Ciocalteu Assay Research Articles

Structure-dependent detection of polyphenols using crown ether-immobilized gold nanoparticles.

Gold nanoparticles functionalized with 18-crown 6-ether (18C6-AuNPs) can be used for detection of tannic acid, epigallocatechin gallate, and epicatechin gallate by color change in the μg mL-1 range. 18C6-AuNPs were insensitive to l-ascorbic acid and l-tyrosine unlike conventional detection methods, such as Folin & Ciocalteu assay, whose principle is based on the redox reaction of polyphenols. Although 18C6-AuNPs did not respond to some polyphenols, such as gallic acid and epicatechin, if the polyphenols of interest are responsive to this approach, these are expected to be effective nanomaterial for simple sensing of polyphenols.

In vitro study of antioxidant, antibacterial, and cytotoxicity properties of Cordia myxa fruit extract.

Background and Objectives:Medicinal plants have recently received much interest because of the low production costs and fewer side effects associated with remedies made from them compared with chemical therapies. The current study investigated the antioxidant, antibacterial, and cytotoxicity properties of an ethanol extract of Cordiamyxa fruit (CMF) extract.Materials and Methods:The antioxidant activity of CMF was determined by measuring electron-donating ability with a 1,1-diphenyl-2picrylhydrazyl (DPPH) assay. The phenolic content was calculated as Gallic acid equivalents using the Folin– Ciocalteu assay. To evaluate the efficiency of CMF, five multidrug-resistant bacterial strains (Salmonella enterica, Escherichia coli, Bacillus subtilis, Staphylococcus aureus, and Pseudomonas aeruginosa) were tested using the agar diffusion method. Furthermore, the cytotoxic activity of CMF was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-dipheltetrazolium (MTT) assay against a healthy fibroblast (L929) cell line.Results:The CMF ethanol extract was revealed to have substantial phenol and flavonoid content (113.71± 0.04 mg gallic acid/g dried extract and 68.9 ± 0.002 mg quercetin/g dried extract, respectively) that showed the highest percentage of DPPH inhibition (86.45%), which was achieved by ethanol extract at the concentration of 60 μg/ml, with excellent antibacterial activity against S. aureus, E. coli, S. enterica, B. subtilis, and P. aeruginosa (17.5 ± 1.0, 14.9 ± 1.0, 13.3 ± 1.5, 15.7 ± 1.0, and 13.8 ± 1.5 mm IZ, respectively). In addition, no expressive antiproliferative effect was recorded in the assessment of cytotoxicity on L929 cells.Conclusion:According to the current findings, CMF exhibits low cytotoxicity, antibacterial activity, and antioxidant properties in vitro and can be developed for pharmaceutical and medical uses in the future.

ASSESSMENT OF TOTAL PHENOLIC, FLAVONOID CONTENT, ANTIOXIDANT POTENTIAL AND HPLC PROFILE OF THREE MORINGA SPECIES LEAF EXTRACTS

In the current investigation, three selected Moringa species (M. stenopetala, M. peregrina and M. oleifera) grown at Orman Botanical Garden, Giza, Egypt were tested to quantify spectrometrically, the total phenolic compounds according to Folin–Ciocalteu's assay and flavonoids content to assess their corresponding effect on their antioxidative activity. Different leaf extracts (hexane, ethyl acetate and ethanol 70%) of the three studied species were prepared. The obtained results revealed that M. peregrina gave the best extract yield for the leaves extracted by the different solvents. Regarding the total phenolic compounds, data exposed ethanol 70% extract of M. peregrina leaves as the highest value among other species (11.66 g GAE/100 g extract), while it was for hexane extract that showed the highest value among other species in flavonoids content (7.21 g QE/100 g extract). Antioxidant activity of leaf extracts was evaluated by means of 2,2-dyphenyl-1-picrylhydrazyl (DPPH) and 2,2-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid (ABTS) scavenging assays. Data exhibited M. peregrina as the highest species to afford free radical scavenging activity with DPPH and ABTS assays in all concentrations of all extracts especially, 1000 μg/ml of ethanol (70%) with 97.00 and 92.67% inhibition, respectively. Moreover, HPLC with UV detection was employed for the identification and quantification of the phenolic compounds and flavonoid content, present in leaf methanolic extracts of the studied species. HPLC assay identified 25 phenolic compounds and 11 flavonoids in the leaves. It was noticed that M. stenopetala leaves emerged the highest values in most of the phenolic compounds and flavonoids. Eventually, it can be concluded that Moringa leaves showed their certain nutritional value and therefore had the potential as source of natural antioxidants. In addition, their regular consumption in diet could provide health benefits to humans by their protection role against oxidative stress.

Evaluation of cell protection by Psephellus pyrrhoblepharus (Boiss.) Wagenitz extracts in MPP+-induced dopaminergic cell damage

Neurodegenerative diseases affect millions of people. Major reasons behind the onset and progression of these diseases are still under investigation. Therefore, any approach that would treat/prevent progression is important. In this study, we aimed to investigate the potential protective effects of Psephellus pyrrhoblepharus (Boiss.) Wagenitz extracts in MPP+-induced dopaminergic cell damage and compare the effectiveness of different extracts (methanol:water (1:1), chloroform and n-hexane). The cells were pretreated with four different concentrations (10, 50, 100, and 200 µg/ml) of methanol:water (1:1), chloroform and n-hexane extracts of P. pyrrhoblepharus following MPP+ treatment for 12 or 24 h. The changes in cell viability were determined using the MTT assay. Additionally, antioxidant activities and total phenolic/flavonoid contents of the extracts were determined with radical scavenging capacity, Folin–Ciocalteu and aluminum chloride assays, respectively. The extracts at selected concentrations were found to be protective in a dose-dependent manner at 12 and 24 h. Nevertheless, the methanol extract of the plant showed the highest protection both at 100 and 200 µg/ml (115.13%±3.98, 121.87%±1.66; p < 0.05) against dopaminergic damage at 24 h. The results showed that selected concentrations were not toxic and did not affect cell proliferation rate. Besides, the chloroform extract was found to have higher antioxidant activity than the other extracts (p < 0.05). The total phenolic and total flavonoid contents were found consistent with antioxidant activities. Our findings support the neuroprotective and antioxidant potential of P. pyrrhoblepharus. However, further studies on identifying the presence of chemicals in P. pyrrhoblepharus extracts which are responsible for protection should be carried out to confirm their therapeutic potential.

Phytochemical screening, in vitro evaluation of the antimicrobial, antioxidant and cytotoxicity potentials of Grewia lasiocarpa E. Mey. ex Harv.

The plant Grewia lasiocarpa E. Mey. ex Harv. (Family Malvaceae sensu lato), is relatively understudied. However, plants of this genus are well known for their phyto-medicinal and ethnopharmacological values. This study evaluated the preliminary phytochemistry, Fourier transform infrared (FTIR), Gas chromatography–mass spectroscopy analysis, total phenolic contents, in vitro antibacterial and antioxidant activities of the crude hexane, chloroform and methanol extracts of the leaves and stem bark of G. lasiocarpa. The antimicrobial activity was investigated by agar-well diffusion method against selected clinical strains. The in vitro antioxidant assay of the crude extracts was done using 2, 2՛-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity and ferric reducing antioxidant power (FRAP). The phenolic content was measured using Folin–Ciocalteu's assay. The cytotoxicity of the crude extracts was tested using MTT assay on HEK293, HeLa and MCF-7 cell lines. In all the extracts, tannins, flavonoids, phenols and carbohydrates are among the primary and secondary metabolites confirmed to be present, while the FT-IR spectroscopic analysis of all extracts confirmed the presence of alkanes, aromatic and alkyl halides in all extracts of the leaves and stem bark. Among, the major compounds found in all extracts phytol, friedelin, n-hexadecanoic acid were present in the leaves, while in the stem bark, hexadecane, lup-20(29)-en-3-ol, acetate and hexanedioic acid were present. The methanol extracts of the leaves and stem bark had the lowest IC50 value of 0.02 μg/mL and 1.34 exp.−5 μg/mL (DPPH), while for FRAP the methanol extract of the leaves and chloroform extract of the stem had the lowest IC50 value of 9.76 and 12 μg/mL, respectively. The methanol extract of the leaves and stem bark had the highest phenolic content of 132.82 ± 0.22 and 171.12 ± 0.39 mg GAE/g dried extract. Most of the isolates showed varying degree of sensitivity to the extracts, with the hexane extracts of the leaves and stem bark having a remarkable inhibitory effect against Methicillin-resistant Staphylococcus aureus (ACCC 14026). The extracts were relatively not cytotoxic to HEK293. The results are suggestive that G. lasiocarpa leaves and stem bark are rich in bioactive compounds which could be a potential source of natural antioxidants and antibacterial agent for the treatment of diseases relating to the pathogenic bacteria studied.

Antioxidant Activity of Glycyrrhiza glabra L. Extract and Protective Effect of its Leaf Extract on Ethanol-Induced Nephrotoxicity in Male Rats

Introduction: Acute alcohol consumption leads to induction of lipid peroxidation in renal tissues, but its chronic consumption has moderate effects on biochemical and histological characteristics of this organ. Antioxidants have protective effects against ethanol-induced oxidative stress and tissue injury. The aim of this study was to assess antioxidant activity of Glycyrrhiza glabra leaf and stem extracts and the protective effect of its leaf extract on ethanol-induced nephrotoxicity. Materials & methods: Total phenol and flavonoid contents of leaf and stem extracts of G. glabra were measured by Folin Ciocalteu and AlCl3 assays, respectively. Antioxidant activity of both extracts was assessed using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging. In addition, protective effect of the leaf extract was assessed using biochemical and histological analyses of renal tissues of male Wistar rats, which were divided into four groups including group 1 or control (received 1 ml distilled water daily), group 2 or ethanol group (received 1 ml of 50% ethanol daily), group 3 or ethanol + leaf extract group (received 1 ml of 50% ethanol + 500 mg/kg leaf extract daily), and group 4 (received 500 mg/kg of leaf extract daily). All treatments are performed through intragastric administration. Biochemical and histological analyses were used for the evaluation of nephrotoxicity. For histological study, the samples were stained with Hematoxylin-Eosin and examined by light microscopy. Finally, all the data were analyzed by SPSS (Ver. 20) and grouped by Duncan's Multiple Range Test at P less-than 0.05 level. Findings: There was no significant difference between total phenol contents of the stem and leaf extracts. However, the stem extract showed a higher total flavonoid content than the leaf extract. Also, both the extracts showed higher antioxidant activities (86-93%) than that of ascorbic acid (71%). Results from biochemical analysis indicated a significant increase in superoxide dismutase (SOD) activity and H2O2 content in the renal tissues of ethanol-treated rats in comparison with other groups; however, there were no significant changes in total protein and malondialdehyde (MDA) contents. Results from histological examination showed that alcohol consumption intensity injured kidney tissues, which was effectively moderated by the studied extract. Discussion & Conclusions: Results from the present study showed that G. glabra extract has biological activity and can be used in future as a new natural antioxidant in food and drug industries.

Role of Calabrian Black Rice in Metabolic Syndrome: In vitro Evaluation of Oryza sativa L. Indica Biological Properties

Background: Metabolic Syndrome is becoming more common and it is characterized by an excess intake of energy, readily available carbohydrates and fats that result in postprandial hyperglycemia and hyperlipidemia. In the treatment of Metabolic Syndrome, a diet characterized by functional food, high fiber intake and low glycemic index is recommended. Objective: The aim of this research was to study, in vitro, the beneficial and biological properties of black rice cultivated in Sibari plain, a particular area of the region of Calabria, and verify if the climatic conditions of this area influence the composition of this pigmented rice. Method: The antioxidant activity was investigated by performing the DPPH radical scavenging assay, while the free phenolic content of CBR extract was measured by Folin Ciocalteu's assay and the obtained results were expressed as mg of gallic acid equivalent/mg of extract. In order to establish the anti-inflammatory effect of CBR extract, its reactivity towards nitric oxide (NO) was evaluated, while, its anti-hypertensive activity was studied by determining the ACE activity inhibition. Results: CBR extract also suppresses pancreatic lipase activity with an IC50 value of 34.3 µg/ml and it decreases cellular lipid accumulation by about 60%. Finally, its hypoglycemic effect was evaluated by measuring the inhibiting activity towards α-glucosidase and α-amylase enzymes. Conclusion: The obtained results demonstrate that this kind of black rice owns different beneficial properties, which make it a functional food that could improve metabolic disorders of MS. Keywords: Calabrian black rice extract, metabolic syndrome, antioxidant activity, anti-inflammatory activity, α-glucosidase, α- amylase, anti-hypertensive activity, hypolipidemic effect.

Chemical Constituents, Total Phenolic Content, Antimicrobial, Antioxidant and Radical Scavenging Properties, Chelating Ability, Tyrosinase Inhibition and In Vitro Cytotoxic Effects of Artemisia Aucheri Herbs

The aim of this study was to investigate the chemical constituents, chelating ability, tyrosinase inhibition, antimicrobial, antioxidant, cytotoxic, and radical scavenging activities of the essential oil of Artemisia aucheri Boiss., an endemic Asteraceae herb growing wild in Iran. Water-distilled essential oil of A. aucheri was analyzed by GC and GC/MS. The antibacterial activity of the oil was evaluated by determination of inhibition zones, minimum inhibitory concentration, minimum bactericidal concentration, and decimal reduction time. Phenolic content of the oil was determined using the Folin – Ciocalteu assay. Antioxidant properties of the oil of A. aucheri were determined by three methods: the ferric reducing antioxidant power, bleaching of DPPH, and a-carotene–linoleic acid assay. Cytotoxicity was measured using a modified MTT assay. Radical scavenging activities, chelating ability, and tyrosinase inhibitory effect were determined by spectrophotometric techniques. Camphor (25.15%), 1,8-cineole (18.26%), and verbenone (16.63%) were the major components in this oil. Bactericidal kinetics of the oil indicates that C. albicans is the most vulnerable strain (MIC = 0.04 mg/mL). Total phenolic content of the oil was found to be 133.87 ± 6.50 ig GAE/mg. The A. aucheri oil exhibited a dose-dependent scavenging of DPPH, nitric oxide, and superoxide anion radicals with IC50 values of 15.75 mg/mL, 21.73 μg and 44.31 μg, respectively. Ferrous-ion chelating activity of the oil (IC50 = 452.35 μg) was lower than that of EDTA. IC50 values for HeLa and lymphocyte cells were found to be 7.11 and 6322.85 μg/mL, respectively. The results suggest application of A. aucheri oil as a natural antioxidant and anticancer agent.

In Vitro Cytobiochemical Potentials and Protective Effects of Bioactive Phytochemicals from Artemisia Turanica

The current study evaluates chemical constituents and estimates the antimicrobial, antioxidant, ferrous-ion chelating, tyrosinase inhibition, cytotoxic, and radical scavenging activities of the essential oil of Artemisia turanica Krasch. from northeastern Iran. The antibacterial activity of the oil was evaluated by determination of inhibition zones, minimal inhibitory concentration, minimum bactericidal concentration and decimal reduction time. Phenolic content of the oil was determined using the Folin – Ciocalteu assay. Antioxidant properties of the oil of A. turanica were determined by three methods: the ferric reducing antioxidant power, bleaching of DPPH or radical scavenging activity, and β-carotene-linoleic acid assay. In vitro cytotoxicity was assessed by the MTT assay. Oxygenated monoterpenes, especially 1,8-cineole (35.2%), α-thujone (24.2%), and cis-chrysanthenol (16.8%) were the major components in the oil of A. turanica. Bactericidal kinetics of this oil indicated that E. coli is the most vulnerable (MIC = 2.5 mg/mL, D = 6.43 min). Total phenolic content of the oil was found to be 237.87 ± 6.66 μg GAE/mg oil. The oil exhibited a dose-dependent scavenging of DPPH, nitric oxide, and superoxide anion radicals with IC50 values of 7.00 mg/mL, 9.69 μg, and 14.63 μg, respectively. Ferrous-ion chelating activity of the oil (IC50 = 16.97 μg) was lower than that of EDTA. IC50 values for Hela and lymphocyte cells were calculated to be 17.67 and 3291.49 μg/mL, respectively. The results suggest application of A. turanica oil as a natural antioxidant and anticancer agent.

High Phenolic Beer Inhibits Protein Glycation in Vitro

Protein glycation is a nonenzymatic process in which amino residues of proteins react with sugar groups, causing protein cross-linking. This contributes to many complications associated with diabetes. Phenolic compounds from fruits and vegetables have been found to inhibit protein glycation. Because of the high volume in which beer is consumed, it has the potential to be an excellent phenolic delivery system. We studied five beer styles (American pale ale, porter, stout, India pale ale, and Imperial India pale ale) for their phenolic and antioxidant contents and their effects on protein glycation. All beers were subjected to the Folin–Ciocalteu and ferric-reducing antioxidant power assays to assess the phenolic and antioxidant contents, respectively. All styles significantly inhibited protein glycation on a volumetric (4 μL/mL) basis, and all but one inhibited glycation based on phenolics (4 μg of phenols/mL). All beers significantly inhibited protein glycation based on antioxidant content (60 nmol of FeSO4 equivalents/mL), showing significant inhibition compared with both a control and a noncraft (i.e., mass production) beer. This demonstrates that certain beers can inhibit protein glycation at low concentrations and may, in certain individuals, significantly contribute to daily consumption of phenolic compounds.

Influence of extrahent on antioxidant capacity of Aesculus hippocastanum seeds

In this study, the optimisation of horse chestnut seed extraction was performed to determine the best extraction solvent in the recovery of pharmacologically active escin from raw material. All extracts were obtained by accelerated solvent extraction and were analysed for their antioxidant potential (DPPH test), phenolic content (Folin–Ciocalteu (FC) assay) and escin content (ESI-TOF-MS extracts profiling). Methanol was found to recover the highest amount of escin from the plant matrix as well as to produce the most active antiradical solutions rich in polyphenols. Radical scavenging properties of methanol extracts were calculated as 2 GAE in DPPH test and 23 GAE (mg/g) in FC assay. Quantitative analysis of extracts performed by ESI-TOF-MS measurements in ion-positive mode confirmed the presence of four major escin isomers in the extracts and showed that the high antioxidant potential of methanolic extracts went hand in hand with the highest content of escin (8.92%).

Evaluation of antioxidant efficacy of different fractions of Tagetes erecta L. Flowers

Oxidative stress is an important pathogenesis of numerous chronic diseases. Free radicals and other reactive oxygen species are recognized as agents involved in the pathogenesis of sicknesses. The main characteristic of an antioxidant is its ability to trap free radical. Plants rich in phenolic compounds are generally reported to show good antioxidant activity. Tagetes erecta L (Marigold) belongs to the family Asteraceae. The flowers are especially employed to cure eye diseases, colds, conjunctivitis, coughs, ulcer, bleeding piles and to purify blood. The extractive efficiency of phenolic compounds from plant material is greatly dependent on the choice of solvent. In this study, six solvents of different polarity viz., hexane, toluene, ethyl acetate, acetone, methanol and water have been used for the extraction of Tagetes erecta L. flower by individual cold percolation method. Phenolic and flavonoid content of extracts were determined using Folin- ciocalteu assays and aluminium chloride colorimetric method respectively. Antioxidant activity was carried out by DPPH radical scavenging activity assay, superoxide free radical scavenging (SO) assay, ABTS radical cation scavenging activity, ferric reducing antioxidant power (FRAP), Reducing capacity assessment. Maximum extractive yield was in water extract followed by methanol extract. There was a direct correlation between phenolic content and antioxidant activity. Methanolic extract had maximum phenolic content and maximum FRAP and SO activity. ABTS and DPPH did not show positive correlation with total phenol content in ethyl acetate extract. Ethyl acetate extract had maximum flavonoid content. T. erecta flowers can be used as a natural source of antioxidants to combat the oxidative stress related disorders. Key word: Tagetes erecta, Influence of solvent, Antioxidant activity, positive correlation

(Bio)-synthesis of Au NPs from soy isoflavone extracts as a novel assessment tool of their antioxidant capacity

In this work, (bio)-synthesis of Au NPs using selected isoflavone classes has been studied. To this end, relevant aglycones (genistein and daidzein) and their glycosides (genistin and daidzin) as well as complex soy-extracts with a well-documented composition have been explored. A sigmoidal curve described the (bio)-synthesis of Au NPs which was used to evaluate the antioxidant activity and to carry out a reliable comparison of the antioxidant activity of soy isoflavone extracts towards the assessment of two relevant parameters: the concentration value at which the absorption reaches its half-value; X50c, and Au NPs production, KAuNPs. Although both isoflavone classes generated Au NPs; however, genistein exhibited a marked bio-synthesis efficiency with the lowest X50c = 70 mg L−1 and the highest KAuNPs = 0.200 mg−1 L values. In addition, complex soy isoflavone extracts with high total isoflavone aglycone content exhibited higher bio-synthesis efficiency than those found with high total glycoside content. Interestingly, excellent correlations between X50c and total phenolics (TP) (from Folin–Ciocalteu (FC) assay as truly antioxidant capacity assay) (r = 0.93, p-value < 0.05) and KAuNPs and TP (r = 0.85, p-value < 0.10) were also obtained confirming the superior antioxidant activity of aglycones isoflavone class. UV-vis and TEM characterization revealed that both genistein standard and soy isoflavone extracts with a high aglycone content produced red colloidal solutions of Au NPs. In contrast, glycoside standards as well as soy isoflavone extracts with a high glycoside content, generated blue colloidal solutions. The overall results obtained from our studies allowed us to hypothesize that the high antioxidant activity found in soy isoflavone extracts could have a significant direct relationship with the (bio)-synthesis of Au NPs with a small diameter and with the strong red colour exhibited at 540 nm. All of this opens new avenues in a very important research field such as the bio-synthesis of Au NPs as a novel tool for evaluation of antioxidant activity of target extracts.

Static–dynamic Superheated Liquid Extraction of Phenols from Prosthechea varicosa and Prosthechea karwinskii (orchids) Prior to Determination by LC–DAD

Nature has evolved overtime to produce a bewildering diversity of secondary metabolites. Based on empirical observations and folklore, natural product extracts were the first, and for a long time, the only medicines available to mankind. In this research superheated liquid extraction was applied to isolate phenolic compounds from two species of orchids (Prosthechea karwinskii and Prosthechea varicosa). Optimization of the variables influencing the extraction step, (based on sequential static and dynamic modes) for each orchid and each phenolic compound, was performed by multivariate approaches in all instances. Optimization was based on tests for measurement of total phenols (Folin– Ciocalteu assay). The extraction kinetics were studied under the optimal conditions in order to maximize isolation efficiency for each phenol. Separation and quantification of individual compounds were performed by LC–DAD. Representative examples of analytes identified and quantified (phenols) in each orchids were as follows: p–coumaric acid, 31.12 μg/g, and ferulic acid, 26.42 μg/g, for P. karwinskii and o–coumaric acid, 33.11 μg/g, and p–coumaric acid, 27.72 μg/g for P. varicosa. Apigenin and luteolin glucosides, and the phenols tyrosol and vanillin were also detected and quantified. Keywords: Chemistry of natural products, LC–DAD, orchids, phenols, superheated liquid extraction (SLE).

Effect of frozen storage on the anthocyanins and phenolic components of pomegranate juice

Pomegranate juice's valuable nutritional components may be reduced during its processing or storage. This work examined the effect of frozen storage at -25°C on some chemical characteristics of pomegranate juice. Total anthocyanin content of pomegranate juice, which was measured using the pH differential method, decreased by 11% after 20days of frozen storage. Phenolic components, measured using a Folin and Ciocalteu assay by means of a UV-vis spectrophotometer, decreased by 29% after 20days of frozen storage. Antioxidant activity, measured based on the radical scavenging properties of the juice using the 2,2-diphenyl-1-picrylhydrazyl method, decreased by 50% after 20days of frozen storage. Pomegranate juice has 5 major anthocyanins, including Cyanidin 3-glucoside, Cyanidin 3,5-diglucoside, Delphinidin 3-glucoside, Pelargonidin 3-glucoside and Pelargonidin 3,5-diglucoside are 5 major anthocyanins of pomegranate juice. They were measured using the LC-MS method and results showed that Pelargonidin 3,5- diglucoside had the greatest decrease. Also, the LC-MS method showed that ellagic acid decreased by 15%.

Pilot-Scale Resin Adsorption as a Means To Recover and Fractionate Apple Polyphenols

The purification and fractionation of phenolic compounds from crude plant extracts using a food-grade acrylic adsorbent were studied at pilot-plant scale. A diluted apple juice concentrate served as a model phenolic solution for column adsorption and desorption trials. Phenolic concentrations were evaluated photometrically using the Folin-Ciocalteu assay and by HPLC-DAD. Recovery rates were significantly affected by increasing phenolic concentrations of the feed solutions applied to the column. In contrast, the flow rate during column loading hardly influenced adsorption efficiency, whereas the temperature and pH value were shown to be crucial parameters determining both total phenolic recovery rates and the adsorption behavior of individual polyphenols. As expected, the eluent composition had the greatest impact on the desorption characteristics of both total and individual phenolic compounds. HPLC analyses revealed significantly different elution profiles of individual polyphenols depending on lipophilicity. This technique allows fractionation of crude plant phenolic extracts, thus providing the opportunity to design the functional properties of the resulting phenolic fractions selectively, and the present study delivers valuable information with regard to the adjustment of individual process parameters.

Antioxidant and α-Glucosidase Inhibitory Activity of Colored Grains in China

Colored grains including red, purple, and black rice, purple corn, black barley, and black soybean contain anthocyanins. The present study was designed to (i) identify and quantify the individual anthocyanins and measure the total phenolic content (TPC), (ii) evaluate the antioxidant and alpha-glucosidase inhibitory activity, and (iii) correlate the TPC with total antioxidant activity and alpha-glucosidase inhibitory potency in these colored grains. The TPC was measured using a Folin-Ciocalteu assay, while the total antioxidant activity was determined by a method based on the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity. Among all of the studied colored grains, black rice possessed the highest TPC, which was 86 times greater than that of red rice. In addition, black rice had the highest total anthocyanin contents and alpha-glucosidase inhibitory activity. A significant positive correlation of the antioxidant activity and alpha-glucosidase inhibitory activity with total anthocyanin content and TPC was observed in this study. It is concluded that black rice possesses the highest antioxidant activity and alpha-glucosidase inhibitory among all of the colored grains tested and can be further explored as a functional food.