Molecular authentication of the Oriental medicines Pericarpium Citri Reticulatae and Citri Unshius Pericarpium using SNP markers

Recent advances in the authentication (geographical origins, varieties and aging time) of tangerine peel (Citri reticulatae pericarpium): A review

The consumption of tangerine peel (Citri reticulatae pericarpium, CRP) has been steadily increasing worldwide due to its proven health benefits and sensory characteristics. However, the price of CRP varies widely based on its origin, variety, and aging time, which has led many manufacturers to offer inferior products by exploiting the sensory similarity of CRP, seriously undermining consumers' interests. Therefore, it is essential to identify the authenticity of the CRP. In this study, the research progress on the authenticity of CRP from different origins, years and varieties over the past 10 years and the application and prospects of the main technologies and techniques were reviewed. The advantages and disadvantages of the commonly used methods were also summarized and compared. Mass spectrometry-based and spectroscopy-based techniques are the most commonly used methods for analyzing CRP authenticity. However, designing fast, non-destructive and green methods for identifying CRP authenticity would be the future trend.

A specific SNP-based multiplex PCR assay for the simultaneous identification of two biological ingredients for the Chinese patent medicine, Danggui Buxue pill

Background: An increasing number of Chinese patent medicines (CPM) have been widely used in East Asian and North American countries, and the safety and efficacy of CPM have highly attracted public attention. However, it is difficult to supervise the authenticity of multiple biological ingredients within CPM based on microscopic inspection and physical and chemical detection. The raw materials may have similar characteristics of tissue structures and ergastic substances or similar chemical composition and contents when substitutes and/or adulterants are added. DNA molecular markers have been used to distinguish the biological ingredients within CPM based on conventional PCR assay. However, it was proved to be time- and labor-consuming and reagent-wasting, as multiple PCR amplification strategies were required for identifying the complex species composition within CPM. Here, we took the CPM (Danggui Buxue pill) as an example and aimed to establish a specific SNP-based multiplex PCR assay and simultaneously determine the authenticity of the two biological ingredients (Angelicae Sinensis Radix and Astragali Radix) within this CPM. Methods: We, respectively, designed the species-specific primers based on highly variable nrITS for discriminating Angelicae Sinensis Radix and Astragali Radix from their common substitutes and adulterants. The specificity of the primers was checked through conventional PCR assay and multiplex PCR assay. Furthermore, we used a handcrafted Danggui Buxue pill sample (DGBXP) to optimize annealing temperatures for the primers with multiplex PCR, and the sensitivity was also assessed. Finally, fourteen batches of commercial Danggui Buxue pills were used to verify the stability and practicability of the established multiplex PCR assay. Results: Two pairs of highly species-specific primers for amplifying Angelicae Sinensis Radix and Astragali Radix were screened, and our established multiplex PCR assay showed high specificity and sensitivity (lowest detection concentration: 4.0 × 10^-3 ng/μL) at an optimal annealing temperature of 65°C. The method could simultaneously identify both biological ingredients within the Danggui Buxue pill. Conclusion: The specific SNP-based multiplex PCR provided a simple, time-, and labor-saving method for the simultaneous identification of the two biological ingredients within Danggui Buxue pills. This study was expected to provide a novel qualitative quality control strategy for CPM.

Rapid Discrimination of Citrus reticulata 'Chachi' by Electrospray Ionization-Ion Mobility-High-Resolution Mass Spectrometry

A common idea is that some dishonest businessmen often disguise Citrus reticulata Blanco varieties as Citrus reticulata 'Chachi', which places consumers at risk of economic losses. In this work, we combined high-resolution ion mobility (U-shaped mobility analyzer) with high-resolution mass spectrometry to rapidly distinguish Citrus reticulata 'Chachi' from other Citrus species. The samples were analyzed directly through simple extraction and the analytes were separated in one second. It only took about 1 min to perform a cycle of sample analysis and data acquisition. The results showed that polymethoxylated flavones and their isomers were separated easily by the ion mobility analyzer and preliminarily identified according to the accurate mass. Moreover, the collision cross-section values of all analytes, which could be used as auxiliary parameters to characterize and identify the compounds in the samples, were measured. Twenty-four samples were grouped as two clusters by multivariate analysis, which meant that Citrus reticulata 'Chachi' could be effectively differentiated. It was confirmed that the developed method had the potential to rapidly separate polymethoxylated flavones and distinguish between Citrus reticulata 'Chachi' and other Citrus reticulata Blanco varieties.

Molecular and morphological discrimination of Chrysanthemum indicum using allele-specific PCR and T-shaped trichome

Chrysanthemum indicum L. is a traditional oriental medicinal herb prepared as a tea from flowers that have been used in China and South Korea since ancient times. It has a long history in the treatment of hypertension, inflammation, and respiratory diseases. Among Chrysanthemum species, C. indicum has more active chemical components as well as better therapeutic effects, and C. indicum is mostly used for medicinal purposes in South Korea. However, the usage of C. indicum has become problematic over the years due to the abundance of adulterated Chrysanthemum and confusion with morphologically related species such as C. morifolium, C. boreale, and Aster spathulifolius. Thus, here we developed a method for molecular authentication using chloroplast universal region rpoC2 and morphological authentication based on T-shaped trichomes of the adaxial leaf surface. By using a species-specific primer derived from the rpoC2 region, we established a multiplex allele-specific PCR for the discrimination of C. indicum. Amplicons of 675 bp for C. indicum and 1026 bp for other Chrysanthemum species were produced using both rpoC2-specific and common primers. These primers can be used to analyze dried samples of Chrysanthemum. Morphological discrimination was performed using T-shaped trichomes present only on the adaxial leaf surface of C. indicum species, and then molecular markers were utilized to authenticate C. indicum products from adulterant samples available in the market. Our results indicate that these molecular markers in combination with morphological differentiation can serve as an effective tool for identifying C. indicum.

Identification and Monitoring of Amomi Fructus and its Adulterants Based on DNA Barcoding Analysis and Designed DNA Markers

Amomi Fructus is one of the traditional medicines derived from the ripe fruits of the Zingiberaceae family of plants, which include Amomum villosum, A. villosum var. xanthioides, and A. longiligulare. Owing to their highly similar morphological traits, several kinds of adulterants of Amomi Fructus have been reported. Therefore, accurate and reliable methods of identification are necessary in order to ensure drug safety and quality. We performed DNA barcoding using five regions (ITS, matK, rbcL, rpoB, and trnL-F intergenic spacer) of 23 Amomi Fructus samples and 22 adulterants. We designed specific DNA markers for Amomi Fructus based on the single nucleotide polymorphisms (SNPs) in the ITS. Amomi Fructus was well separated from the adulterants and was classified with the species of origin based on the detected SNPs from the DNA barcoding results. The AVF1/ISR DNA marker for A. villosum produced a 270 bases amplified product, while the ALF1/ISF DNA marker produced a 350 bases product specific for A. longiligulare. Using these DNA markers, the monitoring of commercially distributed Amomi Fructus was performed, and the monitoring results were confirmed by ITS analysis. This method identified samples that were from incorrect origins, and a new species of adulterant was also identified. These results confirmed the accuracy and efficiency of the designed DNA markers; this method may be used as an efficient tool for the identification and verification of Amomi Fructus.

Molecular authentication of sika deer (Cervus nippon) based on allele-specific PCR

Sika deer (Cervus nippon) is listed as a tonic in many ancient Chinese pharmaceutical. Many adulterants of sika deer products have been found in Chinese medicinal materials markets, which led to detrimental impacts in clinical treatment. However, it is lack of the rapid and effective identification method for sika deer. This study amplified 574 bp fragment of mtDNA COI region of 19 samples from seven Cervidae species, and the relevant five sequences from reindeer (Rangifer tarandus) were downloaded from GenBank. It was found that there were two SNP loci for sika deer. Phylogenetic analysis indicated that individuals from sika deer clustered together. Based on SNP locus, one pair specific primer for allele-specific PCR identification of sika deer was designed, which could be used to rapidly and accurately identify sika deer.

Morphology and Molecular Identification of Twelve Commercial Varieties of Kiwifruit

The quality and safety of food are important guarantees for the health and legal rights of consumers. As an important special fruitcrop, there are frequently shoddy practices in the kiwifruit (Actinidia chinensis) market, which harms the interests of consumers. However, there is lack of rapid and accurate identification methods for commercial kiwifruit varieties. Here, twelve common commercial varieties of kiwifruit were morphologically discriminated. DNA barcodes of chloroplast regions psbA-trnH, rbcL, matK, rpoB, rpoC1, ycf1b, trnL and rpl32_trnL(UAG), the nuclear region At103 and intergenic region ITS2 were amplified. Divergences and phylogenetic trees were used to analyze the phylogenetic relationship of these twelve commercial kiwifruit varieties. The results showed that matK, ITS2 and rpl32_trnL(UAG) can be utilized as molecular markers to identify CuiYu, JinYan, HuangJinGuo, ChuanHuangJin, HuaYou, YaTe, XuXiang and HongYang. This provides experimental and practical basis to scientifically resolve kiwifruit-related judicial disputes and legal trials.

Chemical and genetic discrimination of commercial Guangchenpi (Citrus reticulata ‘Chachi’) by using UPLC-QTOF-MS/MS based metabolomics and DNA barcoding approaches

CRP (Citri Reticulatae Pericarpium), a famous traditional Chinese medicine, has also been extensively used in foods and condiments in dietary practice for centuries. According to the Chinese Pharmacopeia (2015 edition) it contains two subtypes, Guangchenpi (GCP) and Chenpi (CP). GCP exclusively originates from the pericarp of Citrus reticulata ‘Chachi’ cultivar and it's generally believed that GCP has superior qualities compared with the other main cultivars (CP). In the present study, an integrated approach combining LC-QTOF MS-based untargeted metabolomics analysis and DNA barcoding molecular identification was conducted to study the genetic diversity and chemical differences between GCP and CP. A validated UPLC-QTOF MS metabolomics method was established to identify markers by using PCA and OPLS-DA models. 34 identified metabolites could be used as chemical markers to distinguish effectively between the two subtypes. Among them polymethoxyflavones (PMF) such as hexamethoxyflavone (nobiletin and natsudaidain), pentamethoxyflavone (tangeretin and sinensetin), and tetramethoxyflavone are the most influential markers. Support vector machines were employed to classify all the samples and these markers showed good prediction accuracy (100%). The results of DNA barcoding showed that the secondary structure of the ITS2 sequences were significantly different among GCP and other three cultivars. The study indicated the integrated method could be a powerful and reliable analytical tool for differentiating GCP from CP.

An integrated method, combining DNA barcoding with LC-MS metabolomics analysis, is a powerful and reliable way for differentiating Citrus reticulata ‘Chachi’ (GCP) from other Citrus cultivars.

Molecular authentication and quantitative analysis of Sarcandra glabra and adulterated chloranthus products using SNP markers

BACKGROUND

Sarcandra glabra (Thunb.) Nakai is one of the most popular and valuable plant species in the oriental medicinal herb market. Chloranthus (Chloranthaceae) species are the most widely used adulterants, but they are known to have hepatotoxicity effects and different medicinal values.

OBJECTIVE

The aim of this study is to develop a robust and accurate DNA marker for the qualitative and quantitative analyses of their products.

MATERIALS AND METHODS

Four single nucleotide polymorphism (SNP) sites specific to Sarcandra glabra, Chloranthus spicatus, Chloranthus serratus and Chloranthus henryi were exploited from the trnL-F region in chloroplast DNA, which have a higher copy number in the products than the nuclear DNA. Based on the SNP sites, specific primers were designed to identify the products of Sarcandra glabra, Chloranthus spicatus, Chloranthus serratus and Chloranthus henryi in mixed solutions via multiplexed PCR. The primers were also used to quantitatively analyse the ratio of chloroplast DNA in the mixed products using real-time PCR.

RESULTS

The established multiplexed-PCR and real-time PCR methods were determined to be effective for the authentication and relative quantitative assessments of the products of Sarcandra glabra, its adulterants, and their mixtures.

CONCLUSION

We therefore present an effective method for monitoring the quality of these products.

SNP typing for germplasm identification of Amomum villosum Lour. Based on DNA barcoding markers

Amomum villosum Lour., produced from Yangchun, Guangdong Province, China, is a Daodi medicinal material of Amomi Fructus in traditional Chinese medicine. This herb germplasm should be accurately identified and collected to ensure its quality and safety in medication. In the present study, single nucleotide polymorphism typing method was evaluated on the basis of DNA barcoding markers to identify the germplasm of Amomi Fructus. Genomic DNA was extracted from the leaves of 29 landraces representing three Amomum species (A. villosum Lour., A. xanthioides Wall. ex Baker and A. longiligulare T. L. Wu) by using the CTAB method. Six barcoding markers (ITS, ITS2, LSU D1–D3, matK, rbcL and trnH-psbA) were PCR amplified and sequenced; SNP typing and phylogenetic analysis were performed to differentiate the landraces. Results showed that high-quality bidirectional sequences were acquired for five candidate regions (ITS, ITS2, LSU D1–D3, matK, and rbcL) except trnH-psbA. Three ribosomal regions, namely, ITS, ITS2, and LSU D1–D3, contained more SNP genotypes (STs) than the plastid genes rbcL and matK. In the 29 specimens, 19 STs were detected from the combination of four regions (ITS, LSU D1–D3, rbcL, and matK). Phylogenetic analysis results further revealed two clades. Minimum-spanning tree demonstrated the existence of two main groups: group I was consisting of 9 STs (ST1–8 and ST11) of A. villosum Lour., and group II was composed of 3 STs (ST16–18) of A. longiligulare T.L. Wu. Our results suggested that ITS and LSU D1–D3 should be incorporated with the core barcodes rbcL and matK. The four combined regions could be used as a multiregional DNA barcode to precisely differentiate the Amomi Fructus landraces in different producing areas.

Convenient, sensitive and high-throughput method for screening botanic origin

In this work, a rapid (within 4–5 h), sensitive and visible new method for assessing botanic origin is developed by combining loop-mediated isothermal amplification with cationic conjugated polymers. The two Chinese medicinal materials (Jin-Yin-Hua and Shan-Yin-Hua) with similar morphology and chemical composition were clearly distinguished by gene SNP genotyping assays. The identification of plant species in Patented Chinese drugs containing Lonicera buds is successfully performed using this detection system. The method is also robust enough to be used in high-throughput screening. This new method is very helpful to identify herbal materials, and is beneficial for detecting safety and quality of botanic products.

DNA barcoding of medicinal plant material for identification

Because of the increasing demand for herbal remedies and for authentication of the source material, it is vital to provide a single database containing information about authentic plant materials and their potential adulterants. The database should provide DNA barcodes for data retrieval and similarity search. In order to obtain such barcodes, several molecular methods have been applied to develop markers that aid with the authentication and identification of medicinal plant materials. In this review, we discuss the genomic regions and molecular methods selected to provide barcodes, available databases and the potential future of barcoding using next generation sequencing.