[The molecular identification of licorice species and the quality evaluation of licorice slices]

Licorice is one of the most common herbs in traditional Chinese medicine, and classified as top grade in Shen Nong Ben Cao Jing. There are three different original plants of licorice stipulated in Chinese Pharmacopeia, Glycyrrhiza uralensis Fisch., Glycyrrhiza glabra L., and Glycyrrhiza inflata Bat. However, previous investigation showed that the pharmacodynamic effects of the three licorices were quite different. It is very difficult to identify them by the classical identification methods. In order to establish a fast and effective identification method, we collected 240 licorice plants from 21 populations of 7 provinces, and amplified their ITS and psbA-trnH sequences. ITS sequences with a full length of 616 bp and psbA-trnH sequences with a full length of 389 bp were obtained separately. Using DNAMAN to analyze these sequences, 4 variable sites were found in ITS sequences and 2 ITS haplotypes were determined, and 3 variable sites were found in psbA-trnH sequences and 4 psbA-trnH haplotypes were determined. With the combination analysis of ITS and psbA-trnH sequences, the molecular identification method of original licorice was established. Using this method, 40 samples of licorice slices collected from 4 main herbal material markets in China were identified successfully. Furthermore, the contents of 2 triterpenes, 18α-glycyrrhizic acid and 18β-glycyrrhizic acid, and 4 flavonoids, liquiritin, isoliquiritin, liquiritigenin, and isoliquiritigenin in these licorice pieces were examined by HPLC and the results were analyzed using SPSS 21.0. This study provides a new method in identification of licorice, which may serve as a guideline for quality control of licorice slices.

Molecular and ecological investigations on the wild populations of Glycyrrhiza L. taxa distributed in the East Mediterranean Area of Turkey

This paper covers studies on the molecular and ecological aspects of G. glabra var. glandulifera, G. flavescens ssp. flavescens and G. echinata collected from Hatay (Turkey); with the aim to better understand their genetic variation and ecological requirements for possible conservation programs. The material including total genomic DNA was extracted by the CTAB, and for PCR reaction, a total of 14 SSR primers developed for Medicago truncatula were used. PCR amplifications were performed in a Multigen^® Thermal Cycler. Soil samples were analysed for their texture, pH, total soluble salts, calcium carbonate, total N content, total phosphorus and organic matter content. In order to see the association between genetic, ecological and geographical data, a similarity matrix was generated. Genetic similarity distances between genotypes were correlated with those of Eucledian distances obtained from ecological and geographical data. Analysis of molecular variance (AMOVA) was performed using GenAlEx 6.5 software to determine variation among and within genetic variations. The genetic analysis showed that the highest expected heterozygosity values were obtained from G. glabra while the lowest were obtained from G. echinata. In general heterozygosity values were low, especially for G. echinata. Therefore, variation appears to be lower within each species than among three species. The physical and chemical analysis of soil and plant samples indicates that mineral accumulation in plants is substantially affected by the soil characteristics. There is a need for identification of better strategies for the improvement of varieties, especially for small farmers managing marginal soils. More studies should be conducted in order to safeguard these taxa, especially G. glabra var. glandulifera which is collected intensively due to its economic value, the same is true for endemic taxon G. flavescens ssp. flavescens.

Metabolite Profiling and Classification of DNA-Authenticated Licorice Botanicals

Raw licorice roots represent heterogeneous materials obtained from mainly three Glycyrrhiza species. G. glabra, G. uralensis, and G. inflata exhibit marked metabolite differences in terms of flavanones (Fs), chalcones (Cs), and other phenolic constituents. The principal objective of this work was to develop complementary chemometric models for the metabolite profiling, classification, and quality control of authenticated licorice. A total of 51 commercial and macroscopically verified samples were DNA authenticated. Principal component analysis and canonical discriminant analysis were performed on (1)H NMR spectra and area under the curve values obtained from UHPLC-UV chromatograms, respectively. The developed chemometric models enable the identification and classification of Glycyrrhiza species according to their composition in major Fs, Cs, and species specific phenolic compounds. Further key outcomes demonstrated that DNA authentication combined with chemometric analyses enabled the characterization of mixtures, hybrids, and species outliers. This study provides a new foundation for the botanical and chemical authentication, classification, and metabolomic characterization of crude licorice botanicals and derived materials. Collectively, the proposed methods offer a comprehensive approach for the quality control of licorice as one of the most widely used botanical dietary supplements.

Species-specific Standardisation of Licorice by Metabolomic Profiling of Flavanones and Chalcones

INTRODUCTION

Major phenolics from licorice roots (Glycyrrhiza sp.) are glycosides of the flavanone liquiritigenin (F) and its 2′-hydroxychalcone isomer, isoliquiritigenin (C). As the F and C contents fluctuate between batches of licorice, both quality control and standardisation of its preparations become complex tasks.

OBJECTIVE

To characterise the F and C metabolome in extracts from Glycyrrhiza glabra L. and Glycyrrhiza uralensis Fisch. ex DC. by addressing their composition in major F–C pairs and defining the total F:C proportion.

MATERIAL AND METHODS

Three types of extracts from DNA-authenticated samples were analysed by a validated UHPLC/UV method to quantify major F and C glycosides. Each extract was characterised by the identity of major F–C pairs and the proportion of Fs among all quantified Fs:Cs.

RESULTS

The F and C compositions and proportions were found to be constant for all extracts from a Glycyrrhiza species. All G. uralensis extracts contained up to 2.5 more Fs than G. glabra extracts. Major F–C pairs were B-ring glycosidated in G. uralensis, and A-/B-ring apiosyl-glucosidated in the G. glabra extracts. The F:C proportion was found to be linked to the glycosidation site: the more B-ring F-C glycosides were present, the higher was the final F:C proportion in the extract. These results enable the chemical differentiation of extracts from G. uralensis and G. glabra, which are characterised by total F:C proportions of 8.37:1.63 and 7.18:2.82, respectively.

CONCLUSION

Extracts from G. glabra and G. uralensis can be differentiated by their respective F and C compositions and proportions, which are both useful for further standardisation of licorice botanicals.

[Classification and distribution analysis of components in Glycyrrhiza using licorice compounds database]

In order to study the chemical components of licorice deeply and systematically, a licorice compounds database was established after the comprehensive summary of the compounds in Glycyrrhiza. The database was used to classify the licorice components anew in order to statistically analyze the distribution of each type of compounds and the compounds in the medical Glycyrrhiza plants. The results indicated that 422 compounds had been reported in Glycyrrhiza so far, and they could be categorized into 5 classes as flavoids, coumarins, triterpenoids, stilbenoids, and some others. Up to now, 170 compounds were isolated from G. uralensis, 134 compounds from G. glabra, 52 compunds from G. inflata, and 31 from G. yunnanensis. It is the first time to add categorization "stilbenoids", and "dibenzoylmethanes" classified as chalcones. In the meantime, the database is supposed to be convenient for further study.

Comparative metabolite profiling and fingerprinting of medicinal licorice roots using a multiplex approach of GC-MS, LC-MS and 1D NMR techniques

Glycyrrhiza glabra, commonly known as licorice, is a popular herbal supplement used for the treatment of chronic inflammatory conditions and possesses anticancer and antiviral activities. This species contains a plethora of phytochemicals including terpenoids, saponins, flavonoids, polyamines and polysaccharides. The full complement of bioactive compounds has yet to be elucidated, a step necessary in order to explain its medicinal use. There are over 30 species in the Glycyrrhiza genus world-wide, most of which have been little characterized in terms of phytochemical or pharmacological properties. Here, large scale multi-targeted metabolic profiling and fingerprinting techniques were utilized to help gain a broader insight into Glycyrrhiza species chemical composition. UV, MS and NMR spectra of extracted components were connected with NMR, MS, and multivariate analyses data from Glycyrrhiza glabra, Glycyrrhiza uralensis, Glycyrrhiza inflata and Glycyrrhiza echinata. Major peaks in (1)H NMR and MS spectra contributing to the discrimination among species were assigned as those of glycyrrhizin, 4-hydroxyphenyl acetic acid, and glycosidic conjugates of liquiritigenin/isoliquiritigenin. Primary metabolites profiling using GC-MS revealed the presence of cadaverine, an amino acid, exclusively found in G. inflata roots. Both LC-MS and NMR were found effective techniques in sample classification based on genetic and or geographical origin as revealed from derived PCA analysis.

Identification of Glycyrrhiza species by direct analysis in real time mass spectrometry

DART (Direct Analysis in Real Time)-MS is a novel mass spectrometric ion source, and allows the analysis of most compounds at ambient pressure and ground potential by producing [M+H]+ molecular ion species. Using this method, we examined the compounds characteristic of several kinds of licorices. For the analysis of Glycyrrhiza inflata Batalin, the peak at m/z 339 originates mainly from [M+H]+ of licochalcone A (LA), a species-specific compound. This peak was hardly detected in G. glabra Linné and G. uralensis Fischer. These results indicate that G. inflata can be differentiated from the other two species by detection of LA peaks using DART-MS analysis.

[HPLC fingerprint spectrum of honey-fried Radix Glycyrrhizae]

OBJECTIVE

To establish the HPLC fingerprint of the pieces of honey-fried Radix Glycyrrhizae.

METHOD

Using the reverse-performance liquid chromatography, method was performed on a Hyperclone ODS C18 column (4.6 mm x 250 mm, 5 microm) and acetonitrile-0.1% phosphoric acid was selected as mobile phase gradient elution were adopted.

RESULT

Established HPLC fingerprint of Radix et Rhizoma glycyrrhizae pieces were established, and the results of methodological study met the technical requirements for fingerprinting.

CONCLUSION

The HPLC method is stable, accurate, and reliable to provide a scientific basis of quality control standard for the honey-fried Radix et Rhizoma glycyrrhizae.

[Classification of licorice based on inorganic elements characteristics]

The present study focused on the ecological characteristics of medicinal plants Glycyrrhiza uralensis from two typical ecological environments with two different growth patterns respectively. The authors detected the contents of 16 kinds of inorganic elements in 24 licorice samples with two different producing areas (i. e. Gansu and Inner-Mongolia) and growth patterns (i. e., wild species and the cultivated), using the methods of ICP-MS and ICP-AES after microwave-assisted digestion. With the systematic analytic methods, including the analysis of total element distribution, Q-type cluster analysis of the characteristic elements, and the comparison of element and the ratio of two elements among the samples one by one, the authors constructed the inorganic element fingerprint chromatogram of G. uralensis based on the contents of the 16 inorganic elements (K, Ca, Na, Mg, P, Ca, Cr, Mn, Fe, S, Ni, Cu, Zn, Sr, Mo and Sn). Based on the characteristic elements selected by principal component analysis, the result of Q-type cluster analysis showed consistency with the growth pattern of licorice. By comparing the differences of the inorganic elements in different samples, the authors discovered that the combination of elements Mo and Sr not only provides the bases for the growth pattern of licorice, but also can be used as a diagnostic criteria for the division of its producing area. This study also indicated that the content ratios of Na : P and K : Ca can also provide reliable references for the assessment of different production patterns. It gives insight into the differences in the inorganic element of licorice with different producing area and production pattern treatments. In conclusion, the method we founded here turned out to be intuitive, informative, and highly accurate, and can be used to reveal the characteristic of inoganic elements in medicinal plant.

[Study on the identification of standard and false Gancao by Fourier transform infrared spectroscopy]

Standard Gancao (Glycyrrhiza uralensis Fisch) and false Ciguogancao (Glycyrrhiza pallidiflata Batal) were identified fast, nondestructively by Fourier transform infrared spectroscopy (FTIR) combined with derivative spectra and two-dimensional correlation spectroscopy (2D) in the present article. The result shows that although the two kinds of Gancao belong to one genus, there are some certain differences in their chemical components that are reflected in the IR spectra, but with some similarity and dissimilarity in the IR spectra. The two kinds of Gancao are quite different from each other in second derivative spectra and 2D spectra. Based on the differences reflected in the IR and 2D IR, the standard gancao can be identified from the false easily and clearly. The result also proved that there is a relationship between the IR spectra and the chemical components of the herbs. This method is fast, accurate and nondestructive, and the wastage of sample is less. The fast, accurate property of 2D spectroscopy makes it a powerful and new approach to evaluating medicinal herbs impersonally.

[Study on circumscription of medicinal licorice species based on molecular biology]

OBJECTIVE

Elucidate the medicinal licorice species circumscription in order to develop licorice resources in China and select new cultivars.

METHOD

PCR amplification, DNA sequencing and cladistic analysis.

RESULT

Acquire the ITS sequences and phylogenetic tree of 8 licorice species.

CONCLUSION

According to results Glycyrrhiza eurycarpa and G. glabra var. glandulosa should be combined into G. and G. glabra respectively and G. egladulosa is an independent species.

[Dual-index sequence analytical method for IR fingerprint spectra of the chloroform extract of Radix Glycyrrhizae]

OBJECTIVE

To investigate a new method for the analysis of IR fingerprint spectra of Radix Glycyrrhizae.

METHOD

Two indexes, common peak ratio and variation peak ratio, are used to compare the IR spectra of various Radix Glycyrrhizae samples, and the values are calculated by means of sequent analysis.

RESULT AND CONCLUSION

The dual-index sequence method provides a good approach to discriminate Radix Glycyrrhizae samples of different species and geographical origins.

Phylogenetic Relationship of Glycyrrhiza lepidota, American Licorice, in Genus Glycyrrhiza Based on rbcL Sequences and Chemical Constituents

Two known saponins, licorice-saponin H2 and macedonoside A, were isolated from the stolons of Glycyrrhiza lepidota (American licorice) as major saponins. Since licorice-saponin H2 and macedonoside A are minor saponins isolated from the three glycyrrhizin-producing species (i.e. G. glabra, G. uralensis, G. inflata) and the three macedonoside C-producing species (i.e. G. macedonica, G. echinata, G. pallidiflora), respectively, the present study suggests that G. lepidota is an intermediate of both glycyrrhizin-producing and macedonoside C-producing species. The phylogenetic tree constructed from the nucleotide sequences of ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit gene (rbcL) of these seven Glycyrrhiza plants indicated that G. lepidota was separated from the other six Glycyrrhiza species, and this phylogenetic relationship was in accordance with their saponin compositions.

cDNA cloning and expression of isoflavonoid-specific glucosyltransferase from Glycyrrhiza echinata cell-suspension cultures

A cDNA encoding UDP-glucose: formononetin 7- O-glucosyltransferase, designated UGT73F1, was cloned from yeast extract-treated Glycyrrhiza echinata L. cell-suspension cultures using probes from Scutellaria baicalensis UDP-glucose: flavonoid 7- O-glucosyltransferase. The open reading frame of the UGT73F1 cDNA encodes a 441-amino-acid protein with a predicted molecular mass of 48.7 kDa. The deduced amino acid sequence showed that the protein is related to the stress-inducible glucosyltransferases. UGT73F1 mRNA was not detected in untreated G. echinata cultures but was transiently induced by treatment with yeast extract. Recombinant UGT73F1 was expressed as a histidine-tag fusion protein in Escherichia coli and purified to near homogeneity by nickel chelate chromatography. The purified recombinant enzyme was selective for isoflavonoid, formononetin and daidzein as substrates, while flavonoids and various tested non-flavonoid compounds were poor substrates.

[The dual-index sequence analytical method of common peak ratio and variant ratio for analysing UV fingerprint spectra of Radix Glycyrrhizae]

OBJECTIVE

To set up the dual-index sequence analytical method for UV fingerprint spectra (FPS) in which the dual indices are common peak ratio and variant ration.

METHODS

Three kinds of solvents chloroform, alcohol and water were used to extract different polarity components from Radix Glycyrrhizae, and then the UV FPS of the components were measured, which were applied to distinguish the samples.

RESULTS

This method is effective for distinguishing Radix Glycyrrhizae from inner Mongolina, Gansu and Xinjiang.

CONCLUSION

The UV-FPS dual-index sequence analytical method is feasible.

[Pharmaceutical botanical studies on some Glycyrrhiza species]

Some Glycyrrhiza species grown in several domestic research gardens of medicinal plants were collected by the Osaka University of Pharmaceutical Sciences and were cultivated to compare their morphological properties. HPLC profile analysis was performed and index compounds of MeOH extracts of aerial parts and EtOAc extracts of subterranean parts were determined. Glycyrrhizin contents and growth rates of the underground parts of some types of Glycyrrhiza uralensis and Glycyrrhiza glabra were compared and four excellent types were selected as candidates for cultivation. One of them was due to Kanzo-Yashiki (Enzan, Yamanashi prefecture), where G. uralensis was cultivated in the Edo period. Alkaloidal constituents of G. uralensis and G. glabra were also investigated and anabasine (an insecticide) and a new tricyclic alkaloid were obtained.

Field survey of Glycyrrhiza plants in Central Asia (1). Characterization of G. uralensis, G. glabra and the putative intermediate collected in Kazakhstan

The characteristics of Glycyrrhiza plants from 12 collection sites in southeastern Kazakhstan were investigated. G. uralensis was observed at 9 of the sites from Almaty to Shu, and G. glabra was observed at 8 sites. At 4 sites near Shu, and 1 site near Almaty, G. glabra and G. uralensis grew together forming a mixed population, and intermediate-type plants between them were also observed at 3 sites. Although two nucleotide substitutions of the chloroplast rbcL gene were observed between G. uralensis and G. glabra, rbcL sequences of the intermediate-types were divided into G. uralensis-type (G-A type) and G. glabra-type (A-T type). HPLC analysis of the roots indicated that species-specific flavonoids, glabridin and glycycoumarin, were detected in the roots of G. glabra and G. uralensis, respectively, but neither flavonoid was detected in underground parts of the intermediate-types. HPLC analysis of their leaves indicated a significant difference among G. uralensis, G. glabra and the intermediate-type plants. Both G. glabra-specific and G. uralensis-specific compounds were detected in the leaves of the intermediate-type, thus suggesting that the intermediate plants are hybrids of G. glabra and G. uralensis.

Field Survey of Glycyrrhiza Plants in Central Asia (3). Chemical Characterization of G. glabra Collected in Uzbekistan

The chemical characteristics of Glycyrrhiza glabra L. were investigated at a habitat in Uzbekistan. HPLC analysis of the underground parts indicated that glycyrrhizin contents varied from 3.3 to 6.1% of dry weight, and that glabridin, a species-specific flavonoid for G. glabra, was detected in all underground samples (0.08-0.35% of dry weight). HPLC analysis of the leaves indicated that G. glabra plants collected in the present study could be divided into two types, RT-type and IQ-type, according to their major flavonol glycosides, rutin or isoquercitrin, respectively.

Phylogenetic relationship of six Glycyrrhiza species based on rbcL sequences and chemical constituents

The nucleotide sequences of ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit gene (rbcL) of Glycyrrhiza glabra, G. uralensis, G. inflata, G. echinata, G. macedonica and G. pallidiflora have been determined to construct their phylogenetic tree. Based on these sequences, the six Glycyrrhiza species were divided into two groups: three, G. glabra, G. uralensis, and G. inflata, which produce glycyrrhizin as a major saponin, and the others, G. echinata, G. macedonica and G. pallidiflora, which produce macedonoside C as a major saponin. Among the three glycyrrhizin-producing species, only two nucleotide substitutions were observed between the rbcL sequences of G. glabra and G. uralensis, and the sequence of G. uralensis was identical to that of G. inflata, indicating that G. uralensis and G. inflata are closely related. Among the three macedonoside C-producing species, only one nucleotide substitution was observed between those of G. echinata and G. macedonica, indicating that these two species are also closely related.

Phylogenetic relationship of Glycyrrhiza plants based on rbcL sequences

The nucleotide sequences of the ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit gene (rbcL) of Glycyrrhiza glabra, G. uralensis, G. inflata, G. echinata, and G. pallidiflora have been determined to construct the phylogenetic tree. In the phylogenetic tree based on the rbcL sequences, the five Glycyrrhiza species were divided into two groups: the three glycyrrhizin-producing species G. glabra, G. uralensis, and G. inflata; and the two glycyrrhizin-nonproducing species G. echinata and G. pallidiflora. Among the three glycyrrhizin-producing species, only two nucleotide substitutions were observed between the rbcL sequence of G. glabra and G. uralensis, and the sequence of G. uralensis was identical to that of G. inflata, indicating that the three glycyrrhizin-producing species are closely related.

Genetic relationships among Glycyrrhiza plants determined by RAPD and RFLP analyses

The genetic similarities of four species of Glycyrrhiza plants were determined by DNA analyses of random amplified polymorphic DNA (RAPD) and restriction fragment length polymorphism (RFLP). The phylogenic trees were constructed from the genetic similarities estimated from RAPD and RFLP profiles. These results indicated that G. glabra and G. uralensis, rich in glycyrrhizin, are more closely related to each other than to G. echinata or to G. pallidiflora.

[Phenolic constituents of licorice. IV. Correlation of phenolic constituents and licorice specimens from various sources, and inhibitory effects of licorice extracts on xanthine oxidase and monoamine oxidase]

The roots and/or rhizomes of Glychyrrhiza uralensis, G. glabra and G. inflata, and commercial licorice specimens from various regions or countries were analyzed by high-performance liquid chromatography (HPLC), and classified into three types based on their phenolic constituents. i) Type A: The roots and rhizomes of G. uralensis, commercial licorice specimens from northwestern region of China (Seihoku-kanzo) and from northeastern region of China (Tohoku-kanzo) in Japanese markets, and also several licorice specimens from Chinese markets. They contain licopyranocoumarin (6), glycycoumarin (7) and/or licocoumarone (8), which were not found in G. glabra and G. inflata. ii) Type B: The root and rhizome of G. glabra, and the licorice specimens imported from the Soviet Union and Afghanistan. They contain glabridin (9) and glabrene (10), which were not found in the samples of the other two Glycyrrhiza species. A root sample of Glycyrrhiza species from Turkey also contains 9 and 10. iii) Type C: The root sample of G. inflata. They contain licochalcones A (11) and B (12), which were not found in the samples of the other two Glycyrrhiza species. Commercial licorice specimens obtained in Japan, which were imported from Sinkiang of China (Shinkyo-kanzo), and some licorice specimens obtained from Chinese markets, have also been found to contain 11 and 12. The phenolics 6-12, characteristic constituents of types A, B or C, were not found in a specimen of cortex-free licorice from a Japanese market (kawasari-kanzo). Extracts of some licorice specimens of types A and B, and all of the licorice specimens of type C inhibited 40-56% of the xanthine oxidase activity at the concentration of 30 micrograms/ml. Extracts of some licorice specimens of types A and B also showed inhibitory effects on monoamine oxidase (44-64% inhibition, at the concentration of 30 micrograms/ml), which were slightly weaker than that of harmane hydrochloride.