Analysis of flavonoids in tablets and urine by gas chromatography/mass spectrometry and liquid chromatography/mass spectrometry

The Role of Selective Flavonoids on Triple-Negative Breast Cancer: An Update

Among the many types of breast cancer (BC), Triple-Negative Breast Cancer (TNBC) is the most alarming. It lacks receptors for the three main biomarkers: estrogen, progesterone, and human epidermal growth factor, hence the name TNBC. This makes its treatment a challenge. Surgical procedures and chemotherapy, performed either alone or in combination, seem to be the primary therapeutic possibilities; however, they are accompanied by severe complications. Currently, the formulation of drugs using natural products has been playing an important role in the pharmaceutical industries, owing to the drugs’ increased efficacies and significantly lessened side effects. Hence, treating TNBC with chemotherapeutic drugs developed using natural products such as flavonoids in the near future is much warranted. Flavonoids are metabolic compounds largely present in all plants, vegetables, and fruits, such as blueberries, onions, (which are widely used to make red wine,) chocolates, etc. Flavonoids are known to have enormous health benefits, such as anticancer, antiviral, anti-inflammatory, and antiallergic properties. They are known to arrest the cell cycle of the tumor cells and induces apoptosis by modulating Bcl-2, Bax, and Caspase activity. They show a considerable effect on cell proliferation and viability and angiogenesis. Various studies were performed at both the biochemical and molecular levels. The importance of flavonoids in cancer treatment and its methods of extraction and purification to date have been reported as individual publications. However, this review article explains the potentiality of flavonoids against TNBC in the preclinical levels and also emphasizes their molecular mechanism of action, along with a brief introduction to its methods of extraction, isolation, and purification in general, emphasizing the fact that its quantum of yield if enhanced and its possible synergistic effects with existing chemotherapeutics may pave the way for better anticancer agents of natural origin and significantly lessened side-effects.

Multiplex quantitation of 17 drug-derived components in human plasma after administration of a fixed herbal preparation of Sailuotong using combined online SPE-LC-MS/MS methods

ETHNOPHARMACOLOGICAL RELEVANCE

Sailuotong (SLT) is a standardized herbal medicine formula made from extracts of ginseng (the dried root and rhizome of Panax ginseng C. A. Meyer), ginkgo (the leaves of Ginkgo biloba L.), and saffron (the stigma of Crocus sativus L.). It is prescribed compatibly for the treatment of vascular dementia (VaD) following the TCM principle of Qi-invigorating and Blood-activating. Ginseng is widely used as a tonic for the restoration of strength in China. Ginkgo and saffron have been traditionally used for a long time as medicines with the main effect of promoting blood circulation and removing blood stasis.

AIM OF THE STUDY

SLT has been proven to be a promising medicine for VaD by existing pharmacological and clinical evidence. To understand how the formula herbs and their active ingredients cooperate to produce comprehensive effects, the present study aimed to establish a highly sensitive and accurate quantitative method to reveal the plasma exposure profile of SLT in humans.

MATERIAL AND METHODS

Multiplex quantitation of a total of 17 SLT-derived components in human plasma was fulfilled by using online SPE for sample extractions followed by LC-MS/MS determinations. Among them, 8 ginsenoside (Rg1, Re, F1, Rf, Rb1, Rb2, Rc and Rd) were determined in ESI+ mode, and ginkgo flavonoids of quercetin, kaempferol, isorhamnetin were in ESI- mode. Improved sensitivity was achieved through optimizing the condition of sample extraction and LC separation, as well as mass parameters. 4 ginkgolides, including ginkgolide A, B, C and bilobalide, and 2 crocins of crocin-1 and its metabolite crocetin, were analyzed concurrently in negative ion mode, and their stability was ensured by a series of protective solutions.

RESULTS

The lower limit of quantitation was achieved to be extremely sensitive at 0.078 ng/mL for all ginsenosides, 0.033 ‒ 0.2 ng/mL for ginkgo flavonoids, 0.75 or 1.5 ng/mL for ginkgolides and 3 ng/mL for crocins. The methods were fully validated to be accurate and precise, and applicability was demonstrated by the analysis of clinical samples from 2 healthy volunteers.

CONCLUSION

The developed methods should be useful in further detailed clinical pharmacokinetic research for clarifying the effect mechanism of SLT and formulating its rational therapeutic regimens.

Electrospray ionization and matrix-assisted laser desorption/ionization mass spectrometric analysis of extrapolysaccharides of Escherichia coli

RATIONALE

Conventional studies of extracellular polymeric substances (EPS) typically require elaborate separation procedures or complicated sample pretreatment processes such as purification by dialysis and lyophilization. The objective of this study is to demonstrate the use of electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) as powerful techniques for direct analysis of EPS secreted by E. coli.

METHODS

We have compared the extraction efficiency of two widely used extraction methods including physical extraction (room-temperature centrifugation and high-speed centrifugation) and chemical extraction using EDTA and formaldehyde. We specify the most favorable extraction method and the analyte to extractant concentration with respect to mass spectrometric analysis of EPS, based on the results obtained from ESI-MS and MALDI-MS analysis.

RESULTS

Chemical extraction methods were found to be more efficient than physical extraction methods. Of the chemical extractants, EDTA was found more effective compared to formaldehyde and gave more EPS peaks during ESI- and MALDI-MS analysis. We report the classification of E. coli EPS into loosely bound, bound and tightly bound EPS based on a simple modification of an existing methodology. Our studies showed that ESI-MS was very effective for <300 Da EPS studies and MALDI-MS more suitable for rapid analysis of EPS above mass range 400 Da.

CONCLUSIONS

This is a preliminary study reporting for the first time the feasibility of ESI-MS and MALDI-MS techniques for the analysis of bacterial EPS without prior complicated purification and separation methodologies.

Phenolic acids and flavonoids: occurrence and analytical methods

Phenolics are structurally assorted and are generally part of a complex mixture isolated from plant and biological origin matrices. A wide gamut of natural products have been the focus of main study for phenolic compounds while urine and blood are the two main biological fluids that have been analyzed for metabolism studies. Traditional and more advanced techniques have come to prominence for sample preparation, detection, and identification. This review is devoted to a short discussion of the occurrence of phenolic acids and flavonoids, their role in human health, and focuses on a detailed presentation of the analytical methods, concluding with the advantages of analytical methods employed so far and prospects. Strategies and practical aspects for the determination of phenolic acids and flavonoids in biological fluids, beverages, plants, and food are reported. Novel and past applications are provided with significant treatment and detection-related developments on the basis of the employment of separation and non-separation analytical techniques.

Extraction, separation, and detection methods for phenolic acids and flavonoids

The impetus for developing analytical methods for phenolic compounds in natural products has proved to be multifaceted. Hundreds of publications on the analysis of this category of compounds have appeared over the past two decades. Traditional and more advanced techniques have come to prominence for sample preparation, separation, detection, and identification. This review provides an updated and extensive overview of methods and their applications in natural product matrices and samples of biological origin. In addition, it critically appraises recent developments and trends, and provides selected representative bibliographic examples.

SPE-HPLC method for the determination of four flavonols in rat plasma and urine after oral administration of Abelmoschus manihot extract

A SPE-HPLC method was developed and validated for the simultaneous determination of flavonols, isoquercitrin (1), hibifolin (2), myricetin (3), quercetin-3'-O-d-glucoside (4) and quercetin (5) in rat plasma and urine after oral administration of the total flavonoids from Abelmoschus manihot (TFA). The astragalin (6) and kaempferol (7) were used as internal standards (IS). Plasma and urine samples were pretreated by solid-phase extraction using Winchem C(18) reversed-phase cartridges. Analysis of the plasma and urinary extract was performed on YMC-Pack ODS-A C(18) and Thermo ODS-2HYEPRSIL C(18) reversed-phase column, respectively and a mobile phase of acetonitrile-0.1% phosphoric acid was employed. HPLC analysis was conducted with different elution gradients. The flow rate was 1.0 mL/min and the detection wavelength was set at 370 nm. Calibration ranges in plasma for flavonols 2-5 were at 0.011-2.220, 0.014-2.856, 0.022-4.320, and 0.028-5.600 microg/mL, respectively. In urine calibration ranges for flavonols 1, 2, 4 and 5 were at 2.00-16.00, 8.56-102.72, 2.70-21.60, and 3.00-24.00 microg/mL, respectively. The RSD of intra- and inter-day was less than 5.40% and 4.89% in plasma, and less than 3.96% and 6.85% in urine for all the analyses. A preliminary experiment to investigate the plasma concentration and urinary excretion of the flavonols after oral administration of TFA to rats demonstrated that the present method was suitable for determining the flavonols in rat plasma and urine.

A new capillary zone electrophoresis method for the analysis ofGinkgo biloba extracts andGinkgo biloba pharmaceutical products

Ginkgo biloba, traditional Chinese medicine is now generally accepted. Separation and determination of active components in G. biloba is important for the product quality control. Therefore, the development of an effective and reliable separation method is important. In this work, a new capillary electrophoretic (CZE) method for separation of the G. biloba leaf extracts components was developed and optimized by the use of experimental design and artificial neural network (ANN). Under best separation conditions, in gamma-CD-modified buffer, the separation was reached within 10 min (36 mM borate BGE, pH 9.2, 1 mM gamma-CD), while the hydrodynamic mode for sample injection (2 s) and UV detection at 270 nm were applied. The method developed was validated and applied for analysis of various extracts and G. biloba products.

Determination of active components of Ginkgo biloba in human urine by capillary high-performance liquid chromatography/mass spectrometry with on-line column-switching purification

Ginkgo biloba is one of the most popular herbal nutritional supplements, with terpene lactones and flavonoids being the two major active components. An on-line purification high-performance liquid chromatography/mass spectrometry (HPLC/MS) method was successfully developed for the quantitative determination of flavonoids and terpene lactones excreted in human urine after ingesting the herbal supplement. Satisfactory separation was obtained using a C18 capillary column made in-house with sample clean-up and pre-concentration achieved using a C18 pre-column with column switching. High selectivity and limits of detection of 1-18 ng/mL were achieved using a selected ion monitoring (SIM) scan in negative ion mode; the on-line solid-phase extraction (SPE) recovery of the active components in Ginkgo biloba determined in this study was greater than 75%.

Modern analytical techniques for flavonoid determination

We stand at the dawn of the next great period of natural products research. We now have tools to begin unraveling the chemical and physiological mechanisms by which these phytochemicals affect the function of living cells, both in plants and animals. The advances in analytical research will allow us to better use these compounds in the control of diseases in both plants and animals. This chapter used the analysis of soy isoflavones to illustrate the approaches to natural product research, but these principles can be applied to nearly any of the phenolic compounds found in plants.

The biochemistry and medical significance of the flavonoids

Flavonoids are plant pigments that are synthesised from phenylalanine, generally display marvelous colors known from flower petals, mostly emit brilliant fluorescence when they are excited by UV light, and are ubiquitous to green plant cells. The flavonoids are used by botanists for taxonomical classification. They regulate plant growth by inhibition of the exocytosis of the auxin indolyl acetic acid, as well as by induction of gene expression, and they influence other biological cells in numerous ways. Flavonoids inhibit or kill many bacterial strains, inhibit important viral enzymes, such as reverse transcriptase and protease, and destroy some pathogenic protozoans. Yet, their toxicity to animal cells is low. Flavonoids are major functional components of many herbal and insect preparations for medical use, e.g., propolis (bee's glue) and honey, which have been used since ancient times. The daily intake of flavonoids with normal food, especially fruit and vegetables, is 1-2 g. Modern authorised physicians are increasing their use of pure flavonoids to treat many important common diseases, due to their proven ability to inhibit specific enzymes, to simulate some hormones and neurotransmitters, and to scavenge free radicals.

Electron-capture mass spectrometry: recent advances

Electron-capture (EC) is a sensitive and selective ionization technique for mass spectrometry (MS). In the most familiar form of EC, a susceptible analyte (electrophore) is detected after eluting from a gas chromatography (GC) column, where a low attomole detection limit for standards is routine. High-performance liquid chromatography can facilitate sample cleanup prior to detection by GC-EC-MS, but carryover and shifts in retention time for the "invisible" analyte can be difficulties. Solid-phase extraction avoids these difficulties, but the degree of cleanup and recovery can be problems. Alternative electrophoric derivatizing reagents are available to help deal with interferences, and new reagents such as "AMACE1" are emerging. Releasable forms of electrophores can be used as tags for labeling macromolecules, motivated by the desire to multiplex ligand-type assays. The conventional, gas-phase ion source for EC is not well-understood, especially the role of wall reactions. Using an electron monochromator to tune the electron energy adds to the selectivity and information provided by EC-MS. High-resolution and tandem EC-MS measurements are emerging. Electron-capture dissociation is a new technique to sequence small- to medium-sized peptides, having the advantage of providing more extensive sequence information relative to other MS techniques. Particle-beam EC-MS tends to be less sensitive than GC-EC-MS, but not always. Recently it was demonstrated that EC-MS can be accomplished on an ordinary laser desorption time-of-flight mass spectrometer, and also by using atmospheric pressure chemical ionization. Two applications are discussed here in detail: bile acids and oxidized phenylalanine. EC-MS is well-established as a useful technique for trace analysis in special cases, and the scope of its usefulness is broadening (qualitative analysis and detection of more polar and larger molecules), based on advances in both the chemical and instrumental aspects of this technique.

Observation of apigenin anionic clusters in the gas phase

The ubiquity and favorable medicinal properties of flavonoids make essential the determination of flavonoid levels in various matrices. While developing a liquid chromatography/tandem mass spectrometry method for the analysis of the flavonoid, apigenin, anionic oligomers and nitrate- and chloride-bound clusters of this compound were observed. Tandem mass spectrometry of these oligomers and cluster ions showed the cleavage of apigenin molecules from the precursor. The observation of these cluster ions shows the possibility of post-column derivatization techniques to enhance specificity in analysis. Copyright 2000 John Wiley & Sons, Ltd.

Solid-phase extraction and gas chromatography-mass spectrometry determination of kaempferol and quercetin in human urine after consumption of Ginkgo biloba tablets

A method was developed for the quantification of the flavonoids quercetin and kaempferol in human urine using a solid-phase extraction procedure followed by gas chromatography-mass spectrometry. Deuterated internal standards of the analytes were spiked into the samples prior to extraction. The limit of detection of the method was ca. 10 pg on column and precision of the method for quantification in a sample of urine was +/-9.40% for kaempferol and +/-7.34% for quercetin (n = 6). The levels of quercetin and kaempferol found in urine samples were only a small fraction of the amount ingested. The treatment of urine samples with beta-glucuronidase markedly increased the levels of flavonoids detected, supporting the view that kaempferol and quercetin are eliminated in the urine as glucuronides.