Identification of common horsetail (Equisetum arvense L.; Equisetaceae) using Thin Layer Chromatography versus DNA barcoding

Study on essential oil, antioxidant activity, anti-human prostate cancer effects, and induction of apoptosis by Equisetum arvense

In this study, we have reported the chemical composition of Equisetum arvense essential oil and the anti-cancer activity of the plant against the prostate cancer cell line. The essential oil was obtained using the hydro-distillation assay. The chemical composition was identified using the gas chromatographic methods including gas chromatography/flame ionization detector and gas chromatography/mass spectrometry. The antioxidant activity of the essential oil and extract was evaluated using classical methods. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was run to evaluate the cytotoxic effect of the essential oil and extract on the prostate cancer cell line of lymph node carcinoma of the prostate. The induction apoptosis of the extract was analyzed by a flow cytometer. Thymol acetate (14.7%), trans-carveol (12.5%), thymol (11.8%), and δ-elemene (9.4%) were identified as the main compounds for the essential oil. The extract scavenged the free radical of 2,2-diphenyl-1-picrylhydrazyl with a half maximal inhibitory concentration (IC50) of 15.2 ± 1.4 μg/mL for the plant extract. In the MTT assay, the IC50 of the extract and essential oil were 25.2 ± 0.3 and 218.9 ± 10.7 μg/mL after 72 h. The highest apoptosis was 31.6% for the plant extract. The obtained results of the present study revealed that E. arvense can be introduced as a potent agent to prevent the growth of prostate tumors.

A Multi-Pronged Technique for Identifying Equisetum palustre and Equisetum arvense—Combining HPTLC, HPLC-ESI-MS/MS and Optimized DNA Barcoding Techniques

The most prominent horsetail species, Equisetum arvense, has an array of different medicinal properties, thus the proper authentication and differentiation of the plant from the more toxic Equisetum palustre is important. This study sought to identify different samples of E. arvense and E. palustre using three analytical methods. The first method involved the use of HPTLC analysis, as proposed by the European Pharmacopoeia. The second, HPLC-ESI-MS/MS, is capable of both identification and quantification and was used to determine the Equisetum alkaloid content in each sample. A third method was DNA barcoding, which identifies the samples based on their genetic make-up. Both HPTLC and HPLC-ESI-MS/MS proved to be suitable methods of identification, with HPLC-ESI-MS/MS proving the more sophisticated method for the quantification of alkaloids in the Equisetum samples and for determining the adulteration of E. arvense. For DNA barcoding, optimal primer pairs were elucidated to allow for the combined use of the rbcL and ITS markers to accurately identify each species. As new DNA marker sequences were added to GenBank, the reference library has been enriched for future work with these horsetail species.

Biomarker-Based Determination of Equiseti herba Contamination by Equisetum palustre Using HPLC-MS/MS

Equiseti herba has been traditionally indicated in bacterial diseases of the efferent urinary tract or bad healing wounds in many regions worldwide. Most of the plant material used for medical purposes comes from collections of wild growing plants. The European Pharmacopoeia requires that Equiseti herba should consist of a minimum of 95% Equisetum arvense and a maximum of 5% foreign ingredients. This includes Equisetum palustre, which is known for its potentially toxic alkaloid palustrine. However, both Equisetum species are quite common, look morphologically very similar, and share similar habitats, hence, are therefore often confused. Recently, several structurally related Equisetum alkaloids have been identified in E. palustre but not in E. arvense. We have established a hydrophilic interaction liquid chromatography HPLC-ESI-MS/MS method for the detection of these E. palustre-specific Equisetum alkaloids in order to quantify the contamination of Equiseti herba (E. arvense) by E. palustre plant material. In a second, independent approach, the results of the HPLC-MS/MS analysis were confirmed by scanning electron microscopy, looking for the species-specific characteristics of the stoma apparatus of E. palustre. Thirty-four Equiseti herba products obtained from different pharmacies, drug stores, supermarkets, and web stores were analyzed. The majority of the products (26 out of 34) were Equisetum alkaloid positive, with contents ranging from 0.29 - 21.7 mg of Equisetum alkaloids/kg (d. w.). In addition, the transfer of Equisetum alkaloids into tea infusions was investigated, demonstrating a 42 to 60% transfer rate for cold and hot water extraction of Equisetum alkaloid-contaminated Equiseti herba, respectively.

High-Performance Thin-Layer Chromatography (HPTLC) Method for Identification of Meloxicam and Piroxicam

Background: High-performance thin-layer chromatography (HPTLC) is an advantageous, modern analytical technique based on the principles of thin-layer chromatography (TLC), which provides essential benefits, such as improved sample application, better and faster separation, and less mobile phase usage. The aim of this work was to develop a simple and rapid HPTLC method that could be used for the identification of meloxicam and piroxicam. Methods: HPTLC. An analysis was carried out using silica gel 60 F254 glass TLC plates and as the mobile phase: hexane: ethyl acetate: glacial acetic acid, in a ratio of 65:30:5 v/v/v. For the standard solution preparation, ethanol was used. Front: 60 mm. Detection was performed at 366 nm. Results: The Rf value for meloxicam was 0.81 and the Rf value for piroxicam was 0.57. The proposed method can be used in the detection of the analyzed compounds in very low concentrations. It was established that the detection limit of meloxicam was 0.04 μg per band and that of piroxicam was 0.05 μg per band. It was also established that the quantitation limit of meloxicam was 0.12 μg per band and that of piroxicam was 0.15 μg per band. Conclusions: The proposed method is simple, sensitive, stable, cost effective, and eco-friendly. It could be used in research or for routine quality control purposes.

Biogeography and genome size evolution of the oldest extant vascular plant genus, Equisetum (Equisetaceae)

BACKGROUND AND AIMS

Extant plant groups with a long fossil history are key elements in understanding vascular plant evolution. Horsetails (Equisetum, Equisetaceae) have a nearly continuous fossil record dating back to the Carboniferous, but their phylogenetic and biogeographic patterns are still poorly understood. We use here the most extensive phylogenetic analysis to date as a framework to evaluate their age, biogeography and genome size evolution.

METHODS

DNA sequences of four plastid loci were used to estimate divergence times and investigate the biogeographic history of all extant species of Equisetum. Flow cytometry was used to study genome size evolution against the framework of phylogenetic relationships in Equisetum.

KEY RESULTS

On a well-supported phylogenetic tree including all extant Equisetum species, a molecular clock calibrated with multiple fossils places the node at which the outgroup and Equisetum diverged at 343 Mya (Early Carboniferous), with the first major split among extant species occurring 170 Mya (Middle Jurassic). These dates are older than those reported in some other recent molecular clock studies but are largely in agreement with a timeline established by fossil appearance in the geological record. Representatives of evergreen subgenus Hippochaete have much larger genome sizes than those of deciduous subgenus Equisetum, despite their shared conserved chromosome number. Subgenus Paramochaete has an intermediate genome size and maintains the same number of chromosomes.

CONCLUSIONS

The first divergences among extant members of the genus coincided with the break-up of Pangaea and the resulting more humid, warmer climate. Subsequent tectonic activity most likely involved vicariance events that led to species divergences combined with some more recent, long-distance dispersal events. We hypothesize that differences in genome size between subgenera may be related to the number of sperm flagellae.

Chemical Authentication of Botanical Ingredients: A Review of Commercial Herbal Products

Chemical methods are the most important and widely used traditional plant identification techniques recommended by national and international pharmacopoeias. We have reviewed the successful use of different chemical methods for the botanical authentication of 2,386 commercial herbal products, sold in 37 countries spread over six continents. The majority of the analyzed products were reported to be authentic (73%) but more than a quarter proved to be adulterated (27%). At a national level, the number of products and the adulteration proportions varied very widely. Yet, the adulteration reported for the four countries, from which more than 100 commercial products were purchased and their botanical ingredients chemically authenticated, was 37% (United Kingdom), 31% (Italy), 27% (United States), and 21% (China). Simple or hyphenated chemical analytical techniques have identified the total absence of labeled botanical ingredients, substitution with closely related or unrelated species, the use of biological filler material, and the hidden presence of regulated, forbidden or allergenic species. Additionally, affecting the safety and efficacy of the commercial herbal products, other low quality aspects were reported: considerable variability of the labeled metabolic profile and/or phytochemical content, significant product-to-product variation of botanical ingredients or even between batches by the same manufacturer, and misleading quality and quantity label claims. Choosing an appropriate chemical technique can be the only possibility for assessing the botanical authenticity of samples which have lost their diagnostic microscopic characteristics or were processed so that DNA cannot be adequately recovered.

Progress in the use of DNA barcodes in the identification and classification of medicinal plants

DNA barcoding is an emerging molecular identification and classification technology that has been applied to medicinal plants since 2008. The application of this technique has greatly ensured the safety and effectiveness of medicinal materials. In this paper, we review the application of DNA barcoding and some related technologies over the past 10 years with respect to improving our knowledge of medicinal plant identification and authentication. From single locus-based DNA barcodes to combined markers to genome-scale levels, DNA barcodes contribute more and more genetic information. At the same time, other technologies, such as high-resolution melting (HRM), have been combined with DNA barcoding. With the development of next-generation sequencing (NGS), metabarcoding technology has also been shown to identify species in mixed samples successfully. As a widely used and effective tool, DNA barcoding will become more useful over time in the field of medicinal plants.

Biosynthesis, and potential effect of fern mediated biocompatible silver nanoparticles by cytotoxicity, antidiabetic, antioxidant and antibacterial, studies

Equisetum arvense is well known to hold numerous bioactive phytochemicals. In biosynthesis of nanoparticles (NPs), the bioactive compounds existing in natural materials like medicinal fern act as reducing and capping elements and this NPs synthesis process do not comprise of any toxic elements making them advantageous from other NPs synthesis process. After collection, identification and extraction of Equisetum arvense (Ea) aqueous extract, the biosynthesis of AgNPs was achieved followed by its characterization and multi-biopotential activity studies. The UV-visible spectroscopy, confirmed the biosynthesis of Ea-AgNPs. X-ray diffraction configurations (XRD) identified the crystalline nature of the NPs. The Elemental composition of the NPs was elucidated by the energy dispersive X-ray spectroscopy (EDX), and the scanning electron microscopy (SEM) revealed the structure of Ea-AgNPs. Bioactive compounds existing in Ea-extract accounting for Ag + ion reduction, capping and stabilization of NPs was detected by Fourier transform infrared spectroscopy (FTIR). The Dynamic Light Scattering (DLS) and the zeta potential was carried out to know the size and charge of Ea-AgNPs. The Ea-AgNPs exhibited high antidiabetic effect in terms of α-glucosidase inhibition, high cytotoxic effect against HepG2 cell lines along with antibacterial and antioxidant effect. This study reports biosynthesis of Ea-AgNPs using aqueous extract of Ea, its substantial anticancer, antidiabetic, antioxidant and antibacterial effects, which could be advantageous to pharmaceutical industries in the controlling of various diseases including diabetes, cancer, and antibacterial related diseases.

Detection of Seasonal Variation in Aloe Polysaccharides Using Carbohydrate Detecting Microarrays

Aloe vera gel is a globally popular natural product used for the treatment of skin conditions. Its useful properties are attributed to the presence of bioactive polysaccharides. Nearly 25% of the 600 species in the genus Aloe are used locally in traditional medicine, indicating that the bioactive components in Aloe vera may be common across the genus Aloe. The complexity of the polysaccharides has hindered development of relevant assays for authentication of Aloe products. Carbohydrate detecting microarrays have recently been suggested as a method for profiling Aloe polysaccharide composition. The aim of this study was to use carbohydrate detecting microarrays to investigate the seasonal variation in the polysaccharide composition of two medicinal and two non-medicinal Aloe species over the course of a year. Microscopy was used to explore where in the cells the bioactive polysaccharides are present and predict their functional role in the cell wall structure. The carbohydrate detecting microarrays analyses showed distinctive differences in the polysaccharide composition between the different species and carbohydrate detecting microarrays therefore has potential as a complementary screening method directly targeting the presence and composition of relevant polysaccharides. The results also show changes in the polysaccharide composition over the year within the investigated species, which may be of importance for commercial growing in optimizing harvest times to obtain higher yield of relevant polysaccharides.

Hundred Fifty Years of Herbarium Collections Provide a Reliable Resource of Volatile Terpenoid Profiles Showing Strong Species Effect in Four Medicinal Species of Salvia Across the Mediterranean

Herbarium samples are increasingly being recognized for their potential in answering a wide range of research questions. However, the suitability of herbarium samples for chemical analysis is largely unexplored as they are thought to be too degraded. The aim of this study was to explore terpenoid profiles across time and geographic space for four medicinal species of Salvia across the Mediterranean to assess the suitability of using herbarium specimens in chemical analyses. Herbarium samples of Salvia aethiopis, S. multicaulis, S. officinalis, and S. sclarea collected over 150 years across the Mediterranean were compared to modern samples using both targeted and untargeted gas chromatography-mass spectrometry analysis of terpene profiles. There was no effect of collection year on chemical composition, although the total concentration of the 20 assessed standards and two individual standards significantly decreased over time. Instead, chemical profiles were defined by species, with strong species effects identified on both the targeted and untargeted chemical composition. Geographic variation was a factor in regulating the untargeted chemical compositions, suggesting some underlying environmental effects. However, there was no effect of sample altitude on either the targeted or untargeted chemical compositions. Chemical composition of four Salvia species are predominantly defined by species, and there was a substantially smaller effect of year of sampling. Given these results herbarium collections may well represent a considerably underused resource for chemical analyses that can benefit biodiversity and other studies.

Benefits and Limitations of DNA Barcoding and Metabarcoding in Herbal Product Authentication

INTRODUCTION

Herbal medicines play an important role globally in the health care sector and in industrialised countries they are often considered as an alternative to mono-substance medicines. Current quality and authentication assessment methods rely mainly on morphology and analytical phytochemistry-based methods detailed in pharmacopoeias. Herbal products however are often highly processed with numerous ingredients, and even if these analytical methods are accurate for quality control of specific lead or marker compounds, they are of limited suitability for the authentication of biological ingredients.

OBJECTIVE

To review the benefits and limitations of DNA barcoding and metabarcoding in complementing current herbal product authentication.

METHOD

Recent literature relating to DNA based authentication of medicinal plants, herbal medicines and products are summarised to provide a basic understanding of how DNA barcoding and metabarcoding can be applied to this field.

RESULTS

Different methods of quality control and authentication have varying resolution and usefulness along the value chain of these products. DNA barcoding can be used for authenticating products based on single herbal ingredients and DNA metabarcoding for assessment of species diversity in processed products, and both methods should be used in combination with appropriate hyphenated chemical methods for quality control.

CONCLUSIONS

DNA barcoding and metabarcoding have potential in the context of quality control of both well and poorly regulated supply systems. Standardisation of protocols for DNA barcoding and DNA sequence-based identification are necessary before DNA-based biological methods can be implemented as routine analytical approaches and approved by the competent authorities for use in regulated procedures. © 2017 The Authors. Phytochemical Analysis Published by John Wiley & Sons Ltd.

Veronica officinalis Product Authentication Using DNA Metabarcoding and HPLC-MS Reveals Widespread Adulteration with Veronica chamaedrys

Studying herbal products derived from local and traditional knowledge and their value chains is one of the main challenges in ethnopharmacology. The majority of these products have a long history of use, but non-harmonized trade and differences in regulatory policies between countries impact their value chains and lead to concerns over product efficacy, safety and quality. Veronica officinalis L. (common speedwell), a member of Plantaginaceae family, has a long history of use in European traditional medicine, mainly in central eastern Europe and the Balkans. However, no specified control tests are available either to establish the quality of derived herbal products or for the discrimination of its most common substitute, V. chamaedrys L. (germander speedwell). In this study, we use DNA metabarcoding and high performance liquid chromatography coupled with mass spectrometry (HPLC-MS) to authenticate sixteen V. officinalis herbal products and compare the potential of the two approaches to detect substitution, adulteration and the use of unreported constituents. HPLC-MS showed high resolution in detecting phytochemical target compounds, but did not enable detection of specific plant species in the products. DNA metabarcoding detected V. officinalis in only 15% of the products, whereas it detected V. chamaedrys in 62% of the products. The results confirm that DNA metabarcoding can be used to test for the presence of Veronica species, and detect substitution and/or admixture of other Veronica species, as well as simultaneously detect all other species present. Our results confirm that none of the herbal products contained exactly the species listed on the label, and all included substitutes, contaminants or fillers. This study highlights the need for authentication of raw herbals along the value chain of these products. An integrative methodology can assess both the quality of herbal products in terms of target compound concentrations and species composition, as well as admixture and substitution with other chemical compounds and plants.

Comparative authentication of Hypericum perforatum herbal products using DNA metabarcoding, TLC and HPLC-MS

Many herbal products have a long history of use, but there are increasing concerns over product efficacy, safety and quality in the wake of recent cases exposing discrepancies between labeling and constituents. When it comes to St. John’s wort (Hypericum perforatum L.) herbal products, there is limited oversight, frequent off-label use and insufficient monitoring of adverse drug reactions. In this study, we use amplicon metabarcoding (AMB) to authenticate 78 H. perforatum herbal products and evaluate its ability to detect substitution compared to standard methods using thin-layer chromatography (TLC) and high performance liquid chromatography coupled with mass spectrometry (HPLC-MS). Hypericum perforatum was detected in 68% of the products using AMB. Furthermore, AMB detected incongruence between constituent species and those listed on the label in all products. Neither TLC nor HPLC-MS could be used to unambiguously identify H. perforatum. They are accurate methods for authenticating presence of the target compounds, but have limited efficiency in detecting infrageneric substitution and do not yield any information on other plant ingredients in the products. Random post-marketing AMB of herbal products by regulatory agencies could raise awareness among consumers of substitution and would provide an incentive to manufacturers to increase quality control from raw ingredients to commercialized products.