Gastric anti-ulcer activity of leaf fractions obtained of polar extract from Wilbrandia ebracteata in mice

Leaf fractions of Wilbrandia ebracteata were investigated for anti-ulcerogenic effects in ethanol and indomethacin-induced gastric ulcer assays in mice. Protective anti-ulcer effects were detected only in the ethanol-induced ulcer assay effects after pre-treatment with MeOH extract, MeOH chlorophyll-free, chlorophyll residue, HEX, DCM, aqueous MeOH fraction, ethyl acetate (EtOAc) and aqueous fractions. A potent anti-ulcerogenic effect was determined after pre-treatment of animals with EtOAc fraction, which was fractionated for isolation of active constituents. Seven flavonoids, 3',4',5,6,7,8-hexahydroxyflavonol, orientin, isoorientin, vitexin, isovitexin, luteolin, 6-methoxi-luteolin were isolated from the leaves of W. ebracteata (Cucurbitaceae) by chromatographic methods and identified by their spectral data. The data suggest that flavonoids are active anti-ulcerogenic compounds from leaves of W. ebracteata. The ability of scavenging free radicals was evaluated by DPPH reduction assay by TLC of flavonoids isolated.     

Isolation and Densitometric HPTLC Analysis of Rutin,Narcissin, Nicotiflorin,and Isoquercitrin in Caragana spinosa Shoots

JPC – Journal of Planar Chromatography – Modern TLC - Athin-layer chromatographic (TLC) method was used for the quantification of four dominant flavonoids (rutin, narcissin,...     

Separation and Determination of Chemopreventive Phytochemicals of Flavonoids from Brassicaceae Plants

The main aim of this study was to develop a method for the isolation and determination of polyphenols—in particular, flavonoids present in various morphological parts of plants belonging to the cabbage family (Brassicaceae). Therefore, a procedure consisting of maceration, acid hydrolysis and measurement of the total antioxidant capacity of plant extracts (using DPPH assay) was conducted. Qualitative analysis was performed employing thin-layer chromatography (TLC), which was presented to be a suitable methodology for the separation and determination of chemopreventive phytochemicals from plants belonging to the cabbage family. The study involved the analysis of 25 vegetal samples, including radish, broccoli, Brussels sprouts, kale, canola, kohlrabi, cabbage, Chinese cabbage, red cabbage, pak choi and cauliflower. In addition, selected flavonoids content in free form and bonded to glycosides was determined by using an RP-UHPLC-ESI-MS/MS method.     

4种黄酮小分子对DPPH自由基的清除作用及构效关系研究

通过紫外可见光谱测定了4种黄酮小分子芦丁、牡荆素、山奈素、金丝桃苷对DPPH自由基的清除率、稳定性及半抑制浓度(IC50),并以常用的天然抗氧化剂抗坏血酸作为对照,考察了其抗氧化效果,探讨了黄酮类化合物的抗氧化性与结构的关系。结果表明：不同的抗氧化剂清除DPPH自由基达到平衡的时间不同,芦丁所需时间最长。4种黄酮小分子及抗坏血酸均对DPPH自由基有清除效果,并存在一定的量效关系。对DPPH自由基的清除能力从大到小依次为金丝桃苷、抗坏血酸、芦丁、山奈素、牡荆素。结构分析表明,B环邻二酚羟基是黄酮类化合物抗氧化所必需的基团,其羟甲基化及A环羟基糖苷化不利于黄酮类化合物的抗氧化活性。而C环3-OH的糖苷化对抗氧化活性有利,且单糖苷优于双糖苷。     

Determination of antioxidant activity of extracts and fractions obtained from Galinsoga parviflora and Galinsoga quadriradiata, and a qualitative study of the most active fractions using TLC and HPLC methods

Taking into account the role of reactive oxygen species in the development of inflammation, and the application of the plants of genus Galinsoga Ruiz & Pav. in folk medicines for inflammatory states, we investigated and compared the antioxidant activities of particular Galinsoga extracts and fractions. The compositions of the most active fractions were studied using thin layer chromatography (TLC) and high-performance liquid chromatography (HPLC) methods. The extracts and fractions from Galinsoga parviflora Cav. and Galinsoga quadriradiata Ruiz et Pav. possess dose-dependent free radical-scavenging ability against DPPH? and superoxide radicals, as well as inhibitory effects on linoleic acid peroxidation in a manner comparable to gallic acid. In the most active fractions, flavonoids, patulitrin, quercimeritrin, quercitagetrin and caffeoyl derivatives were detected. Our research demonstrates that the investigated herbs are an interesting source of preparations with significant antioxidant effects. Our results justify the use of both raw materials in inflammatory diseases, among others, due to their ability to prevent free radical-induced deleterious effects.     

An Improved Method to Resolve Plant Saponins and Sugars by TLC

Thin-layer chromatography (TLC) plays an important role in the initial selection of mutants having a unique seed saponin composition from the germplasm collections of the subgenus Soja. In the conventional TLC procedure, the dehydrated free sugars are retained just below the major saponins and interrupt the identification of some minor saponin constituents. To resolve this problem, we developed an efficient and reliable method to move sugars from the saponin area on TLC. A developing chamber was saturated with the lower phase of chloroform:methanol:water (65:35:10, v/v) for 2?h and the TLC plates were developed in it for 50?min. Plates were then dried at 100?°C for 10?min to evaporate the excess mobile phase and developed again with 10?% H₂SO₄ for 15?min. While sulfuric acid migrates over the surface of SiO₂, sugar molecules are dehydrated and hydrophilic interactions between free sugars and SiO₂ are strongly reduced. Thus, the positions of dehydrated sugars were shifted to above the saponin area on the TLC plate. This resulted in easy recognition of the saponin composition without any discrimination. This amended protocol would be applicable to all TLC analyses in which the target components should be separate from the interrupting sugar molecules.     

Simultaneous Quantification of Flavonoids and Biflavonoids in Ginkgo biloba Using RP-HPTLC Densitometry Method

JPC – Journal of Planar Chromatography – Modern TLC - A reversed-phase high-performance thin-layer chromatography (RP-HPTLC) method was developed for the determination of flavonoids...     

Evaluation of antioxidative activity of Croatian propolis samples using DPPH* and ABTS*+ stable free radical assays

Propolis is one of the richest sources of plant phenolics (flavonoids and phenolic acids), which are widely recognized as rather strong antioxidants. The aim of our work was to use colored stable free radical (DPPH* and ABTS*+) spectrophotometric and thin-layer chromatographic (TLC) assays to study the antioxidative behavior of the phenolics (caffeic acid, galangin and pinocembrin) most commonly present in Croatian propolis samples obtained from different Croatian regions. We propose a mathematical model providing a more sophisticated interpretation of the obtained results and a new parameter named antioxidative efficiency (AOE) is introduced. The kinetic behaviour of chosen standards determined by spectrophotometric assays follows the exponential decrease of the absorption curve. Explained numerically, AOE represents the absolute value of the first derivative of an absorbance curve in the point A0/e (where A0 is the absorbance measured at t = 0 and e is the natural logarithm base). The advantage of this newly introduced parameter is that it provides an easy and accurate mutual comparison between the rates of antioxidative efficiency of different propolis samples. A TLC assay was only applicable in the case of the DPPH* radical. Dose-response curves were described using a linear function with AOE expressed as a coefficient of the slope. The chromatographic method was shown to be very rapid, reliable and easy-to-perform.     

A rapid RP-HPTLC densitometry method for simultaneous determination of major flavonoids in important medicinal plants

A simple, sensitive, selective, precise, and robust high-performance TLC (HPTLC) method was developed and validated for determination of flavonoids in herbal extracts Bauhinia variegata, Bacopa monnieri, Centella asiatica, Ginkgo biloba, Lonicera japonica, Rosa bourboniana, Rosa brunonii, and Rosa damascena. The HPTLC of flavonoids was performed on RP-18 F(254) TLC plates with dual run, water (5% formic acid)/methanol (70:30) and water (5% formic acid)/methanol (50:50) as mobile phases. Densitometric determination of flavonoids was performed at lambda = 280 nm in reflectance/absorbance mode. The linear regression analysis data for the calibration plots showed a good linear relationship with r(2 )= 0.998 +/- 0.0003 in the concentration range of 150-800 ng/spot for apigenin and rutin and 200-1000 ng/spot for quercetin, luteolin, and quercitrin with respect to peak area. The average recovery for apigenin, quercetin, rutin, luteolin, and quercitrin was 97-99.8% indicating the excellent reproducibility. Statistical analysis of the data showed that the method is reproducible and selective for determination of flavonoids.     

An Improved Method to Resolve Plant Saponins and Sugars by TLC

Thin-layer chromatography (TLC) plays an important role in the initial selection of mutants having a unique seed saponin composition from the germplasm collections of the subgenus Soja. In the conventional TLC procedure, the dehydrated free sugars are retained just below the major saponins and interrupt the identification of some minor saponin constituents. To resolve this problem, we developed an efficient and reliable method to move sugars from the saponin area on TLC. A developing chamber was saturated with the lower phase of chloroform:methanol:water (65:35:10, v/v) for 2 h and the TLC plates were developed in it for 50 min. Plates were then dried at 100 °C for 10 min to evaporate the excess mobile phase and developed again with 10 % H₂SO₄ for 15 min. While sulfuric acid migrates over the surface of SiO₂, sugar molecules are dehydrated and hydrophilic interactions between free sugars and SiO₂ are strongly reduced. Thus, the positions of dehydrated sugars were shifted to above the saponin area on the TLC plate. This resulted in easy recognition of the saponin composition without any discrimination. This amended protocol would be applicable to all TLC analyses in which the target components should be separate from the interrupting sugar molecules.

     

Synthesis, characterization and antioxidant activity copper-quercetin complex

Quercetin (3,3',4',5,7-pentahydroxyflavone) one of the most abundant dietary flavonoids, has been investigated in the presence of Cu(II) in methanol. The spectroscopic studies (UV-vis, (1)H NMR and IR) were useful to assess the relevant interaction of Quercetin with Cu(II) ions, the chelation sites and dependence of the complex structure from the metal/ligand ratio. A 1:2 (L:M) complex was indicated by Job's method of continuous variation, which was applied to ascertain the stoichiometric composition of the complex. The antioxidant activities of the compounds were evaluated by using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging method. The complexed flavonoid was much more effective free radical scavengers than the free flavonoids.     

Supercritical fluid extraction of flavonoids from Scutellariae Radix

An optimal condition of supercritical fluid extraction (SFE) for flavonoids of Scutellaria baicalensis was developed. In this study, various temperatures, pressures and modifiers were studied. The conventional extraction methods were conducted in parallel for comparison. The crude extracts were qualitatively compared by TLC and GC–MS, and the contents of flavonoids were determined by HPLC. The amounts of baicalin, baicalein and wogonin in the Scutellariae Radix obtained by supercritical fluid extraction and a conventional sonic shaking method were 137.6 mg/g, 8.6 mg/g and 2.2 mg/g, 113.5 mg/g, 5.7 mg/g and 2.3 mg/g, respectively. Application of SFE for extraction of the flavonoids from Scutellariae Radix was preferable. The optimal conditions of SFE was as follows: supercritical carbon dioxide–MeOH–water (20:2.1:0.9), 50°C and 200 bar.     

Synthesis, spectral and electrochemical properties of Al(III) and Zn(II) complexes with flavonoids

The synthesis, electrochemical and spectral (UV-vis, 1H NMR, IR, fluorescence) properties as well as thermal behaviors of Al(III) and Zn(II) complexes with the flavonoids quercetin (H2L(1)), rutin (H2L(2)) and galangin (HL(3)) are presented. The complexes may be formulated as [Al2(L(1))(H2O)8]Cl4, [Al3(L(2))2(H2O)12]Cl5, [Al(L(3))(H2O)4]Cl2, [Zn2(L(1))(H2O)4]Cl2, [Zn3(L(2))2(H2O)6]Cl2 and [Zn(L(3))(H2O)2]Cl. The higher fluorescence intensities of the complexes related to the free flavonoids, are attributed to the coordination of the ligands to the small, highly charged Al(III) and Zn(II) ions. The coordination effectively increases the rigidity of the ligand structure and increases the fluorescence quantum yield by reducing the probability of non-radiative energy dissipation process. Antioxidant activities of the compounds were also investigated under an electrochemical point of view. The cyclic voltammetric data show a considerable decrease of the oxidation potentials of the complexes related to that of the free flavonoids. Thus, the flavonoid-metal complexes are more effective antioxidants than the free flavonoids.     

Fast screening for antioxidant properties of flavonoids from Pterogyne nitens using electrochemical methods

A fast, low-cost, convenient, and especially sensitive voltammetric screening approach for the study of the antioxidant properties of isoquercitrin and pedalitin from Pterogyne nitens is suggested in this work. These flavonoids were investigated for their redox properties using cyclic voltammetry in nonaqueous media using N,N-dimethylformamide and tetrabutylammonium tetrafluorborate as the supporting electrolyte, a glassy carbon working electrode, A6(see symbol in text)AgCI reference electrode, and Pt bare wire counter electrode. The comparative analysis of the activity of rutin has also been carried out. Moreover, combining HPLC with an electrochemical detector allowed qualitative and quantitative detection of micromolecules (e.g., isoquercitrin and pedalitin) that showed antioxidant activities. These results were then correlated to the inhibition of beta-carotene bleaching determined by TLC autographic assay and to structural features of the flavonoids.     

Comparison between thin-layer chromatography and overpressured layer chromatography fingerprints of commercial essential oils and accelerated solvent extraction plant extracts

Developing fit-to-purpose analytical screening methods for plant marker constituents by simple and affordable techniques represents a constant and important request from the current transformation chain of plant products. In this work, methods developed on classical thin-layer chromatography (TLC) and overpressured layer chromatography (OPLC) have been applied on some of the most valuable commercial plant products, such as star anise (Illicium verum Hook. f.) essential oil and extracts, common thyme (Thymus vulgaris L.) and sweet fennel (Foeniculum vulgare Mill.) essential oils and acerola fruit (Malpighia punicifolia L.) hydroalcoholic extracts, to evaluate OPLC potentiality in comparison with TLC performances in the detection of some characteristic constituents. OPLC provided higher performance with respect to TLC in all experiments performed due to higher selectivity demonstrated on all the tested marker compounds except for flavonoids in acerola extracts. Considering the usage of planar chromatography in the quality control of plant derivatives, the present paper shows how the OPLC protocols were both highly time- and solvent-saving in comparison with classical TLC.

     

Bioactive Betalain Extracts from Cactus Pear Fruit Pulp,Beetroot Tubers,and Amaranth Leaves

Natural food items and the additional benefits they provide have received considerable attention in recent years. Betalains are nutritious pigments which have valuable biological properties, e.g., antioxidant and free radical scavenging activity. In this study, aqueous betalain extracts were obtained from different coloured cactus pears (purple, red/pink, and orange), amaranth, and beetroot, with and without the addition of ascorbic acid, microwave-heated, and freeze-dried and subsequently analysed by thin layer chromatography (TLC). Beetroot samples without the addition of ascorbic acid (AA) had lower phenols, flavonoids, and ascorbic acid content than beetroot samples extracted with the addition of AA. Amaranth had significantly higher contents of antioxidants than all the other plants. Results for phenolic compounds showed that there were no significant differences between cactus pear cultivars, however, significant differences were seen between the two beetroot samples (microwave-heated with and without AA) as well as amaranth. For flavonoid compounds, amaranth had significantly higher values than all other samples. The lowest flavonoid content was found in beetroot without AA (0.49 mgCE/g). For ascorbic acid, significant differences were noticed between amaranth (71.71 mg/100 g) and samples from cactus pear and beetroot. TLC results showed that purple and red cactus pear samples had the most vivid colours, a reflection of the high betacyanin and betaxanthin contents in the cultivars. Moreover, extracts from cactus pear, beetroot, and amaranth were classified according to a decision tree which was designed by the Code of Federal Regulations/Food Additives Regulation of the EU. The classification of betalain pigment extracts as colouring foods was achieved through enrichment factor calculations and the colourant decision tree. The results showed that the betalain pigment extraction method used is inexpensive, time-saving, energy-saving, non-toxic, and chemical solvent free and yields high concentrations of betalains.     

HPTLC Quantification of Some Flavonoids in Extracts of Satureja hortensis L. Obtained by Use of Different Techniques

JPC – Journal of Planar Chromatography – Modern TLC - A study of quantitative analysis of some flavonoids in Satureja hortensis L. extracts is presented. The HPTLC analyses were...     

Isointricatinol, a new antioxidant homoisoflavonoid from the roots of Caesalpinia digyna Rottler

A new homoisoflavonoid, isointricatinol (1), together with eight known homoisoflavonoids, three flavonoids, bergenin and 11-O-galloylbergenin were isolated from the EtOAc fraction of MeOH extract of Caesalpinia digyna roots and evaluated for the antioxidant activity against DPPH and ABTS free radicals. The structure of 1 was elucidated by various spectroscopic techniques and found to be a Z-isomer of 7,8-dihydroxy-3-(4'-methoxybenzyl)chroman-4-one. Compound 1 was found to exhibit mild to moderate free radical scavenging effect against DPPH (IC(50), 85.50?μM) and ABTS (IC(50), 44.13?μM) radicals.     

Antibacterial activity of three medicinal Thai plants against Campylobacter jejuni and other foodborne pathogens

Leaves of Adenanthera pavonina, Moringa oleifera and Annona squamosa are used in traditional Thai medicine to treat dysentery and other diseases. This study investigated the antibacterial activity of these plants against six species of foodborne pathogen. Methods and solvents employed to extract active constituents were optimised using the disc diffusion assay. Phytochemical analysis of the optimised extracts was performed by thin layer chromatography (TLC). Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were determined by broth microdilution. A. pavonina contained flavonoids, terpines and tannins, and was the most active extract against Campylobacter jejuni, inhibiting growth at 62.5-125 μg mL(-1). The A. squamosa extract contained flavonoids, terpines, tannins and alkaloids, and had the broadest spectrum of antibacterial activity, inhibiting Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus and C. jejuni between 62.5 and 500 μg mL(-1). MBCs were 2- to 4-fold higher than MICs against C. jejuni and B. cereus, suggesting the extracts are bactericidal against these species. Negligible activity was detected from M. oleifera. The data presented here show that A. pavonina and A. squamosa could potentially be used in modern applications aimed at the treatment or prevention of foodborne diseases.     

Inhibitory effects of flavonoids on free radical-induced hemolysis and their oxidative effects on hemoglobin

To investigate the effects of flavonoids on free radical-mediated biological membrane damage and the interaction of flavonoids with heme proteins, we studied the effects of quercetin, its glycosides (rutin and quercetin-3-O-glucoside), morin and (-)epicatechin on the hemolysis of the bovine erythrocytes induced by the hydrophilic free radical initiator, 2,2'-azobis(2-amidinopropane)dihydrochloride (AAPH), and their interaction with hemoglobin. These flavonoids retarded the onset of the hemolysis dose-dependently. The effects of quercetin and other flavonoids were much greater than those of dihydric-phenols studied previously. The inhibitory effects of quercetin and its glycosides were stronger than those of morin and (-)epicatechin. In the absence of AAPH, the relatively hydrophobic flavonoids quercetin and morin induced the oxidation of oxyhemoglobin to methemoglobin. Oxidation by quercetin was especially marked. However, this oxidation did not induce hemolysis. These findings indicate that relatively hydrophobic flavonoids penetrate the cytoplasm of erythrocytes, interact with hemoglobin, and oxidize the heme iron.