Direct analysis of 18 flavonol glycosides, aglycones and terpene trilactones in Ginkgo biloba tablets by matrix solid phase dispersion coupled with ultra-high performance liquid chromatography tandem triple quadrupole mass spectrometry

Mass spectrometry-based approaches to assess the botanical authenticity of dietary supplements

Dietary supplements are legally considered foods despite frequently including medicinal plants as ingredients. Currently, the consumption of herbal dietary supplements, also known as plant food supplements (PFS), is increasing worldwide and some raw botanicals, highly demanded due to their popularity, extensive use, and/or well-established pharmacological effects, have been attaining high prices in the international markets. Therefore, botanical adulteration for profit increase can occur along the whole PFS industry chain, from raw botanicals to plant extracts, until final PFS. Besides the substitution of high-value species, unintentional mislabeling can happen in morphologically similar species. Both cases represent a health risk for consumers, prompting the development of numerous works to access botanical adulterations in PFS. Among different approaches proposed for this purpose, mass spectrometry (MS)-based techniques have often been reported as the most promising, particularly when hyphenated with chromatographic techniques. Thus, this review aims at describing an overview of the developments in this field, focusing on the applications of MS-based techniques to targeted and untargeted analysis to detect botanical adulterations in plant materials, extracts, and PFS.

Biflavonoids from Ginkgo biloba leaves as a novel anti-atherosclerotic candidate: Inhibition potency and mechanistic analysis

BACKGROUND

Ginkgo biloba L. is one of the oldest trees on earth, and its leaves have been used since ages as herbal medicine to treat cerebrovascular disorders. It is worth noting that in addition to the widely concerned flavonoids and terpenoids, it also contains various thus far neglected biflavonoids. In fact, biflavonoids are flavonoids consisting of apigenin or its derivatives as monomeric scaffold, and are linked via C-C or C-O-C bond.

PURPOSE

Based on the structural similarity of flavonoids, we hypothesized that biflavonoids may play a potential role in the treatment of cerebrovascular diseases. Here, we describe the effectiveness and underlying mechanisms for prevention and treatment of atherosclerosis (AS) by biflavonoids.

STUDY DESIGN AND METHODS

Four main biflavonoids in Ginkgo biloba leaves were screened by oleic acid-induced lipid production in HepG2 cells. The non-covalent effects of biflavonoids on the potential targets of atherosclerosis were screened by reverse targeting and molecular dynamics simulation. The interactions between biflavonoids and potential targets were evaluated by an exogenous cell model, which verified the consistency of the simulation results.

CONCLUSION

Among all four biflavonoids, ginkgetin significantly inhibited oleic acid-induced lipid production in HepG2 cells and reduced total cholesterol and triglyceride levels. The interaction of ginkgetin with CDK2 through π-alkyl and hydrogen bonds increased the binding of molecules and proteins. Ginkgetin arrested the cells in the G1-S phase, which significantly inhibited abnormal cell growth which closely related to the occurrence and development of atherosclerosis. Biflavonoids could be a promising natural medicine for the treatment of atherosclerosis.

Changes in Polar Metabolites Content during Natural and Methyl-Jasmonate-Promoted Senescence of Ginkgo biloba Leaves

The present study clarified changes in the contents of polar metabolites (amino acids, organic acids, saccharides, cyclitols, and phosphoric acid) in leaf senescence in Ginkgo biloba with or without the application of methyl jasmonate (JA-Me) in comparison with those in naturally senescent leaf blades and petioles. The contents of most amino acids and citric and malic acids were significantly higher in abaxially, and that of myo-inositol was lower in abaxially JA-Me-treated leaves than in adaxially JA-Me-treated and naturally senescent leaves. The levels of succinic and fumaric acids in leaves treated adaxially substantially high, but not in naturally senescent leaves. In contrast, sucrose, glucose, and fructose contents were much lower in leaf blades and petioles treated abaxially with JA-Me than those treated adaxially. The levels of these saccharides were also lower compared with those in naturally senescent leaves. Shikimic acid and quinic acid were present at high levels in leaf blades and petioles of G. biloba. In leaves naturally senescent, their levels were higher compared to green leaves. The shikimic acid content was also higher in the organs of naturally yellow leaves than in those treated with JA-Me. These results strongly suggest that JA-Me applied abaxially significantly enhanced processes of primary metabolism during senescence of G. biloba compared with those applied adaxially. The changes in polar metabolites in relation to natural senescence were also discussed.

HPLC-UV/HRMS methods for the unambiguous detection of adulterations of Ginkgo biloba leaves with Sophora japonica fruits on an extract level

CONTEXT

Ginkgo biloba L. (Ginkgoaceae) leaf extract is one of the most frequently sold herbal extracts. There have been reports on poor quality and adulteration of ginkgo leaf extracts or the powdered plant material with extracts or powder of Styphnolobium japonicum (L.) Schott (Fabaceae) (syn. Sophora japonica L.) fruits, which is rich in flavone glycosides.

OBJECTIVE

The study investigates whether ginkgo leaves genuinely contain genistein and sophoricoside and whether these two substances could be used as markers to detect adulterations with sophora fruits.

MATERIALS AND METHODS

A total of 33 samples of dried ginkgo leaves were sourced from controlled plantations in China, the USA, and France. After extraction, the samples were analyzed using two high-performance liquid chromatography (HPLC) coupled with UV/HRMS methods for the detection of genistein and sophoricoside, respectively. Chromatograms were compared to standard reference materials.

RESULTS

In none of the tested ginkgo samples, neither genistein nor sophoricoside could be detected. The applied method was designed to separate genistein from apigenin. The latter is a genuine compound of ginkgo leaves, and its peak may have been previously misidentified as genistein because of the same molecular mass. The method for the detection of sophoricoside allows identification of the adulteration with sophora fruit without prior hydrolysis. By both HPLC methods, it was possible to detect adulterations of ≥2% sophora fruits in the investigated ginkgo extract.

CONCLUSION

The methods allow unambiguous detection of adulterations of ginkgo leaves with sophora fruits, using genistein and sophoricoside as marker compounds.

Target profiling of flavonol glycosides in the extract of Ginkgo biloba leaf and their pharmacokinetics in rat plasma by ultra-high-performance liquid chromatography with tandem mass spectrometry

The extract of Ginkgo biloba leaf is a popular herbal product or dietary supplement in the world to treat various diseases, and flavonol glycosides are considered as the main bioactive constituents. In this study, 37 flavonol glycosides were rapidly screened out by precursor ion scanning in positive ion mode with production ions at m/z 287.05, 303.05, and 317.06. Subsequently, a reliable and sensitive ultra-high-performance liquid chromatography coupled with triple quadrupole-linear ion trap mass spectrometry approach was established and validated to quantify the 20 prototype flavonol glycosides in rat plasma. Calibration curves showed good linearity (R² ≥ 0.9894) over the corresponding concentration range. The precision, accuracy, extraction recovery, matrix effect, and stability were also satisfactory. The validated method was successfully applied to a pharmacokinetic study of prototype flavonol glycosides in rat after oral administration of the extract of G. biloba leaf. As a result, the T_max of flavonol glycosides was short at 0.11-0.60 h. Quercetin-3-O-(2",6″-di-O-rhamnosyl)-glucoside, kaempferol-3-O-(2'',6''-di-O-rhamnosyl)-glucoside, quercetin-3-O-rutinoside, quercetin- 3-O-glucosyl-(1-2)-O-rhamnoside, and kaempferol-3-O-glucoside presented relatively high systemic exposure levels with AUC_0-∞  > 500 μg h/L and C_max  > 100 μg/L. This study would provide the valuable information for further scientific research and clinical application of the extract of G. biloba leaf.

Effect of Methyl Jasmonate on the Terpene Trilactones, Flavonoids, and Phenolic Acids in Ginkgo biloba L. Leaves: Relevance to Leaf Senescence

The present study compared the effects of natural senescence and methyl jasmonate (JA-Me) treatment on the levels of terpene trilactones (TTLs; ginkgolides and bilobalide), phenolic acids, and flavonoids in the primary organs of Ginkgo biloba leaves, leaf blades, and petioles. Levels of the major TTLs, ginkgolides B and C, were significantly higher in the leaf blades of naturally senesced yellow leaves harvested on 20 October compared with green leaves harvested on 9 September. In petioles, a similar effect was found, although the levels of these compounds were almost half as high. These facts indicate the importance of the senescence process on TTL accumulation. Some flavonoids and phenolic acids also showed changes in content related to maturation or senescence. Generally, the application of JA-Me slightly but substantially increased the levels of TTLs in leaf blades irrespective of the difference in its application side on the leaves. Of the flavonoids analyzed, levels of quercetin, rutin, quercetin-4-glucoside, apigenin, and luteolin were dependent on the JA-Me application site, whereas levels of (+) catechin and (−) epicatechin were not. Application of JA-Me increased ferulic acid and p-coumaric acid esters in the petiole but decreased the levels of these compounds in the leaf blade. The content of p-coumaric acid glycosides and caffeic acid esters was only slightly modified by JA-Me. In general, JA-Me application affected leaf senescence by modifying the accumulation of ginkogolides, flavonoids, and phenolic acids. These effects were also found to be different in leaf blades and petioles. Based on JA-Me- and aging-related metabolic changes in endogenous levels of the secondary metabolites in G. biloba leaves, we discussed the results of study in the context of basic research and possible practical application.

Green and cost-effective extraction techniques of quercetin from mixture of nutraceuticals with yield analysis via spectrophotometry and high performance liquid chromatograph methods

BACKGROUND

Extraction is the leading critical stage in the analysis of nutraceuticals. Ginkgo biloba (GB) has gained an interest because of its therapeutic usages.

OBJECTIVES

Development of four cost effective extraction techniques for extraction of quercetin from GB in mixture of nutraceuticals sachet. These techniques are solid phase extraction (SPE), liquid-liquid extraction (LLE), inverted dispersive liquid-liquid microextraction (IDLLME) and QuEChERS.

METHODS

Direct spectrophotometry was used to monitor the recovery of the standard quercetin throughout the optimization steps. HPLC-UV method of analysis was optimized to quantify the yields from the extracts present in the complicated sachets. The presented study was assessed by analytical eco-scale assessment (ESA) and National Environmental Method Index (NEMI) for greenness in comparison with literature.

RESULTS

Only SPE showed the best cleanup outcomes. ESA and NEMI showed an adequate greenness of proposed extraction protocol.

CONCLUSION

Quercetin (marker for GB) extraction from market nutraceutical sachets is considered an exemplary for analysis in quality control of nutraceuticals. Regarding the greenness results, the proposed method of extraction is grander even with adequate greenness as the extraction was one-step, in comparison with multi-steps in previously published protocols. Accordingly, it is recommended to be used in routine extraction and analysis of such kind of nutraceuticals.

HIGHLIGHTS

Four extraction protocols had been developed. For GB ternary sachets, proper recovery was obtained from C18 SPE. The assessment of greenness of the proposed protocol guaranteed the superiority of the presented study. Safer sorbents and chemicals favor to be used for routine extraction of nutraceuticals.

Quantitative GC-FID and UHPLC-DAD Evaluation of Bioactive Compounds Extracted from Ginkgo biloba

Background:

The official compendium of the quantification of ginkgo flavonoids from Ginkgo biloba extract has been proposed using HPLC. The drawbacks of this technique appear to be due to the restricted efficiency in terms of the recovery results and suitability of the system for the quantification of these compounds. This study investigated the potential advantages and limitations of the development of efficient extraction methods for the recovery of flavonol glycosides (quercetin, kaempferol and isorhamnetin) and terpene trilactones (bilobalide, ginkgolide A, ginkgolide B and ginkgolide C) using extraction, quantification and detection techniques, namely, GC-FID and UHPLC-DAD, which are alternatives to those techniques available in the literature.

Methods:

Two different extraction methodologies have been developed for the determination of flavonoids (quercetin, kaempferol and isorhamnetin) and terpene trilactones (bilobalide, ginkgolide A, ginkgolide B and ginkgolide C) using ultra-high-pressure liquid chromatography coupled to a diode array detector and gas chromatography coupled to a flame ionization detector.

Results:

In this study, the Ginkgo biloba extract mass, hydrolysis preparation method (with or without reflux), and volume of the extraction solution seemed to affect the ginkgo flavonoid recovery. The UHPLC-based method exhibited higher extraction efficiency for ginkgo flavonoid quantification compared to the pharmacopoeial method. The developed method exhibited higher extraction efficiency for terpene quantification compared to the previous method that used extractive solution without pH adjustment, with less time of extraction and less amount of the sample and organic solvent aliquots.

Conclusion:

The UHPLC and GC analysis methods established in this study are both effective and efficient. These methods may improve the quality control procedures for ginkgo extract and commercial products available in today´s natural health product market. The results indicate that redeveloped extraction methods can be a viable alternative to traditional extraction methods.

Simultaneous Identification of Characteristic Components in HPLC-PDA-ELSD Fingerprint Profile of Ginkgo biloba Leaves Extract

This is an updated fingerprint profile for the simultaneous identification of 29 compounds, mainly including characteristic -terpene trilactones and flavonoid glycosides from Ginkgo biloba leaves (EGb) by employing a high-performance liquid chromatography-photodiode array-evaporative light scattering detector method. Compounds 1 and 6 had not been previously either detected or described in any EGb samples. In general, these 29 compounds were distributed into 5 regions in the fingerprint according to their different structural properties. This efficient analytical method could be generally applied to the quality control of EGb761 and other commercially available EGb products in the Chinese active pharmaceutical ingredients market.

A sensitive and selective multiple reaction monitoring mass spectrometry method for simultaneous quantification of flavonol glycoside, terpene lactones, and biflavonoids in Ginkgo biloba leaves

In this study, an efficient and sensitive UHPLC-QQQ-MS/MS (MRM) analytical strategy was established firstly for simultaneous determination of 11 components, including 3 original flavonol glycoside, 4 terpene lactones and 4 biflavonoids in Ginkgo biloba leaves. The validated strategy exhibited proper linearity (R² ≥0.99) in the range of 0.5-125 μg/mL, and intra and inter-day precision were lower than 4.09% and 4.80%, respectively. Limit of detection (LOD) and quantification (LOQ) were calculated, ranging from 0.2-4.6 ng/mL, with repeatability values between 1.98% and 4.48%. The average recoveries were all in the range of 98.45-106.67% with RSD (n = 3) for the related compounds. Subsequently, the proposed method was used for the analysis of Ginkgo biloba leaves during leaf senescence. Results showed the dominant flavonol glycosides were kaempferol-3-O-rutinoside and isorhamnetin-3-O-rutinoside, the level of terpene lactones and biflavonoids reached the highest in the latest harvest samples. Compared with conventional detection method, the present method could directly analyze original flavonol glycoside without acid hydrolysis process and terpene lactones without the ELSD in a high sensitivity. Moreover, the biflavonoids in Ginkgo biloba leaves were also simultaneously quantified. The results demonstrated that the developed method was accurate, sensitive and reliable for simultaneous quantification of multi-components in Ginkgo biloba leaves, and this study should be significant for the comprehensive utilization and development of Ginkgo biloba resources.

Determination of Total Flavonoids Contents and Antioxidant Activity of Ginkgo biloba Leaf by Near-Infrared Reflectance Method

Background

Total flavonoids content (TFC) is one of the most important quality indexes of Ginkgo biloba leaf, and it is concerned with total antioxidant activity. Near-infrared spectroscopy (NIR) method has showed its advantages in fast, accurate, qualitative, and quantitative analysis of various components in many quality control researches. In this study, a calibration model was built by partial least squares regression (PLSR) coupling with NIR spectrum to quantitatively analyze the TFC and total antioxidant activity of Ginkgo biloba leaf.

Results

During the model establishing, some spectrum pretreatment and outlier diagnosis methods were optimized to establish the final model. The coefficients of determination (R² ) for TFC and total antioxidant activity prediction were 0.8863 and 0.8486, respectively; and the root mean square errors of prediction (RMSEP) were 2.203 mg/g and 0.2211 mM/g, respectively.

Conclusion

These results showed that NIR method combined with chemometrics is suitable for quantitative analysis of main components and their activities and might be applied to quality control of relevant products.

Simultaneous determination of hydrophilic and lipophilic constituents in herbal medicines using directly-coupled reversed-phase and hydrophilic interaction liquid chromatography-tandem mass spectrometry

Limitations in the separation ability of conventional liquid chromatography system remains a challenge in developing a versatile method for simultaneously determining both hydrophilic and lipophilic constituents in herbal medicines (HMs). To measure compounds covering a broad polarity span in HMs, we developed a directly-coupled reversed-phase and hydrophilic interaction liquid chromatography-tandem mass spectrometry system. Samples were firstly separated according to lipophilicity by using a C₁₈ column. Utilizing a T-piece as connector, the eluent was then pumped into an amide column to get further separation that mainly based on the hydrogen bonding effects. Dan-Qi pair, an extensively used herb-combined prescription in China, was selected to test the practicability and performance of the established system. A total of 27 components, containing 9 hydrophilic and 18 lipophilic constituents, were simultaneously determined using a schedule multiple reaction monitoring method in 15 min. Up to 69.9% content could be monitored in one injection in Dan-Qi pair extract, showing a significant advantage over previous methods. The proposed method was expected to benefit the controllability of herbal medicines.

Combining Metabolic Profiling and Gene Expression Analysis to Reveal the Biosynthesis Site and Transport of Ginkgolides in Ginkgo biloba L

The most unique components of Ginkgo biloba extracts are terpene trilactones (TTLs) including ginkgolides and bilobalide. Study of TTLs biosynthesis has been stagnant in recent years. Metabolic profiling of 40 compounds, including TTLs, flavonoids, and phenolic acids, were globally analyzed in leaf, fibrous root, main root, old stem and young stem extracts of G. biloba. Most of the flavonoids were mainly distributed in the leaf and old stem. Most of phenolic acids were generally distributed among various tissues. The total content of TTLs decreased in the order of the leaf, fibrous root, main root, old stem and young stem. The TTLs were further analyzed in different parts of the main root and old stem. The content of TTLs decreases in the order of the main root periderm, the main root cortex and phloem and the main root xylem. In old stems, the content of TTLs in the cortex and phloem was much higher than both the old stem periderm and xylem. The expression patterns of five key genes in the ginkgolide biosynthetic pathway were measured by real-time quantitative polymerase chain reaction (RT-Q-PCR). Combining metabolic profiling and RT-Q-PCR, the results showed that the fibrous root and main root periderm tissues were the important biosynthesis sites of ginkgolides. Based on the above results, a model of the ginkgolide biosynthesis site and transport pathway in G. biloba was proposed. In this putative model, ginkgolides are synthesized in the fibrous root and main root periderm, and these compounds are then transported through the old stem cortex and phloem to the leaves.

Quality Evaluation of Pseudostellariae Radix Based on Simultaneous Determination of Multiple Bioactive Components Combined with Grey Relational Analysis

Pseudostellariae Radix (PR) is an important traditional Chinese herbal medicine (TCM) with vast clinical consumption because of its positive effects. However, little attention has been devoted to simultaneous analysis of its bioactive components for quality control of PR based on its different harvesting times, different growing habitats, and different processing methods. In this research, the quality of PR was evaluated based on simultaneous determination of multiple bioactive components combined with grey relational analysis (GRA). A reliable method based on ultra-fast liquid chromatography tandem triple quadrupole mass spectrometry (UFLC-QTRAP-MS/MS) was established to simultaneously determine the contents of 30 components in PR, including two cyclopeptides, 12 nucleosides, and 16 amino acids. Furthermore, grey relational analysis was performed to evaluate the quality of PR samples according to the contents of these 30 components. The results showed that the quality of PR harvested in 6 August 2013, cultivated in Jurong, Jiangsu, and treated by oven drying 60 °C was better than that of other PR samples. The proposed method is useful for the overall assessment on the quality of PR, and this study provides valuable information for revealing the dynamic change laws of metabolite accumulation in PR and choosing the most suitable harvesting time and reasonable processing method of PR to obtain the best quality.

Mass spectrometric imaging of flavonoid glycosides and biflavonoids in Ginkgo biloba L

Ginkgo biloba L. is known to be rich in flavonoids and flavonoid glycosides. However, the distribution within specific plant organs (e.g. within leaves) is not known. By using HPLC-MS and MS/MS we have identified a number of previously known G. biloba flavonoid glycosides and biflavonoids from leaves. Namely, kaempferol, quercetin, isorhamnetin, myricetin, laricitrin/mearnsetin and apigenin glycosides were identified. Furthermore, biflavonoids like ginkgetin/isoginkgetin were also detected. The application of MALDI mass spectrometric imaging, enabled the compilation of concentration profiles of flavonoid glycosides and biflavonoids in G. biloba L. leaves. Both, flavonoid glycosides and biflavonoids show a distinct distribution in leaf thin sections of G. biloba L.

Method validation of analytical method for 12 flavonol glycosides in foods using ultra high-performance liquid chromatography coupled with photodiode array detection

An analytical method for the simultaneous determination of 12 flavonol glycosides in buckwheat, black tea, and wild parsley using ultra high-performance liquid chromatography (UHPLC) coupled with a simple liquid extraction method using dimethyl sulfoxide (DMSO) was validated in precision, accuracy, and linearity. The UHPLC separation of target compounds was performed on a C18 column using a photodiode array (PDA) detector and the wavelength was fixed at 350 nm. The recovery values for flavonol glycosides ranged from 85.44 to 108.79%. The limits of detection and limits of quantification were less than 0.32 mg/kg and less than 0.97 mg/kg, respectively. The intraday and interday precisions were less than 13.69% for all the test samples. This method coupled with UHPLCPDA detection could be expected to provide more convenient sample preparation than conventional methods in the tested foods.

Advancement in the chemical analysis and quality control of flavonoid in Ginkgo biloba

Flavonoids are the main active constituents in Ginkgo biloba L., which have been suggested to have broad-spectrum free-radical scavenging activities. This review summarizes the recent advances in the chemical analysis of the flavonoids in G. biloba and its finished products (from 2009 to 2014), including chemical composition, sample preparation, separation, detection and different quality criteria. More than 70 kinds of flavonoids have been identified in this plant. In this review, various analytical approaches as well as their chromatographic conditions have been described, and their advantages/disadvantages are also compared. Quantitative analyses of Ginkgo flavonoids applied by most pharmacopeias start with an acidic hydrolysis followed by determination of the resulting aglycones using HPLC. But increasing direct assay of individual flavonol glycosides found that many adulterated products were still qualified by the present tests. To obtain an authentic and applicable analytical approach for quality evaluation of Ginkgo and its finished products, related suggestions and opinions in the recent publications are mainly discussed in this review. This discussion on chemical analyses of Ginkgo flavonoids will also be found as a significant guide for widely varied natural flavonoids.