Separation and identification of flavonoids from complex samples using off-line two-dimensional liquid chromatography tandem mass spectrometry

Two-dimensional liquid chromatography with reversed phase in both dimensions: A review

Two-dimensional liquid chromatography (2D-LC), and in particular comprehensive two-dimensional liquid chromatography (LC×LC), offers increased peak capacity, resolution and selectivity compared to one-dimensional liquid chromatography. It is commonly accepted that the technique produces the best results when the separation mechanisms in the two dimensions are completely orthogonal; however, the use of similar separation mechanisms in both dimensions has been gaining popularity as it helps avoid difficulties related to mobile phase incompatibility and poor column efficiency. The remarkable advantages of using reversed phase in both dimensions (RPLC×RPLC) over other separation mechanisms made it a promising technique in the separation of complex samples. This review discusses some physical and practical considerations in method development for 2D-LC involving the use of RP in both dimensions. In addition, an extensive overview is presented of different applications that relied on RPLC×RPLC and 2D-LC with reversed phase column combinations to separate components of complex samples in different fields including food analysis, natural product analysis, environmental analysis, proteomics, lipidomics and metabolomics.

Methodology for dyes purification by preparative bidimensional offline reversed-phase high-performance liquid chromatography separation based on mobile phase pH change: Case study of Justicia spicigera

The extensive characterization of the natural dyes involves the purification of their colored compounds for their structural analysis and stability studies. As most natural compounds being ionizable, herein is presented the optimization of an easy and affordable preparative bidimensional offline reversed-phase high-performance liquid chromatography purification based on mobile phase pH change. At the analytical scale, several combinations of stationary phases and mobile phases at different pH values were investigated first. The orthogonality between the dimensions was quantitatively evaluated using the nearest-neighbor distance approach. The optimized separation method was transferred to the preparative scale for the successful isolation of two colored compounds from Justicia spicigera, a traditional dye plant from Central America. They were identified as perisbivalvine B (2-amino-8-hydroxy-7-methoxy-3H-phenoxazin-3-one) and one of its derivatives, also found in another tinctorial plant species, Peristrophe bivalvis growing in Asia.

Alpinetin: a Dietary Flavonoid with Diverse Anticancer Effects

Cancer is  a global burden and mechanistically complex disease with a plethora of genetic, physiological, metabolic, and environmental alterations. The development of dietary nutraceuticals into cancer chemotherapeutics has emerged as a new paradigm in cancer treatment. Alpinetin (ALPI) is a novel flavonoid component of multiple edible and medicinal plants and possesses a wide range of biological and pharmacological activities including antibacterial, anti-hemostatic, anti-oxidative, anti-hepatotoxic, stomachic, immunosuppressive, and anti-inflammatory. Recently, ALPI has been reported as a bioactive dietary nutraceutical with promising anticancer activity in various human cancers through multiple mechanisms. The purpose of this review is to compile the data on natural sources of ALPI, and its anticancer activity including cellular targets and anticancer mechanism in various human cancers. Moreover, this review will set the stage for further design and conduct pre-clinical and clinical trials to develop ALPI into a lead structure for oncological therapy.

Extraction approaches used for the determination of biologically active compounds (cyclitols, polyphenols and saponins) isolated from plant material

Based on the bioactive properties of certain compounds, such as antioxidant and anti-inflammatory activities, an interesting subject of research are natural substances present in various parts of plants. The choice of the most appropriate method for separation and quantification of biologically active compounds from plants and natural products is a crucial step of any analytical procedure. The aim of this review article is to present an overview of a comprehensive literature study from the last 10 years (2007-2017), where relevant articles exposed the latest trends and the most appropriate methods applicable for separation and quantification of biologically active compounds from plant material and natural products. Consequently, various extraction methods have been discussed, together with the available procedures for purification and pre-concentration and dedicated methods used for analysis.

Qualitative and Quantitative Analysis of Polyphenols in Lamiaceae Plants-A Review

Lamiaceae species are promising potential sources of natural antioxidants, owing to their high polyphenol content. In addition, increasing scientific and epidemiological evidence have associated consumption of foods rich in polyphenols with health benefits such as decreased risk of cardiovascular diseases mediated through anti-inflammatory effects. The complex and diverse nature of polyphenols and the huge variation in their levels in commonly consumed herbs make their analysis challenging. Innovative robust analytical tools are constantly developing to meet these challenges. In this review, we present advances in the state of the art for the identification and quantification of polyphenols in Lamiaceae species. Novel chromatographic techniques that have been employed in the past decades are discussed, ranging from ultra-high-pressure liquid chromatography to hyphenated spectroscopic methods, whereas performance characteristics such as selectivity and specificity are also summarized.

Non-destructive geographical traceability of sea cucumber (Apostichopus japonicus) using near infrared spectroscopy combined with chemometric methods

Sea cucumber is the major tonic seafood worldwide, and geographical origin traceability is an important part of its quality and safety control. In this work, a non-destructive method for origin traceability of sea cucumber (Apostichopus japonicus) from northern China Sea and East China Sea using near infrared spectroscopy (NIRS) and multivariate analysis methods was proposed. Total fat contents of 189 fresh sea cucumber samples were determined and partial least-squares (PLS) regression was used to establish the quantitative NIRS model. The ordered predictor selection algorithm was performed to select feasible wavelength regions for the construction of PLS and identification models. The identification model was developed by principal component analysis combined with Mahalanobis distance and scaling to the first range algorithms. In the test set of the optimum PLS models, the root mean square error of prediction was 0.45, and correlation coefficient was 0.90. The correct classification rates of 100% were obtained in both identification calibration model and test model. The overall results indicated that NIRS method combined with chemometric analysis was a suitable tool for origin traceability and identification of fresh sea cucumber samples from nine origins in China.

Purification of flavonoids from licorice using an off-line preparative two-dimensional normal-phase liquid chromatography/reversed-phase liquid chromatography method

An orthogonal (71.9%) off-line preparative two-dimensional normal-phase liquid chromatography/reversed-phase liquid chromatography method coupled with effective sample pretreatment was developed for separation and purification of flavonoids from licorice. Most of the nonflavonoids were firstly removed using a self-made Click TE-Cys (60 μm) solid-phase extraction. In the first dimension, an industrial grade preparative chromatography was employed to purify the crude flavonoids. Click TE-Cys (10 μm) was selected as the stationary phase that provided an excellent separation with high reproducibility. Ethyl acetate/ethanol was selected as the mobile phase owing to their excellent solubility for flavonoids. Flavonoids co-eluted in the first dimension were selected for further purification using reversed-phase liquid chromatography. Multiple compounds could be isolated from one normal-phase fraction and some compounds with bad resolution in one-dimensional liquid chromatography could be prepared in this two-dimensional system owing to the orthogonal separation. Moreover, this two-dimensional liquid chromatography method was beneficial for the preparation of relatively trace flavonoid compounds, which were enriched in the first dimension and further purified in the second dimension. Totally, 24 flavonoid compounds with high purity were obtained. The results demonstrated that the off-line two-dimensional liquid chromatography method was effective for the preparative separation and purification of flavonoids from licorice.

A Bioactivity-Based Method for Screening, Identification of Lipase Inhibitors, and Clarifying the Effects of Processing Time on Lipase Inhibitory Activity of Polygonum Multiflorum

Traditional Chinese medicine (TCM) has been used for the treatment of many complex diseases. However, the bioactive components are always undefined. In this study, a bioactivity-based method was developed and validated to screen lipase inhibitors and evaluate the effects of processing on the lipase inhibitory activity of TCM by ultrahigh performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry and fraction collector (UHPLC/Q-TOF-MS-FC). The results showed that both Polygonum multiflorum and processed P. multiflorum extracts had inhibitory effect against lipase with IC50 values of 38.84 μg/mL and 190.6 μg/mL, respectively. Stilbenes, phenolic acid, flavonoids, and anthraquinones were considered to be the potential lipase inhibitors. Eleven potential lipase inhibitors were simultaneously determined by UHPLC. Principal component analysis (PCA) was employed in exploring the effects of processing time on lipase inhibitory activity of P. multiflorum. Compared with conventional methods, a bioactivity-based method could quantitatively analyze lipase inhibitory activity of individual constituent and provide the total lipase inhibitory activity of the samples. The results demonstrated that the activity integrated UHPLC/Q-TOF-MS-FC method was an effective and powerful tool for screening and identifying lipase inhibitors from traditional Chinese medicines.

Comparative evaluation of different cultivars of Flos Chrysanthemi by an anti-inflammatory-based NF-κB reporter gene assay coupled to UPLC-Q/TOF MS with PCA and ANN

ETHNOPHARMACOLOGICAL RELEVANCE

Flos Chrysanthemi (FC), a commonly used traditional Chinese medicine, has five major cultivars ("Boju", "Chuju", "Gongju", "Hangbaiju" and "Huaiju") from different sources. However, the active constituents of these cultivars have not been studied or characterized with respect to their bioactivity, which is a serious problem when considering quality and safety.

AIM OF THE STUDY

To evaluate the differences among the five cultivars of FC, and to establish a method for the standardization and quality control of FC related to its bioactivity.

MATERIALS AND METHODS

In this study, the different ingredients in five cultivars of FC were identified by UPLC-Q/TOF and PCA, and the anti-inflammatory ingredients of FC were predicted and screened by artificial neural network (ANN) and an NF-κB luciferase reporter gene assay system. Using this comprehensive method, we successfully screened the anti-inflammatory markers of different cultivars of FC.

RESULTS

Nineteen marker ingredients were confirmed to contribute strongly to the cluster, and eleven compounds in the five cultivars of FC were found to exert potential anti-inflammatory effects. Among these compounds, the NF-κB inhibitor activity of apigenin-7-O-6″-malonyl-glucoside, luteolin-7-O-rutinoside, quercetin-7-O-galactoside, quercetin-3-O-glucoside, apigenin-7-O-rutinoside and apigenin-7-O-glucoside were first reported here. Chlorogenic acid, luteolin-7-O-glucoside, 3,5-dicaffeoylquinic acid and luteolin were confirmed to be the most important anti-inflammatory marker ingredients useful for the quality control of FC.

CONCLUSIONS

The proposed efficient and systematic method is helpful for the standardization and quality control of FC. Moreover, this comprehensive strategy may prove to be a powerful technique for the rapid establishment of quality control procedures related to bioactivity for other herbal samples and foods.

Enrichment and purification of polyphenols in pine cone extracts of Pinus koraiensis Sieb. et Zucc. using a novel multi-channel parallel–serial chromatographic system packed with macroporous resin

Structure of multi-channel parallel–serial chromatographic system, and optimization of ethanol concentration, elute rate, sample volume and the concentration of polyphenols in the enrichment process of polyphenols.

Alkaloids analysis using off-line two-dimensional supercritical fluid chromatography × ultra-high performance liquid chromatography

2-D SFC × UHPLC method with high orthogonality for analysis of the amide alkaloids fraction of P. longum L.

Techniques for analysis of plant phenolic compounds

Phenolic compounds are well-known phytochemicals found in all plants. They consist of simple phenols, benzoic and cinnamic acid, coumarins, tannins, lignins, lignans and flavonoids. Substantial developments in research focused on the extraction, identification and quantification of phenolic compounds as medicinal and/or dietary molecules have occurred over the last 25 years. Organic solvent extraction is the main method used to extract phenolics. Chemical procedures are used to detect the presence of total phenolics, while spectrophotometric and chromatographic techniques are utilized to identify and quantify individual phenolic compounds. This review addresses the application of different methodologies utilized in the analysis of phenolic compounds in plant-based products, including recent technical developments in the quantification of phenolics.

Dual-bioactivity-based liquid chromatography-coupled quadrupole time-of-flight mass spectrometry for NF-κB inhibitors and β2AR agonists identification in Chinese Medicinal Preparation Qingfei Xiaoyan Wan

Traditional Chinese medicine (TCM) preparations have been used as an effective multitarget strategy for the treatment of complex diseases; however, their bioactive constituents are undefined and difficult to identify. In this study, a simple and dual-target method based on ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry combined with dual-bioactive (NF-κB and β(2)-adrenergic receptor) luciferase reporter assay systems was developed for the rapid determination of various bioactive compounds of TCM preparations. Qingfei Xiaoyan Wan, a TCM preparation used for the clinical therapy of asthma, was analyzed with this method. Potential anti-inflammatory and spasmolytic constituents were screened using NF-κB and β(2)-adrenergic receptor activity luciferase reporter assay systems and simultaneously identified according to the time-of-flight mass spectrometry data. One β(2)-adrenergic receptor agonist (ephedrine) and four structural types of NF-κB inhibitors (arctigenin derivatives, cholic acid derivatives, chlorogenic acid, and sinapic acid) were characterized. Tracheloside was considered a new NF-κB inhibitor. Further cytokine and chemokine detection confirmed the anti-inflammatory effects of the potential NF-κB inhibitors. The integration of ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry and dual-bioactive human cell functional evaluation systems proved to be a simple and effective strategy for the rapid screening of various bioactive compounds in TCM preparations used to treat complex diseases.