HPLC-DAD Quantification of Phenolic Compounds Contributing to the Antioxidant Activity of Maclura pomifera,Ficus carica and Ficus elastica Extracts

Abstract

The concentration and antioxidant activity of the known phenolics macluraxanthone, rutin, chlorogenic acid, and psoralen present in M. pomifera, F. carica, and F. elastica extracts were determined to evaluate the plant extracts potency as new antioxidant suppliers.

The quantification of the compounds was obtained by HPLC-DAD. The antioxidant activity of plant extracts and compounds was evaluated using DPPH and ABTS methods. The results seem to indicate that these extracts can be promising as new antioxidant suppliers, particularly F. carica and F. elastica leaves because only about 30% and about 50%, respectively, of the total activity was due to the phenolics determined.     

Application of matrix solid-phase dispersion to the determination of amitrole and urazole residues in apples by capillary electrophoresis with electrochemical detection

A new method based on matrix solid-phase dispersion (MSPD) extraction was studied for the extraction of amitrole (3-amino-1,2,4-triazole), and its metabolite urazole (3,5-dihydroxy-1,2,4-triazole), in apple samples. The influence of experimental conditions on the yield of the extraction process and on the efficiency of the cleanup step was evaluated. Determination was carried out by capillary electrophoresis (CE) with electrochemical detection, demonstrating the compatibility between MSPD and CE techniques. The method has been successfully applied to different apple varieties. Recoveries in samples spiked at 1.6 and 1.7 μg g⁻¹ for amitrole and urazole were 88 and 82%, respectively. The limits of detection were 0.4 μg g⁻¹ for both compounds using electrochemical detection.     

A simple; efficient and environmentally friendly method for the extraction of pesticides from onion by matrix solid-phase dispersion with liquid chromatography-tandem mass spectrometric detection

An evaluation of the extraction of pesticides from onion by matrix solid-phase dispersion (MSPD) with the determination by liquid chromatography tandem mass spectrometry using electrospray as the ionization source (LC-ESI-MS/MS) was carried out. The performance of different sorbents, including reused C18 bonded silica, was evaluated. Different parameters affecting the extraction efficiency were evaluated, such as the type and amount of sorbent, the time of interaction after the fortification step, the time of sample dispersion and the elution solvent. The matrix effect regarding the recovery of the pesticides by MSPD was also investigated. The best results were obtained using 0.5 g of sample, 1.0 g reused C18, interaction time of 1 h, dispersion time of 5 min, and acetonitrile as the elution solvent. The method was validated by the fortification of the onion sample, free of pesticides, at different concentration levels (0.01, 0.1 and 1.0 mg kg⁻¹). Average recoveries ranged from 78.3 to 120.4% and relative standard deviation below 20% was obtained. Detection and quantification limits ranged from 0.003 to 0.03 mg kg⁻¹ and from 0.01 to 0.1 mg kg⁻¹, respectively.     

Application of matrix solid-phase dispersion to the propham and maleic hydrazide determination in potatoes by differential pulse voltammetry and HPLC

The application of the matrix solid-phase dispersion (MSPD) process as sample treatment in connection with the electrochemical detection is studied for the first time. For this purpose, a novel methodology is introduced for the extraction of propham and maleic hydrazide herbicides from potatoes samples based in the MSPD process prior to their electrochemical detection. Potato samples disruption was done by blending them with C₈ bonded-phase and selective herbicide extraction was achieved by successive treatment of the blended with 50 mM phosphate buffer pH 7.4 (for maleic hydrazide) and methanol (for propham). The extraction procedure efficiency was estimated using differential pulse voltammetry in potato samples spiked with the herbicides yielding recovery values of 98% and 68% for propham and maleic hydrazide, respectively. No significant adverse effect of the MSPD process was observed on the herbicides electrochemical signals. For comparison, recovery studies using HPLC with UV detection were carried out and a good correlation in the results obtained by using both techniques was observed.     

Copper-catalyzed aryldifluoromethylenation of N-arylacrylamides to synthesis of the diheterocyclic compounds linked by gem-difluoromethylene moiety

An efficient method of copper-catalyzed aryldifluoromethylenation of N-arylacrylamides is described to step-economic synthesis of the various biologically important biheterocyclic compounds linked by gem-difluoromethylene moiety through addition of benzo-1,3-azolic (oxa- or thia-)difluoromethyl radicals generated in situ to terminal of C–C double bond of N-arylacrylamides then cyclization cascade. This protocol has demonstrated to have broad substrate scope and excellent functional-group tolerance under mild reaction conditions.     

Synthesis of gentianine N-oxide by enzymatic hydrolysis of swertiamarin in the presence of hydroxylamine and reaction pathway to gentianine and gentianol

Gentianine is a metabolite of gentiopicroside and swertiamarin. Several biological activities have been reported for gentianine, such as antiinflammatory and antidiabetic activity, and hypotensive effect. Gentiopicroside is found in 0.9–9.8% content in Gentian root or Gentian scabra root, and Swertiamarin is contained in Swertia herb in 2–10%. These natural products can be potential starting materials for the synthesis of gentianine. This study describes the β-glucosidase-catalyzed hydrolysis of gentiopicroside and swertiamarin in the presence of hydroxylamine to afford gentianine N-oxide, which can be a synthetic precursor of gentianine derivatives. Enzymatic hydrolysis of swertiamarin selectively afforded gentianine N-oxide in 81% yield, whereas gentiopicroside afforded gentianine N-oxide and gentianol N-oxide. Plausible reaction pathways leading to gentianine, gentianol, and their N-oxides were also investigated.     

A Parham Cyclization route to the 2,3-dihydro-1H-indazole-1,2-dicarboxylate ring systems via condensation of thermolabile aryllithium reagents and azodicarboxylate esters

The Parham Cyclization reaction of o-lithiobenzyl chlorides (generated by low temperature halogen-metal exchange of the corresponding o-bromobenzyl chlorides with n-butyllithium) with azodicarboxylate esters provides a new entry to the 2,3-dihydro-1H-indazole-1,2-dicarboxylate ring system in moderate to good yield.     

A New Phenolic Diglycoside Produced in Response to Copper Toxicity and a New Flavan Dimer from the Leaves of Viburnum ichangense (Hemsl.) Rehd.

A new phenolic digycoside 1 was produced as stress metabolite in the fresh leaves of Viburnum ichangense (Hemsl.) Rehd ., in response to abiotic stress elicitation by CuCl₂. The stress metabolite was characterized as 1‐O‐[α‐L ‐arabinofuranosyl(1→6)‐β‐D ‐glucopyranosyl]‐erythro‐1,2‐bis(4‐hydroxy‐3‐methoxyphenyl)propane‐1,3‐diol ( 1 ). A new flavan dimer, 2,3‐epoxyflavan‐3′,4′,5,7‐tetraol‐(4→8″)‐flavan‐3″,3′′′,4′′′,5′′′,6″‐pentaol ( 2 ), and two known compounds, hovetrichoside A ( 3 ) and asperglaucide ( 4 ), were also isolated. Their structures were established by spectroscopic means.     

Determination of polybrominated diphenyl ethers in fish tissues by matrix solid-phase dispersion and gas chromatography coupled to triple quadrupole mass spectrometry: Case study on European eel (Anguilla anguilla) from Mediterranean coastal lagoons

This paper describes the development and validation of an analytical methodology to determine 28 polybrominated diphenyl ethers (PBDEs) in European eel (Anguilla anguilla) tissues using matrix solid-phase dispersion (MSPD) and gas chromatography coupled to triple quadrupole mass spectrometry (GC-QQQ-MS/MS). A total of 28 PBDEs were targeted, including tri- to deca-brominated congeners.The robustness and effectiveness of the proposed sample preparation procedure was demonstrated in lipid-rich eel tissues. The use of batch MSPD with activated silica gel and H₂SO₄-impregnated silica gel, followed by H₂SO₄ digestion and multilayer cartridge clean-up allowed for complete lipid removal and eliminated matrix effects during GC-QQQ-MS/MS analysis. The average PBDE recoveries from eel muscle samples spiked with PBDEs at two levels were in the range 56.2-119.0%. Precision was satisfactory since relative standard deviations were lower than 19.6%, regardless of spike level, and method quantification limits ranged between 1 and 170 pg g⁻¹ (wet weight).The method demonstrated its successful application for the analysis of eel samples from two coastal lagoons located on the western French Mediterranean coast. All samples tested positive, but for tri- to hexa-brominated congeners only and total PBDE levels observed in this study were in the range 0.08-1.80 ng g⁻¹ wet weight.     

Combination of Sea Sand Disruption Method and Ion-Pair Solid-Phase Extraction for Effective Isolation and Purification of Chlorogenic Acid from Plants Prior to the HPLC Determination

Chlorogenic acid (CQA) is one of phenolics commonly found in higher plants, possessing numerous health-promoting effects on humans. Unfortunately, it is easily degraded/transformed into other substances during extraction. Therefore, its reliable analysis requires a special approach that does not involve high temperatures. This paper presents a very simple method of CQA isolation using the sea sand disruption method with subsequent purification of the extract using the ion-pair solid-phase extraction process, followed by HPLC–DAD detection. It was found that control of the ion pairing reagent concentration and sample pH is crucial to improve purification, and that the best results, with recovery exceeding 98%, were obtained for 0.05 M tetrabutylammonium bisulfate at pH 7 when the ion pairs were formed directly in the extract and eluted from the C18 sorbent using an acidified methanol–water mixture. The practical potential of the developed procedure was verified by using it for CQA isolation from different plants. The approach represents one of the contemporary analytical trends and current advances in the solid phase extraction, in which several sorption extraction techniques are combined to ensure high-quality analytical results.     

Separation of three phenolic high‐molecular‐weight compounds from the crude extract of Terminalia Chebula Retz. by ultrasound‐assisted extraction and high‐speed counter‐current chromatography

This study presents an efficient strategy for separation of three phenolic compounds with high molecular weight from the crude extract of Terminalia chebula Retz. by ultrasound‐assisted extraction and high‐speed counter‐current chromatography. The ultrasound‐assisted extraction conditions were optimized by response surface methodology and the results showed the target compounds could be well enriched under the optimized extraction conditions. Then the crude extract was directly separated by high‐speed counter‐current chromatography without any pretreatment using n‐hexane/ethyl acetate/methanol/water (1:7:0.5:3, v/v/v/v) as the solvent system. In 180 min, 13 mg of A, 18 mg of B, and 9 mg of C were obtained from 200 mg of crude sample. Their structures were identified as Chebulagic acid (A, 954 Da), Chebulinic acid (B, 956 Da), and Ellagic acid (C) by ¹H NMR spectroscopy.     

Hofmann rearrangement of primary carboxamides and cyclic imides using DCDMH and application to the synthesis of gabapentin and its potential peptide prodrugs

Two protocols for the efficient transformation of aromatic as well as aliphatic primary carboxamides to the corresponding carbamates and aromatic as well as aliphatic cyclic imides to the corresponding anthranilic acid derivatives & amino acid derivatives, respectively, are described. We also developed a novel methodology to the multigram scale synthesis of gabapentin and (S)-pregabalin. The gabapentin methyl carbamate was converted to novel potential peptide prodrugs of gabapentin.     

Determination of the volatile chemical constituents of Notoptergium incium by gas chromatography-mass spectrometry and iterative or non-iterative chemometrics resolution methods

The qualitative and quantitative determination of the chemical constitutes in traditional Chinese medicine (TCM) is an important task, which builds the foundation of the theory of pharmacological activity. The hyphenated chromatography instruments combined with the related chemometric methods provide powerful tools for the resolution of such complex systems. The familiar chemometrics methods can be roughly divided into two different kinds, the iterative one such as orthogonal projection approach (OPA) and non-iterative one representing by evolving window orthogonal projection (EWOP). One can use different kinds of methods according to overlapping condition, and then the measured data matrix can be resolved into pure concentration profiles and mass spectra of the chemical components with relative high efficiency and acceptable accuracy. One kind of TCM, named Notoptergium incium (NI) was analyzed by gas chromatography-mass spectrometry (GC-MS) and resolved by above chemometric approach. Experiment results show the efficiency and convenience of the proposed approach. 65 of the 98 separated constituents in essential oil, accounting for 92.13%, were identified by mass spectroscopy (MS).     

Preparative isolation and purification of trans-3,5,4'-trihydroxystilbene-4'-O-beta-D-glucopyranoside and (+)catechin from Rheum tanguticum Maxim. ex Balf. using high-speed counter-current chromatography by stepwise elution and stepwise increasing the flow-rate of the mobile phase

Preparative high-speed counter-current chromatography (HSCCC) was successfully used for isolation and purification of trans-3,5,4'-trihydroxystilbene-4'-O-beta-D-glucopyranoside (compound 1) and (+)catechin (compound 2) from Rheum tanguticum Maxim. ex Balf. by stepwise elution with a pair of two-phase solvent system composed of ethyl acetate-ethanol-water (25:1:25, v/v) and (5:1:5, v/v), and stepwise increasing the flow-rate of the mobile phase from 0.8 to 2.0 mlmin(-1) after 5 h. The preparative HSCCC separation was performed on 250 mg of crude extract yielding pure compound 1 (10.2 mg) and compound 2 (26.7 mg) all at purities of over 96% in a single run. The structures of the two compounds have been elucidated by means of spectroscopic methods including MS and 1H, 13C nuclear magnetic resonance spectroscopy.     

Indirect fluorescence detection of amino sugars with the use of copper complexes of tryptophan and its analogues following high-performance liquid chromatographic separation

A simple, indirect fluorescence detection method has been developed for detecting specific mono-amino sugars (D-glucosamine, D-galactosamine, D-mannosamine) following chromatographic separation. The eluting amino sugars release L-tryptophan (L-Trp) from a copper-tryptophan complex which is introduced postcolumn. Analyte detection is based on measuring the increase in L-Trp fluorescence, which is quenched when complexed with copper. Two tryptophan analogues, 5-hydroxy-L-tryptophan (5-HTP) and DL-5-methoxytryptophan (5-MTP), were also evaluated as postcolumn reagents. 5-MTP was found to be a suitable alternative to L-Trp for the detection of these mono-amino sugars. Detection limits for D-glucosamine, D-galactosamine, and D-mannosamine are in the range of 0.15-0.30 nmol injected.     

A Novel Approach to Evaluate the Quality and Identify the Active Compounds of the Essential Oil from Curcuma longa L.

Composition-Activity Relationship (CAR) modeling is a novel approach to evaluate the quality and identify active components of herbal medicine. In this study, Grid Search Method (GSM) and Heuristics algorithms, particularly Genetic Algorithm (GA) and Particle Swarm Optimization (PSO), were adopted to determine the optimal parameters automatically. Then, support vector regression (SVR) combined with a linear kernel function or a radial basis kernel function (RBF) and back propagation artificial neural networks (BPANN) were employed to construct the model that correlated the main chemical components with the cytotoxicity of the essential oil from Curcuma longa L., respectively. Considering the robustness and predictive ability, the ν-SVR-RBF-PSO model had the best performance in various tests performed in this paper. Nine components were then identified to have significant cytotoxicity based on the superior model and Mean Impact Value (MIV) analysis. An optimal model can therefore be a useful tool to predict the bioactivity for quality evaluation and active components identification of herbal medicine.     

Investigation of electrocoagulation reactor design parameters effect on the removal of cadmium from synthetic and phosphate industrial wastewater

This study investigates the effect of reactor design parameters on cadmium removal from industrial wastewater discharged by the Tunisian Chemical Group (TCG) to improve as much as possible efficiency and cost of electrocoagulation (EC) process. Based on an examination of the design parameters one by one, the best cadmium removal was achieved for an inter-electrode distance (d_ie) of 0.5 cm, monopolar connection mode, stirring speed of 300 rev min^?1, surface-area-to-volume ratio (S/V) of 13.6 m^?1, and an initial temperature of 50 °C. These operating conditions are allowed to achieve efficient removal in a relatively short operating time with the lowest energy consumption and cost possible. The present study proved that the parameters that have an effect on the operating cost are the electrode configuration, inter-electrode distance and S/V ratio. The energy consumption, the pH evolution, and the treatment cost were studied. The investigation of the effect of all the selected optimum EC design parameters together on the removal of cadmium from the TCG wastewater proved that the treatment was highly efficient; 100% of cadmium removal was reached in 5 min, with a very low power consumption (1.6 kW h m^?3) and very low cost (0.116 TND m^?3). Moreover, EC was found to be capable of removing cadmium as well as other pollutants at the same time from the case-study industrial wastewater. The investigation carried out in this work explores and proposes a very cost-effective treatment method to remove heavy metals from industrial wastewater if compared to results reported about cost of this treatment process through other widely used technologies such as coagulation (4.36 Tunisian National Dinar (TND) m^?3) and precipitation (9.96 TND m^?3) employed in previous studies.     

Synthesis of Naturally Occurring Pyrazine and Imidazole Alkaloids from Botryllus LeachiRID=”a”ID=”a”?Dedicated to Prof. G. M?rkl on the occasion of his 75th birthday

The synthesis of the naturally occurring and biologically active alkaloids 1 and 2, first isolated from the red ascidian Botryllus leachi by Duran et al. [1], is described and the structure proposed for Botryllazine B (1) is confirmed. The analytical data for 2-(p-hydroxybenzoyl)-4-(p-hydroxyphenyl)imidazole (2) are discussed and compared with the literature. With special emphasis of ¹H NMR data the tautomerism of aroylimidazolemethanones is described.