Challenges in Medicinal and Aromatic Plants DNA Barcoding-Lessons from the Lamiaceae

Foliar application of various biostimulants produces contrasting response on yield, essential oil and chemical properties of organically grown sage (Salvia officinalis L.)

Sage (Salvia officinalis L.) is a medicinal and aromatic plant (MAP) belonging to the Lamiaceae family. Its morphological, productive and chemical characteristics are affected by abiotic and biotic factors. The use of biostimulants seems to be one of the most interesting innovative practices due to fact they can represent a promising approach for achieving sustainable and organic agriculture. Despite a large application in horticulture, the use of biostimulants on MAPs has been poorly investigated. On this basis, a field experiment in a 2-year study was done to assess the effect of foliar treatments with different types of biostimulants (containing seaweeds, fulvic acids and protein hydrolysates) and two frequencies of application on morphological, productive, and chemical characteristics of S. officinalis grown organically in Mediterranean environment. Morphological, productive, and chemical parameters were affected by the factors. The biostimulant application generated higher plant height, chlorophyll content, relative water content, biomass yield and essential oil yield compared to control plants. In addition, more frequent application of biostimulants produced higher biomass and essential oil yield. The application of fulvic acid and protein hydrolysates every week produced the highest total fresh yields (between 3.9 and 8.7 t ha-1) and total dry yields (between 1.3 and 2.5 t ha-1). The essential oil yield almost doubled (33.9 kg ha-1) with a higher frequency of protein hydrolysates application. In this study, 44 essential oil compounds were identified, and the frequency factor significantly influenced the percentage of 38 compounds. The highest percentage of some of the most representative monoterpenes, such as 1,8-cineole, α-thujone and camphor, were observed in biostimulated plants, with average increases between 6% and 35% compared to control plants. The highest values for total phenolics, rosmarinic acid, antioxidant activity were obtained in control plants and with a lower frequency of biostimulant applications. This study emphasizes how biostimulant applications may be used to improve sage production performance and essential oil parameters when produced in agricultural organic system. At the same time, biostimulants application caused a decrease in total phenolic, antioxidant activity and rosmarinic acid values.

DNA barcoding of herbal supplements on the US commercial market associated with the purported treatment of COVID-19

INTRODUCTION

The COVID-19 pandemic was associated with an increased global use of traditional medicines, including Ayurvedic herbal preparations. Due to their growing demand, their processed nature, and the complexity of the global supply chain, there is an increased risk of adulteration in these products.

OBJECTIVES

The objective of this study was to assess the use of DNA barcoding for species identification in herbal supplements on the US market associated with the Ayurvedic treatment of respiratory symptoms.

METHODS

A total of 54 commercial products containing Ayurvedic herbs were tested with four DNA barcoding regions (i.e., rbcL, matK, ITS2, and mini-ITS2) using two composite samples per product. Nine categories of herbs were targeted: amla, ashwagandha, cinnamon, ginger, guduchi, tribulus, tulsi, turmeric, and vacha.

RESULTS

At least one species was identified in 64.8% of products and the expected species was detected in 38.9% of products. Undeclared plant species, including other Ayurvedic herbs, rice, and pepper, were detected in 19 products, and fungal species were identified in 12 products. The presence of undeclared plant species may be a result of intentional substitution or contamination during harvest or processing, while fungal DNA was likely associated with the plant material or the growing environment. The greatest sequencing success (42.6-46.3%) was obtained with the matK and rbcL primers.

CONCLUSION

The results of this study indicate that a combination of genetic loci should be used for DNA barcoding of herbal supplements. Due to the limitations of DNA barcoding in identification of these products, future research should incorporate chemical characterization techniques.

DNA Barcoding and Fertilization Strategies in Sideritis syriaca subsp. syriaca, a Local Endemic Plant of Crete with High Medicinal Value

Herein, we applied DNA barcoding for the genetic characterization of Sideritis syriaca subsp. syriaca (Lamiaceae; threatened local Cretan endemic plant) using seven molecular markers of cpDNA. Five fertilization schemes were evaluated comparatively in a pilot cultivation in Crete. Conventional inorganic fertilizers (ChFs), integrated nutrient management (INM) fertilizers, and two biostimulants were utilized (foliar and soil application). Plant growth, leaf chlorophyll fluorescence, and color were assessed and leaf content of chlorophyll, key antioxidants (carotenoids, flavonoids, phenols), and nutrients were evaluated. Fertilization schemes induced distinct differences in leaf shape, altering quality characteristics. INM-foliar and ChF-soil application promoted yield, without affecting tissue water content or biomass partitioning to inflorescences. ChF-foliar application was the most stimulatory treatment when the primary target was enhanced antioxidant contents while INM-biostimulant was the least effective one. However, when the primary target is yield, INM, especially by foliar application, and ChF, by soil application, ought to be employed. New DNA sequence datasets for the plastid regions of petB/petD, rpoC1, psbK-psbI, and atpF/atpH were deposited in the GenBank for S. syriaca subsp. syriaca while the molecular markers rbcL, trnL/trnF, and psbA/trnH were compared to those of another 15 Sideritis species retrieved from the GenBank, constructing a phylogenetic tree to show their genetic relatedness.

Ethnomedicinal Importance of Patuletin in Medicine: Pharmacological Activities and Analytical Aspects

BACKGROUND

Plant-derived bioactive molecules have been a major source of therapeutic agents for human and veterinarian purposes. Different traditional medicine system across the globe had relied on natural resources to meet their demand of healthcare. Still in modern world, pharmaceutical industries look for phytochemicals to develop new drugs. The current review explores patuletin, a flavonoid for its diverse reported pharmacological activities along with its analytical techniques.

METHODS

Scientific data published on patuletin was collected from Scopus, Science Direct, Pubmed, Google, and Google Scholar. The collected data were analyzed and arranged as per specific pharmacological activities performed using in-vitro or in-vivo methods. Analytical methods of patuletin have been presented next to pharmacological activities Results: Available scientific literature indicates patuletin has anti-inflammatory, cytotoxic, genotoxic, hepatoprotective, antiproliferative, antiplatelet, antinociceptive, and antioxidant activity. In addition to these activities, its biological potential on breast cancer, rheumatoid arthritis, aldose reductase, and different types of microorganisms has been also presented in this work. Analytical data on patuletin signified the importance of patuletin for the standardization of herbal products and derived medicine.

CONCLUSION

It may be concluded that patuletin with its diverse biological activities and readily available analytical methods, holds the potential to be translated into a new drug entity.

Standardization of Euphorbia tithymaloides (L.) Poit. (Root) by Conventional and DNA Barcoding Methods

Adulteration and substitution of medicinal plants have become a matter of great concern in recent years. Euphorbia tithymaloides is one such medicinal plant that has gained importance but is often confused with other plants of the same species. In order to address this issue, this study aimed to conduct a conventional and molecular pharmacognostic study for the identification of the root of E. tithymaloides. The root of the plant was studied for the macroscopic observations, and then, the root was ground into coarse powder for microscopic studies and to determine the physiochemical properties. The powder was subjected to extraction with solvents such as ethanol, ethanol/water (1:1), hexane, and ethyl acetate. The extracts were then used for qualitative and quantitative (phenol, alkaloids, and flavonoids) phytochemical analysis. The molecular study was performed with the DNA barcoding technique. The DNA was extracted from the root of the plant, and its purity was examined by gel electrophoresis (1% w/v). The DNA was then amplified using an Applied Biosystems 2720 thermal cycler for the rbcL, matK, and ITS primers. The amplified primers were sequenced with a 3130 Genetic Analyzer, and the generated sequences were searched for similarity in the GenBank Database using the nucleotide BLAST analysis. The micro- and macroscopic studies revealed the morphological and organoleptic characters as well as the presence of medullary rays, fiber, cork, sclereids, parenchymal cells, and scalariform vessels. The physiochemical properties were found within the limit. The phytochemical analysis revealed the presence of terpenoids, flavonoids, saponins, and alkaloids. In addition, the alkaloidal content was high in the ethanol extract (63.04 ± 3.08 mg At E/g), while the phenol content was high in the hexane extract (10.26667 ± 1.77 mg At E/g), and the flavonoid content was high in the ethyl acetate extract (41.458 ± 1.33 mg At E/g). After the BLAST analysis from the GenBank database, the rbcL, ITS, and matK primers showed a similarity percentage of 99.83, 99.84, and 100. The phylogenetic tree for the species closest to each primer was generated using the MEGA 6 software. The matK loci had the highest percentage similar to the rbcL and ITS loci, indicating that the matK loci can be used to identify the root of E. tithymaloides as a standalone. The results from this study can be used to establish a quality standard for E. tithymaloides that will ensure its quality and purity.

Morphological, phytochemical, and transcriptome analyses provide insights into the biosynthesis of monoterpenes in Monarda citriodora

MAIN CONCLUSION

Morphological, phytochemical, and transcriptome analyses revealed candidate genes involved in the biosynthesis of volatile monoterpenes and development of glandular trichomes in Monarda citriodora. Monarda citriodora Cerv. ex Lag. is a valuable aromatic plant due to the presence of monoterpenes as major constituents in its essential oil (EO). Thus, it is of sheer importance to gain knowledge about the site of the biosynthesis of these terpenoid compounds in M. citriodora, as well as the genes involved in their biosynthesis. In this study, we studied different types of trichomes and their relative densities in three different developmental stages of leaves, early stage of leaf development (L1), mid-stage of leaf development (L2), and later stage of leaf development (L3) and the histochemistry of trichomes for the presence of lipid and terpenoid compounds. Further, the phytochemical analysis of this plant through GC-MS indicated a higher content of monoterpenes (thymol, thymoquinone, γ-terpinene, p-cymene, and carvacrol) in the L1 stage with a substantial decrease in the L3 stage of leaf development. This considerable decrease in the content of monoterpenes was attributed to the decrease in the trichome density from L1 to L3. Further, we developed a de novo transcriptome assembly by carrying out RNA sequencing of different plant parts of M. citriodora. The transcriptome data revealed several putative unigenes involved in the biosynthesis of specialized terpenoid compounds, as well as regulatory genes involved in glandular trichome development. The data generated in the present study build a strong foundation for further improvement of M. citriodora, in terms of quantity and quality of its essential oil, through genetic engineering.

Volatile metabolites from new cultivars of catnip and oregano as potential antibacterial and insect repellent agents

Plant based natural products have been widely used as antibacterial and insect repellent agents globally. Because of growing resistance in bacterial plant pathogens and urban pests to current methods of control, combined with the long- and short-term negative impact of certain chemical controls in humans, non-target organisms, and the environment, finding alternative methods is necessary to prevent and/or mitigate losses caused by these pathogens and pests. The antibacterial and insect repellent activities of essential oils of novel cultivars of catnip (Nepeta cataria L. cv. CR9) and oregano (Origanum vulgare L. cv. Pierre) rich in the terpenes nepetalactone and carvacrol, respectively, were evaluated using the agar well diffusion assay and petri dish repellency assay. The essential oils exhibit moderate to high antibacterial activity against three plant pathogens, Pseudomonas cichorii, Pseudomonas syringae and Xanthomonas perforans of economic interest and the individual essential oils, their mixtures and carvacrol possess strong insect repellent activity against the common bed bug (Cimex lectularius L.), an urban pest of major significance to public health. In this study, the essential oils of catnip and oregano were determined to be promising candidates for further evaluation and development as antibacterial agents and plant-based insect repellents with applications in agriculture and urban pest management.

A DNA Metabarcoding Workflow to Identify Species in Spices and Herbs

BACKGROUND

Spices and herbs are food categories regularly cited as highly susceptible to be adulterated. To detect potential adulteration with undeclared species, DNA-based methods are considered the most suitable tools.

OBJECTIVE

In this study, the performance of the ready-to-use Thermo Scientific™ NGS Food Authenticity Workflow (Thermo Fisher Scientific)-a commercial DNA metabarcoding approach-is described. The tool was further applied to analyze 272 commercial samples of spices and herbs.

METHOD

Pure samples of spices and herbs were analyzed with the Thermo Scientific NGS Food Authenticity Workflow to assess its specificity, and spikings down to 1% (w/w) allowed evaluation of its sensitivity. Commercial samples, 62 and 210, were collected in Asian and European markets, respectively.

RESULTS

All tested species were correctly identified often down to the species level, while spikings at 1% (w/w) confirmed a limit of detection at this level, including in complex mixtures composed of five different spices and/or herbs. The analysis of 272 commercial samples showed that 78% were compliant with the declared content, whereas the rest were shown to contain undeclared species that were in a few cases allergenic or potentially toxic.

CONCLUSIONS

The Thermo Scientific NGS Food Authenticity Workflow was found to be suitable to identify food plant species in herbs and spices, not only when tested on pure samples, but also in mixtures down to 1% (w/w). The overall workflow is user-friendly and straightforward, which makes it simple to use and facilitates data interpretation.

HIGHLIGHTS

The Thermo Scientific NGS Food Authenticity Workflow was found to be suitable for species identification in herbs and spices, and it allowed the detection of undeclared species in commercial samples. Its ease of use facilitates its implementation in testing laboratories.

The Cultural and Commercial Value of Tulsi (Ocimum tenuiflorum L.): Multidisciplinary Approaches Focusing on Species Authentication

Tulsi (Holy basil, Ocimum tenuiflorum L., Lamiaceae), native to Asia, has become globalised as the cultural, cosmetic, and medicinal uses of the herb have been popularised. DNA barcoding, a molecular technique used to identify species based on short regions of DNA, can discriminate between different species and identify contaminants and adulterants. This study aimed to explore the values associated with Tulsi in the United Kingdom (UK) and authenticate samples using DNA barcoding. A mixed methods approach was used, incorporating social research (i.e., structured interviews) and DNA barcoding of Ocimum samples using the ITS and trnH-psbA barcode regions. Interviews revealed the cultural significance of Tulsi: including origins, knowledge exchange, religious connotations, and medicinal uses. With migration, sharing of plants and seeds has been seen as Tulsi plants are widely grown in South Asian (SA) households across the UK. Vouchered Ocimum specimens (n = 33) were obtained to create reference DNA barcodes which were not available in databases. A potential species substitution of O. gratissimum instead of O. tenuiflorum amongst SA participants was uncovered. Commercial samples (n = 47) were difficult to authenticate, potentially due to DNA degradation during manufacturing processes. This study highlights the cultural significance of Tulsi, despite a potential species substitution, the plant holds a prestigious place amongst SA families in the UK. DNA barcoding was a reliable way to authenticate Ocimum species.

Sideritis elica, a New Species of Lamiaceae from Bulgaria, Revealed by Morphology and Molecular Phylogeny

Sideritis elica, from the Rhodope Mountains, is described as a species new to science. Results of a detailed morphological analysis were combined with the data of molecular analyses using DNA barcoding as an efficient tool for the genetic, taxonomic identification of plants. The combination of morphological features distinguishes the new species well: Its first three uppermost leaf pairs are significantly shorter and wider, the branchiness of the stems is much more frequent, the whole plant is much more lanate, and it looks almost white, as opposed to the other closed species of section Empedoclia, which look grayish green. The molecular analysis, based on the rbcL and trnH-psbA regions, supports the morphological data about the divergence of Sideritis scardica and Sideritis elica. The studied populations of the two taxa were found to be genetically distant (up to 6.8% polymorphism for trnH-psbA) with distinct population-specific nucleotide patterns, while no polymorphism in the DNA barcodes was detected within the Sideritis elica population. The results confirm the existence of a new species called Sideritis elica, which occurs in the nature reserve Chervenata Stena, located in the northern part of the Central Rhodope Mountains. There were only 12 individuals found in the locality, which underlines the necessity of conservation measures.

Rapid Identification of Paeoniae Radix and Moutan Radicis Cortex Using a SCAR Marker-Based Conventional PCR Assay

Paeoniae Radix is a herbal medicine prepared from the dried roots of Paeonia lactiflora, P. anomala subsp. veitchii, and P. japonica. Although the herbal medicines prepared from these species are morphologically similar, they have different pharmacological effects depending on how they are processed. In addition, P. japonica is more expensive than other Paeonia spp. in the Korean herbal market. Although there is a clear difference between the Korean and Chinese pharmacopeias of Paeoniae Radix, the processed roots of P. lactiflora and P. anomala subsp. veitchii are commonly used indiscriminately in the herbal market. Moreover, Paeonia suffruticosa, an allied genus of P. lactiflora, is prescribed as Moutan Radicis Cortex. Therefore, accurate taxonomic identification of plant species is vital for quality assurance. A genetic assay is a reliable tool for accurately discriminating species in processed herbal medicines. To develop a genetic assay for the identification of four Paeonia species (P. lactiflora, P. anomala subsp. veitchii, P. japonica, and P. suffruticosa), we analyzed the sequences of two DNA barcoding regions, internal transcribed spacer and rbcL. A conventional PCR assay was established in this study for simple and rapid species identification using sequence characterized amplified region (SCAR) markers based on arbitrary nucleotide-containing primers. This assay was verified to be species specific and highly sensitive and could be applied to Paeonia species identification at an affordable rate.

Larvicidal and adulticidal activity of essential oils from plants of the Lamiaceae family against the West Nile virus vector, Culex pipiens (Diptera: Culicidae)

Culex pipiens mosquitoes are the most widely distributed primary vector of the West Nile virus worldwide. Many attempts for investigation of botanical pesticides to avoid the development of pesticide resistance to conventional synthetic pesticides that are recognized as a threat to the diversity of ecosystems. The study aimed to determine the components of three essential oils of Lamiaceae family, lavender (Lavandula angustifolia), peppermint (Mentha piperita L.), and rosemary (Rosmarinus officinalis L.) by gas chromatography-mass spectrometry (GC–MS) analysis. Furthermore, aimed to validate the insecticidal activities of these oils as larvicidal agents against the third instar larvae of Culex pipiens using five different concentrations (62.5, 125, 250, 500, and 1000 ppm) for each oil in five replicates and as an adulticidal agent against approximately three-day-old female adults of Cx. Pipiens using 0.5, 1, 2, 4, and 5% concentrations in three replicates. The results generally showed a dose-related response. At 1000 ppm, rosemary oil showed the highest larvicidal (100%) (LC₅₀, 214.97 ppm), followed by peppermint oil (92.00% mortality and LC₅₀ (269.35 ppm). Lavender oil showed the lowest efficacy with 87.20% mortality and LC₅₀ (301.11 ppm). At 5% oil concentration, the highest knockdown rate at 1 h was recorded for lavender oil (95.55%), followed by peppermint oil (88.89%) and lastly rosemary oil (84.44%). After 24 h, rosemary oil showed the lowest adult mortality rate (88.89%; LC₅₀, 1.44%), while lavender and peppermint oils both showed a 100% mortality rate, with (LC₅₀, 0.81% and 0.91%, respectively). The chemical constituents of the oils consisted of monoterpenes and sesquiterpenes that determined their insecticidal activities against the target insect stage. The study proposed that rosemary essential oil may be useful for the control of Cx. pipiens larvae as part of an integrated water treatment strategy, and lavender and peppermint oils may be used in an integrated plan for adult’s control.

Chemical Composition and Antibacterial and Antioxidant Activities of Stem Bark Essential Oil and Extracts of Solanecio gigas

Herbal medication developed from natural resources has to have antibacterial and antioxidant effects. The aim of this research is to look at the chemical makeup of Solanecio gigas (S. gigas) stem bark essential oil (EO), as well as the effectiveness of EO and extracts (chloroform, ethyl acetate, and methanol) against human pathogenic bacteria and their antioxidant activity. The GC-MS analysis identified 23 components, accounting for 98.7% of the total oil containing Methylene chloride (49.2%), sabinene (10.5%), 1-nonene (11.3%), Terpinen-4-ol (6.9%), Camphene (4.3%), γ-terpinene (3.6%), α-phellandrene (2.9%) β-myrcene (2.6%), 1,2,5-Oxadiazol-3-carboxamide, 4,4′-azobis-2,2′-dioxide (2.4%), α-terpinene (1.9%), 1-Octanamine, N-methyl- (1.9%), ρ-cymene (1.6%) as major components. The antibacterial efficacy of the EO and extracts (25, 50, 100, and 200 mg/ml) was demonstrated by the inhibitory zones (8.5 ± 0.47–23.3 ± 0.36 and 7.2 ± 0.25–22.0 ± 0.45 mm), respectively. The MIC values of the extracts and the EO were 120–150 and 240 to <1100 μg/ml, respectively. The EO also demonstrated a significant antibacterial impact. The EO and methanolic extract had free radical scavenging activities with IC₅₀ value, 13.8 ± 0.48 and 4.2 ± 0.04 μg/ml, respectively. In comparison to the other extracts, the methanolic extract had the greatest phenolics (100.2 ± 0.13 μg GAE/mg of dry extract) and flavonoid contents (112.1 ± 0.18 μg CE/mg of dry extract).

DNA Barcodes for Accurate Identification of Selected Medicinal Plants (Caryophyllales): Toward Barcoding Flowering Plants of the United Arab Emirates

The need for herbal medicinal plants is steadily increasing. Hence, the accurate identification of plant material has become vital for safe usage, avoiding adulteration, and medicinal plant trading. DNA barcoding has shown to be a valuable molecular identification tool for medicinal plants, ensuring the safety and efficacy of plant materials of therapeutic significance. Using morphological characters in genera with closely related species, species delimitation is often difficult. Here, we evaluated the capability of the nuclear barcode ITS2 and plastid DNA barcodes rbcL and matK to identify 20 medicinally important plant species of Caryophyllales. In our analysis, we applied an integrative approach for species discrimination using pairwise distance-based unsupervised operational taxonomic unit “OTU picking” methods, viz., ABGD (Automated Barcode Gap Analysis) and ASAP (Assemble Species by Automatic Partitioning). Along with the unsupervised OTU picking methods, Supervised Machine Learning methods (SML) were also implemented to recognize divergent taxa. Our results indicated that ITS2 was more successful in distinguishing between examined species, implying that it could be used to detect the contamination and adulteration of these medicinally important plants. Moreover, this study suggests that the combination of more than one method could assist in the resolution of morphologically similar or closely related taxa.