Performance Liquid Chromatography-diode Array Detection Research Articles

Microwave-assisted ionic liquid microextraction combined with high performance liquid chromatography for the determination of naphthoquinones from Arnebia euchroma (Royle) Johnst

A simple, rapid, and green microwave-assisted ionic liquid microextraction was established and applied to the extraction of naphthoquinones in Arnebia euchroma (Royle) Johnst., including shikonin, acetylshikonin, and β,β′-dimethylacrylshikonin. In this study, 100 μL of 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6mim][PF6]) was used as extraction solvent. After the sample powder and ionic liquid were mixed homogeneously by the vortex, microwave extraction was performed. The sample extract was diluted with methanol and then filtered. Finally, the resulting solution was separated and determined by high performance liquid chromatography-diode array detection. In this work, the experimental parameters affecting the extraction yields, including size of sample particle, sample amount, type and volume of ionic liquid, microwave power, and time were optimized. The experimental results showed that the compounds have a good linear relationship (r > 0.9999). The limits of detection and quantification were 5.0–19.2 ng mL−1 and 16.7–63.9 ng mL−1. The spiked recoveries were between 76.95% and 93.55%. The intra-day and inter-day precision were lower than 3.14% and 8.53%, respectively. Compared with ultrasound-assisted extraction and soxhlet extraction, the present method consumed less sample, extraction solvent, and extraction time. So, the present method can be used for the extraction and determination of naphthoquinones in Chinese herbal medicine.

Phenol Profiling and Nutraceutical Potential of Lycium spp. Leaf Extracts Obtained with Ultrasound and Microwave Assisted Techniques.

In recent years, agricultural and industrial residues have attracted a lot of interest in the recovery of phytochemicals used in the food, pharmaceutical, and cosmetic industries. In this paper, a study on the recovery of phenol compounds from Lycium spp. leaves is presented. Ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) have been used with alcoholic and hydroalcoholic solvents. Methanolic UAE was the most successful technique for extracting phenols from Lycium leaves, and we used on leaves from L. barbarum and L. chinense cultivated in Italy. The extracts were then characterized as regards to the antioxidant properties by in vitro assays and the phenol profiling by a high performance liquid chromatography-diode array detector (HPLC-DAD). Chlorogenic acid and rutin were the main phenol compounds, but considerable differences have been observed between the samples of the two Lycium species. For example, cryptochlorogenic acid was found only in L. barbarum samples, while quercetin-3-O-rutinoside-7-O-glucoside and quercetin-3-O-sophoroside-7-O-rhamnoside only in L. chinense leaves. Finally, multivariate statistical analysis techniques applied to the phenol content allowed us to differentiate samples from different Lycium spp. The results of this study confirm that the extraction is a crucial step in the analytical procedure and show that Lycium leaves represent an interesting source of antioxidant compounds, with potential use in the nutraceutical field.

Identification of C-glycosyl flavones by high performance liquid chromatography electrospray ionization mass spectrometry and quantification of five main C-glycosyl flavones in Flickingeria fimbriata

Flickingeria fimbriata is commonly applied in China as a traditional Chinese medicine (TCM), however the quality control of it is incomplete. In this work, we aim to identify and quantify the structures of C-glycosyl flavones in F. fimbriata. High performance liquid chromatography-diode array detector (HPLC-DAD) and High performance liquid chromatography–electrospray ionization–multiple stage tandem mass spectrometry (HPLC–ESI–MSn) methods were combined to identify C-glycosyl flavones and determine their contents. Twenty acylated C-glycosyl flavones and ten non-acylated C-glycosyl flavones were identified for the first time in F. fimbriata on systematic MSn analysis via HPLC–ESI–MSn. The aglycones of all of these compounds were apigenin or chrysoeriol and were acylated with p-coumaric, ferulic, 3,4-dimethoxycinnamic or 3,4,5-trimethoxycinnamic acids. Furthermore, the quantification result suggest that two C-glycosyl flavones (vicenin-I and vicenin-III) with relative high contents were revealed to be more strongly acylated in F. fimbriata. The method is sufficiently precise, accurate, and sensitive for the qualitative and quantitative analysis of C-glycosyl flavones, which is expected to establish a standard for quality control and identification in this plant.

Liquid chromatography fingerprint analysis and antioxidant activity of selected lavender species with chemometric calculations.

The extracts of seven Lavandulae species (Lavandula stoechas, Lavandula lanata, Lavandula viridis, Lavandula angustifolia „Rosea”, Lavandula angustifolia „Afropurpurea”, Lavandula angustifolia and one unknown) were analyzed using the reversed-phase-high performance liquid chromatography–diode array detection (RP-HPLC–DAD) with gradient elution technique to obtain the chromatographic fingerprint profiles. The HPLC analysis was performed using the Kinetex RP18 chromatographic column and eluent consisting of methanol-water-0.1% formic acid (5–100% (v/v)) at 30 °C with the run time of 60 min. and the detection wavelength 280 nm. The chromatograms were preliminary processed with the smoothing, noise reduction, background subtraction and alignment using the SpecAlign program (version 2.4.1). The presence of selected standards (apigenin, myricetin, luteolin, luteolin 7-glucoside, chlorogenic acid, caffeic acid, ferulic acid) in the extracts was confirmed. The chemical similarity between studied plants was evaluated using the Cluster Analysis (Pearson correlation coefficient, r, and Euclidean) and PCA. The preliminary antioxidant activity of studied extracts was evaluated based on the total phenolic content (Folin-Ciocalteu method), ferric ion reducing antioxidant parameter (FRAP) and α,α-diphenyl-β-picrylhydrazyl (DPPH) free radical scavenging method using the spectrophotometric technique.

Magnetic naphthalene-based polyimide polymer for extraction of Sudan dyes in chili sauce

A facile and rapid method was reported for the preparation of magnetic nanocomposite of naphthalene-based polyimide polymer modified Fe3O4 (Fe3O4@NPI), which was characterized and explored as sorbents for extraction of Sudan dyes (Sudan I, II, III and IV) in chili sauce prior to their HPLC determination.Some potential parameters influencing the MSPE efficiency were optimized using response surface methodology (RSM). Under the optimal experimental conditions an approach for the analysis of Sudan dyes was developed by coupling with high performance liquid chromatography-diode array detector (HPLC-DAD). Good linearity (r > 0.9932) with linear range of 0.05–50 ng L−1was obtained. The enrichment factors, LODs and LOQs for the proposed method were found to be in the ranges of 80.9–88.9, 0.02–0.05 ng g−1 and 0.07–0.17 ng g−1, respectively. The method was utilized to analyze target Sudan dyes in real chili sauce samples, and sufficient recoveries ranged from 92.6 to 98.6% were obtained with RSDs <5.8%. These results indicate that the prepared Fe3O4@NPI is an effective sorbent for the extraction of Sudan dyes prior determination.

Structural characterization and determination of biological activities for different polysaccharides extracted from tree mushroom species.

Chemical composition and structural characterization of polysaccharides of Fomes fomentarius (FF), Fuscoporia torulosa, Ganoderma adspersum, Ganoderma applanatum (GAP), Ganoderma lucidum, Phellinus igniarius, Pleurotus ostreatus (PO), and Porodaedalea pini (PP) tree mushrooms with antioxidant and anticholinesterase activities were determined in this research. Total carbohydrate contents of the polysaccharides were ranged between 65.06±6.76 and 88.27±5.15µg/mg and total protein contents were ranged between 3.18±0.72 and 6.56±1.25µg/mg. Galactose, glucose, and mannose were identified as major monosaccharides in all polysaccharides using gas chromatography-mass spectrometry. FT-IR analysis showed the characteristic peaks of the polysaccharides and high performance liquid chromatography-diode array detection was used to determine the molecular weight of the polysaccharides. In β-carotene-linoleic acid assay FF (IC50 : 2.55±0.40µg/ml) displayed the highest antioxidant activity, whereas GAP indicated the highest antioxidant activity in cupric reducing antioxidant capacity (A0.50 :59.90±0.53μg/ml), ABTS•+ (IC50 : 16.62±0.31μg/ml), and DPPH• (IC50 : 45.58±0.21μg/ml) assays. In cholinesterase inhibitory activity test, PO (56.31±0.0.74%) showed significant inhibitory activity against butyrylcholinesterase enzyme. PRACTICAL APPLICATIONS: Polysaccharides from mushrooms are the major class of bioactive compounds with various biological activities. Several studies were performed on the biological activity of the polysaccharide extracts from different mushrooms. However, to our knowledge, this is the first report on the chemical composition, structural characterization, antioxidant, and anticholinesterase activities of extracted polysaccharides from studied mushrooms in detail. This investigation shows that polysaccharide extracts obtained from tree mushrooms show a significant bioactivity and these polysaccharides might be used as bioactive natural sources in the pharmaceutical, food, and cosmetic industries.

Preventive Effect of an Infusion of the Aqueous Extract of Chaya Leaves (Cnidoscolus aconitifolius) in an Aberrant Crypt Foci Rat Model Induced by Azoxymethane and Dextran Sulfate Sodium.

Aberrant crypt foci (ACF) is the precursor lesion of colorectal carcinogenesis (CRC), one of the most common malignancies in the world. Many studies have reported that people with higher phytochemical intake are at a reduced risk of developing ACF. One example of the botanical potential of preventive plant products is Cnidoscolus aconitifolius (CA), commonly known as Chaya. This study evaluated the phenolic profile of CA and the effects of the daily consumption of CA leaf infusion on the formation of ACF, histopathological lesions, and molecular biomarkers after azoxymethane (AOM) and dextran sulfate sodium (DSS) induced premalignant colon lesions in rats treated with for 16 and 32 weeks. The phenolic composition of the CA infusion was identified by reversed phase-high performance liquid chromatography-diode array detection (RP-HPCC-DAD). After sacrifice, a 4 cm segment was collected from the distal part of the colon and stained with methylene blue to look for ACF. Furthermore, 4 μm of colon, liver, and kidney was collected and stained with hematoxylin and eosin for histopathological analysis, along with 7 μm of colon for immunohistochemistry analysis. Eleven phenolic compounds were identified in the infusions, and ACF formation was reduced by 29.5% at the subchronic and by 64.6% at chronic stages. Lesions on kidney, liver, and colon tissue were also reduced. Our data suggest that CA treatment has preventive effects against AOM-/DSS-induced premalignant colon lesions in colon rats at the promotion level, inhibiting the cell proliferation of early neoplastic lesions and colonic inflammation through the decrease of β-catenin by 41.8% at the subchronic stage and 29% at the chronic stage, along with a 46.2% reduction of cyclooxygenase 2 (COX-2) at long term, despite a high expression of NF-κB (30.3% at the subchronic stage and 22.8% at the chronic stage).

Rapid Magnetic Solid-Phase Extraction Based on Graphene Oxide/Magnetite Nanoparticles for the Determination of Non-Steroidal Anti-Inflammatory Drugs and Bisphenol-A in Tap Water

A simple and rapid magnetic solid-phase extraction based on reduced graphene oxide/ferroferic oxide (rGO/Fe3O4) coupled with high performance liquid chromatography-diode array detector (HPLC-DAD), was proposed for the determination of naproxen and diclofenac sodium of non-steroidal anti-inflammatory drugs (NSAIDs) and bisphenol-A residue in tap water sample. Fe3O4 was assembled with graphene oxide by facile method. Several important parameters, such as extraction time, desorption time and desorption solvent were studied and optimized. Optimal conditions were then used for the extraction of NSAIDs and bisphenol-A from real samples, prior to HPLC-DAD analysis using C18 column. The proposed method provides good linearity in the range of 1.0-5.0 mg L-1 (R2 naproxene = 0.9983, R2 diclofenac = 0.9960) for NSAIDs and R2 = 0.9919 for bisphenol-A; limit of detection of 0.031 mg L-1 and 0.023 mg L-1 for naproxen and diclofenac, respectively and 0.1785 mg L-1 for bisphenol-A; limit of quantification for naproxen and diclofenac were 0.102 and 0.076 mg L-1, respectively and 0.5949 mg L-1 for bisphenol-A; relative recoveries between 66.21 and 105.60 % for diclofenac and naproxen, respectively and 72.74 % for bisphenol-A; and acceptable reproducibility relative standard deviation (RSD, n = 3) of 6.79 and 11.32 % for diclofenac and naproxen, respectively and 0.93 % for bisphenol-A. The method was successfully applied to tap water sample and the results indicates that small residue of bisphenol-A is present the sample while no traces of NSAIDs was detected.

Fabric phase sorptive extraction for the isolation of five common antidepressants from human urine prior to HPLC-DAD analysis

An innovative fabric phase sorptive extraction-high performance liquid chromatography-diode array detection (FPSE-HPLC-DAD) method is developed and validated herein for the simultaneous extraction and analysis of five common antidepressants (venlafaxine, paroxetine, fluoxetine, amitriptyline, clomipramine) in human urine samples. Separation was obtained using a reverse phase column LiChroCART-LiChrospher®100 RP-8e (5 μm, 250 × 4 mm) with diode array detection monitoring at 235 nm. Gradient elution was applied at a flow rate of 1.2 mL/min with a mobile phase that consisted of acetonitrile and ammonium acetate (0.05 M). Fabric Phase Sorptive Extraction was evaluated for the first time with regards to the extraction of the examined antidepressants from human urine and proved to be a rapid, simple, environmentally friendly, efficient, and selective sample preparation approach. Sol-gel graphene sorbent, coated on cellulose FPSE media, were the most efficient among other with different polarities. The absolute recovery values were 25.5% for venlafaxine, 33.9% for paroxetine, 67.0% for fluoxetine, 43.0% for amitriptyline and 29.0% for clomipramine, while relative recoveries were higher than 90%. The developed method provides satisfactory limit of detection 0.15 ng/μL.

Determination of Ibuprofen and Phenylephrine in Tablets by High-Performance Thin Layer Chromatography and in Plasma by High-Performance Liquid Chromatography with Diode Array Detection.

Two chromatographic methods (high performance thin layer chromatography (HPTLC) and high performance liquid chromatography-diode array detector (HPLC-DAD)), were addressed for the analysis of a mixture consisted of phenylephrine hydrochloride and ibuprofen in two forms bulk and their combined dosage form. This binary mixture is considered to be a challenging one as the two drugs differ greatly in their chemical and physical properties. Not only this affects their simultaneous analysis, but also hinders their simultaneous extraction from biological fluids as plasma. That is the reason the literature lacks any report for the simultaneous extraction and analysis of these drugs from biological fluids. The concentration ranges of both drugs were 0.1-2.5 μg/spot and 0.1-100 μg/mL by HPTLC and HPLC, respectively. Not only was the HPLC-DAD method applied to the investigated drugs determination in pharmaceutical preparations, but also in spiked human plasma. Extensive study was conducted to optimize their simultaneous extraction from plasma as it was a crucial step for the in vivo analysis. The results obtained by proposed methods and a reference one were statistically comparable by analysis of variance test. No significant difference was recorded between the mean percent levels determined by the proposed methods and the reference one.

Solid phase extraction of carbamate pesticides with porous organic polymer as adsorbent followed by high performance liquid chromatography-diode array detection

A solid phase extraction (SPE) method with a porous organic polymer as adsorbent was established for the extraction of five carbamate pesticides (metolcarb, carbaryl, isoprocarb, bassa and diethofencarb) from milk, white wine and juice samples prior to high performance liquid chromatography-diode array detection. The main factors affecting the SPE were optimized, including sample volume, sample loading rate, sample solution pH, desorption conditions and cartridge reusability. Under the optimal conditions, a good linearity existed in the range from 1.0 to 320.0 ng mL−1 for milk and white wine samples and from 0.5 to 160.0 ng mL−1 for juice sample with the correlation coefficients between 0.9956 and 0.9998. The method recoveries of the carbamates were 82.0%–110.0%. The limits of detection were 0.12-0.40 ng mL-1 for milk and white wine samples, and 0.06-0.20 ng mL−1 for juice sample. The adsorption mechanism of the adsorbent was investigated by the extraction of different types of organic compounds (carbamates, benzoylurea insecticides, endocrine disrupting chemicals and polycyclic aromatic hydrocarbons) with the adsorbent. The results showed that the existence of the hydrogen-bonding between the adsorbent and the analytes is favorable for the adsorption and strong hydrophobicity seems to have an adverse effect.

Target-based metabolomics for fast and sensitive quantification of eight small molecules in human urine using HPLC-DAD and chemometrics tools resolving of highly overlapping peaks

Chemometrics multivariate calibration coupled with high performance liquid chromatography-diode array detection (HPLC-DAD) analytical strategy was applied for fast and sensitive quantification of the eight small molecules (uric acid, creatinine, tyrosine, homovanillic acid, hippuric acid, indole-3-acetic acid, tryptophan and 2-methylhippuric acid) in human urine. The objective of this work was to get the successful resolution of the complex matrix with minimum experimental time in the presence of highly overlapping peaks, of distortions in the time and baseline aspects among chromatograms, and of the presence of unknown and background interferences. All the analysis were based on a short C18 column with the chromatographic system operating in isocratic mode and all analytes can be successfully quantified within 6 min. The second-order HPLC-DAD data acquired were handled intelligently by two typical chemometrics tools including alternating trilinear decomposition (ATLD) and multivariate curve resolution-alternating least squares (MCR-ALS). Reasonable resolution and satisfactory quantification results were obtained regardless of the complex matrix interferences from the urine samples and the second-order advantage was fully exploited. With the validation by classic HPLC method, the proposed strategy could take extra advantages such as increased selectivity and sensitivity, shorter analysis time, undemanding elution conditions and sufficiency of lower limit of quantification benefit from multivariate calibration. The method was shown as a promising means for fast and sensitive determination of small molecules in human urine and also for fast diagnosis or surveillance in related diseases.

Determination of eumelanin and pheomelanin in melanomas using solid-phase extraction and high performance liquid chromatography–diode array detection (HPLC-DAD) analysis

Determination of eumelanin and pheomelanin in melanomas that exhibit different pigmentation was carried using a solid-phase extraction (SPE) preparation method based on weak anion exchange chemistry. This extraction significantly enhanced the chromatographic profile obtained by reverse phase high performance liquid chromatography-diode array detection (RP-HPLC-DAD). The SPE method was developed using aqueous standards of melanin markers: thiazole-2,4,5-tricarboxylic acid (TTCA), thiazole-4,5-dicarboxylic acid (TDCA), pyrrole-2,3-dicarboxylic acid (PDCA) and pyrrole-2,3,5-tricarboxylic acid (PTCA) and non-pigmented cell lines spiked with those markers. An excellent average recovery, above 90%, was obtained for the four markers with a relative standard deviation below 7%. We have also optimized the stationary phase and the mobile phase (phosphate concentration and pH) to improve sensitivity and to reduce the analysis time. Elution of the four markers is achieved in 5 min and total analysis of biological samples is completed in 15 min. The quantification limits for TDCA, TTCA, PDCA and PTCA are 60, 50, 47 and 48 ng/mL respectively. Furthermore, DAD detection improves the marker identification in complex matrices through the analysis of UV spectra. We have successfully applied this method to melanoma tumors and cells. Murine B16BL6 tumor are highly pigmented with mostly eumelanin (98.1% of eumelanin) while human SK-MEL-3 tumor contain about 30% pheomelanin. B16BL6 and B16F10 are eumelanic cells lines and NHEM melanocytes contain about 24% of pheomelanin.

Recognition and Optimization of Ingredients Treating Nitroglycerin-Induced Migraine Rats from Wuzhuyu Decoction.

Wuzhuyu decoction (WZYD) has been clinically used to treat migraine effectively since Eastern Han Dynasty of ancient China. However, its antimigrainic ingredients remain unclear. In present study, the antimigrainic ingredients of WZYD were explored and optimized in nitroglycerin-induced migraine rats through correlation analysis of decoction spectra-pharmacological effects and absorption spectra-pharmacological using entropy-weighted partial least squares regression method. The decoction spectra and absorption spectra were obtained through the determination of nine main ingredients in ten kinds of WZYDs and WZYDs' single-pass intestinal perfusion samples using high performance liquid chromatography-diode array detector. The pharmacodynamics indexes related to migraine model rats were detected using high performance liquid chromatography method and kits after oral administration of WZYDs. Then, the key ingredients influencing indexes were achieved through the correlation analysis. And the optimization of key ingredients was acquired through uniform design experiment. The pharmacodynamic verification test was used to clarify the advantages of the optimized sample. The results showed that the final optimized sample, in which the concentrations of rutaecarpine, evodiamine, ginsendside Rb1, 6-gingerol, ginsendside Rg1, rutaevine, and limonin were 0.081, 0.565, 1.455, 0.159, 0.871, 0.178, and 0.009 mg·mL−1, respectively, provided the best comprehensive effect than another optimized sample and the best uniform design sample. Therefore, a new reliable method for rapidly recognizing and optimizing the effective constituents of WZYD treating migraine was established.

Qualitative identification of impurities and principal component quantitative analysis of zearalanone on purity certified reference material

A liquid chromatography method was established for the determination of zearalanone (ZAN) raw material. The qualitative analysis of ZAN and its trace impurities was performed by ultra performance liquid chromatography-diode array detector (UPLC-DAD) and ultra performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS), and the response factors of each impurity were calculated. The three main organic impurities in the ZAN raw material were identified as β -zearalanol, α -zearalanol and a dehydration product of zearalanol with relative response factors of 0.5352, 0.8594 and 0.6973, respectively. The main component of the ZAN raw material was determined by the calibration factor normalization method. The purity of zearalanone was determined to be 99.6% with a standard deviation of 0.01%. This method can provide a technical support for the development of ZAN standard materials.

Monitoring of nine pesticides in different cereal flour samples with high performance liquid chromatography-diode array detection

A method based on LLLE-DLLME-HPLC-DAD has been developed for the extraction and determination of nine multiclass pesticides from selected cereals.

Determination of organic ultraviolet filters in environmental waters by magnetic solid phase extraction-high performance liquid chromatography

A method for the determination of organic ultravioletfilters (OUFs) in water samples was developed by the combination of polymeric ionic liquid-based magnetic solid-phase extraction (PIL-MSPE) and high performance liquid chromatography-diode array detection (HPLC-DAD). To achieve the optimum extraction performance for the target analytes, several key variables, including desorption solvent, adsorption and desorption time, sample pH value and ionic strength in the sample matrix, were investigated in detail. Under the most favorable extraction conditions, linear behaviors were observed in the ranges of 0.5-200.0 μg/L for octyl salicylate and 0.2-200.0 μg/L for the other analytes. The limits of detection (LODs, S/N=3) and limits of quantification (LOQs, S/N=10) for the target OUFs were in the ranges of 0.009-0.13 μg/L and 0.031-0.43 μg/L, respectively. The developed PIL/MSPE-HPLC-DAD method was successfully applied to detect trace OUFs in real water samples. The spiked recoveries at different spiked levels were 71.4%-120%, and the RSDs were below 10% for all the compounds in all the samples. The proposed method has some unique merits including simple operation, fast extraction procedure, high sensitivity and environmental friendliness. It can become a useful method for the monitoring of trace OUFs in water samples.

English

Berlinia grandiflora is used for managing numerous ailments including tumor in South-west, Nigeria. The phytochemical contents, antioxidant and antiproliferative activities of B. grandiflora leaf were determined in this study. The absolute ethanol extract was evaluated by high performance liquid chromatography-diode array detection (HPLC-DAD). The antioxidant activity was carried out by standard analytical methods. The antiproliferative activity was done using growth inhibition activity of Sorghum bicolor seed radicle with methotrexate as the reference drug. The presence of some phytochemicals known to have antioxidant properties and exert anticancer effects is revealed in this study. The HPLC analysis revealed the presence of betulinc acid, ferulic acid, rutin and caffeic acid. However, ferulic acid, rutin, and caffeic acid were identified for the first time in B. grandiflora. Free radical scavenging activity, reducing power capacity and nitric oxide inhibitory activity were exhibited by the extract, with IC50 values of 88.3, 7.4 and 99 µg/mL, respectively. While ascorbic acid, the reference compound, used in this study has IC50 values of 0.7, 3.4 and 7.4 µg/mL, respectively. The total phenol content expressed in gallic acid equivalent (GAE) was 75 mg/g. A dose-dependent antiproliferative activity was observed with IC50 values of 0.50, 0.59 and 0.29 µg/mL after 48, 72 and 96 h of treatment, respectively. This result justifies the folklore use of the plant for managing cancer in Nigeria and the plant’s potential as a new phyto-chemo-therapy. Key words: Antiproliferative, antioxidant, phytochemicals, cancer, Berlinia grandiflora, betulinic acid.

Polyphenolic profile, macro- and microelements in bioaccessible fractions of grape juice sediment using in vitro gastrointestinal simulation

Grape and grape constituents have high amounts of essential minerals and polyphenols. Health benefits of these nutrients and other bioactive substances depend on their level of intake and bioaccessibility. The behavior and levels of individual phenolic compounds, macro- and microelements of the grape juice sediment that was removed from red grape juices of Bordo and Isabel varieties were investigated using an in vitro digestion and determined using high performance liquid chromatography-diode array detection and inductively coupled plasma optical emission spectrometry. During digestion, important changes were observed in concentrations of polyphenols and minerals upon passage through the gastric and enteric phases. Bioactive compounds such as trans-resveratrol, catechin and epicatechin were highly bioaccessible from the Bordo sample. A significant decrease in levels of polyphenolics and minerals was observed at the end of the intestinal phase. The grape juice sediment of both varieties showed higher antioxidant capacity in the gastric phase, which was related to the high concentration of polyphenols. The anthocyanins identified at higher concentrations in samples included malvidin-3-O-glucoside and malvidin-3,5-diglucoside that were 7% and 60% bioaccessible, respectively. The elements Ca, Mg, Cu, Fe, Sr, Mn, Zn, Al, Ni and Pb were not detected at the last phase of digestion, being poorly bioaccessible. The bioaccessibility indexes found for this grape juice sediment are consistent with the bioactive properties of grape products.

Fabrication of N,N-dimethyldodecylamine functionalized magnetic adsorbent for efficient enrichment of flavonoids

A new N,N-dimethyldodecylamine functionalized magnetic adsorbent (Fe3O4@MDHM) was fabricated and used for the efficient enrichment of flavonoids under the format of magnetic solid phase extraction (MSPE). Different techniques were utilized to characterize the spectroscopic, morphology and magnetic properties of the prepared adsorbent. Under the optimized extraction conditions, the Fe3O4@MDHM displayed satisfactory enrichment performance to flavonoids by means of hydrophobic, ion-exchange and electrostatic interactions. Furthermore, a sensitive, quick and environmentally friendly analytical method for the determination of flavonoids in grape juice was established by the combination of Fe3O4@MDHM/MSPE with high performance liquid chromatography-diode array detection (HPLC-DAD). Results indicated that the linear ranges for target analytes were in the range of 0.5–200.0 μg/L, with good correction coefficients (R2＞0.99). The limits of detection (S/N = 3) and limits of quantification (S/N = 10) for flavonoids were in the ranges of 0.080–0.12 μg/L and 0.27–0.40 μg/L, respectively. The quantification of flavonoids in real grape juices were used to inspect the applicability of proposed Fe3O4@MDHM/MSPE-HPLC-DAD method. As a new MSPE adsorbent, the Fe3O4@MDHM exhibited some merits such as quick extraction procedure (extraction time, 13 min), high enrichment performance (enrichment factors, 60–69), low consumption of organic solvent (0.49 mL methanol) for the separation and determination of flavonoids.