Malonyl Glucosides Research Articles

Root uptake and metabolization of Alternaria toxins by winter wheat plants using a hydroponic system

Fungi of the genus Alternaria are ubiquitous in the environment. Their mycotoxins can leach out of contaminated plants or crop debris into the soil entering the plant via the roots. We aim to evaluate the importance of this entry pathway and its contribution to the overall content of Alternaria toxins (ATs) in wheat plants to better understand the soil–plant-phytopathogen system. A hydroponic cultivation system was established and wheat plants were cultivated for up to two weeks under optimal climate conditions. One half of the plants was treated with a nutrient solution spiked with alternariol (AOH), alternariol monomethyl ether (AME), and tenuazonic acid (TeA), whereas the other half of the plants was cultivated without mycotoxins. Plants were harvested after 1 and 2 weeks and analyzed using a QuEChERS-based extraction and an in-house validated LC–MS/MS method for quantification of the ATs in roots, crowns, and leaves separately. ATs were taken up by the roots and transported throughout the plant up to the leaves after 1 as well as 2 weeks of cultivation with the roots showing the highest ATs levels followed by the crowns and the leaves. In addition, numerous AOH and AME conjugates like glucosides, malonyl glucosides, sulfates, and di/trihexosides were detected in different plant compartments and identified by high-resolution mass spectrometry. This is the first study demonstrating the uptake of ATs in vivo using a hydroponic system and whole wheat plants examining both the distribution of ATs within the plant compartments and the modification of ATs by the wheat plants.

Bioavailability of Korean mint (Agastache rugosa) polyphenols in humans and a Caco-2 cell model: a preliminary study exploring the efficacy.

Agastache rugosa, commonly known as Korean mint (KM), is a medicinal plant renowned for its potential health-promoting properties. However, the lack of bioavailability studies has hindered the acquisition of conclusive evidence. In this study, we investigated the bioavailability of six key polyphenols present in KM, including rosmarinic acid (RA), acacetin (AC), and four glycosides of AC. Utilizing UPLC-MS/MS, we analyzed their presence in human plasma and Caco-2 monolayers grown in permeable filter supports. Following single ingestion, we were able to detect RA, AC, and tilianin (TA) in the plasma. Consistent results were obtained for AC and TA but no transport was found for RA in a highly tight Caco-2 cell monolayer, indicating transport through the intercellular space for RA and transepithelial transport for AC and TA. Other AC glucosides with acetyl and/or malonyl groups were rarely found in the plasma. Interestingly, AC glucosides with only an acetyl group appeared at the basolateral side in Caco-2 monolayers, suggesting exclusive hydrolysis of malonyl glucosides in the colon. These findings highlight the high potential of RA, AC, and TA as bioactive compounds that may confer health benefits.

Quantitative determination of isoflavonoids in Ononis species by UPLC-UV-DAD.

The root of the Ononis species has been used internally and externally in ethnomedicine for centuries and contains biologically valuable isoflavonoid compounds. Therefore, it is important to obtain quantitative information about the isoflavonoid profile of these plants. In this article we aimed to develop an optimised sample preparation protocol alongside a validated method for the quantitative measurement of isoflavones, isoflavanones and pterocarpans in the form of glucosides and aglycones, in order to compare the specialised metabolites of Ononis spinosa L. and O. arvensis L. Quantitative determination was carried out by the means of ultra-performance liquid chromatography coupled with ultraviolet diode-array detection (UPLC-UV-DAD). An optimised sample preparation method was developed to transform malonyl glucosides to their glucosidic forms. Chromatographic methods were created for the baseline separation of isoflavones, isoflavanones and pterocarpans alongside with their glucosides. Altogether 12 compounds were evaluated quantitatively in samples of O. spinosa and O. arvensis. As a result, no characteristic change could be observed between the two species regarding their isoflavonoid pattern.

Effect of acetic acid treatment on isoflavones and carbohydrates in pickled soybean

Acetic acid treatment improves the physical, chemical, and physiological properties of soybeans. This study investigated the changes in isoflavone and carbohydrate profiles in four soybean cultivars subjected to different acetic acid treatment durations. The sum of total isoflavone content of the pickled soybeans and the pickling solution was increased by 30–93% after acetic acid treatment for 30days. In the comparison to four isoflavone groups of the untreated soybean, malonyl glucosides were decreased by 17–41%, whereas glucosides were increased by 54–160% in the pickled soybeans. In particular, aglucones were found in the pickled soybeans, but not in the untreated soybeans. Following acetic acid treatment, the total carbohydrate content in the pickled soybeans was 50–65% less than that of untreated soybeans. In particular, oligosaccharides and sucrose in the pickled soybeans decreased significantly (>50%) within the first 24h. This study provides important information on the changes in isoflavone and certain carbohydrates profiles during soybean pickling, and may be useful to produce functional soybean-based foods containing more bioactive compounds.

Changes in the Relationship Between Temperature During the Seed‐Filling Period and Soya Bean Seed Isoflavones Under Water‐Deficit Conditions

AbstractIsoflavones have been shown to have health‐promoting activities in humans and are particularly abundant in soya bean. This study was conducted to determine how water deficit during seed fill affects the already known relationship between temperature and, alternately, solar radiation with soya bean seed isoflavone content. Isoflavone profile was analysed from seed samples of commercial cultivars grown in 76 environments in Argentina (29–38°S). Significant explanatory multiple linear regressions were detected for total isoflavones (TI), aglycones (AGL), glucosides (GLC), malonyl glucosides (MAL) and acetyl glucosides (ACE) regarding the following: temperature during seed fill (TmR5R7) and precipitation minus potential evapotranspiration during the reproductive period (pp‐PETR1R7), as well as for the combinations of these climatic variables. Cumulative solar radiation predicted isoflavone content but was less robust than TmR5R7 and pp‐PETR1R7. To our knowledge, this is the first report of changes in the relationship between TI, as well as AGL, GLC, MAL, and ACE and TmR5R7 as a function of drought in the field. When pp‐PETR1R7 was below 70 mm (indicating drought), TI, as well as AGL, GLC, MAL, and ACE decreased linearly with rising temperatures and with increasing water deficit (decreasing values of pp‐PETR1R7), with both climatic variables exhibiting additive effects on isoflavones. Our results also suggest that water deficit (estimated by pp‐PETR1R7) would be important for modelling the relationship between temperature and soya bean seed isoflavones in rainfed crops.

Antioxidant properties of tofu whey concentrate by freeze concentration and nanofiltration processes

The objective of this study was to add value to tofu whey by enhancing its potential as a source of isoflavones which are associated with the antioxidant activity of soybean. The concentration processes used were the block freeze concentration and the nanofiltration. The concentrates obtained from these processes were evaluated for their isoflavone content and antioxidant activity. The concentrated fluid obtained from freeze concentration showed an increase in the isoflavone contents for all stages. It was observed retention of isoflavones in the ice, however the concentration efficiency remained above 80% in all stages. The nanofiltration process promoted the concentration of β-glucosides and malonyl glucosides conjugates, but it was not possible to concentrate the aglycones. The values for the antioxidant activity of the concentrated fluid obtained from each freeze concentration and nanofiltration stage, measured applying FRAP and ABTS assays, were significantly higher than that of the tofu whey. Moreover, the antioxidant activity was significantly correlated with the isoflavone content of the tofu whey samples.

Malonyl Isoflavone Glucosides Are Chiefly Hydrolyzed and Absorbed in the Colon

Malonyl isoflavone glucosides are water-soluble derivatives of soybean hypocotyls. This study compared the hydrolysis and absorption of malonyl isoflavone glucosides and nonmalonyl isoflavone glucosides in rats. Plasma concentrations of isoflavones were measured after oral administration of malonyl isoflavone glucosides or isoflavone glucosides. After fasting, the duodenum, jejunum, ileum, and colon were excised, and homogenates were prepared. The extent of hydrolysis of each glucoside by each intestinal homogenate was measured. Plasma levels of isoflavone aglycones, such as daidzein and glycitein, were higher in rats administered malonyl isoflavone glucosides than in those administered isoflavone glucosides. The area under the curve of daidzein in plasma of rats administered malonyl isoflavone glucosides was also significantly greater than that in those administered isoflavone glucosides. A transport experiment using Caco-2 cells suggested that degradation of malonyl glucosides to aglycones is necessary for intestinal absorption. Malonyl isoflavone glucosides were hydrolyzed only in the colon, whereas hydrolysis of isoflavone glucosides occurred in the jejunum, ileum, and colon. These results indicated more effective absorption of malonyl isoflavone glucosides than of nonmalonyl isoflavone glucosides. Moreover, effective absorption of malonyl isoflavone aglycones in the colon contributed to the significant increase in plasma isoflavone levels.

Fast simultaneous determination of free and conjugated isoflavones in soy milk by UHPLC–UV

Ultra high pressure liquid chromatography (UHPLC) has become a widely used technique in separation science as it can shorten analysis time while maintaining resolution and increasing sensitivity. Here we developed a UHPLC method with UV detection for the simultaneous determination of isoflavone aglycones (daidzein, glycitein and genistein), their corresponding glycoside forms (daidzin, glycitin and genistin), and acetyl and malonyl conjugate forms of glycosides (malonyldaidzin, malonylglycitin, malonylgenistin, acetyldaidzin, acetylglycitin, acetylgenistin) in soy milk. The method allowed reliable determinations of 12 isoflavones in less than 8min of chromatographic elution. It provided a satisfactory linearity ranging from 0.1 to 5mg/L, except for daidzin and genistin, for which it ranged from 0.1 to 10mg/L. In addition, it showed acceptable chromatographic sensitivity, with a detection limit lower than 0.05mg/L and a determination limit below 0.2mg/L. The precision, in terms of relative standard deviation, was lower than 5% and the accuracy, as mean recovery, was greater than 95%. Total isoflavone content in commercial soy milk samples (n=8) ranged from 1805.22 to 3195.59mg/kg dw. Genistin and Daidzin were the major isoflavones in all samples. The proportion of aglycones, ß-glucosides, and acetyl and malonyl glucosides differed among the samples. ß-Glucosides were identified as the predominant forms.

Concentration of soybean isoflavones by nanofiltration and the effects of thermal treatments on the concentrate

An investigation was performed on the profile and the content of isoflavones in the concentrate of aqueous Defatted Soy Flour (DSF) extract obtained by nanofiltration. The effect of thermal treatments on these isoflavones was also evaluated according to a Central Composite Design (CCD 2k) with varying temperatures (70 to 90°C) and times (15 to 45min). Through nanofiltration it was possible to concentrate β-glucosides and malonyl glucosides (p<0.05) in aqueous DSF extract but it was not possible to concentrate aglycones (p>0.05). The thermal treatments applied on the concentrate showed that the malonyl glucosides were influenced by temperature (p<0.05), while the β-glucosides were influenced not only by temperature but also by the time of interaction of the factors investigated (p<0.05). Moreover, there was no alteration in the contents (p>0.05) of aglycone or total isoflavones.

Influence of the Application of Three Different Elicitors on Soybean Plants on the Concentrations of Several Isoflavones in Soybean Seeds

Soybean [Glycine max (L.) Merr.] is a rich source of isoflavones that are often affected by biotic and abiotic factors. The objectives of this study were to evaluate the effect of various concentrations of three natural elicitors applied at different soybean growth stages on isoflavone content and to compare the efficiency of several solvent systems in isoflavone extraction and quantification. The isoflavones extracted from R96-3444 soybean using eight solvent systems were separated, identified, and quantified by a high-performance liquid chromatography (HPLC) procedure. The soybean plants were sprayed with salicylic acid, methyl salicylate, or ethyl acetate at 0, 10(-6), 10(-3), and 10(-1) M at R1 (blooming) or R4 (full pods) growth stage. Results showed that 10(-3) M ethyl acetate sprayed at the R1 stage significantly increased total isoflavone content and the levels of some individual isoflavones in soybean seeds. With all the elicitors that were tested, concentration was a more important factor than application time with respect to isoflavone content with lower concentrations being more effective on most isoflavones. A 53% acetonitrile solvent system was the best solvent system for extracting total isoflavone, malonyl glucosides, genistein, glycitin, genistin, acetyl-daidzin, and acetyl-genistin. The results of this study will be useful for increasing the isoflavone content in desirable soybean varieties and improving isoflavone concentration during extraction.

Red Clover Trifolium pratense L. Phytoestrogens: UV-B Radiation Increases Isoflavone Yield, and Postharvest Drying Methods Change the Glucoside Conjugate Profiles

Isoflavone extracts of red clover Trifolium pratense L. (cv. Pawera) with dissimilar glucoside conjugate profiles were obtained by employing different postharvest drying methods. The most prominent isoflavones found were formononetin and biochanin A and their corresponding glucosides and malonyl glucoside esters. Postharvest freeze drying inhibited the conversion of the glycosides to the aglycones, while vacuum drying allowed for maximum conversion of the glycosides to their corresponding aglycones. Air drying produced a low level of the aglycones formononetin and biochanin A, and oven drying promoted decarboxylation of the malonyl glucosides to the acetyl glucosides. Exposure to enhanced UV-B radiation resulted in an increase in total formononetin and biochanin A isoflavone levels, indicating that harvest during a period of high ambient UV-B radiation may be appropriate for maximum yield. The levels of caffeic acid and flavonols also increased by about 40 and 250%, respectively, on exposure to enhanced UV-B radiation.

A simplified HPLC method for total isoflavones in soy products

Soybeans and soy products are the main source of isoflavones, a well-studied group of phytoestrogens with numerous biological effects. Several methods have been published to quantify soy isoflavones in food samples. We have earlier applied enzyme hydrolysis followed by acid hydrolysis to measure isoflavones as total aglycone equivalents. Alternatively, other published methods have mainly been developed to measure all 12 forms of isoflavones. In order to simplify the analyses, a new extraction method for determination of total amount of isoflavones was developed and validated. Acetyl and malonyl glucosides were hydrolysed to 7- O-glucosides with 80% EtOH containing 1 M HCl to remove the acetyl and malonyl groups. Aglycones and 7- O-glucosides were analysed with HPLC using coulometric electrode array detection.

Effects of processing on the content and composition of isoflavones during manufacturing of soy beverage and tofu

Isoflavones present in soybean ( Glycine max) have been credited with performing several health-promoting functions, such as, prevention of cardiovascular diseases, cancers, and menopausal symptoms. In this study, the effect of the processing of soybean on the total content of isoflavones (including aglycones and glucosides) and the relative concentrations of 12 isoflavone compounds during the preparation of soy beverage and tofu were investigated. The mean recoveries of isoflavones in soy beverage and tofu in relation to their initial concentration in the raw soybeans were 54 and 36%, respectively. The estimated percentage of total isoflavones lost in the water used to soak raw soybeans, the okara (waste from heat-treated slurry), and whey were 4, 31, and 18%, respectively. The isoflavone profile of raw soybeans was altered as a result of processing. During processing, the detectable levels of aglycones, glucosides, and acetyl glycoside groups increased, whilst the corresponding malonyl glucosides decreased. The loss of isoflavones through the by-products, such as, okara and whey, was considerable. Appropriate techniques should be developed to recover and utilize these functional constituents from soybean by-products. In addition, processing techniques have to be optimized, so that the final products contain the nutrient and nutraceutical content of the starting material as much as possible.

Rapid metabolism of isoflavonoids in elicitor-treated cell suspension cultures of Pueraria lobata

Upon treatment with yeast extract as an elicitor to cell suspension cultures of Pueraria lobata, the constitutive isoflavonoid conjugates (7- O-glucoside-6″- O-malonyl esters) showed a rapid decline in their contents within 4 hr, followed by both reaccumulation of the conjugates and formation of isoflavones. Simultaneous treatment of a potent translation inhibitor, cycloheximide (200 μM), could not suppress the elicitor-inducible decrease of the pre-existing isoflavonoids, although it resulted in almost complete inhibition of both reaccumulation of the conjugates and formation of isoflavones. Exogenously applied 14C-labelled isoflavones were readily converted to their respective malonyl glucosides in the cells. When yeast extract was applied to the cell cultures in which [ 14C]-daidzein had been incorporated into its malonyl glucoside, the methanol-soluble radioactivity decreased rapidly within 4 hr and it was not recovered for 48 hr, indicating that most of the conjugate was incorporated into an insoluble cell wall fraction. The rapid response upon elicitation was selective for isoflavonoids and not for flavonoids.

Isoflavonoid Conjugate Accumulation in the Roots of Lucerne (Medicago Sativa) Seedlings Following Infection By the Stem Nematode (Ditylenchus Dipsaci)

Susceptible (cv. Sabilt) and resistant (cv. Vertus) lucerne (Medicago sativa) seedlings were infected with the stem nematode, Ditylenchus dipsaci and foliar and root tissue analysed for the presence of isoflavonoids. Within 10 days of inoculation, clear differences were seen in the responses of resistant and susceptible plants. Neither cultivar accumulated detectable concentrations of isoflavonoids or their metabolites in the foliar tissue, where all the nematodes were localized; in the roots of infected Vertus plants, the malonyl glucosides of medicarpin and formononetin and the glucosides of coumestrol and formononetin were present at two to three times the concentrations in the uninfected controls. In susceptible Sabilt, these changes were less marked and were restricted to a transient increase in the glucosides of formononetin and coumestrol. Increases in these isoflavonoid conjugates in the roots were associated with increased activities of the enzyme phenylalanine ammonia lyase, but the enzyme was not induced in infected shoots. The results suggest that although increases in isoflavonoid conjugates in the roots were not directly responsible for resistance to D. dipsaci, their accumulation was in response to a systemic signal from the infected shoots, and was correlated with resistance.