Comprehensive Two-dimensional Liquid Chromatography Method for the Determination of Flavonoids in Complex Plant Extracts.

Fast analysis of flavonoids in plant extracts by liquid chromatography–ultraviolet absorbance detection on poly(carboxylic acid)-coated silica and electrospray ionization tandem mass spectrometric detection

The total quantity of metals (Mg, Ca, Ni, Fe, Mn, Zn, Cu) in soil samples and in sixteen different extracts from plant parts of Peucedanum oreoselinum (L.) Moench as well as the content of total phenols and flavonoids in plant extracts was determined. The contents of metals were determined by the atomic absorption spectrometer. Based on the average values of the metal concentration in the soil, they could be arranged in the following sequence: Fe > Ca > Mg > Mn > Zn > Cu > Ni. Soil concentrations of all tested metals were lower than the maximum allowed concentration. The results demonstrated that the analyzed plant extracts contained higher quantities of Ni and Ca. Although the studied species accumulate analyzed metals in different quantities, they are not hyperaccumulators of these metals. Total phenols were determined using Folin-Ciocalteu reagent and their amounts ranged from 1.94 to P. oreoselinum, hyperaccumulation, phenols, flavonoids32.38 mg GA/g. The amounts of flavonoids in plant extracts were in range from 0.69 to 25.83 mg RU/g. We examined the correlation of metals and the phenolic compounds content in the extracts. According to our results the use P. oreoselinum for tea preparation is safe to a great extent for people, because in spite of the determined metal absorption by plant organs, the tea does not contain dangerous quantity of heavy metals. Also, it is suitable for the preparation of teas and herbal extracts due to minimal content of toxic metal (Ni), phenols and flavonoids.

A design of Tetrastigma hemsleyanum's flavonoid loaded polyvinylpyrrolidone nanoparticles for improving its bioavailability and biological activities.

Plant extracts contain a large number of organic compounds, and one of the large groups of compounds present are phenolic compounds. Researchers have shown that a certain number of these compounds can be used as effective metal corrosion inhibitors. Plant extracts of raspberries (leaves, flowers, and fruit) were obtained by ultrasonic extraction using 96% ethanol as a solvent. The UV/Vis spectrophotometric method was used to determine the content of total phenols in plant extracts. Phenolic acids and flavonoids in plant extracts were separated and quantified using the HPLC method. Tafel extrapolation was used for electrochemical characteristics. The corrosion characteristics and behavior of bronze in 3% NaCl solution, with and without the presence of plant extracts were investigated. The content of total phenols in leaves was found to be 107.14±3.63 mg/g in flowers 148.99±9.02 mg/g and in fruits was 8.75±0.61 mg/g. Leaf extract in a concentration of 0.04828 g/L according to the Tafel extrapolation method provides the best protection for bronze in a 3% NaCl solution. The same concentration in the case of flower and fruit extracts proved to be the most favorable.

An integrated and fully automated high resolution mass spectrometric and bioinformatic approach was set‐up for the rapid and unequivocal identification of flavonoids and other phenol compounds in plant extract. The approach consists of the following steps: 1) direct infusion of the extract into an Orbitrap mass analyzer (resolution 100,000; negative ion‐mode, ESI source); 2) automated identification of the monoisotopic masses and of the corresponding isotopic patterns by a Boolean logic algorithm; 3) searching the experimental monoisotopic masses (tolerance 5 ppm) in a database of flavonoids (http://www.phenol‐explorer.eu/compounds; http://www.metabolome.jp/download/flavonoid/) implemented with phenol compounds (i.e. chalcons). Final identification is achieved by matching the isotopic pattern and by MS/MS fragmentation studies. In particular, experimental MS/MS fragments are matched with those retrieved by the data base http://www.massbank.jp and by the predicted ions obtained by the software ACD/MS‐fragmenter. The method was firstly validated by mixtures of standard polyphenols and was then applied for the identification of phenols and flavonoids contained in an EtOH extract of Angelica keiskei. The method can also be used for semiquantitative analysis using Trolox as internal standard. [Supported by USDA ARS #58‐1950‐7‐707, USA and BioGreen 21 #20070301034009 RDA, Korea]

DETERMINATION OF THE FLAVONOID QUERCETIN IN PLANT EXTRACTS BY INFRARED SPECTROSCOPY (ATR-FTIR) AND CHEMOMETRICS. This work evaluated mid-infrared spectroscopy combined with chemometrics for qualitative and quantitative analysis of flavonoids in plant extracts. The exploratory data analysis was conducted using principal component analysis (PCA) and hierarchical cluster analysis (HCA), while the calibration model was developed using the partial least squares (PLS) regression technique. Methanolic extracts were obtained from 15 plant species collected during rainy and dry seasons, totaling 26 samples. Ultraviolet-visible (UV-Vis) spectroscopy was used as a reference method for the determination of flavonoids. PCA and HCA grouped the samples according to their chemical composition, with no significant variations due to seasonality. The extract of “quebra-pedra” (Phyllanthus niruri) formed a distinct cluster related to the spectral bands at 1012 and 1047 cm–1, attributed to C–O stretching in carbohydrates and cellulose derivatives. The regression model presented a root mean square error of calibration (RMSEC) of 0.06, root mean square error of cross-validation (RMSECV) of 0.13, root means square error of prediction (RMSEP) of 0.20, and residual predictive deviation (RDP) of 1.62. These results demonstrate that the combination of Fourier transform infrared spectroscopy (FTIR) and PLS presents itself as an alternative to predicting the concentration of flavonoids in complex samples, such as plant extracts.

Microwave assisted biosynthesis of silver nanoparticles from Achyranthes aspera for burn wound healing activity

Preferential role of distinct phytochemicals in biosynthesis and antibacterial activity of silver nanoparticles

The current study sought to synthesize silver nanoparticles (AgNPs) from Amaryllis vittata (L.) leaf and bulb extracts in order to determine their biological significance and use the toxic plants for human health benefits. The formation of silver nanoparticles was detected by a change in color from whitish to brown for bulb-AgNPs and from light green to dark brown for leaf-AgNPs. For the optimization of silver nanoparticles, various experimental physicochemical parameters such as pH, temperature, and salt were determined. UV-vis spectroscopy, Fourier transform infrared spectroscopy, X-ray dispersion spectroscopy, scanning electron microscopy, and energy dispersion spectroscopy analysis were used to characterize nanoparticles. Despite the fact that flavonoids in plant extracts were implicated in the reduction and capping procedure, the prepared nanoparticles demonstrated maximum absorbency between 400 and 500 nm. SEM analysis confirmed the preparation of monodispersed spherical crystalline particles with fcc structure. The bioinspired nanoparticles were found to show effective insecticidal activity against Tribolium castaneum and phytotoxic activity against Lemna aequincotialis. In comparison to plant extracts alone, the tested fabricated nanoparticles showed significant potential to scavenge free radicals and relieve pain. Antibacterial testing against human pathogenic strains, i.e., Escherichia coli and Pseudomonas aureginosa, and antifungal testing against Aspergillus niger revealed the significant potential for microbe resistance using AgNPs. As a result of the findings, the tested silver nanoparticles demonstrated promising potential for developing new and effective pharmacological and agricultural medications. Furthermore, the effects of biogenic AgNPs on an in vitro culture of Solanum tuberosum L. plants were investigated, and the findings indicated that bulb-AgNPs and leaf-AgNPs produced biomass and induced antioxidants via their active constituents. As a result, bulb-AgNPs and leaf-AgNPs may be recommended for use in Solanum tuberosum L. tissue culture for biomass fabrication and metabolic induction.

Off-line Coupling of Isotachophoresis and High Performance Liquid Chromatography for Determination of Flavonoids in Plant Extract

Quantification of isoflavones by capillary zone electrophoresis in soybean seeds: effects of variety and environment

Development and validation of a fast SFC method for the analysis of flavonoids in plant extracts

Flavonoids are the largest family of plant secondary metabolites, and which are important for medicinal development due to their biological and physiological functions. Though there are many kinds of detectors and analytic methods [1], e.g. nuclear magnetic resonance (NMR), liquid chromatography-mass spectrometry (LC-MS), it is still a tough work to identify flavonoids from natural resources. The efficiency of the analytical tools are limited by the experience of analysts, the concentration of analytes, and the number of references. Recently, scientists used liquid chromatography coupled with high resolution mass spectrometry (LC/HR-MS) [2], and developed data processing network to deduce chemical structures of secondary metabolites [3]. HR-MS is efficient analytical equipment due to small sample amount needed, high signal to noise ratio, capabilities of predicting molecular formula and constructing MS database. Although scientists could possibly identified the known compounds by MS database matching, however, in most cases the database are incapable of identifying most of the unknown compounds in plant. So far, most of MS database are built human or animal-based, while botanical MS data are still limited [3]. These problems are also encountered in identification of flavonoids. With an attempt to overcome the above-mentioned problems, we developed a rapid and rational method for identifying flavonoids using HR-MS and tandem MS fragmentation analysis. In this process, we don't use LC system to separate compounds from plant extracts preliminarily, and apply HR-MS directly to predict the chemical formula of flavonoids. Subsequently, the structures of flavonoids are approached by the fragment ions arisen from tandem MS. By using this method, the flavonoids of the alfalfa (Medicage sativa L.) extracts have been predicted and identified successfully.

Ethnobotanical claims regarding Kigelia africana reported antiulcer properties as part of its medicinal application. In this work, aqueous leaf extract from K. africana was investigated for its phytochemical constituents and antiulcer potential against ethanol-induced ulcer in rats. The participation of oxidative stress on ethanol-induced ulcer and the potential protective antioxidant activity of K. africana extracts were investigated by determining vitamin C and thiobarbituric acid reactive species (TBARS) contents in the gastric mucosa of rats. The HPLC analysis showed the presence of gallic acid, chlorogenic acid, caffeic acid and also the flavonoids rutin, quercetin and kaempferol in the aqueous plant extract. Oral treatment with K. africana extract (1.75; 3.5; 7 and 14 mg/kg) one hour after ulcer induction with ethanol decreased in a dose dependent manner the ulcer index. Ethanol increased significantly stomachal TBARS levels and decreased vitamin C content when compared to the control animals. K. africana blunted the ethanol-induced oxidative stress and restored vitamin C content to the control levels. The present results indicate that the aqueous leaf extract from K. africana possesses antiulcer potential. The presence of flavonoids in plant extract suggests that its antiulcerogenic potential is associated with antioxidant activity. Of particular therapeutic potential, K. africana was effective against ethanol even after the induction of ulcer, indicating that it can have protective and curative effects against gastric lesion.

This paper deals with antioxidant activity of phenol and flavonoid contents in twenty different extracts obtained from the whole plant and plant parts of Teucriumchamaedrys L. var. glanduliferum Haussk. Antioxidant activity was determined in vitro using 2,2-diphenyl-1-picrylhydrazyl (DPPH) reagent and expressed as IC50values ranged from 1165.75 to 24.51 µg/ml. Total phenols were determined using Folin-Ciocalteu reagent and their amounts ranged from 15.98 to 208.17 mg/g. The amounts of flavonoids in plant extracts were in range from 16.42 to 110.13 mg/g. Concentrations of phenols in different plant parts compared with concentrations for the whole plant were of uneven value. The highest concentration of flavonoids was in all the leaf extracts, while slightly lower was found in the stem extracts and the lowest in the flowered ones. A significant linear correlation was noticed between the values of the concentration of phenols and antioxidant activity. Parallel to the analysis of T. chamaedrys, Ginkgo biloba and Green tea extracts were analyzed for comparison, and the results indicated that some extracts of T. chamaedrys were equal in activity with Ginkgo or Green tea and some appeared to have greater activity. Based on these results, T. chamaedrys is a potential source of phenols as natural antioxidant substance of high value. Key words: Teucrium chamaedrys L., wall germander, antioxidant activity, phenols, flavonoids.