila melanogaster are identified. In conclusion, the presented biotransformation approach improves the bioactivity of flavonoids, clearly traced back to the increase in aglycone content.

Endophytic fungus-suspension cell co-culture: A new strategy for more rapid and sustainable screening of plant beneficial microorganisms

Microbial fertilizers are increasingly used as alternatives to conventional fertilizers, while the screening process for beneficial microorganisms is inefficient and time-consuming, often taking months or years. This study aimed to evaluate whether the endophytic fungus-suspension cell co-culture strategy could be used for rapid screening of plant beneficial microorganisms. Therefore, we investigated the effects and molecular mechanisms of Fusarium oxysporum GU-7 and GU-60 on the growth and accumulation of secondary metabolites in Glycyrrhiza uralensis suspension cells and potted seedlings. GU-7 significantly promoted the growth of suspension cells and potted seedlings, which may be related to its strong phosphorus-solubilizing and indole-3-acetic acid production capacity. In contrast to GU-60, GU-7 promoted the accumulation of flavonoids and glycyrrhizin at different co-culture times and growth times. Both strains accelerated the accumulation of liquiritigenin, liquiritin, and glycyrrhizin in suspension cells after 24 h of co-culture. Meanwhile, they differentially altered the expression of critical genes. The defense response of suspension cells was enhanced at 72 h, the antioxidant enzyme activity and flavonoid aglycone content were increased and the flavonoid glycoside content was decreased. RNA-seq revealed that the two strains had five times as many glycoside hydrolases as glycosyltransferases and differed in biological processes and biosynthetic pathways involved. Conclusively, the effects of these two strains on suspension cells were consistent with those on potted seedlings, while different strains produced different effects. These results suggest that co-culture with suspension cells is a promising strategy for rapid screening of beneficial microorganisms, even for conspecific fungi. GU-7 has the potential to be further developed as a microbial fertilizer to improve the growth and secondary metabolite accumulation of cultivated licorice.

Study of lignans in wine originating from different types of oak barrels

This study aimed to determine the concentrations of the lignans pinoresinol, secoisolariciresinol, matairesinol and isolariciresinol in white wines aged in twelve different oak barrels originating from different cooperages and regions and with different toasting levels. In a two-year experiment the influence of oak barrels and of variety on lignan content was monitored. The results of this study show that the use of oak barrels affects only syringaresinol concentrations. Wines from low-releasing barrels contained mean concentrations of 20-50 ng/ml of syringaresinol, while wines from high-releasing barrels contained mean concentrations of 140-160 ng/ml of syringaresinol. Wines from the other barrels contained mean concentrations of 70-100 ng/ml of syringaresinol. The amounts of matairesinol and pinoresinol were affected by grapevine cultivar. In Veltliner Grün, the mean matairesinol concentration was significantly higher than in all other cultivars except for Chardonnay (mean concentrations 11, 6 and 3-5 ng/ml in Veltliner Grün, Chardonnay and other cultivars respectively). The amounts of isolariciresinol and secoisolariciresinol and total amount of lignan aglycones were affected by the interaction of cultivar and year. The mean concentrations of both lignans and total aglycone were significantly higher in Chardonnay from 2017 (210, 120 and 460 ng/ml for isolariciresinol, secoisolariciresinol and total aglycones respectively) than in all the other samples (60-130, 0-50 and 180-280 ng/ml for isolariciresinol, secoisolariciresinol and total aglycones respectively).

Dead heart of pith-decayed Scutellariae Radix: a study based on multi-omics

Dead heart is an important trait of pith-decayed Scutellariae Radix. The purpose of this study was to clarify the scientific connotation of the dead heart using multi-omics. Metabolomics and transcriptomics combined with multivariate statistical analysis such as principal component analysis(PCA) and partial least squares discriminant analysis(PLS-DA) were used to systematically compare the differences in chemical composition and gene expression among phloem, outer xylem and near-dead xylem of pith-decayed Scutella-riae Radix. The results revealed significant differences in the contents of flavonoid glycosides and aglycones among the three parts. Compared with phloem and outer xylem, near-dead xylem had markedly lowered content of flavonoid glycosides(including baicalin, norwogonin-7-O-β-D-glucuronide, oroxylin A-7-O-β-D-glucuronide, and wogonoside) while markedly increased content of aglycones(including 3,5,7,2',6'-pentahydroxy dihydroflavone, baicalin, wogonin, and oroxylin A). The differentially expressed genes were mainly concentrated in KEGG pathways such as phenylpropanoid metabolism, flavonoid biosynthesis, ABC transporter, and plant MAPK signal transduction pathway. This study systematically elucidated the material basis of the dead heart of pith-decayed Scutellariae Radix with multiple growing years. Specifically, the content of flavonoid aglycones was significantly increased in the near-dead xylem, and the gene expression of metabolic pathways such as flavonoid glycoside hydrolysis, interxylary cork development and programmed apoptosis was significantly up-regulated. This study provided a theoretical basis for guiding the high-quality production of pith-decayed Scutellariae Radix.

MicroRNA Identification and Integrated Network Analyses for Age-Dependent Flavonoid Biosynthesis in Ginkgo biloba

Ginkgo biloba leaves contain abundant flavonoids, and flavonoid accumulation is affected by age. MicroRNAs (miRNAs) play an important role in the plant aging pathway. However, the miRNAs involved in flavonoid biosynthesis related to age in G. biloba have rarely been studied. In this study, we compared 1-, 4-, and 7-year-old ginkgo seedings and found a significant decrease in the content of quercetin, kaempferol, and total flavonol aglycones with age. We then profiled miRNAs in G. biloba through high-throughput sequencing on leaf samples of 1-, 4-, and 7-year-old ginkgo. GO and KEGG analyses suggest that photosynthesis and hormones may influence the flavonoid content. In particular, we identified 29 miRNAs related to the aging pathway according to their miRNA expression patterns. Correlation analysis of age-related miRNAs and major flavonoid compounds screened 17 vital miRNAs, including miRN79, miR535a, miR166a, miR171a, and miR396. Interactive miRNA-transcription factor network analysis suggested that the pivotal miRN79-DELLA and miR535a-SPL modules may be involved in flavonoid biosynthesis and aging pathways through post-transcriptional regulation. Our findings provide insights into the age-dependent regulatory roles of miRNAs in flavonoid biosynthesis.

Effect of Fermented Matrix on the Color and Stability of Strawberry and Blueberry Anthocyanins during the Storage of Fruit Yogurts and Soy-Based and Bean-Based Fruit Yogurt Alternatives.

The effect of the fermented matrix on the color and the stability of anthocyanins contained in strawberry (Fragaria ananassa D.) and highbush blueberry (Vaccinium corymbosum L.) preparations for fruit yogurts, as well as soy-based (Glycine max L. Merr.) and bean-based (Phaseolus vulgaris L.) yogurt alternatives, stored for 8 weeks, was evaluated. To produce the fermented bean matrix, germinated seeds of white and black beans were used. The obtained fermented matrices had similar pH levels, while the soy-based and black bean-based yogurt alternatives were characterized by their high content of isoflavone aglycones and phenolic acids. The degradation of anthocyanins in strawberry and blueberry fermented products during storage followed first-order reaction kinetics. Significant differences were found depending on the fermented plant-based matrix. The fermented soy-based matrix demonstrated the highest T1/2 values for total anthocyanins (26.3 and 88.8 weeks for strawberry and blueberry products, respectively), whereas the yogurts exhibited the lowest values (13.3 and 49.3 weeks for strawberry and blueberry products, respectively). In the comparison of anthocyanin degradation during the storage of bean-based products, the pigments in the matrix obtained from fermented black beans showed better stability. During storage, the loss of anthocyanins was higher in strawberry products than in blueberry products, particularly with respect to malvidin and petunidin derivatives and acylated anthocyanins, which exhibited high stability. The total color difference (ΔE*) of blueberry plant-based products after an 8 week storage period ranged from 1.1 to 1.5. This data suggests that the addition of a coloring ingredient for industrial production may not be required.

Changes in isoflavone profile, antioxidant activity, and phenolic contents in Taiwanese and Canadian soybeans during tempeh processing

Soybean seeds of eight different varieties were processed to tempeh. Factors affecting each step of tempeh making include isoflavone profile, FRAP (ferric ion reducing antioxidant power) and DPPH (1,1-diphenyl-2-picrylhydrazyl radical scavenging ability) assayed antioxidant activity, and TPC (total phenolic content) in the prolonged fermentation were investigated respectively. The total isoflavone contents in the dry seeds of the tested varieties ranged from 893.3 to 1386.0 μmol/100 g, and more than 99% was in the form of isoflavone glucosides. Tempeh fermentation increased the isoflavone aglycone contents by more than 20 times. Principle component analysis provided evidence of the significant correlation (p < 0.05) between isoflavone aglycone content and FRAP and DPPH assayed antioxidant activities. Molar concentration (μmol/100 g) was the preferred unit to precisely present the conversion from isoflavone glucosides to aglycones, and the total isoflavone content (μmol/100 g) was not decreased after 10 d of fermentation in most varieties. In the prolonged fermentation, daidzein kept increasing throughout but genistein decreased after day 2. For extracting a higher amount of daidzein, longer fermentation could be considered. Our results provide information of preferable fermentation periods and soybean varieties and show that tempeh may be a functional food with readily bioavailable form of isoflavones.

Liquid submerged fermentation by selected microbial strains for onion skins valorization and its effects on polyphenols

Onion skins, actually recycled as organic fertilizers, could be used as a substrate in environmental-friendly bioprocesses to recover high-value bioactive compounds and food ingredients.In this work, a bioprospecting method was carried out including 94 bacterial and 45 yeast strains from several agri-food and environmental niches to verify their ability to grow on onion skins as unique nutrients source.Red and yellow onion skins were assessed by newly selected starter-driven liquid submerged fermentation assays mainly aimed at the release and modification of polyphenols through microbial activities. Fermented onion skins were also investigated as a inexpensive favourable source of microbial enzymes (amylases, proteases, lipases, esterases, cellulases, xylanases).In red onion skins, the treatment with Lactiplantibacillus plantarum TB 11–32 produced a slight increase of bioactive compounds in terms of total phenolics, whereas with the yeast strain Zygosaccharomyces mrakii CL 30 − 29 the quercetin aglycone content increased of about 25% of the initial raw material.In yellow onion skins inoculated, the highest content of phenolic compounds was detected with the yeast strain Saccharomyces cerevisiae En SC, while quercetin aglycone increased of about 60% of the initial raw material in presence of the bacterial strain L. plantarum C 180 − 34.In conclusion, the proposed microbial pre-treatment method can be a potential strategy to re-use onion skins as a fermentation substrate, and as a first step in the development of a biorefinery process to produce value-added products from onion by-products.

Evaluation of the Antioxidant and Anti-Lipoxygenase Activity of Berberis vulgaris L. Leaves, Fruits, and Stem and Their LC MS/MS Polyphenolic Profile.

Berberis vulgaris L. is currently widely studied for its antioxidant and chemopreventive properties, especially with regard to the beneficial properties of its fruits. Although the bark and roots have been well known and used in traditional medicine since ancient times, little is known about the other parts of this plant. The aim of the research was to determine the antioxidant and LOX inhibitory activity effects of extracts obtained from the leaves, fruits, and stems. Another aim of the work was to carry out the quantitative and qualitative analysis of phenolic acids, flavonoid aglycones, and flavonoid glycosides. The extracts were obtained with the use of ASE (accelerated solvent extraction). The total content of polyphenols was determined and was found to vary depending on the organ, with the highest amount of polyphenols found in the leaf extracts. The free radical scavenging activity of the extracts was determined spectrophotometrically in relation to the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical, with results ranging from 63.9 mgTE/g for the leaves to 65.2 mgTE/g for the stem. Antioxidant activity was also assessed using the ABTS test. The lowest value was recorded for the barberry fruit (117.9 mg TE/g), and the highest level was found for the barberry leaves (140.5 mgTE/g). The oxygen radical absorbance capacity test (ORAC) showed the lowest value for the stem (167.7 mgTE/g) and the highest level for the leaves (267.8 mgTE/g). The range of the percentage inhibition of LOX was determined as well. The percentage inhibition of the enzyme was positively correlated with the sum of the flavonoids, TPC, TFC, and the content of selected flavonoids. Phenolic acids, flavonoid aglycones, and flavonoid glycosides were determined qualitatively and quantitatively in individual parts of Berberis vulgaris L. The content of phenolic acids, flavonoid aglycones, and flavonoid glycosides was determined with the LC-MS/MS method. The following phenolic acids were quantitatively and qualitatively identified in individual parts of Berberis vulgaris L.: gallic acid, 3-caffeoylquinic acid, protocatechuic acid, 5-caffeoylquinic acid, 4-caffeoylquinic acid, and caffeic acid. The flavonoid glycosides determined were: eleutheroside E, Eriodictyol-7-glucopyranoside, rutin, hyperoside, isoquercitin, luteoloside, narcissoside, naringenin-7-glucoside, isorhamnetin-3-glucoside, afzeline, and quercitrin. Flavonoid aglycones such as catechin, luteolin, quercetin, and eriodictyol were also determined qualitatively and quantitatively.