Characterization of a suite of ginkgo-containing standard reference materials

Effect of Ginkgo biloba leaves on the removal efficiency of Cr(VI) in soil and its underlying mechanism

Cr(VI) is a toxic, teratogenic, and carcinogenic heavy metal element in soil that poses major ecological and human health risks. In this study, microcosm tests combined with X-ray absorption near-edge spectra (XANES) and 16Sr DNA amplification techniques were used to explore the effect of Ginkgo biloba leaves on the removal efficiency of Cr(VI) in soil and its underlying mechanism. Ginkgo biloba leaves had a favorable remediation effect on soil varying in Cr(VI) contamination levels, and the optimal effect was observed when 5% Ginkgo biloba leaves were added. The occurrence state of Cr(VI) in soil before and after the addition of Ginkgo biloba leaves was analyzed by XANES, which revealed that Cr(VI) was fully converted to the more biologically innocuous Cr(III), and the hydroxyl-containing quercetin in Ginkgo biloba leaves was one of the primary components mediating this reduction reaction. The Cr(VI) content was significantly lower in non-sterilized soil than in sterilized soil, suggesting that soil microorganisms play a key role in the remediation process. The addition of Ginkgo biloba leaves decreased the α-diversity and altered the β-diversity of the soil bacterial community. Actinobacteria was the dominant phylum in the soil remediated by Ginkgo biloba leaves; four genera of Cr(VI)-reducing bacteria were also enriched, including Agrococcus, Klebsiella, Streptomyces, and Microbacterium. Functional gene abundances predicted by PICRUST indicated that the expression of glutathione synthesis genes was substantially up-regulated, which might be the main metabolic pathway underlying the mitigation of Cr(VI) toxicity in soil by Cr(VI)-reducing bacteria. In sum, Ginkgo biloba leaves can effectively remove soil Cr(VI) and reduce Cr(VI) to Cr(III) via quercetin in soil, which also functions as a carbon source to drive the production of glutathione via Cr(VI)-reducing bacteria and mitigate Cr(VI) toxicity. The findings of this study elucidate the chemical and microbial mechanisms of Cr(VI) removal in soil by Ginkgo biloba leaves and provide insights that could be used to enhance the remediation of Cr(VI)-contaminated soil.

From urban dust and marine sediment to Ginkgo biloba and human serum-a top ten list of Standard Reference Materials (SRMs)

During the past 40 years, the National Institute of Standards and Technology (NIST) has developed over 180 natural matrix Standard Reference Materials® (SRMs) for the determination of trace organic constituents in environmental, clinical, food, and dietary supplement matrices. A list of the Top Ten SRMs intended for organic analysis was identified based on selection criteria including analytical challenge to assign certified values, challenges in material preparation, novel matrices, longevity, widespread use, and unique design concept or intended use. The environmental matrix SRMs include air particulate matter, marine sediment, mussel tissue, and human serum with the focus on contaminants such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), chlorinated pesticides, and polybrominated diphenyl ethers (PBDEs). Human serum and plasma SRMs for clinical diagnostic markers including vitamin D metabolites represent clinical analysis, whereas infant formula, multivitamin/multielement tablets, and Ginkgo biloba constitute the food and dietary supplement matrices on the list. Each of the SRMs on the Top Ten list is discussed relative to the selection criteria and significance of the material, and several overall lessons learned are summarized.

A nontargeted approach to determine the authenticity of Ginkgo biloba L. plant materials and dried leaf extracts by liquid chromatography-high-resolution mass spectrometry (LC-HRMS) and chemometrics

The lack of stringent regulations regarding raw materials for herbal supplements used for medicinal purposes has been a constant challenge in the industry. Ginkgo biloba L. leaf extracts attract consumers because of the supposed positive effect on mental performance and memory. Supplements are produced using dried leaf materials and standardized leaf extracts such as EGb 761. Adulteration of Ginkgo biloba L. plants and extracts are becoming more and more common practice due to economically driven motivation from increasing demand in the market and the high cost of raw materials and production. Reinforcement in quality control (QC) to avoid adulterations is necessary to ensure the efficacy of the supplements. In this study, liquid chromatography-high-resolution mass spectrometry (LC-HRMS) was used with principal component analysis (PCA) as an unsupervised exploratory method to analyze, identify, and evaluate the adulterated Ginkgo biloba L. plant materials and dried leaf extracts using the PCA scores and loadings obtained and compound identification.

Hesperetin Liposomes for Cancer Therapy

Hesperetin is a compound from citrus fruit that has previously been found to exert anticancer activity through a variety of mechanisms. However, the application of hesperetin to cancer therapy has been hampered by its hydrophobicity, necessitating the use of toxic solubilizing agents. Here, we have developed the first liposome-based delivery system for hesperetin. Liposomes were fabricated using the thin-layer evaporation technique and physical and pharmacological parameters were measured. The liposomes remained stable for prolonged periods of time in serum and under storage conditions, and displayed anticancer efficacy in both H441 lung cancer cells and MDA-MB-231 breast cancer cells. Furthermore, the anticancer activity was not impaired in cells expressing the multidrug resistance protein 1 (MDR-1). In conclusion, the encapsulation of hesperetin in liposomes does not interfere with therapeutic efficacy and provides a biocompatible alternative to toxic solubilizing agents, thereby enabling future clinical use of this compound for cancer therapy.

High-resolution gas chromatography/mass spectrometry method for characterization and quantitative analysis of ginkgolic acids in Ginkgo biloba plants, extracts, and dietary supplements

A high-resolution gas chromatography/mass spectrometry (GC/MS) with selected ion monitor method focusing on the characterization and quantitative analysis of ginkgolic acids (GAs) in Ginkgo biloba L. plant materials, extracts, and commercial products was developed and validated. The method involved sample extraction with (1:1) methanol and 10% formic acid, liquid-liquid extraction with n-hexane, and derivatization with trimethylsulfonium hydroxide (TMSH). Separation of two saturated (C13:0 and C15:0) and six unsaturated ginkgolic acid methyl esters with different positional double bonds (C15:1 Δ8 and Δ10, C17:1 Δ8, Δ10, and Δ12, and C17:2) was achieved on a very polar (88% cyanopropyl) aryl-polysiloxane HP-88 capillary GC column. The double bond positions in the GAs were determined by ozonolysis. The developed GC/MS method was validated according to ICH guidelines, and the quantitation results were verified by comparison with a standard high-performance liquid chromatography method. Nineteen G. biloba authenticated and commercial plant samples and 21 dietary supplements purported to contain G. biloba leaf extracts were analyzed. Finally, the presence of the marker compounds, terpene trilactones and flavonol glycosides for Ginkgo biloba in the dietary supplements was determined by UHPLC/MS and used to confirm the presence of G. biloba leaf extracts in all of the botanical dietary supplements.

Comprehensive analysis of Ginkgo tablets by easy ambient sonic spray ionization mass spectrometry

We report here that easy ambient sonic spray ionization − mass spectrometry (EASI−MS) allowed direct, rapid, and comprehensive analysis of active components (e.g., terpenetrilactones and intact flavonol glycosides) in Ginkgo tablets. Unlike conventional methods that hydrolyze flavonol glycosides to flavonoids prior to analysis, EASI−MS detects intact flavonol glycosides directly from the tablets enabling differentiation of these natural glycosides from the synthetic flavonoids. Adulteration of Ginkgo tablets is therefore readily recognized in less than 10 s measurement time. Sample preparation is simple and requires only 0.5 mL of methanol and a mortar and pestle. Additionally, no reference standards are needed and a comparison is made to a certified Ginkgo tablet. To demonstrate these abilities, 22 commercial Ginkgo tablets were analyzed by EASI−MS. The data revealed large variations of ingredients and strong deviations from the specified Ginkgo extract levels. These results emphasize the importance of monitoring Ginkgo products using appropriate methodologies as suggested in our work. The technique may replace more demanding LC−MS/MS methods, which can achieve comparable results but are considerably more labor-intensive. Importantly, the presented method is cheaper, faster, and much simpler to operate than chromatography-based mass spectrometric techniques.

Orthogonal analytical methods for botanical standardization: determination of green tea catechins by qNMR and LC-MS/MS

The development of analytical methods for parallel characterization of multiple phytoconstituents is essential to advance the quality control of herbal products. While chemical standardization is commonly carried out by targeted analysis using gas or liquid chromatography-based methods, more universal approaches based on quantitative (1)H NMR (qHNMR) measurements are being used increasingly in the multi-targeted assessment of these complex mixtures. The present study describes the development of a 1D qHNMR-based method for simultaneous identification and quantification of green tea constituents. This approach utilizes computer-assisted (1)H iterative Full Spin Analysis (HiFSA) and enables rapid profiling of seven catechins in commercial green tea extracts. The qHNMR results were cross-validated against quantitative profiles obtained with an orthogonal LC-MS/MS method. The relative strengths and weaknesses of both approaches are discussed, with special emphasis on the role of identical reference standards in qualitative and quantitative analyses.

Role of chromatography in the development of Standard Reference Materials for organic analysis

The certification of chemical constituents in natural-matrix Standard Reference Materials (SRMs) at the National Institute of Standards and Technology (NIST) can require the use of two or more independent analytical methods. The independence among the methods is generally achieved by taking advantage of differences in extraction, separation, and detection selectivity. This review describes the development of the independent analytical methods approach at NIST, and its implementation in the measurement of organic constituents such as contaminants in environmental materials, nutrients and marker compounds in food and dietary supplement matrices, and health diagnostic and nutritional assessment markers in human serum. The focus of this review is the important and critical role that separation science techniques play in achieving the necessary independence of the analytical steps in the measurement of trace-level organic constituents in natural matrix SRMs.

The tandem of full spin analysis and qHNMR for the quality control of botanicals exemplified with Ginkgo biloba

Botanical dietary supplements and herbal remedies are widely used for health promotion and disease prevention. Due to the high chemical complexity of these natural products, it is essential to develop new analytical strategies to guarantee their quality and consistency. In particular, the precise characterization of multiple botanical markers remains a challenge. This study demonstrates how a combination of computer-aided spectral analysis and 1D quantitative ¹H NMR spectroscopy (qHNMR) generates the analytical foundation for innovative means of simultaneously identifying and quantifying botanical markers in complex mixtures. First, comprehensive ¹H NMR profiles (fingerprints) of selected botanical markers were generated via ¹H iterative full spin analysis (HiFSA) with PERCH. Next, the ¹H fingerprints were used to assign specific ¹H resonances in the NMR spectra of reference materials, enriched fractions, and crude extracts of Ginkgo biloba leaves. These ¹H fingerprints were then used to verify the assignments by 2D NMR. Subsequently, a complete purity and composition assessment by means of 1D qHNMR was conducted. As its major strengths, this tandem approach enables the simultaneous quantification of multiple constituents without the need for identical reference materials, the semiquantitative determination of particular subclasses of components, and the detection of impurities and adulterants.

Development of saw palmetto (Serenoa repens) fruit and extract standard reference materials

As part of a collaboration with the National Institutes of Health's Office of Dietary Supplements and the Food and Drug Administration's Center for Drug Evaluation and Research, the National Institute of Standards and Technology has developed two standard reference materials (SRMs) representing different forms of saw palmetto (Serenoa repens), SRM 3250 Serenoa repens fruit and SRM 3251 Serenoa repens extract. Both of these SRMs have been characterized for their fatty acid and phytosterol content. The fatty acid concentration values are based on results from gas chromatography with flame ionization detection (GC-FID) and mass spectrometry (GC/MS) analysis while the sterol concentration values are based on results from GC-FID and liquid chromatography with mass spectrometry analysis. In addition, SRM 3250 has been characterized for lead content, and SRM 3251 has been characterized for the content of beta-carotene and tocopherols. SRM 3250 (fruit) has certified concentration values for three phytosterols, 14 fatty acids as triglycerides, and lead along with reference concentration values for four fatty acids as triglycerides and 16 free fatty acids. SRM 3251 (extract) has certified concentration values for three phytosterols, 17 fatty acids as triglycerides, beta-carotene, and gamma-tocopherol along with reference concentration values for three fatty acids as triglycerides, 17 fatty acids as free fatty acids, beta-carotene isomers, and delta-tocopherol and information values for two phytosterols. These SRMs will complement other reference materials currently available with concentrations for similar analytes and are part of a series of SRMs being developed for dietary supplements.