Product authenticity versus globalisation-The Tulsi case

Monitoring Indian "Superfood" Moringa oleifera Lam. - species-specific PCR-fingerprint-based authentication for more consumer safety

Moringa oleifera Lam. has become one of the major new superfoods commonly available in the aisles of bio-shops and health-food sections in supermarkets of North America and Europe. While most of these products appear under the generic and scientifically inconclusive term "Moringa", the European Union, so far, has allowed commercialisation for the use in food and feed for M. oleifera only. M. oleifera is indigenous to India and South Asia, but large-scale cultivation of this species has spread to the tropical regions on all continents, with a strong focus on Africa, leading to a high risk of admixture with species like M. stenopetala (Baker f.) Cufod. that is native to Africa. In the present study, we have characterised six species of Moringa in order to develop a simple and robust authentication method for commercial products. While the plants can be discriminated based on the pinnation of the leaves, this does not work for processed samples. As alternative, we use the plastidic markers psbA-trnH igs and ycf1b to discern different species of Moringa and develop a diagnostic duplex-PCR that clearly differentiates M. oleifera from other Moringa species. This DNA-based diagnostic assay that does not rely on sequencing was validated with commercial products of "Moringa" (including teas, powders, or capsules). Our method provides a robust assay to detect adulterations, which are economically profitable for costly superfood products such as "Moringa".

Development of an allele-specific PCR (AS-PCR) method for identifying high-methyl eugenol-containing purple Tulsi (Ocimum tenuiflorum L.) in market samples

BACKGROUND

Ocimum tenuiflorum L. is a highly traded medicinal with several therapeutic values. Green Tulsi and purple Tulsi are two subtypes in O. tenuiflorum and both have the same medicinal properties. Recent reports have revealed that purple Tulsi contains higher quantities of methyl eugenol (ME), which is moderately toxic and potentially carcinogenic. Therefore, we developed an allele-specific PCR (AS-PCR) method to distinguish the green and purple Tulsi.

METHODS AND RESULT

Using the green Tulsi as a reference, 12 single nucleotide polymorphisms (SNPs) and 10 insertions/deletions (InDels) were identified in the chloroplast genome of the purple Tulsi. The C > T SNP at the 1,26,029 position in the ycf1 gene was selected for the development of the AS-PCR method. The primers were designed to amplify 521 bp and 291 bp fragments specific to green and purple Tulsi, respectively. This AS-PCR method was validated in 10 accessions from each subtype and subsequently verified using Sanger sequencing. Subsequently, 30 Tulsi powder samples collected from the market were subjected to molecular identification by AS-PCR. The results showed that 80% of the samples were purple Tulsi, and only 3.5% were green Tulsi. About 10% of the samples were a mixture of both green and purple Tulsi. Two samples (6.5%) did not contain O. tenuiflorum and were identified as O. gratissimum.

CONCLUSION

The market samples of Tulsi were predominantly derived from purple Tulsi. The AS-PCR method will be helpful for quality control and market surveillance of Tulsi herbal powders.

Chloroplast genome of Ocimum basilicum var. purpurascens Bentham 1830 (Lamiaceae)

Ocimum basilicum var. purpurascens Bentham 1830 (Red Rubin Basil) is an aromatic herb belonging to the family Lamiaceae and is known for its medicinal uses. It is commonly used in traditional medicine to treat cardiovascular diseases and obesity. It possesses anti-inflammatory, antioxidant, antifungal, and anti-spasmodic properties. In our recent study, we assembled the chloroplast genome sequence of O. basilicum var. purpurascens using Illumina paired-end sequencing technology. The assembled chloroplast genome was 152,407 base pairs (bp), inclusive of a large single-copy (LSC) region accounting for 83,409 bp and a small single-copy (SSC) region spanning 17,604 bp. Two inverted repeats (IRs) interspersed these regions, each 25,697 bp long. The chloroplast genome harbored 132 genes, comprising 88 protein-coding genes, 36 transfer RNA (tRNA), and eight rRNA genes. Among these, nine genes encompassed a single intron, two presented with two introns, with the remaining devoid of any introns. The overall GC content of the chloroplast genome was determined to be 38%. The GC content in the LSC, SSC, and IR regions was 35.9%, 31.6%, and 43.1%, respectively. Our phylogenetic exploration of the chloroplast genomes elucidated that O. basilicum var. purpurascens exhibits close genetic affinity with O. basilicum var. basilicum and other constituents of the Ocimum genus within the Lamiaceae family.

DNA barcoding as new diagnostic tool to lethal plant poisoning in herbivorous mammals

Reliable identification of plant species in the digestive tract of a deceased animal often represents the major key to diagnose a lethal intoxication with poisonous plants in veterinary pathology. In many cases, identification of the species is challenging or even impossible because the diagnostic morphological features have been degraded, and because the interpretation of such features requires a considerable expertise in plant anatomy and biodiversity. The use of DNA barcoding markers can support or even replace classical morphological assessment. While these markers have been widely used for plant taxonomy, their forensic application to clarify causes of animal poisoning is novel. In addition, we use specific single-nucleotide polymorphisms as fingerprints. This allows for a clear decision even in cases, where the conventionally used statistical e-values remain ambiguous. In the current work, we explore the feasibility of this strategy in a couple of exemplary cases, either in concert with anatomical diagnostics, or in cases where visual species identification is not possible, or where chemical toxin detection methods are not well established, complex, time consuming and expensive.

Comparative Morpho-micrometric Investigations in Six Indigenous Ocimum Species of India with DOE Based HPTLC Method for Multi-class Component Analysis

The Ocimum genus is one of India's prominent botanical classes of traditional medicinal culture comprising medicinally and agronomically important plants. Morphological resemblances, overlapping geographical distribution, and history of traditional nomenclature have necessitated a comprehensive qualitative report for effective quality control and removing the species ambiguity pertaining to this genus. This paper provides detailed morpho-micrometric characteristics used to differentiate between six indigenous Ocimum species of India. Among them, O. gratissimum was distinguished as the only shrub with a fleshy petiole. In green and purple forms, O. tenuiflorum leaves had serrate margins and showed no particular anatomical differences except for the anthocyanins containing epidermal cells of the latter. O. basilicum had glabrous leaves except for the veins, which were puberulous. O. filamentosum had tenuous anther filaments and was the least aromatic while O. africanum had a citrusy odour, which along with the number of xylary rows, size of mesophyll cells, and epidermal cell wall architecture, distinguished it from O. americanum. An HPTLC method was developed using experimental design and validated for quantification of multi-class compounds from terpenoic, phenolic acids, and flavonoids in Ocimum leaves. It was found linear (r ² > 0.99) with recoveries between 95 - 100% for all compounds. The eluted bands of marker compounds were subjected to HPTLC-MS analysis as a confirmative tool. This is the first anatomical and analytical report of O. filamentosum Forssk. The obtained results could be effectively used for species identification using vegetative characters alone with the anatomical-HPTLC data backing up the former as a rapid and economical tool.

Real-time qPCR for the detection of puffer fish components from Lagocephalus in food: L. inermis, L. lagocephalus, L. gloveri, L. lunaris, and L. spadiceus

Puffer fish is a type of precious high-end aquatic product, is widely popular in Asia, especially in China and Japan, even though it naturally harbors a neurotoxin known as tetrodotoxin (TTX) that is poisonous to humans and causes food poisoning. With the increasing trade demand, which frequently exceeds existing supply capacities, fostering fraudulent practices, such as adulteration of processed products with non-certified farmed wild puffer fish species. To determine the authenticity of puffer fish processed food, we developed a real-time qPCR method to detect five common puffer fish species in aquatic products: Lagocephalus inermis, Lagocephalus lagocephalus, Lagocephalus gloveri, Lagocephalus lunaris, and Lagocephalus spadiceus. The specificity, cross-reactivity, detection limit, efficiency, and robustness of the primers and probes created for five species of puffer fish using TaqMan technology have been determined. No cross-reactivity was detected in the DNA of non-target sample materials, and no false-positive signal was detected; the aquatic products containing 0.1% of a small amount of wild puffer fish materials without certification can be reliably tracked; the statistical p-value for each method's Ct value was greater than 0.05. The developed qPCR method was sensitive, highly specific, robust, and reproducibility, which could be used to validate the authenticity of wild puffer fish in aquatic products sold for commercial purposes.

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.

A rapid, simple, and reliable assay to authenticate Peruvian kiwicha (A. caudatus) for food applications

Amaranth has acquired great economic impact as functional food, with species originating from Mexico dominating global trade. In contrast, the Peruvian A. caudatus (kiwicha) has been vastly neglected, although it is endowed with very promising nutritive traits. Morphological plasticity and taxonomic ambiguities render authentication of Amaranth difficult, such that the identity of commercial samples is often unclear. To safeguard the authenticity of kiwicha and, thus, consumer safety, we characterised a germplasm collection of 84 Amaranth accessions on both, the morphological and the genetic level. We show that kiwicha can be delineated phenotypically from other species by its late flowering, taller posture, and lower grain yields. Instead, flower and seed color, often used as proxy for identity, do not qualify as taxonomic markers. Using the plastidic barcoding marker psbA-trnH igs we were able to identify a specific Single Nucleotide Polymorphism (SNP) that separated kiwicha from all other species of Amaranth. This allowed us to develop a sequencing-free authentication assay using an Amplified Refractory Mutation System (ARMS) strategy. As a result kiwicha in commercial samples can be authenticated by a single duplex-PCR yielding a diagnostic side band reporting A. caudatus against all other species of Amaranthus. This fingerprinting assay will help to develop the nutritive potential of kiwicha and to safeguard seed material for A. caudatus against adulteration by the far more prevalent species from Mexico.

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

The potential value of DNA barcoding for the identification of medicinal plants and authentication of traded plant materials has been widely recognized; however, a number of challenges remain before DNA methods are fully accepted as an essential quality control method by industry and regulatory authorities. The successes and limitations of conventional DNA barcoding are considered in relation to important members of the Lamiaceae. The mint family (Lamiaceae) contains over one thousand species recorded as having a medicinal use, with many more exploited in food and cosmetics for their aromatic properties. The family is characterized by a diversity of secondary products, most notably the essential oils (EOs) produced in external glandular structures on the aerial parts of the plant that typify well-known plants of the basil (Ocimum), lavender (Lavandula), mint (Mentha), thyme (Thymus), sage (Salvia) and related genera. This complex, species-rich family includes widely cultivated commercial hybrids and endangered wild-harvested traditional medicines, and examples of potential toxic adulterants within the family are explored in detail. The opportunities provided by next generation sequencing technologies to whole plastome barcoding and nuclear genome sequencing are also discussed with relevant examples.

Development and Validation of RP-HPLC Method for Vicenin-2, Orientin, Cynaroside, Betulinic Acid, Genistein, and Major Eight Bioactive Constituents with LC-ESI-MS/MS Profiling in Ocimum Genus

BACKGROUND

Ocimum genus, known as Tulsi or Basil, is a prominent botanical class in Asian culture, especially in India. The leaves have immunomodulatory, antioxidant, stress-relieving, and adaptogenic roles in traditional and modern medicine, with prominent usage in herbal teas and nutraceuticals.

OBJECTIVE

An high-performance liquid chromatography-photodiode array (HPLC-PDA) method was developed and validated for quantification of vicenin-2, orientin, cynaroside, betulinic acid, genistein with syringic acid, rosmarinic acid, eugenol, carnosic acid, oleanolic acid, ursolic acid, luteolin, and apigenin and was confirmed using a novel electrospray ionisation-mass spectrometry (ESI-MS/MS) method in the Ocimum genus samples.

METHOD

The methodology parameters were developed on an reverse phase (RP) C18 column with a gradient elution of 1 mL/min flow rate for 0.1% o-phosphoric acid and acetonitrile at 210 and 340 nm wavelengths.

RESULTS

The validation data for 13 bioactive compounds showed good linearity (r2 > 0.99) with sensitive LOD (0.034-0.684 µg/mL) and LOQ (0.100-2.068 µg/mL) with recoveries (83.66-101.53%). The results of the quantification were found to be precise (RSD, <5.0%) and accurate (relative error (RE), -0.60-1.06). The method performance was verified by analyzing 10 samples of O. tenuiflorum from the 10 geographical states of India (RSD, <5.0%) and were found to be robust. This HPLC-PDA method with ESI-MS/MS confirmation was applicable to the 13 cultivars from O. thyrsiflorum, O. citriodorum, O. americanum, O. africanum, O. basilicum, O. gratissimum, and O. tenuiflorum species.

CONCLUSIONS

The validated HPLC-PDA and LC-ESI-MS/MS method was found to be selective and suitable for analyzing 13 compounds in O. tenuiflorum and 12 cultivars from the Ocimum genus as a quality control tool. This method can be used in routine analysis as an inexpensive alternative to advanced techniques.

HIGHLIGHTS

This work is the first to report for vicenin-2, orientin, cynaroside, betulinic acid, and genistein, with simultaneous analysis of eight bioactive compounds in the Ocimum genus.

Authentication of holy basil using markers relating to a toxicology-relevant compound

Holy Basil—Ocimumtenuiflorum—is one of the popular new “superfoods” thought to act as an antioxidant and to reduce stress and anxiety. However, it is often surrogated with other Ocimum species differing in their chemical profiles that may even pose health risks to the consumers. Moreover, even specific chemotypes of Holy Basil itself can be toxicologically relevant, because they sometimes contain the carcinogen compound methyleugenol. Using DNA barcoding based on plastidic markers, O.tenuiflorum can be differentiated from other species of Ocimum. However, this approach is still suboptimal in handling larger sample numbers and in tracing chemotypes that accumulate methyleugenol. We have, therefore, designed a trait-related DNA barcode based on the enzyme eugenol O-methyltransferase (EOMT), responsible for the synthesis of methyleugenol. We show that a multiplex PCR combining trait-related and trait-independent markers can differentiate O.tenuiflorum from other Ocimum species and identify methyleugenol chemotypes of O.tenuiflorum, even in dried material sold as mixtures.

Sniff Species: SURMOF-Based Sensor Array Discriminates Aromatic Plants beyond the Genus Level

Lamiaceae belong to the species-richest family of flowering plants and harbor many species that are used as herbs or in medicinal applications such as basils or mints. The evolution of this group has been driven by chemical speciation, mainly volatile organic compounds (VOCs). The commercial use of these plants is characterized by adulteration and surrogation to a large extent. Authenticating and discerning this species is thus relevant for consumer safety but usually requires cumbersome analytics, such as gas chromatography, often coupled with mass spectroscopy. Here, we demonstrate that quartz-crystal microbalance (QCM)-based electronic noses provide a very cost-efficient alternative, allowing for fast, automated discrimination of scents emitted from the leaves of different plants. To explore the range of this strategy, we used leaf material from four genera of Lamiaceae along with lemongrass, which is similarly scented but from an unrelated outgroup. To differentiate the scents from different plants unambiguously, the output of the six different SURMOF/QCM sensors was analyzed using machine learning (ML) methods together with a thorough statistical analysis. The exposure and purging of data sets (four cycles) obtained from a QCM-based, low-cost homemade portable e-Nose were analyzed using a linear discriminant analysis (LDA) classification model. Prediction accuracy with repeated test measurements reached values of up to 0%. We show that it is possible not only to discern and identify plants at the genus level but also to discriminate closely related sister clades within a genus (basil), demonstrating that an e-Nose is a powerful device that can safeguard consumer safety against dangers posed by globalized trade.

Composition of the metabolomic bio-coronas isolated from Ocimum sanctum and Rubia tinctorum

Objective

Nanoharvesting from intact plants, organs, and cultured cells is a method in which nanoparticles are co-incubated with the target tissue, which leads to the internalization of nanoparticles. Internalized nanoparticles are coated in situ with specific metabolites that form a dynamic surface layer called a bio-corona. Our previous study showed that metabolites that form the bio-corona around anatase TiO₂ nanoparticles incubated with leaves of the model plant Arabidopsis thaliana are enriched for flavonoids and lipids. The present study focused on the identification of metabolites isolated by nanoharvesting from two medicinal plants, Ocimum sanctum (Tulsi) and Rubia tinctorum (common madder).

Results

To identify metabolites that form the bio-corona, Tulsi leaves and madder roots were incubated with ultra-small anatase TiO₂ nanoparticles, the coated nanoparticles were collected, and the adsorbed molecules were released from the nanoparticle surface and analyzed using an untargeted metabolomics approach. Similar to the results in which Arabidopsis tissue was used as a source of metabolites, TiO₂ nanoparticle bio-coronas from Tulsi and madder were enriched for flavonoids and lipids, suggesting that nanoharvesting has a wide-range application potential. The third group of metabolites enriched in bio-coronas isolated from both plants were small peptides with C-terminal arginine and lysine residues.

Development of Real-Time Polymerase Chain Reaction Systems for the Detection of So-Called "Superfoods" Chia and Quinoa in Commercial Food Products

Chia (Salvia hispanica) and quinoa (Chenopodium quinoa) seeds are often referred to as a "superfood" or functional food as a result of the claims of numerous health benefits. This often resulted in a sudden increase in demand, which frequently exceeds existing supply capacities, fostering fraudulent practices, such as mislabeling and use of other species of inferior quality. To assess the authenticity of food products containing chia and quinoa, we developed real-time polymerase chain reaction systems for the detection of seeds of these plant species. The developed methodology using chia- and quinoa-specific primer-probe sets based on TaqMan technology was validated, and specificity, cross-reactivity, limit of detection, efficiency, and robustness were determined. The methods were successfully applied to 12 (chia) and 7 (quinoa) commercial samples, proving its suitability for the verification of the authenticity of chia- and quinoa-containing products in commercial trade.

Cellular Base of Mint Allelopathy: Menthone Affects Plant Microtubules

Plants can use volatiles for remote suppression of competitors. Mints produce essential oils, which are known to affect the growth of other plants. We used a comparative approach to identify allelopathic compounds from different Mints (genus Mentha, but also including Cat Mint, Nepeta cataria, and Corean Mint, Agastache rugosa, belonging to sisters clades within the Mentheae) using the standard cress germination assay as readout. To understand the mechanism behind this allelopathic effect, we investigated the response of tobacco BY-2 cell lines, expressing GFP-tagged markers for microtubules and actin filaments to these essential oils. Based on the comparison between bioactivity and chemical components, we identified menthone as prime candidate for the allelopathic effect, and confirmed this bioactivity targeted to microtubules experimentally in both, plant cells (tobaccoBY-2), and seedlings (Arabidopsis thaliana). We could show that menthone disrupted microtubules and induced mortality linked with a rapid permeabilization (less than 15 min) of the plasma membrane. This mortality was elevated in a tubulin marker line, where microtubules are mildly stabilized. Our study paves the way for the development of novel bioherbicides that would be environmentally friendly.