Isolation and Purification of Kaempferol-3,7-O-α-L-Dirhamnopyranoside from Siraitia grosvenori Leaves by High-Speed Counter-Current Chromatograph and Its Free Radical Scavenging Activity

Semi-preparative high-speed counter-current chromatography (HSCCC) was successfully used for the isolation and purification of flavonoid glycoside from the leaves of Siraitia grosvenori by using a two-phase-solvent system composed of ethyl acetate–n-butanol–water (4:1:5, v/v/v). kaempferol-3,7-O-α-L-dirhamnopyranoside was obtained in one-step separation and less than 5.5 h from 90 mg of crude extract from the S. grosvenori leaves. The chemical structure of this compound was identified by MS, ¹H NMR, and ¹³C NMR. Free radical scavenging activity of kaempferol-3,7-O-α-L-dirhamnopyranoside was also evaluated and the results showed that it had good free radical scavenging activity with its IC₅₀ value being 3.97 mg/ml.     

Application of High-Speed Counter-Current Chromatography Preparative Separation of Flavone C-Glycosides From Lophatherum gracile

Preparative high-speed counter-current chromatography (HSCCC) was used to separate and purify bioactive constituents from the stems and leaves of Lophatherum gracile Brongn. Six flavone C-glycosides each at over 95% purity including two new compounds were obtained in one-step separation by HSCCC with an optimized two-phase solvent system composed of ethyl acetate-n-butanol-ethanol-water at volume ratio of 4:2:1.5:8.5 (v/v/v/v). The experiment yielded 19.9 mg of luteolin 6-C-β-D-galactopyranosiduronic acid (1→2)-β-D-glucopyranoside (1), 28.5 mg of luteolin 6-C-α-L-arabinopyranosyl-7-O-β-D-glucopyranoside (2), 31.5 mg of isoorientin (3), 44.8 mg of orientin (4), 25.3 mg of swertiajaponin (5) and 12.1 mg of apigenin 6-C-β-D-galactopyranosiduronic acid (1→2)-β-D-glucopyranoside (6) from 500 mg of crude extracts. The purity of these compounds was determined by high-performance liquid chromatography (HPLC). Their chemical structures were identified by electron spray ionization mass spectroscopy (ESI-MS), ¹H and ¹³C nuclear magnetic resonance spectroscopy (NMR).     

Sonochemical Synthesis,Characterization and Sonocatalytic Performance of Terbium-Doped CdS Nanoparticles

Terbium-doped cadmium sulfide nanoparticles with different terbium contents were successfully synthesized via sonochemical route. The prepared samples were characterized by X-ray diffraction, scanning electron microscopy, photoelectron X-ray spectroscopy, and UV–Vis diffuse reflectance spectroscopy techniques. The as-prepared nanocatalyst were used for sonocatalytic degradation of Methylene Blue. Among the different amounts of dopant, 8 % Tb-doped CdS showed the highest sonocatalytic activity. The order of inhibitory effect of radical scavengers was 1, 4 Benzoquinone > SO₃ ^2? > CO₂ ^3?> I^?. The effects of various parameters such as initial dye concentration, catalyst loading, ultrasonic power, and the presence of radical scavengers were investigated.     

Separation and Purification of Three High-Purity Isoflavonoids from Belamcanda chinensis (L.) DC. by Supercritical Fluid Extraction and High-Speed Counter-Current Chromatography

Supercritical fluid extraction (SFE) was used to extract three isoflavonoids including irigenin, irisfloretin and dichtomitin from Belamcanda chinensis (L.) DC. The parameters including pressure, temperature, sample particle size, and flow rate of CO₂ were optimized with an orthogonal test. Under the optimized conditions of 15 MPa, 55°C, a sample particle size of 20–40 mesh and CO₂ flow rate of 40 L h^?1. The process was then scaled up by 10 times using a preparative SFE system. The yield of the crude extract from SFE was 4.1%, which contained irigenin, irisfloretin, and dichtomitin 0.71%, 0.49%, and 0.05%, respectively. To compare the extraction methods, Soxhlet Extraction (SE) was performed. The results indicated that SFE was better than SE. Irigenin, irisfloretin, and dichtomitin in the SFE extract were then separated and purified by high-speed counter-current chromatography (HSCCC) with a two-phase solvent system composed of petroleum ether–ethyl acetate–methanol–water (2:4:3:3, v/v). From 5.0 g of dry crude extract, 27.8 mg irigenin, 16.4 mg irisfloretin, and 2.1 mg dichtomitin were obtained at purities of 97.1%, 96.4%, and 98.0%, respectively, as determined by HPLC-PDA. These results well indicate that SFE and HSCCC are very powerful techniques for the extraction and purification of irigenin, irisfloretin, and dichtomitin from B. chinensis.     

Activity-Guided Isolation and Purification of Three Flavonoid Glycosides from Neo-Taraxacum siphonanthum by High-Speed Counter-Current Chromatography

DPPH (1,1-diphenyl-2-picryhydrazyl) radical scavenging assay was used to screen different fractions of Neo-Taraxacum siphonanthum ethanol extracts. The potent active fraction was isolated and purified by preparative high-speed counter-current chromatography (HSCCC) with a solvent system composed of n-hexane-n-butanol-water (3:4:7, v/v/v). The flow rate was 1.5 mL/min and resolution speed was 800 rpm. Three flavonoid glycosides with the purity over 99% were obtained and identified as luteolin- 3′-O-β-D-glucopyranoside (I), luteolin-7-O-β-D-glucopyranoside (II), and luteolin-4′-O-β-D-glucopyranoside (III) by ESI-MS, ¹H NMR and ¹³C NMR analysis. Antioxidant activity of three flavonoid glycosides was assessed by DPPH assay, all of which showed potent activity.     

Separation and Purification of Two Isomeric Saponins from Albiziae Cortex by High-Speed Counter-Current Chromatography and Preparative High-Performance Liquid Chromatography

Following constituents’ enrichment steps with the AB-8 macroporous resin, silica gel, and ODS columns, high-speed counter-current chromatography (HSCCC) and preparative HPLC were successfully used for the isolation and purification of two complex isomeric saponins including a new one from albiziae cortex. The two-phase solvent system used for separation was composed of n -hexane/ n -butanol/water (1:10:5, v/v/v ). A total of 8.2 mg julibroside J _{5 a} and 11.6 mg julibroside J ₅ with purity of higher than 98%, respectively, as determined by HPLC-ELSD were obtained from the constituents enriched fraction (475.4 mg) of albiziae cortex. Their structures were identified by HR-MS, ¹ H NMR ¹³ C NMR, and 2D NMR. This is the first ever report on the separation of complex isomeric saponins from albiziae cortex by HSCCC.     

Isolation and Purification of Two Constitutes from Dendrobium fimbriatum Hook by High-Speed Counter-current Chromatography Using Stepwise Elution

Abstract

Preparative high-speed counter-current chromatography (HSCCC) was successfully used for the isolation and purification of 2-hydroxyethyl caffeate and denhydroshizukanolide from Dendrobium fimbriatum Hook using stepwise elution with a pair of two-phase solvent systems composed of n-hexane-ethyl acetate-methanol-water at (1:1:1:1, v/v) and (3:1:3:1, v/v). Using a preparative unit of the HSCCC centrifuge, about a 100 mg amount of the sample was separated, yielding 13.3 mg of 2-hydroxyethyl caffeate and 18.0 mg of denhydroshizukanolide at a high purity of over 95%. The peak fraction of HSCCC was identified by ¹H NMR and ¹³C NMR.     

Structure Elucidation and Evaluation of Antioxidant and Tyrosinase Inhibitory Effect and Mechanism of Proanthocyanidins from Leaf and Fruit of Leucaena Leucocephala

This study aimed to investigate the structural features, antioxidant activity, tyrosinase inhibitory effect, and mechanism of proanthocyanidins from leaf and fruit of Leucaena leucocephala. MALDI-TOF-MS, thiolysis coupled with HPLC-ESI-MS, and ¹³C-NMR confirmed that these proanthocyanidins were complex mixtures of propelargonidins, procyanidins, and prodelphinidins. (Epi)catechin, (epi)gallocatechin, (epi)catechin gallate, and (epi)gallocatechin gallate were the main constitutive units. The findings obtained from enzyme analysis revealed that the proanthocyanidins had inhibitory effects on both monophenolase and diphenolase of tyrosinase. The IC₅₀ values of leaf and fruit proanthocyanidins were 73.5?±?2.7 and 52.3?±?3.5 µg/mL for monophenolase activity, and 27.2?±?1.4 and 16.1?±?1.1 µg/mL for diphenolase activity, respectively. The inhibition of diphenolase by proanthocyanidins were proved to be reversible and mixed type. In addition, it was also found from various antioxidant methods that the proanthocyanidins in leaf and fruit possessed potent DPPH radical scavenging activity with IC₅₀ values of 103.4?±?0.8 and 87.8?±?1.1 µg/mL, ABTS radical scavenging activity with IC₅₀ values of 72.9?±?0.4 and 65.7?±?0.9 µg/mL, and ferric reducing antioxidant power with FRAP values of 3.74?±?0.03 and 4.02?±?0.15?mmol AAE/g, respectively. The results obtained suggested that the proanthocyanidins from leaf and fruit of L. leucocephala might have the potential to be exploited as natural tyrosinase inhibitors and antioxidants.     

Chemometric analysis of selective polyphenolic groups in Asparagus racemosus (Shatavar) root extracts by traditional and supercritical fluid (CO2) based extractions

ABSTRACT

Asparagus racemosus root extracts were prepared by supercritical fluid (CO₂), soxhlet, and maceration-based methods also with various pretreatments. Thereafter, these root extracts were analyzed by High-Performance Liquid Chromatography, along with the chemometric study of the disparate phenolic groups. Among these, supercritical fluid (CO₂) based extract has a larger number of polar compounds and the antioxidant activity (98.54 ± 0.22 µM Trolox equivalent mg^?1). It also has the best cell viability (94.37 ± 1.12%) and insulin release (0.82 ± 1.12 ng mL^?1) on β-pancreatic RINm-5F cells whereas, the best extractive yield (75.80 ± 3.44% w/w) was observed for pretreated aqueous soxhlet-based extract.     

Separation and Purification of Arctiin,Arctigenin, Matairesinol,and Lappaol F from Fructus Arctii by High-Speed Counter-Current Chromatography

Arctiin (I), arctigenin (II), matairesinol (III), and lappaol F (IV) were isolated and purified from the traditional Chinese medicine Fructus Arctii by high-speed counter-current chromatography (HSCCC). The crude extracts from Fructus Arctii were treated with D101 macroporous resin first and divided into two parts: fraction 1 and fraction 2. Fraction 1 was separated by ethyl acetate-n-butanol-water (4:0.5:5, v/v/v) and yielded 164 mg of I from 250 mg of fraction 1. Fraction 2 was separated by n-hexane-ethyl acetate-methanol-water (2:3:2:3, v/v/v/v) and yielded 27 mg of II, 5 mg of III, and 3 mg of IV from 150 mg of fraction 2. The purities of the four compounds were 99.64%, 98.48%, 96.16%, and 91.41%, respectively, as determined by HPLC-DAD. The chemical structures of the isolated compounds were identified by MS, UV, ¹H NMR, and ¹³C NMR analysis.     

Biography

Ho_xCd_1?xS (0 ≤ x ≤ 0.12) nanoparticles with different Holmium contents were successfully synthesized via hydrothermal method. The prepared samples were characterized by X-ray diffraction, scanning electron microscopy, Energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and UV–Vis diffuse reflectance spectroscopy techniques. Photocatalytic efficiency of pure and Ho_xCd_1?xS samples was evaluated by monitoring the decolorization of RRed 43 in aqueous solution under visible light irradiation. 8 % Ho-doped CdS nanoparticles indicated the highest decolorization among the different amounts of dopant agent used. The effect of operational parameters including doping level, catalyst dosage, initial dye concentration and radical scavengers on the photocatalytic activity were evaluated. The Langmuir–Hinshelwood (L–H) model was evaluated for the photocatalytic process.     

An Efficient Strategy Based on Macroporous Resins and Semi-Preparative High Performance Liquid Chromatography for Rapid Separation of Five Flavonoids Components From Flaveria Bidentis(L.) Kuntze

In this study, a simple, rapid, and efficient purification method of five major flavonoids from crude Flaveria bidentis extracts was established. Five flavonoids components were initially obtained by ethanol-water extraction of Flaveria bidentis (L.) Kuntze, followed by using D4020 resin-based column chromatography and semi-preparative high performance liquid chromatography. 9.3 mg hyperoside, 6.5 mg patuletin-3-O-glucoside, 1.7 mg isorhamnetin 3-sulphate, 8.4 mg astragalin, and 4.9 mg 6-methoxykaempferol-3-O-galactoside at high purity of over 94% were obtained from 580 mg Flaveria bidentis extracts. This method is more efficient than HSCCC comparing with the results of these two methods regarding analysts’ purity, recovery, and running time.     

Enrichment and Separation of Sinomenine and Acutumine from Sinomenium acutum by pH-Zone-Refining Counter-Current Chromatography

Enrichment and separation of alkaloids from a chloroform extract of Sinomenium acutum has been successfully performed for the first time using pH-zone-refining counter-current chromatography. The two-phase solvent system used for enrichment was composed of Methyl tert-butyl ether (MtBE)–acetonitrile (CH₃CN)–water (4:1:5, v/v), where 10 mM triethylamine (TEA) was added to the upper organic stationary phase as a retainer and 10 mM hydrochloric acid (HCl) to the aqueous mobile phase as an eluter, which could enrich the alkaloids from the crude extract well. For the preparative separation, the solvent system consisted of MtBE–CH₃CN–water (4:0.5:5, v/v) with 10 mM TEA in organic stationary phase and 5 mM HCl in the aqueous mobile phase, which could separate and purify the enriched crude alkaloids successfully. 0.82 g of crude alkaloids was enriched from 1.60 g of chloroform extract in the first step separation. From the enriched crude alkaloids, 376 mg of sinomenine and 85 mg of acutumine were obtained in the second step separation with the purity of 98.1% and 98.7%, respectively. The chemical structures of the isolated compounds were identified by UV, ESI-MS and ¹H NMR.     

Separation and Purification of Bioactive Flavonol Glycosides from Hedyotis diffusa Willd by High-Speed Counter-Current Chromatography

Three flavonoid glycosides including quercetin-3-O-[2″-O-(6″′-O-E-sinapoyl)-β-D-glucopyranosyl]-β-D-glucopyranoside(I), quercetin-3-O-[2″-O-(6″′-O-E-feruloyl)-β-D-glucopyranosyl]-β-D-glucopyranoside(II) and quercetin-3-O-[2″-O-(6″′-O-E-feruloyl)-β-D-glucopyranosyl]-β-D-galactopyranoside(III) were isolated and purified from Hedyotis diffusa Willd by high-speed counter-current chromatography (HSCCC). This run was carried out with a two-phase solvent system composed of n-hexane–ethyl acetate–n-butanol–methanol–1.0% acetic acid (1:1:3.5:1:4.5, v/v) by eluting the lower phase as the mobile phase with a flow-rate at 2.0 ml/min. Consequently, 29.6 mg of I, 35.1 mg of II, 41.3 mg of III with purities of over 95% were obtained from 200 mg of the crude extracts in a single run in less than 130 min. The structure of the isolated compounds was confirmed by MS, ¹H NMR, and ¹³C NMR analysis.     

Separation of tin from tellurium: performance of different extraction chromatographic materials

An analytical study was carried out on Eichrom resins (TRU, TEVA, UTEVA, and DGA) to identify a suitable solid phase extraction substrate to separate tin (Sn) from tellurium (Te). Standard metal solutions were spiked on batch tests in HCl and HNO₃ media and the spiked analytes were determined by inductively coupled plasma mass spectrometry. The TRU resin exhibited the highest distribution coefficient (K_D) for Sn in 1.0 mol L^–1 HCl and the lowest K_D for Te. The TRU resin charged on Bio-Rad columns showed, respectively, 99.8 ± 0.4% and 59.3 ± 1.3% Sn and Te retention, and the hydrofluoric acid (0.50 mol L^–1) could wash down up to 92% of the loaded Sn, and the Te desorption can be kept as low as 5%.     

Biologically Active Digests from Pumpkin Oil Cake Protein: Effect of Cross-linking by Transglutaminase

The objective of this study was to show that biologically active hydrolysates can be obtained by simulated human gastrointestinal digestion (HGD) of transglutaminase cross-linked pumpkin oil cake protein (Tg-C) which was previously reported as a potential functional food additive. A two-stage in vitro digestion model system (by pepsin and α chymotrypsin and trypsin, simultaneously) was used to simulate the process of HGD on native and Tg-C major storage pumpkin oil seed/cake protein, cucurbitin (C). The biologically active potential of the digests was evaluated, measuring the angiotensin-converting-I enzyme (ACE) inhibitory and anti-oxidant capacity. The ACE inhibitory activity was determined in both final digests, with IC₅₀ = 0.30 ± 0.04 mg/ml for C and IC₅₀ = 0.28 ± 0.01 for Tg-C. The anti-oxidant potency of the examined proteins was enhanced by the digestion process. The 2,2-diphenyl-1-picrylhydrazyl and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical cation activities and reducing power testing showed that all the hydrolysates act as a radical quencher and reducing agents. Overall, the results showed that the cross-linking by Tg did not influence the digestion process, as well as having no effect on the biological activity of the hydrolysates. These also indicate that Tg-C, if used as functional food additive, after food consumption can be digested and become a source of peptides exerting positive effects on human health.     

Mechanochemical tuning of molecular weight distribution of styrene homopolymers as postpolymerization modification in solvent-free solid-state

Mechanochemical degradation by planetary ball milling (PM) is used for postpolymerization modification of styrene homopolymers (PS). A complete factorial design was chosen to study the effect of radical scavengers, milling time, initial molecular weight, and revolution radius (R_p), on the shape of molecular weight distributions (MWDs) of PS. Size-exclusion chromatography analysis shows the feasibility of fine-tuning MWD of PS at up to 40% conversion. Distributions ranged from unimodal to bimodal in a PM with R_p = 150 mm at different stage of milling, whereas in a PM with R_p of 60.8 mm the adjustment of unimodal distributions is achieved. Initial polydispersity is more important to develop bimodal distributions when compared with initial molecular weight. Fourier transform infrared and X-ray electron spectrometry analysis show some suppression of PS degradation and complete oxidation inhibition of macromolecular radicals with the incorporation of radical scavengers, which we considered as additional aids when adjusting the MWDs.     

Autoxidation of methyl linoleate initiated by the ozonide of allylbenzene

Allylbenzene ozonide (ABO), a model for polyunsaturated fatty acid (PUFA) ozonides, initiates the autoxidation of methyl linoleate (18∶2 ME) at 37°C under 760 torr of oxygen. This process is inhibited by d-α-tocopherol (α-T) and 2,6-di-ert-butyl-4-methylphenol (BHT). The autoxidation was followed by the appearance of conjugated diene (CD), as well as by oxygen-uptake. The rates of autoxidation are proportional to the square root of ABO concentration, implying that the usual free radical autoxidation rate law is obeyed. Activation parameters for the thermal decomposition of ABO were determined under N₂ in the presence of radical scavengers and found to be E_a=28.2 ±0.3 kcal mol⁻¹ and log A=13.6±0.2; k_d (37°C) is calculated to be (5.1±0.3)×10⁻⁷ sec⁻¹. Autoxidation data are also reported for ozonides of 18∶2 ME and methyl oleate (18∶1 ME).     

Extraction of phenolic compounds from sour cherry pomace with supercritical carbon dioxide: Impact of process parameters on the composition and antioxidant properties of extracts

Sour cherry (Prunus cerasus) is rich in biologically active phenolic compounds. These compounds are concentrated in fruit skin and most of them remain in the leftovers during the production of juice. Supercritical carbon dioxide extraction was used to separate phenolic compounds from sour cherry pomace. The effects of temperature, pressure and the addition of ethanol on anthocyanin and the total phenolic content and radical scavenging activity of the extracts were investigated. The best results were acquired for 35°C, 10 MPa and 80% ethanol addition. A strong correlation was found between the phenolic content and other features of the extracts.     

Optimization of Heat Pump–Assisted Intermittent Drying

In the present study, heat pump–assisted drying of salak fruit was optimized by dividing the dehydration process into three distinct phases, namely, the initial, intermittent, and final stages. Drying variables considered for the optimization were the intermittent duration (X ₁), intermittent ratio (X ₂), and intermittent cycle (X ₃); the response variables studied were the total drying time (Y ₁), total heating time during intermittent drying (Y ₂), total heating time after intermittent drying (Y ₃), total color change (Y ₄), ascorbic acid content (Y ₅), and total phenolic content (Y ₆). Response surface methodology was used to determine the best combination of the drying variables that could provide the shortest drying period and premium product quality. Experimental results showed that all of the response variables were improved under the optimized intermittent drying conditions compared to the conventional method using constant drying conditions. The optimized heat pump–assisted intermittent drying reduced the drying time by 36% and improved phytochemicals retention with ascorbic acid and total phenolic content recorded at 18.4 ± 1.8 mg ascorbic acid/100 g dw and 43.3 ± 2.2 mg gallic acid equivalent (GAE)/g dw, respectively. The color change of the final product was minimum with a ΔE* value of 7.26 ± 2.03.