Fehling's Solution Research Articles

Assessment of Secondary Metabolites and Thin-Layer Chromatographic Analysis of Carica papaya (Caricaceae) Leaves Ethanolic Extract

Carica papaya, also referred to as pawpaw, is a tropical fruit-bearing tree in the Caricaceae family. Papaya is one of the world's most extensively grown crops. Its fruits, seeds, and leaves are widely utilized in cooking and traditional medicine. Papaya leaf extract, tea, and juices are extensively used to cure ailments and promote health. The study aimed to quantify the presence of potential chemical compounds in Carica papaya leaves using Thin-Layer Chromatographic analysis (TLC). Standard qualitative phytochemical tests were performed on the leaves of C. papaya to determine the presence of various phytochemicals, and TLC analysis to ascertain the presence of potential chemical constituents. Extract of Carica papaya leaves in ethanol showed the presence of tannins, alkaloids, glycosides steroids, proteins, flavonoids, carbohydrates, etc., after the phytochemical screening, all of which are useful chemical ingredients responsible for a variety of pharmacological effects. The lack of color change noticed when the heated sample was treated with Fehling's solution revealed the absence of reducing sugar. TLC analysis using several solvent systems revealed the presence of potential chemical constituents with varying Rf values. This variance in the Rf values showed the phytochemicals and potential chemical constituents' polarity and this gave a hint on the type of solvent systems suitable for the analysis and separation of pure components. Hence, Carica papaya leaf extract contains a high concentration of both primary and secondary plant metabolites. TLC profiling yielded a good result, suggesting the existence of numerous possible chemical ingredients in the plant leaves used for the analysis.

Copper-Treated Environmentally Friendly Antipathogenic Cotton Fabric with Modified Reactive Blue 4 Dye to Improve Its Antibacterial and Aesthetic Properties

The objectives of the present study were to develop an environmentally friendly, low-price, easy, and fast method for developing antipathogenic (antibacterial, antifungal, and antiviral) cuprous-oxide-coated multifunctional fabrics. The fabrics were first sensitized with citric acid, and then Cu2O particles were formed using the Fehling solution method. The cuprous oxide particles were then applied to the cotton fabrics. To create the Cu2O particles, three different kinds of reducing agents with varying concentrations were used. SEM, dynamic light scattering, FTIR, EDS, and XRD were used to examine the surface morphologies and metal presences. In the second step, a reactive antibacterial dye was made (by reacting Reactive Blue 4 with triclosan). The molecular structure of the modified dye was confirmed with FTIR. The resultant antibacterial dye was applied on the copper-treated cotton fabrics in accordance with the exhaust dyeing protocol. The dyed fabrics were characterized through the colorimetric data (L*, a*, b*, C, H, and K/S), levelness of dye, fastness properties as well as exhaustion and fixation rates. Cuprous-oxide-coated fabrics were tested for antipathogenic activity using quantitative and qualitative measurement results. The fabrics treated with cuprous oxide particles reduced with sodium hydrosulfite at 1 g/L seemed to have the highest antipathogenic effect. Moreover, the versatility of the hygienically developed bioactive fabrics in terms of their comfort properties such as air permeability and stiffness were investigated. Finally, the coating’s durability was confirmed by evaluating its antibacterial properties and performing an SEM analysis after laundry.

The chemistry of Crismer’s test for glucose in urine

The study of what is going on in a chemical test is important, the more if the involved substance is glucose in urine. In the Crismer’s test the blood-red colour of safranin solution in alkaline medium is discharged if the glucose concentration is higher than 100 mg/dl. The reagent is not affected by uric acid or creatinine as is the case with the Fehling solution. The safranin test detects sugar in saliva when other reagents failed. Since the reaction mechanism of this test has not been advanced, we provide the electron flow, step by step.

In celebration of the 70thbirthday of Peter Klüfers

In celebration of the 70^thbirthday of Peter Klüfers

Preparation of thin layer CuO from Cu2O using the Spin Coating Method at Various Annealing Temperature and Number of Dripping for Photoelectrochemical Water Splitting

A thin layer preparation of CuO from Cu2O powder using Fehling's solution for photoelectrochemical applications has been performed. The research was focused on studying the effect of annealing temperature and the number of drops on the performance of CuO thin layer semiconductors from Cu2O powder prepared by spin coating with a rotation rate of 500 rpm for 15 seconds. The thin layers were treated with annealing with temperature variations of 300°C, 400°C, and 500°C for 1 hour and variations in the number of drops of 10, 20, and 50 drops. The CuO thin layer was tested in a photoelectrochemical process as a photocathode to split water with a simulated light of 1.5 AM (100 mW/cm2). The process of splitting water as a method of producing hydrogen energy by photoelectrochemistry is assisted by semiconductors, such as CuO, in an electrolyte solution to capture photons and drive the water-splitting reactions. Copper (II) Oxide (CuO) is a p-type semiconductor with a band gap of 1.2-2.5 eV, which can be used as a photocathode. The optimum photoelectrochemical measurement results were obtained at an annealing temperature of 400°C and 50 drops with a current density of 0.584 mA/cm2 at a potential of 0.2 V versus the Reversible Hydrogen Electrode (RHE). The results of the Scanning Electron Microscopy (SEM) analysis show that the morphology of the oxide is spherical. Energy dispersive X-ray (EDX) analysis displays that the sample contained 51.46% and 48.54% of Cu and O, respectively. The X-ray diffraction pattern (XRD) analysis shows that the oxide grain size is 44.137 nm.

Emergence of complex chiral coordination clusters {CuII48Na12} by using multiple ligands under oxidizing conditions

Two chiral coordination clusters {CuNa12}, which can only be revealed by synchrotron single-crystal X-ray diffraction, were assembled unexpectedly from a system resembling the long-studied Fehling's solution. As the intricate structures themselves indicate, the ingenuity of using multiple ligands should inspire new strategies to fabricate new compounds.

Photoelectrochemical and Non-Enzymatic Glucose Sensor Based on Modified Fehling's Test by Using Ti/TiO2 NTs-rGO-Cu2O Electrode

Herein, semiconductor Cu2O/reduced graphene oxide (rGO) coated TiO2 nanotubes (NTs) arrayed titanium foil was used as a photoelectrochemical (PEC) glucose sensor. The concentration of Cu2O nanoparticles (NPs) obtained by Fehling's solution is directly proportional to glucose amount, and the sensor combined the sensitive feature of PEC analysis and low-cost production of enzymeless sensors with the modified Fehling's test for the first time. The greatly enhanced photocurrent can be attributed to the p-n heterojunction formation between Cu2O NPs and TiO2 NTs, combined with the excellent conductive rGO, which can simultaneously enhance the charge separation efficiency and facilitate electron transfer. Also, rGO caused Cu2O NPs to cohere with each other on the electrode surface. The wide linear measurement range was found to be 0.0007–20 mM, with a sensitivity of 0.87 μAmM−1 at 0 V vs Ag/AgCl. The proposed nanocomposite can be used for the glucose measurements in beverages.

Inhibition of Leishmania amazonensis arginase by fucogalactan isolated from Agrocybe aegerita mushroom

The inhibition of arginase from Leishmania spp. is considered a promising approach to the leishmaniasis treatment. In this study, the potential of a fucogalactan isolated from the medicinal mushroom Agrocybe aegerita was evaluated against arginase (ARG) from Leishmania amazonensis. The polysaccharide was obtained via aqueous extraction, and purified by freeze thawing and precipitation with Fehling solution. Its chemical structure was established by monosaccharide composition, methylation analysis, partial acid hydrolysis, and NMR spectroscopy. The data indicated that it is a fucogalactan (FG-Aa; Mw = 13.8 kDa), having a (1→6)-linked α-D-Galp main-chain partially substituted in O-2 by non-reducing end-units of α-L-Fucp. FG-Aa showed significant inhibitory activity on ARG with IC50potency of 5.82 ± 0.57 μM. The mechanism of ARG inhibition by the heterogalactan was the competitive type, with Kiof 1.54 ± 0.15 μM. This is the first report of an inhibitory activity of arginase from L. amazonensis by biopolymers, which encourages us to investigate further polysaccharides as a new class of ARG inhibitors.

Partially methylated galactans containing different proportions of 3-O-methyl-galactose from Pleurotus citrinopileatus

Pleurotus citrinopileatus, popularly known as “golden oyster mushroom” have medicinal properties, which are attributed mainly to the presence of bioactive polysaccharides. In this work, two partially 3-O-methylated galactans were isolated from the fruiting bodies of this fungus, via successive aqueous extraction, followed by fractionation by freeze-thawing, and precipitation of soluble material with Fehling solution. The structural assignments were carried out using mono- and bidimensional NMR spectroscopy, monosaccharide composition, and methylation analyses. The polysaccharides were characterized as linear, partially 3-O-methylated (1 → 6)-linked α-galactopyranans, containing only Gal and 3-O-Me-Gal, in 2:1 and 1:1 molar ratios, with molar masses of 37.6 × 103 g/mol and 28.5 × 103 g/mol, respectively. Similar structures have been described for other Pleurotus spp., but showing a lower content of 3-O-Me-Gal.

Chemical structure of a partially 3-O-methylated mannofucogalactan from edible mushroom Grifola frondosa

An unusual heteropolysaccharide was isolated from the fruiting bodies of the medicinal mushroom Grifola frondosa, via successive cold aqueous extraction, followed by fractionation through freeze-thawing, precipitation with Fehling solution and dialysis using a membrane with a size exclusion cut-off of 500 kDa. Its chemical structure was determined based on total acid hydrolysis, methylation analysis and NMR studies. The mannofucogalactan had a molar mass of 15.9 × 103 g mol−1, which was determinate by HPSEC-MALLS. This heteropolymer showed to have a main chain of (1 → 6)-linked α-d-Galp partially substituted at O-2 by 3-O-α-d-mannopyranosyl-α-l-fucopyranosyl groups and in a minor proportion with α-l-Fucp single-unit side chains. Moreover, the presence of 3-O-Me-Galp units could also be observed in the main chain of the G. frondosa mannofucogalactan.

Macronutrients compliance between foods labels and marketing package content values

Background: Nutrient labeling raises consumers' awareness of nutritional values of foods. However, uncertainties with regard to amluracy of nutrition facts' labels have recently increased. Objective: The objective of this study is to determine the compliance between information presented in food labeling of widely consumed foods and their true values. Materials and Methods: This study investigated 24 types of foods including dairy, meat, and protein rich foods, snacks, dressings and tomato paste, and pasta. In total, 1764 experiments were conducted. The levels of fat, carbohydrate, and protein were measured using Folch method, Fehling's solution, and Kjeldahl device, respectively. The data were then analyzed using Spearman correlation coefficient and Wilcoxon test. Results: The amount of fat, carbohydrate, and protein content in 67.8%, 48.4%, and 38.5% of analyzed foods was different from their nutrition fact labels. The fat content on nutrition facts label of dressings was lower than their analyzed values (10.15 ± 15.87 vs. 11.40 ± 21.44 g, P = 0.001). In total, the fat content on food labels was significantly different from analyzed values (15.54 ± 13.02 vs. 12.60 ± 10.77 g, P = 0.001). The carbohydrate content on food labels of meat and protein foods was less than their analyzed values (5.49 ± 3.24 vs. 6.88 ± 4.47 g, P = 0.001). Conclusion: The study showed a significant difference between laboratory analyzed values and food labels nutrition facts which may have misleading effects on foods choice of customers. In general, lack of amluracy in labeling nutritional value of foods and providing inamlurate information might lead to public unhealthy eating.

Fehling solution/DIPEA/hydrazine: an alternative catalytic medium for regioselective synthesis of 1,4-disubstituted-1H-1,2,3-triazoles using azide–alkyne cycloaddition reaction

The development of copper catalyzed azide–alkyne cycloaddition in aqueous solvent system at room temperature is a notable contribution to the field of green chemistry. In this work, 1,4-disubstitued-1H-1,2,3-triazoles are synthesized in the Fehling solution, a widely used system in practical laboratory classes but totally unexplored in research field, with N,N-diisopropylethylamine/hydrazine without using any organic solvent under mild reaction conditions.

The Species of Fehling's Solution

AbstractA species model for the copper(II)/L‐(+)‐tartaric acid (LH2, tartH2) aqueous system between pH 1.9 and 12.3 has been established by potentiometric, UV/Vis spectroscopic, solubility and crystallographic studies. Eight species were detected, including the oligonuclear major species Cu8L6H–10 in the neutral region and the mononuclear major species CuL2H–4 in the alkaline region, the latter being associated with Fehling's solution. The octanuclear complex was isolated as its lithium salt Li7[Cu8(L‐tartH–2)4(L‐tartH–1)2(H2O)6]NO3·19H2O (1). The “Fehling species” CuL2H–4 was crystallized as its sodium, potassium and caesium salts, namely K2Na4[Cu(L‐tartH–2)2]·12H2O (2), Na6[Cu(L‐tartH–2)2]·9H2O (3), Na6[Cu(L‐tartH–2)2]·14H2O (4), and Cs6[Cu(L‐tartH–2)2]·8H2O (5). Each of them shows a distorted square‐planar environment of copper(II), similar to the related non‐chiral cuprate [Cu(rac‐tartH–2‐κ2O2,O3)2]6– (S. Albrecht, P. Klüfers, Z. Anorg. Allg. Chem. 2013, 639, 280–284). By comparing the components of the UV/Vis spectra of Fehling's solution and the solids, we confirmed the identity of the major solution species.

Research of polysaccharide complexes from asteraceae family plants

Aim of research. Depth study of polysaccharides in some little-known plant species of Asteraceae family is pressing question, considering that polysaccharides are important biologically active compounds widely used in pharmaceutical and medical practice as remedies and preventive medications. The aim of research was to determinate both quantitative content and monomeric composition of polysaccharide complexes from Asteraceae family plant species – Tagetes genus, Arnica genus, and Bellis genus.Materials and methods. Determination of polysaccharides was carried out by the precipitation reaction, using 96 % ethyl alcohol P and Fehling's solution after acid hydrolysis; quantitative content of this group of compounds was determined by gravimetric analysis. On purpose to identify the monomeric composition hydrolysis under sulfuric acid conditions was conducted. Qualitative monomeric composition of polysaccharides after hydrolysis was carried out by paper chromatography method in n-Butanol – Pyridine – Distilled water P (6:4:3) system along with saccharides reference samples.Results. Polysaccharide complexes from Tagetes erecta, Tagetes patula, Tagetes tenuifolia, Arnica montana, Arnica foliosa, wild and cultivated Bellis perennis herbs were studied. Water-soluble polysaccharides and pectin fractions were isolated from studied objects; their quantitative content and monomeric composition were determined.Conclusion. The highest amount of water-soluble polysaccharides was found in cultivated Bellis perennis herb (10,13 %), the highest amount of pectin compounds – in Tagetes tenuifolia herb (13,62 %); the lowest amount of water-soluble polysaccharides and pectin compounds was found in Arnica montana herb (4,61 %) and Tagetes patula herb (3,62 %), respectively. It was found that polysaccharide complexes from all studied species include glucose and arabinose

SiO2-Cu2O: An efficient and recyclable heterogeneous catalyst for N-benzylation of primary and secondary amines

A mild, effective, and selective procedure is reported for the mono N -benzylation and N , N -dibenzylation of primary amines as well as mono N -benzylation of secondary amines using silica-supported copper(I) oxide in water. The silica-supported Cu 2 O was generated in situ by the reaction of Fehling solution and glucose at 100 °C onto activated silica. The catalyst was filtered, washed with water, and oven-dried, and was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, and atomic absorption spectroscopy. The prepared Cu 2 O-SiO 2 was found to be thermally stable up to 325 °C. The copper was uniformly distributed onto the surface of the silica, and the mean particle diameter was 7 nm. The catalyst served as a selective heterogenous catalyst for the N -benzylation of primary and secondary amines. The catalyst is recyclable and was used effectively upto fifth run without a significant loss of catalytic activity. Various reaction solvents including water, acetonitrile, and toluene were screened for N -benzylation of amines, and the success of the aqueous system highlights the low environmental impact of the procedure. Silica-supported Cu 2 O was prepared in situ using inexpensive and widely available starting materials and used as a catalyst for N -benzylation and N , N -dibenzylation of primary and secondary amines.

The Structural Chemistry of Text‐Book Species: the Tartrato‐Cuprates in Fehling's Solution

AbstractFehling's solution is an aqueous alkaline solution (pH ca. 13) of D‐, L‐, or rac‐tartrato‐cuprates(II) and both excess tartrate and hydroxide. The isolation of crystalline solids succeeded for rac‐tartrate‐containing samples. Crystal structure analyses revealed the formulas K8[Cu10(rac‐tartH‐1)4(rac‐tartH‐2)4(H2O)4]·18H2O (1), Li4[Cu2(rac‐tartH‐2‐κ2O1,O2:κ2O3,O4)2]·11.75H2O (2), and Na6[Cu(rac‐tartH‐2‐κ2O2,O3)2]·14H2O (3). The cupric central atom is in a square‐planar tetracoordination in the bis(diolato) chelate in 3, and in square‐pyramidal 4+1 coordination in the mixed carboxylato‐alkoxido chelates 1 and 2. In terms of stoichiometry, 3 is closest to typical Fehling recipes.

Effect of Different Purification Techniques on the Characteristics of Heteropolysaccharide-Protein Biopolymer from Durian (Durio zibethinus) Seed

Natural biopolymers from plant sources contain many impurities (e.g., fat, protein, fiber, natural pigment and endogenous enzymes), therefore, an efficient purification process is recommended to minimize these impurities and consequently improve the functional properties of the biopolymer. The main objective of the present study was to investigate the effect of different purification techniques on the yield, protein content, solubility, water- and oil-holding capacity of a heteropolysaccharide-protein biopolymer obtained from durian seed. Four different purification methods using different chemicals and solvents (i.e., A (isopropanol and ethanol), B (isopropanol and acetone), C (saturated barium hydroxide), and D (Fehling solution)] to liberate the purified biopolymer from its crude form were compared. In most cases, the purification process significantly (p < 0.05) improved the physicochemical properties of heteropolysaccharide-protein biopolymer from durian fruit seed. The present work showed that the precipitation using isopropanol and acetone (Method B) resulted in the highest purification yield among all the tested purification techniques. The precipitation using saturated barium hydroxide (Method C) led to induce the highest solubility and relatively high capacity of water absorption. The current study reveals that the precipitation using Fehling solution (Method D) most efficiently eliminates the protein fraction, thus providing more pure biopolymer suitable for biological applications.

Isolation and structural characterization of the water-extractable polysaccharides from Cassia obtusifolia seeds

The seed of Cassia obtusifolia is a food or herbal medicine used for improving eyesight, treating constipation and other disorders, and polysaccharides have been implicated in these pharmacological activities. The endosperm of the seeds, Cassia gum, is a commercial thickening or gelling agent, composed mainly of galactomannans. However, the whole seeds of C. obtusifolia, rather than the endosperm, are used in folk medicine or food, which might contain more complex constituents of polysaccharides. In this study, the whole seeds of C. obtusifolia were extracted with boiling water, and from the water extract, three homogeneous fractions were isolated, designated CFAA-1, CFAA-3, and CFBB2, respectively, after treatment with Fehling solution followed by anion-exchange and gel permeation chromatography. Using chemical and spectroscopic methods, CFAA-1, and CFAA-3 were elucidated to be both branched galactomannans with different molecular weights, consisting of 1,4-linked β-d-mannopyranosyl backbone with single-unit α-d-galactopyranosyl branches attached to O-6 of mannose, while CFBB2 was shown to be a linear (1→4)-α-polygalacturonic acid.

Hydrogel of Guar Gum in Experimental Osteoarthritis in Rats

AbstractSummary:Commercial Guar Gum, a galactomannan polysaccharide, was purified by the use of two subsequent methods, including precipitation with Fehling solution in order to eliminate protein impurities. The protein content (3.6%) was totally removed. Glutaraldehyde cross‐linked gels were prepared with purified (GGP) and unpurified gum (GGU). The viscosity of the gels is similar to that of Hylan G‐F 20, a commercial substitute of hyaluronic acid, used in viscosupplementation in human osteoarthritis. Guar Gums (gel and solution) were injected intra‐articularly into the knee joints of rats subjected to experimental OA and the effect in hypernociception and cells influx measured. GGU promoted hypernociception and cell influx in naïve rats. GGP was innocuous to naïve rats and inhibited hypernociception, both as a gel or solution, to the same extent as Hylan G‐F20. GGP promotes analgesia in OA due to its carbohydrate component.

Acidic heteroxylans from medicinal plants and their anti-ulcer activity

Xylans are the main hemicelluloses found in higher plants, and are often present in phytotherapic medicines. An acidic heteroxylan was obtained from Maytenus ilicifolia leaves by hot 10% aqueous KOH extraction. This was subjected to freeze-thawing process, giving insoluble and soluble fractions and the latter treated with Fehling solution. Its insoluble fraction (MI-HX) was further examined. The acidic heteroxylan gave xylose, galactose, glucose, and 4- O-methylglucuronic acid in a 76:6:9:9 molar ratio and methylation analyses and 13C NMR spectroscopy showed its main chain consists of 4- O-linked β- d-Xyl p units. This polysaccharide and another acidic heteroxylan from Phyllanthus niruri had anti-ulcer activity and were able to reduce gastric lesions induced by ethanol by 65% and 78%, with ED 50 = 40.0 and 20.4 mg/kg, each respectively. These results suggest that this class of polysaccharide has a protective anti-ulcer effect, and that there is a relation between its chemical structure and biological function.