Analysis of plant complex matrices by use of nuclear magnetic resonance spectroscopy: St. John's wort extract

NMR technique and methodology in botanical health product analysis and quality control

Botanicals have played an important role in maintaining human health and well-being throughout history. During the past few decades in particular, the use of botanical health products has gained more popularity. Whereas, quality, safety and efficacy concerns have continuously been critical issues due to the intrinsic chemical complexity of botanicals. Chemical analytical technologies play an imperative role in addressing these issues. Nuclear magnetic resonance (NMR) spectroscopy has proven to be a powerful and useful tool for the investigation of botanical health products. In this review, NMR techniques and methodologies that have been successfully applied to the research and development of botanical health products in all stages, from plants to products, are discussed and summarized. Furthermore, applications of NMR together with other analytical techniques in a variety of domains of botanical health products investigation, such as plant species differentiation, adulteration detection, and bio-activity evaluation, are discussed and illustrated with typical examples. This article provides an overview of the potential uses of NMR techniques and methodologies in an attempt to further promote their recognition and utilization in the field of botanical health products analysis and quality control.

Harvest time affects antioxidant capacity, total polyphenol and flavonoid content of Polish St John's wort's (Hypericum perforatum L.) flowers

The polyphenol content and antioxidant capacity of hyperforin and hypericin-standardized H. perforatum L. extracts may vary due to the harvest time. In this work, ethanol and ethanol-water extracts of air-dried and lyophilized flowers of H. perforatum L., collected throughout a vegetation season in central Poland, were studied. Air-dried flowers extracts had higher polyphenol (371 mg GAE/g) and flavonoid (160 mg CAE/g) content, DPPH radical scavenging (1672 mg DPPH/g), ORAC (5214 µmol TE/g) and FRAP (2.54 mmol Fe2+/g) than lyophilized flowers extracts (238 mg GAE/g, 107 mg CAE/g, 1287 mg DPPH/g, 3313 µmol TE/g and 0.31 mmol Fe2+/g, respectively). Principal component analysis showed that the collection date influenced the flavonoid and polyphenol contents and FRAP of ethanol extracts, and DPPH and ORAC values of ethanol-water extracts. The ethanol extracts with the highest polyphenol and flavonoid content protected human erythrocytes against bisphenol A-induced damage. Both high field and benchtop NMR spectra of selected extracts, revealed differences in composition caused by extraction solvent and raw material collection date. Moreover, we have shown that benchtop NMR can be used to detect the compositional variation of extracts if the assignment of signals is done previously.

Quality control of Hypericum perforatum L. analytical challenges and recent progress

Objectives

The most widely applied qualitative and quantitative analytical methods in the quality control of Hypericum perforatum extracts will be reviewed, including routine analytical tools and most modern approaches.

Key findings

Biologically active components of H. perforatum are chemically diverse; therefore, different chromatographic and detection methods are required for the comprehensive analysis of St. John's wort extracts. Naphthodianthrones, phloroglucinols and flavonoids are the most widely analysed metabolites of this plant. For routine quality control, detection of major compounds belonging to these groups seems to be sufficient; however, closer characterization requires the detection of minor compounds as well.

Conclusions

TLC and HPTLC are basic methods in the routine analysis, whereas HPLC-DAD is the most widely applied method for quantitative analysis due to its versatility. LC-MS is gaining importance in pharmacokinetic studies due to its sensitivity. Modern approaches, such as DNA barcoding, NIRS and NMR metabolomics, may offer new possibilities for the more detailed characterization of secondary metabolite profile of H. perforatum extracts.

Human serum albumin-specific recognition of the natural herbal extract of Stryphnodendron polyphyllum through STD NMR, hyphenations and docking simulation studies

Over the last two decades, new and more advanced strategies that help in the rapid screening and identification of new ligands for a specific macromolecule have become an important domain.

Science meets regulation

ETHNOPHARMACOLOGICAL RELEVANCE

The European Pharmacopoeia (Ph. Eur.) is a standard reference for both European and non-European countries and defines requirements for the qualitative and quantitative composition of medicines. Herbal drug (HD) monographs state which aspects have to be considered for quality assurance through the relevant chapters "Definition", "Characters", "Identification", "Tests", and "Assay". Identification of botanical material is achieved by macroscopic and microscopic morphology, generally examined by a trained expert. Content or assay is the most difficult area of quality control to perform, since in most herbal drugs the active constituents are unknown and markers should be used which cannot be really related to the quality. The other critical points are represented by the purity tests, in particular some tests such as heavy metals, aflatoxins and pesticides are laborious and time intensive, requiring a significant investment in equipment, materials, and maintenance.

MATERIAL AND METHODS

A literature survey concerning alternative and/or complementary tools for quality control of botanicals has been performed by searching the scientific databases Pubmed, SciFinder, Scopus and Web of Science.

RESULTS

Diverse analytical methods including DNA fingerprinting, Nuclear Magnetic Resonance (NMR), Near Infra Red (NIR) and (bio)sensors have been reported in the literature to evaluate the quality of botanical products. Identification of plants at the species level can be successfully based on genome-based methods, using DNA barcodes, the nucleotide sequence of a short DNA fragment. NMR can provide direct NMR fingerprint determination (complete assignment of the signals by 1D and 2D experiments), quantitative NMR and chemometric analysis (the metabolite fingerprint is based on the distribution of intensity in the NMR spectrum to provide sample classification). NIR spectroscopy is a fast qualitative and quantitative analytical method, getting knowledge about plant species and/or its geographic origin. Finally, the development of chemical and biological sensors is currently one of the most active areas of analytical research. Immobilization of specific enzymes led to recognize definite class of compounds such as cysteine sulfoxides, glucosinolates, cyanogenic glycosides, and polyphenols. Other recognition elements are nucleic acids to evaluate the ability of different molecules to bind DNA. Sensors have also been developed for the detection of heavy metals in botanicals. Moreover, the analysis of mycotoxins and pesticides, could represent another field of possible application.

CONCLUSIONS

These alternative/complementary analytical methods represent tools which appear to be an analyst's dream: they are able to give rapid analysis responses; to operate directly on complex matrices, in many cases; to be selective and sensitive enough for the required application; to be portable and sometimes also disposable; and to have fast analysis times.

A review of the antibacterial activity of Hypericum perforatum L

Hypericum perforatum L. (Hypericaceae) is a perennial herb that is commonly known as St. John's Wort. The plant has been valued for its important biological and chemical perspectives and its use in the treatment of infectious diseases has been documented in ethnobotanical reports. Most recent interest in H. perforatum has focused on its antidepressant effects, and only recently has its antimicrobial activity been evaluated against a number of bacterial and fungal strains. The present review gives a comprehensive summary of the ethnobotanical uses, chemical constituents and biological effects (antibacterial and antifungal) of this species. A comprehensive account of the chemical constituents including anthraquinone derivatives (naphthodianthrones), flavonoids, prenylated phloroglucinols, tannins and volatile oils is also included. Various types of preparations, ointments, creams and extracts prepared with and compounds isolated from this species have been found to possess a broad spectrum of biological and pharmacological effects such as antidepressant effects, wound-healing, antiviral and antimicrobial activity. The antibacterial activity of crude extracts can be related to the use of the herb as a wound healer in ancient times. The sole antibacterial principle isolated to date is a tetraketone, hyperforin, also thought to be responsible for the antidepressant activity of the herb. The available literature indicates that it has a higher antibacterial activity against Gram-positive than Gram-negative bacteria, and alcoholic extracts (methanolic/ethanolic) were shown to possess more pronounced activity than aqueous extracts. Based on the chemical and pharmacological characteristics of H. perforatum, we concluded that this species has beneficial therapeutic properties and has the potential for use as an effective adaptogenic herbal remedy.

Recent analytical approaches in quality control of traditional Chinese medicines--a review

Traditional Chinese medicines (TCMs) are gaining more and more attention all over the world, due to their specific theory and long historical clinical practice. But the uncontrollable quality is a bottleneck for its modernization and globalization. This paper reviewed the recent analytical methods in the quality control of TCMs, including screening strategies of bioactive markers from TCMs through biochromatographic methods, the traditional chromatographic methods, DNA methods, as well as the spectroscopic methods, including FT-IR, NIR and NMR. The comprehensive methods, such as fingerprint and multi-component quantification are emphasized; hyphenated techniques, like HPLC-MS, GC-MS, CE-MS, LC-NMR, chemometric methods, and combination of chemical and biological methods, such as biofingerprint, metabolic fingerprint are now more and more widely used in TCMs. In a few word, the analysis and quality control of TCMs are moving towards an integrative and comprehensive direction, in order to better address the inherent holistic nature of TCMs.

Direct metabolic fingerprinting of commercial herbal tinctures by nuclear magnetic resonance spectroscopy and mass spectrometry

INTRODUCTION

Tinctures are widely used liquid pharmaceutical preparations traditionally obtained by maceration of one or more medicinal plants in ethanol-water solutions. Such a process results in the extraction of virtually hundreds of structurally diverse compounds with different polarities. Owing to the large chemical diversity of the constituents present in the herbal tinctures, the analytical tools used for the quality control of tinctures are usually optimised only for the detection of single chemical entities or specific class of compounds.

OBJECTIVE

In order to overcome the major limitations of the current methods used for analysis of tinctures, a new methodological approach based on NMR spectroscopy and MS spectrometry has been tested with different commercial tinctures.

METHODOLOGY

Diffusion-edited 1H-NMR (1D DOSY) and 1H-NMR with suppression of the ethanol and water signals have been applied here for the first time to the direct analysis of commercial herbal tinctures derived from Echinacea purpurea, Hypericum perforatum, Ginkgo biloba and Valeriana officinalis. The direct injection of the tinctures in the MS detector in order to obtain the corresponding metabolic profiles was also performed.

RESULTS

Using both NMR and MS methods it was possible, without evaporation or separation steps, to obtain a metabolic fingerprint able to distinguish between tinctures prepared with different plants. Batch-to-batch homogeneity, as well as degradation after the expiry date of a batch, was also investigated.

CONCLUSION

The techniques proposed here represent fast and convenient direct analyses of medicinal herbal tinctures.

Fast determination of histamine in cheese by nuclear magnetic resonance (NMR)

A rapid and quantitative (1)H nuclear magnetic resonance (NMR) method was developed to analyze histamine in cheeses. The procedure is simple because the acid extract is analyzed directly, without any need for further filtration, derivatization, or other manipulation. This NMR method was demonstrated to be specific by 2D total correlation spectroscopy (TOCSY) and heteronuclear multiple-quantum coherence (HMQC) experiments and reliable in terms of linearity, accuracy, recovery, repeatability, and limits of detection (LOD). Good precision, with relative standard deviation (RSD) <4%, recovery of 100%, and a range of 0.6-1 mg/kg for the LOD were obtained. The NMR method was successfully applied to different types of cheese, ranging from soft to hard. No interference from free amino acids, proteins, and other natural components was detected. The NMR method could be transferred to other kinds of food.

1968–2008: 40 Years of Franco F. Vincieri's Natural Products Research

This paper presents an overview of Prof. Vincieri's accomplishments in his career as a researcher in the field of pharmacognosy (pharmaceutical biology), analytical phytochemistry and pharmaceutical technology applied to herbal drug preparations at the Department of Pharmaceutical Sciences of the University of Florence. This article is a recognition of his valuable contributions to these research fields, especially for his outstanding and innovative interdisciplinary studies on the quality control of herbal drugs, herbal drug preparations, herbal medicinal products, botanical food supplements, and some “special foods” such as grapes, wines, olives and olive oil.

Ginsenosides chemistry, biosynthesis, analysis, and potential health effects

Ginsenosides are a special group of triterpenoid saponins that can be classified into two groups by the skeleton of their aglycones, namely dammarane- and oleanane-type. Ginsenosides are found nearly exclusively in Panax species (ginseng) and up to now more than 150 naturally occurring ginsenosides have been isolated from roots, leaves/stems, fruits, and/or flower heads of ginseng. Ginsenosides have been the target of a lot of research as they are believed to be the main active principles behind the claims of ginsengs efficacy. The potential health effects of ginsenosides that are discussed in this chapter include anticarcinogenic, immunomodulatory, anti-inflammatory, antiallergic, antiatherosclerotic, antihypertensive, and antidiabetic effects as well as antistress activity and effects on the central nervous system. Ginsensoides can be metabolized in the stomach (acid hydrolysis) and in the gastrointestinal tract (bacterial hydrolysis) or transformed to other ginsenosides by drying and steaming of ginseng to more bioavailable and bioactive ginsenosides. The metabolization and transformation of intact ginsenosides, which seems to play an important role for their potential health effects, are discussed. Qualitative and quantitative analytical techniques for the analysis of ginsenosides are important in relation to quality control of ginseng products and plant material and for the determination of the effects of processing of plant material as well as for the determination of the metabolism and bioavailability of ginsenosides. Analytical techniques for the analysis of ginsenosides that are described in this chapter are thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC) combined with various detectors, gas chromatography (GC), colorimetry, enzyme immunoassays (EIA), capillary electrophoresis (CE), nuclear magnetic resonance (NMR) spectroscopy, and spectrophotometric methods.

1H NMR determination of hypericin and pseudohypericin in complex natural mixtures by the use of strongly deshielded OH groups

The (1)H NMR spectra of the commercially available compounds hypericin and its derivative pseudohypericin in CD(3)OH solutions indicate significantly deshielded signals in the region of 14-15 ppm. These resonances are attributed to the peri hydroxyl protons OH(6), OH(8) and OH(1), OH(13) of hypericins which participate in a strong six-membered ring intramolecular hydrogen bond with CO(7) and CO(14), respectively, and therefore, they are strongly deshielded. In the present work, we demonstrate that one-dimensional (1)H NMR spectra of hypericin and pseudohypericin, in Hypericum perforatum extracts show important differences in the chemical shifts of the hydroxyl groups with excellent resolution in the region of 14-15 ppm. The facile identification and quantification of hypericin and its derivative compound pseudohypericin was achieved, without prior HPLC separation, for two H. perforatum extracts from Greek cultivars and two commercial extracts: a dietary supplement, and an antidepressant medicine. The results were compared with those obtained from UV-vis and LC/MS measurements.

Nondestructive quantification of organic compounds in whole milk without pretreatment by two-dimensional NMR spectroscopy

In this study, various organic compounds in commercial whole milk were quantified simultaneously by 1H 1D and 1H - 13C HSQC 2D NMR spectra without any pretreatment. 2D NMR spectroscopy was applied to quantification of milk compounds for the first time. Milk fat content was easily determined to be 3.6 +/- 0.1%, and the lactose content was 47.8 +/- 1.0 mg/mL by 1H NMR spectra. From 1H-13C HSQC spectra, the concentrations of citrate, N-acetylcarbohydrates, and trimethylamine were determined to be 3.2 +/- 0.2, 2.9 +/- 0.1, and 4.0 +/- 0.6 mM, respectively. The latter two compounds were quantified in milk for the first time. Butyric acid, total monounsaturated fatty acids, and total polyunsaturated fatty acids of triacylglycerols were 6.2 +/- 0.5, 9.1 +/- 0.9, and 2.9 +/- 0.3 mM, respectively. The fatty acid compositions (mol %) of triacylglycerols were then calculated and were observed to be in good agreement with reference values. The results indicated that 1H 1D and 1H-13C HSQC 2D NMR spectroscopy is useful for the rapid and nondestructive determination of various compounds in milk.

Current analytical methods to study plant water extracts: the example of two mushrooms species, Inonotus hispidus and Sparassis crispa

The analytical study of two hot-water extracts from the mushrooms Inonotus hispidus (Bull.) P. Karst and Sparassis crispa Wulf.:Fr was performed by NMR, HPLC-PAD-MS and GC-MS. The simultaneous use of different analytical techniques highlighted the diverse classes of natural products contained in these extracts. This study describes an attempt to adapt a useful phytochemical method to the direct investigation of plant water extracts, which represent the typical traditional manner for the administration of natural remedies. The heritage concerning plant processing procedures, known as traditional pharmaceutical knowledge, could play an important role in future research on medicinal species. This kind of study could be used as an update for current and future perspectives in this research field.

Identification and quantification of glycoside flavonoids in the energy crop Albizia julibrissin

Oxygen radical absorbance capacity (ORAC) values showed that methanolic extracts of Albizia julibrissin foliage displayed antioxidant activity. High performance liquid chromatography (HPLC) and mass spectrometry (MS) techniques were utilized in the identification of the compounds. The analysis confirmed the presence of three compounds in A. julibrissin foliage methanolic extract: an unknown quercetin derivative with mass of 610 Da, hyperoside (quercetin-3-O-galactoside), and quercitrin (quercetin-3-O-rhamnoside). Fast performance liquid chromatography (FPLC) was employed to fractionate the crude A. julibrissin foliage methanolic extract into its individual flavonoid components. The flavonoids were quantified in terms of mass and their respective contribution to the overall ORAC value. Quercetin glycosides accounted for 2.0% of total foliage.

Overview on the Analytical Tools for Quality Control of Natural Product-Based Supplements: A Case Study of Ginseng

The quality of pharmaceutical products like ginseng is important for ensuring consumer safety and efficacy. Many ginseng products sold today are in various formulations such as powder, capsules, tablets, soft-gels, liquid extracts, and tea. This renders ginseng less identifiable by smell, taste, or physical appearance. Furthermore, as ginseng is expensive, adulteration with other cheaper products occurs. Hence quality assurance of ginseng is needed. This paper reviews the major techniques for ascertaining the level of ginsenosides, the primary active ingredients for ginseng, and covers high-performance liquid, gas, and thin-layer chromatographies, infrared and nuclear magnetic resonance spectroscopies, enzyme immunoassays, and other molecular methods. Supporting techniques such as ultraviolet, fluorescence, diode array and evaporative light scattering detections, and mass spectrometry will also be touched upon. This review also discusses the principles and applications of biosensors-in particular fiber optic-based sensors-and their feasibility in ginseng analysis based on preliminary studies. Despite their potential, there is currently no or limited commercial exploitation of fiber optic-based sensors to perform ginseng quality analysis. The opportunity for biosensors to be used for the rapid quality surveillance of ginseng is appealing, but several key issues still need to be addressed before they find widespread applications in the traditional Chinese medicine industry.

Toxicity and drug interactions associated with herbal products: ephedra and St. John's Wort

Health care providers are being increasingly confronted with the use of herbal medications by their patients. It is imperative that patients be questioned regarding herbal preparation use and that health care providers become familiar with these agents. Research into the active components and mechanisms of action of various herbals is ongoing [350]. Long-range studies need to be performed to follow patients for efficacy or toxicity in chronic use [351,352]. Adverse reactions to herbal remedies should be reported to the FDA MedWatch at http://www.fda.gov/medwatch. As withany therapeutic agent, risk of use must always be weighed against potential benefits.

Quantitative 1H NMR: development and potential of a method for natural products analysis

Based on a brief revision of what constitutes state-of-the-art "quantitative experimental conditions" for (1)H quantitative NMR (qHNMR), this comprehensive review contains almost 200 references and covers the literature since 1982 with emphasis on natural products. It provides an overview of the background and applications of qHNMR in natural products research, new methods such as decoupling and hyphenation, and analytical potential and limitations, and compiles information on reference materials used for and studied by qHNMR. The dual status of natural products, being single chemical entities and valuable biologically active agents that need to be purified from complex matrixes, results in an increased analytical demand when testing their deviation from the singleton composition ideal. The outcome and versatility of reported applications lead to the conclusion that qHNMR is currently the principal analytical method to meet this demand. Considering both 1D and 2D (1)H NMR experiments, qHNMR has proved to be highly suitable for the simultaneous selective recognition and quantitative determination of metabolites in complex biological matrixes. This is manifested by the prior publication of over 80 reports on applications involving the quantitation of single natural products in plant extracts, dietary materials, and materials representing different metabolic stages of (micro)organisms. In summary, qHNMR has great potential as an analytical tool in both the discovery of new bioactive natural products and the field of metabolome analysis.

Biosynthesis of hyperforin in Hypericum perforatum

Cut sprouts of Hypericum perforatum were proffered solutions containing [1-(13)C]glucose or [U-(13)C(6)]glucose. Hyperforin was isolated and analyzed by quantitative NMR spectroscopy. The labeling patterns show that the biosynthesis of hyperforin involves five isoprenoid moieties, which are derived entirely or predominantly (>98%) via the deoxyxylulose phosphate pathway. The phloroglucinol moiety is generated via a polyketide type mechanism.

NMR spectroscopy: a useful tool for characterisation of plant extracts, the case of supercritical CO2 arnica extract

The efficiency of two-dimensional homonuclear (1)H-(1)H correlated spectroscopy (COSY) and two-dimensional reverse heteronuclear shift correlation spectroscopy (i.e. heteronuclear multiple quantum correlation, HMQC) in characterising the content of the constituents of innovative extracts is demonstrated. These experiments were performed directly on a supercritical carbon dioxide (CO(2)) commercial extract of arnica and were able to fully characterise the active constituents, sesquiterpenes, and other metabolites extracted with the supercritical CO(2), namely polyketides. Identification of constituents was performed by combining literature data and information obtained by 2D-NMR experiments.

Characterization of commercial kava-kava herbal drug and herbal drug preparations by means of nuclear magnetic resonance spectroscopy

The efficiency of one- and two-dimensional NMR experiments in characterizing the content of the constituents of both herbal drugs and herbal drug preparations is demonstrated for kava-kava. These experiments directly detect active constituents represented by kavalactones in both a finely powdered herbal drug and a commercial extract. In addition, NMR spectroscopy can detect all other compounds present in the extract. As previously evidenced, NMR experiments can represent a generally applicable technique for rapid screening and are a complement to the classical analytical techniques such as high-performance thin-layer chromatography, high-performance liquid chromatography, capillary gas chromatography, and electrophoresis. These experiments can be considered a very simple and fast analytical method to obtain a fingerprint of the herbal drugs and their preparations, and to quantify the content of the active principles of the extract.

Pharmacokinetics and bioavailability of herbal medicinal products

The use of herbs for treating various ailments dates back several centuries. Usually, herbal medicine has relied on tradition that may or may not be supported by empirical data. The belief that natural medicines are much safer than synthetic drugs has gained popularity in recent years and led to tremendous growth of phytopharmaceutical usage. Market driven information on natural products is widespread and has further fostered their use in daily life. In most countries there is no universal regulatory system that insures the safety and activity of phytopharmaceuticals. Evidence-based verification of the efficacy of HMPs (herbal medicinal products, botanicals) is still frequently lacking. However, in recent years, data on evaluation of the therapeutic and toxic activity of herbal medicinal products became available. The advances in analytical technology have led to discovery of many new active constituents and an ever-increasing list of putatively active constituents. Establishing the pharmacological basis for efficacy of HMPs is a constant challenge. Of particular interest is the question of bioavailability to assess to what degree and how fast compounds are absorbed after administration of HMPs. Of further interest is the elucidation of metabolic pathways (yielding potentially new active compounds), and the assessment of elimination routes and their kinetics. These data become an important issue to link data from pharmacological assays and clinical effects. Of interest are currently also interactions of herbal medicinal products with synthetically derived drug products. A better understanding of the pharmacokinetics and bioavailability of phytopharmaceuticals can also help in designing rational dosage regimens. In this review, pharmacokinetic and bioavailability studies that have been conducted for some of the more important or widely used phytopharmaceuticals are critically evaluated. Furthermore, various drug interactions are discussed which show that caution should be exercised when combining phytopharmaceuticals with chemically derived active pharmaceutical ingredients.