Development of a capillary electrophoresis method for the separation of flavonolignans in silymarin complex.

CE method for the baseline separation of structurally similar flavonolignans silybin A, silybin B, isosilybin A, isosilybin B, silychristin, silydianin, and their precursor taxifolin in silymarin complex has been developed and validated. The optimized background electrolyte was 100 mmol/L boric acid (pH 9.0) containing 5 mmol/L heptakis(2,3,6-tri-O-methyl)-ß-CD and 10% (v/v) of methanol. The separation was carried out in an 80.5/72 cm (50 µm id) fused silica capillary at +25 kV with UV detection at 200 nm. Genistein (10 µg/mL) was used as internal standard. The resolution between the diastereomers of silybin and isosilybin was 1.73 and 2.59, respectively. The method was validated for each analyte in a concentration range of 2.5-50 µg/mL. The calibration curves were rectilinear with correlation coefficients ≥0.9972. The method was applied to determine flavonolignans in two dietary supplements containing Silybum marianum extract. The accuracy was evaluated by comparing the results of the CE analyses of the dietary supplements with those of the reference United States Pharmacopeial HPLC method. The unpaired t-test did not show a statistically significant difference between the results of both the proposed CE and the reference method (p > 0.05, n = 3).

Cytotoxic, Antioxidant, and Antidiabetic Activities versus UPLC-ESI-QTOF-MS Chemical-Profile Analysis of Ipomoea aquatica Fractions.

Ipomoea aquatica is a common green leafy vegetable that has numerous uses in traditional medicine. This study focused on the determination of the cytotoxic, antiradical, and antidiabetic properties of various fractions of the I. aquatica methanolic extract, as well as on the tentative identification of some bioactive compounds in the same fractions. The cytotoxicity was determined by the brine shrimp lethal test. The antioxidant activities of the I. aquatica fractions were investigated through 3 assays. The antidiabetic activity (in vitro) was measured by α-glucosidase and α-amylase inhibition assays. Phytochemical qualitative analyses demonstrated the presence of alkaloids, terpenoids, phenols, and flavonoids in the ethyl acetate-methanol and methanol fractions. The total phenolic and total flavonoid contents were found to be highest in the ethyl acetate-MeOH fractions. The evaluation of the cytotoxicity showed that the hexane-dichloromethane fraction is the most toxic, while the others are moderately toxic. The antioxidant activity assays showed that the ethyl acetate-MeOH fractions are the most potent, while the α-glucosidase and α-amylase assays revealed that the hexane-dichloromethane fraction might contain a potent antidiabetic agent. Some bioactive substances in the MeOH fractions, such as salicylic acid glucoside, 1-O-sinapoyl-ß-D-glucose derivative, and dihydroferulic acid derivative, were tentatively identified. To the best of our knowledge, this is the first report to detect and identify these compounds in this species. Based on the results of this study, it may be concluded that I. aquatica is a potent antioxidant agent and could be a good candidate as a natural antioxidant in food and therapeutics.

Potentially antidiabetic and antihypertensive compounds identified from Pistacia atlantica leaf extracts by LC fingerprinting.

The objective of this paper is to evaluate the variations in the ability of Pistacia atlantica leaves to inhibit enzymes linked to type 2 diabetes (α-amylase and α-glucosidase) and to hypertension (angiotensin converting enzyme-I (ACE-I)), depending on harvesting month, gender and growing region, as well as to identify the peaks in chromatographic fingerprints that potentially correspond to components with enzymatic inhibitory activities. In this study, LC fingerprints of P. atlantica leave extracts were developed. Peaks which were probably responsible for the anti-amylase, anti-glucosidase and anti-ACE-I activities were assigned. For the latter purpose, the relevant information was extracted, linking the chromatographic fingerprints with the activities using a linear multivariate calibration technique, i.e., Partial Least Squares (PLS) regression. Prior to the construction of the models, the fingerprints are aligned using a warping method, called Correlation Optimized Warping (COW). Besides COW, different other data pretreatment methods were applied and compared. Our findings revealed that the influence of the growing region and gender on the α-amylase, α-glucosidase and ACE-I inhibitory activities of P. atlantica leaves was less important than the harvest time. Thirteen common peaks were selected from the chromatograms and used as a dataset to model the biological activities. The peaks potentially responsible for the biological activity of the samples were indicated by studying the regression coefficients of the models. Seven peaks corresponding to possibly anti-amylase compounds were found, while 6 peaks were considered important for inhibiting the α-glucosidase activity. Furthermore, the regression coefficients of the hypertension model indicated eight peaks as being important for inhibiting the ACE-I activity. The contributions of individual phenolic compounds of P. atlantica leaves to the α-amylase, α-glucosidase and ACE-I inhibitory activities were also identified. This investigation showed that the extract of P. atlantica leaves provides a rational basis for the isolation and development of antidiabetic and antihypertensive agents.

Identification of some Bioactive Metabolites in a Fractionated Methanol Extract from Ipomoea aquatica (Aerial Parts) through TLC, HPLC, UPLC-ESI-QTOF-MS and LC-SPE-NMR Fingerprints Analyses.

INTRODUCTION: The plant species Ipomoea aquatica contains various bioactive constituents, e.g. phenols and flavonoids, which have several medical uses. All previous studies were executed in Asia; however, no reports are available from Africa, and the secondary metabolites of this plant species from Africa are still unknown. OBJECTIVE: The present study aims finding suitable conditions to identify the bioactive compounds from different fractions. METHODOLOGY: Chromatographic fingerprint profiles of different fractions were developed using high-performance liquid chromatography (HPLC) and then these conditions were transferred to thin-layer chromatography (TLC). Subsequently, the chemical structure of some bioactive compounds was elucidated using ultra-performance liquid chromatography-quadrupole time of flight-tandem mass spectrometry (UPLC-QTOF-MS) and liquid chromatography-solid phase extraction-nuclear magnetic resonance (LC-SPE-NMR) spectroscopy. RESULTS: The HPLC fingerprints, developed on two coupled Chromolith RP-18e columns, using a gradient mobile phase (methanol/water/trifluoroacetic acid, 5:95:0.05, v/v/v), showed more peaks than the TLC profile. The TLC fingerprint allows the identification of the types of chemical constituents, e.g. flavonoids. Two flavonoids (nicotiflorin and ramnazin-3-O-rutinoside) and two phenolic compounds (dihydroxybenzoic acid pentoside and di-pentoside) were tentatively identified by QTOF-MS, while NMR confirmed the structure of rutin and nicotiflorin. CONCLUSION: The HPLC and TLC results showed that HPLC fingerprints give more and better separated peaks, but TLC helped in determining the class of the active compounds in some fractions. Bioactive constituents were identified as well using MS and NMR analyses. Two flavonoids and two phenolic compounds were tentatively identified in this species for the first time, to the best of our knowledge. Copyright © 2017 John Wiley & Sons, Ltd.

Seasonal, gender and regional variations in total phenolic, flavonoid, and condensed tannins contents and in antioxidant properties from Pistacia atlantica ssp. leaves.

CONTEXT: The widespread use of Pistacia atlantica Desf. ssp. (Anacardiaceae) in traditional medicine can be partly attributed to the content of its secondary metabolites, in particular, the phenolic compounds. OBJECTIVE: The effects of harvest period, growing region and gender on the phenolic compounds, flavonoids and condensed tannins contents were studied, as well as on the antioxidant activities of P. atlantica leaves in order to provide a scientific basis for optimal collection. MATERIALS AND METHODS: Leaves were collected monthly from April to October 2010 in two Algerian sites. The powdered leaves were used for preparing the ethyl acetate extract. Contents of total phenolics (TPC), flavonoids (FC) and condensed tannins (CTC) were determined spectrophotometrically. Antioxidant activity was evaluated through radical scavenging activity (RSA) of 2,2-diphenyl-1-picrylhydrazyl (250 µM) and the reducing power capacity (RPC) determination by K3Fe(CN)6 (1%). RESULTS: The TPC was found to vary from 79 ± 13 to 259 ± 8 mg gallic acid equivalents/g of dry weight (DW) during the study period. The RSA and RPC varied between 262 ± 18 and 675 ± 21 mg Ascorbic Acid Equivalent (AAE)/g DW, and from 259 ± 16 to 983 ± 20 mg AAE/g DW, respectively. A seasonal pattern was observed consisting of a decrease in TPC content and RPC from spring to autumn. The FC, CTC and RSA did not show a seasonal pattern. DISCUSSION AND CONCLUSION: Our findings showed that secondary metabolite content and antioxidant activities of P. atlantica leaves were more influenced by harvest time and growing region than by gender.

Fingerprint development for Ginkgo biloba extracts by pressurized capillary electrochromatography: comparison of column types.

A pressurized capillary electrochromatographic (pCEC) fingerprint of Ginkgo biloba leaf extract was developed on three different types of capillary columns. A commercial column packed with 3-microm particles and an in-house column packed with 5-microm particles were investigated for their performance. Additionally, a monolithic column was included in the fingerprint study as a potential alternative to the conventional packed columns. The effects of experimental parameters, such as the composition of the mobile phase, the concentration and pH of the buffer, and the applied voltage, were studied. Binary mobile phases consisting of acetonitrile and a 5 mM sodium dihydrogen phosphate electrolyte at pH 2.8 were used in gradient elution mode with an applied voltage of 5 kV. Under optimal gradient conditions, at least 45 peaks were observed within 60 min on the commercial packed column, whereas only about 20 peaks were separated on the methacrylate-based monolithic and the in-house packed columns. The commercial column thus clearly outperforms the two other. However, the properties of the monolithic stationary phase still might be adapted (i.e., by changing the polymerization-mixture composition, the porosity, and thus the selectivity of the phase might be changed), which could lead to an improved efficiency.