Analysis of isoflavones and flavonoids in human urine by UHPLC

Supervised Statistical Learning Prediction of Soybean Varieties and Cultivation Sites Using Rapid UPLC-MS Separation, Method Validation, and Targeted Metabolomic Analysis of 31 Phenolic Compounds in the Leaves

Soybean (Glycine max; SB) leaf (SL) is an abundant non-conventional edible resource that possesses value-adding bioactive compounds. We predicted the attributes of SB based on the metabolomes of an SL using targeted metabolomics. The SB was planted in two cities, and SLs were regularly obtained from the SB plant. Nine flavonol glycosides were purified from SLs, and a validated simultaneous quantification method was used to establish rapid separation by ultrahigh-performance liquid chromatography-mass detection. Changes in 31 targeted compounds were monitored, and the compounds were discriminated by various supervised machine learning (ML) models. Isoflavones, quercetin derivatives, and flavonol derivatives were discriminators for cultivation days, varieties, and cultivation sites, respectively, using the combined criteria of supervised ML models. The neural model exhibited higher prediction power of the factors with high fitness and low misclassification rates while other models showed lower. We propose that a set of phytochemicals of SL is a useful predictor for discriminating characteristics of edible plants.

A brief history and spectroscopic analysis of soy isoflavones

The production of soybean continues to increase worldwide. People are showing more interest in the beneficial health effects of soybeans than before. However, the origin and history of soybeans are still being discussed among many researchers. Chromatographic methods enable the desirable separation of a variety of isoflavones from soybeans. The structures of isolated soy isoflavones have been successfully identified in tandem with spectroscopic analytical instruments and technologies such as liquid chromatography, mass spectrometry, and nuclear magnetic resonance spectroscopy. The theoretical background behind spectroscopy may help improve the understanding for the analysis of isoflavones in soybeans and soy-derived foods. This review covers the origin of the English name of soybean and its scientific name, Glycine max (L.) Merrill, based on the evidence reported to date. Moreover, the reports of soy isoflavones discovered over a period of about 100 years have been briefly reviewed.

Application of "spider-web" mode in discovery and identification of Q-markers from Xuefu Zhuyu capsule

BACKGROUND

The selection of quality control indicators in a complex system is a key scientific issue for the study of Chinese materia medica (CMM), which is directly related to its safety and efficacy. In order to scientifically understand and control the quality of CMM, quality marker (Q-marker) has been recently raised as a new concept, which provided a novel research idea for the quality control and evaluation of CMM.

PURPOSE

By a new and integrated "spider-web" mode, Q-markers of Xuefu Zhuyu capsule (XZC) were comprehensively uncovered, conducing to great improvement of quality control of XZC.

METHODS

Mainly established by three dimensions derived from six variables including content, stability and activity, "spider-web" mode was constructed to evaluate Q-marker property of candidate compounds by taking regression area of the tested compounds into account.

RESULTS

The candidate compounds with larger regression area were preferentially adopted as Q-markers, which should possess the satisfactorily integrated properties of content, stability and activity. Six compounds, naringin, isoliquiritin, paeoniflorin, protocatechuic acid, neohesperidin and ferulic acid, were identified and preferred as Q-markers of XZC.

CONCLUSION

Based on "spider-web" mode, Q-markers from Xuefu Zhuyu capsule were successfully screened, which would substantially perform quality control of XZC and prove the feasibility of "spider-web" mode in solving the selection of quality control indicators from compound formulae.

Quantification of isoflavone glycosides and aglycones in rat plasma by LC-MS/MS: Troubleshooting of interference from food and its application to pharmacokinetic study of Semen Sojae Praeparatum extract

The isoflavones widely exist in the daily diets and interferences are usually inevitable in the determination of the in vivo level of the same analytes. A new strategy to eliminate the dietary interference was established to evaluate the exposure of isoflavones including daidzin, glycitin, genistin, daidzein, glycitein, and genistein in rats fed with Semen Sojae Praeparatum (SSP) extract. Plasma samples were pretreated by liquid-liquid extraction with ethyl acetate using quercetin as the internal standard (IS). The chromatographic separation was achieved on a Symmetry C18 column (100 mm × 3.0 mm) using a gradient mobile phase consisting of acetonitril and water (containing 0.1% formic acid) with a run time of 13.0 min at a flow rate of 0.4ml/min. The detection was carried out by a triple-quadrupole tandem mass spectrometer in multiple reaction monitoring (MRM) mode via polarity switching between negative (for and positive (for daidzin glycitin) ionization mode. All calibration curves exhibited good linearity (r> 0.99) over a wide concentration range for all components. The lower limit of quantitation (LLOQ) was in the range of 0.1-0.4 ng/ml. The intra-day and inter-day precisions (RSD) at three different levels were both less than 14.9% and the accuracies (RE) ranged from -9.3% to 14.5%. The extraction recoveries of the analytes and the IS ranged from 85.7% to 100.2%. The validated method was first successfully applied to pharmacokinetic study of the six isoflavones in rat plasma after oral administration of SSP extract. The dynamic baseline levels of six isoflavones in blank plasma from rats consuming food containing dietary isoflavones were measured for the correction of the plasma concentrations. The principle pharmacokinetic parameters were calculated from rats with or without regular commercial food, and found to be altered by the dietary food containing some isoflavones.

A novel molybdenum disulfide nanosheet self-assembled flower-like monolithic sorbent for solid-phase extraction with high efficiency and long service life

A novel material consisting of molybdenum disulfide (MoS₂) nanosheet that self-assemble into flower-like microspheres which aggregate to form a monolithic matrix with a micro or nano-scaled mesopore structure was successfully synthesized and used as an efficient sorbent for solid-phase extraction (SPE) due to its large specific adsorption area and good stability. The extraction properties of the as-prepared sorbent were evaluated by high-performance liquid chromatography with variable wavelength detection (HPLC-VWD) by analyzing four flavonoids (apigenin, quercetin, luteolin, and kaempferol). Under optimal conditions, the LODs and LOQs were found to be in the ranges of 0.1-0.25 and 0.4-0.5μgL^-1, respectively, and wide linear ranges were obtained with correlation coefficients (R) ranging from 0.9991 to 0.9996. Compared with commercial C18 and Alumina-N sorbents, the as-prepared sorbent showed high extraction efficiency at different concentrations of flavonoids. After 100 uses, the extraction ability of the self-assembled MoS₂ nanosheet monolithic sorbent had no evident decline, denoting a long service life. Finally, the SPE-HPLC-VWD method using the as-prepared sorbent was applied to flavonoid analysis in beverage samples with satisfactory results.

Is enzymatic hydrolysis a reliable analytical strategy to quantify glucuronidated and sulfated polyphenol metabolites in human fluids?

Phenolic compound recovery decreases with the amount of β-glucuronidase enzyme used.

Polymeric ionic liquid modified graphene oxide-grafted silica for solid-phase extraction to analyze the excretion-dynamics of flavonoids in urine by Box-Behnken statistical design

A solid-phase extraction method for the efficient analysis of the excretion-dynamics of flavonoids in urine was established and described. In this work, in situ surface radical chain-transfer polymerization and in situ anion exchange were utilized to tune the extraction performance of poly(1-vinyl-3-hexylimidazolium bromide)-graphene oxide-grafted silica (poly(VHIm(+)Br(-))@GO@Sil). Graphene oxide (GO) was first coated onto the silica using a layer-by-layer fabrication method, and then the anion of poly(VHIm(+)Br(-))@GO@Sil was changed into hexafluorophosphate (PF6(-)) by in situ anion exchange. The interaction energies between two PILs and four flavonoids were calculated with the Gaussian09 suite of programs. A Box-Behnken design was used for the optimization of four greatly influential parameters after single-factor experiments to obtain more accurate and precise results. Coupled to high performance liquid chromatography, the poly(VHIm(+)PF6(-))@GO@Sil method showed acceptable extraction recoveries for the four flavonoids, with limits of detection in the range of 0.1-0.5μgL(-1), and wide linear ranges with correlation coefficients (R) ranging from 0.9935 to 0.9987. Under the optimum conditions, the proposed method was applied to analyze the urines collected from a healthy volunteer. The excretion amount-time profiles revealed that 4-15h was the main excretion time for the detected flavonoids. The results indicated that the newly developed method offered the advantages of being feasible, green and cost-effective, and could be successfully applied to the extraction and enrichment of flavonoids in human body systems allowing the study of the metabolic kinetics.

A novel UHPLC method for the rapid and simultaneous determination of daidzein, genistein and equol in human urine

This work reports on a novel method involving reverse-phased ultra-high performance liquid chromatography (UHPLC) plus a spectrophotometric photodiode array/fluorescence (FLR) detection system for determining the concentration of equol and major soy isoflavones (daidzein and genistein) in human urine. The proposed method was validated in terms of its linearity, sensitivity, accuracy (recovery) and precision (intra- and inter-day repeatability). The isoflavone profiles of urine samples from a group of menopausal women following oral soy isoflavone supplementation were determined and compared. Screening for equol-producer status was accomplished with high sensitivity (detection limit of the FLR detector 2.93nM). The method involves a short chromatographic run time compared to conventional HPLC methods while allowing for the simultaneous and reliable quantification of daidzein, genistein and equol in human urine. It also allows for the rapid screening of multiple urine samples when testing for equol production status and checking patient adherence to isoflavone treatment regimens.

Magnetic solid-phase extraction based on Fe3O4nanoparticle retrieval of chitosan for the determination of flavonoids in biological samples coupled with high performance liquid chromatography

Schemes of two-step magnetic retrieval of chitosan and its application as MSPE adsorbents for simultaneous extraction and preconcentration of targeted analytes in urine and serum samples.

Use of multivariate statistical techniques to optimize the separation of isoflavones by liquid chromatography

The aim of this paper is to optimize and validate a high performance liquid chromatography (HPLC) method for separation and quantification of five isoflavones. A statistical central composite design was used to separate all peaks. These multivariate procedures were efficient in determining the optimal separation condition using resolution, capacity factor, asymmetry and number of theoretical plates. The effective separation of the examined compounds was applied on a Develosil RP Aqueous AR 5 RP-30 column with a gradient mobile phase system and a DAD detector. The isolation and preconcentration of the isoflavones from urine and plasma samples were conducted by means of the solid-phase extraction (SPE). For optimize SPE conditions various sorbents were tested. Furthermore, high recoveries and good relative standard deviations were obtained when the samples were passed through the Oasis HLB column. The developed method was validated and successfully applied for determination of isoflavones in urine and plasma.