Search

Uridine diphosphate (UDP)-Galactose/Glucose-4-epimerase (UGE) is the third enzyme involved in the Leloir pathway. It catalyzes the conversion of UDP-Galactose to UDP-Glucose, which is a rate-limiting step for polysaccharides biosynthesis. As the main cell wall materials, polysaccharides play an irreplaceable role throughout the whole life history of plant. In this review, 1243 UGE mRNA sequences registered in NCBI were obtained and their evolutionary relationship was analyzed by constructing a neighbor-joining tree based on representative sequences. The physicochemical properties of 15 specific UGEs were analyzed, and four UGE sequences of Setaria italica, Zea mays, Ricinus Communis, and Oryza sativa were selected for further secondary structure, three-dimensional protein modeling, transmembrane structure, and signal peptide prediction analyses. The results demonstrate that UGEs are mostly conservative without signal peptides and exert activities in cytoplasm. Then, studies related to the catalytic reaction, characteristic structure, function, and regulation of UGE were summarized, which provide strong evidence that UGE plays a crucial role in cell growth, cell differentiation, cell-to-cell communication, primary metabolism, secondary metabolism, and defense responses. However, the molecular mechanisms whereby UGE regulates the plant stress resistance and useful secondary metabolites accumulation are far from clear. This paper will lay a foundation for further studies and applications of UGE.

Licorice has been used in traditional Chinese medicine for more than 2000 years. Chalcone isomerase (CHI) is the second rate-limiting enzyme involved in the biosynthetic pathway of flavonoids in licorice. The purpose of this study is to analyze the CHI gene polymorphism and identify CHI haplotypes associated with high/low flavonoid contents. Five Glycyrrhiza uralensis samples with the high flavonoids contents and five Glycyrrhiza inflate samples with low flavonoids contents were selected to clone the CHI cDNA sequences. The CHI haplotypes related to the accumulation of flavonoids were determined and induced to express in Pichia pastoris GS115. Enzymatic reactions and HPLC method were used to verify the functions of the specific CHI haplotypes. 100 CHI cDNA sequences with a full length of 690 bp were obtained and 48 haplotypes were determined. Haplotype 1 and 31 are the major haplotypes in groups with high/low flavonoids contents, respectively. CHI-1 and CHI-31 were successfully expressed and the HPLC results indicated that the catalytical activities of CHI-1 were higher than that of CHI-31. This study analyzed the gene polymorphism of CHI and determined that CHI-1 was conducive to flavonoid biosynthesis. The results of this study will provide a basis for clarifying the function of CHI and further molecular breeding of the high-quality licorice.

Liquiritin, a flavonoid, is a key medicinal ingredient in licorice (Glycyrrhiza uralensis), a commonly used herb in traditional Chinese medicine. Biosynthesis of flavonoids is a complex process that involves not only the phenylpropanoid biosynthetic pathway but also many other secondary metabolic pathways. In this study, we tried to identify the key enzymes and pathways for the biosynthesis of flavonoids in G. uralensis by analyzing the gene expression patterns in samples containing different levels of flavonoid. G. uralensis seeds were mutagenized by X-ray irradiation and samples were selected based on HPLC analysis. RNA-seq was used to examine the gene expression in two samples with high flavonoid content (H1 and H2) and one control sample (L1) with low flavonoid content. 61.37 million, 54.21 million, and 54.22 million clean reads were obtained in sample H1, H2, and L1, respectively. A total of 1875 core differentially expressed genes (DEGs) were identified. The expression patterns of core DEGs were similar in samples H1 and H2 but not in sample L1. Flavonoid metabolic pathway, terpenoid biosynthetic pathway, plant hormone signal transduction pathway, plant circadian rhythm pathway, and starch and sucrose metabolic pathway were found to play significant roles for flavonoid biosynthesis in licorice. Ten co-expressed DEGs on the five metabolic pathways were further verified by qRT-PCR, which confirmed that the RNA-Seq results were accurate and reliable. This study provides a basis for future functional genes mining and molecular regulatory mechanism elucidation of flavonoid biosynthesis in licorice.

Flavonoids are key bioactive ingredients in Glycyrrhizia uralensis, a widely used herbal medicine in China. Chalcone synthase (CHS) is the first rate-limiting enzyme involved in the flavonoid biosy...

Licorice is one of the most-frequently-used Chinese herbs. Glycyrrhizic acid (GA), as the most important marker component in licorice, is biosynthesized by mevalonic acid (MVA) pathway and regulated by many key enzymes. Among them, β-amyrin synthase (β-AS) is responsible for the triterpene skeleton formation. In this paper, we tried to find out the influence of β-AS gene polymorphism on the GA biosynthesis. The contents of 18α-glycyrrhizic acid (18α-GA) and 18β-glycyrrhizic acid (18β-GA) in 60 licorice samples were assayed by HPLC. For the β-AS gene polymorphism analysis, six samples with high GA content and seven samples with low GA content were selected. Thirteen β-AS cDNA sequences were obtained and eleven haplotypes were determined. The full length of these β-AS cDNA sequences is 2289 bp, with a complete open reading frame (ORF), encoding 762 amino acid residues. Haplotype-3 was the major haplotype in the group with high GA content, while haplotype-8 was the major haplotype in the group with low GA content. The missense mutation sites between haplotype-3 and haplotype-8 were G/C at 104 bp and 106 bp, resulting in the mutations of serine/threonine at the 35th amino acid residue site and alanine/proline at the 36th amino acid residue site. The yeast expression vectors, GS115-BAS-3 and GS115-BAS-8, containing haplotype-3 or haplotype-8 were constructed, and later transformed into Pichia pastoris GS115 by electrotransformation, respectively. The catalytic efficiency of protein BAS-3 and BAS-8 expressed in the different recombinant P. pastoris GS115 strains were analyzed by GC–MS. It was showed that compared with BAS-8, BAS-3 had a higher catalytic activity. The relative expression analysis showed that there was a positive correlation between the expression level of β-AS gene and the content of GA. We hope this paper will provide a basis for functional gene studies involved in the biosynthetic pathway of GA and high-quality cultivated licorice selection in the future.

Ethnopharmacological relevance Licorice has been commonly used in traditional Chinese medicine for treatment of gastric, liver, and respiratory disease conditions for more than two thousand years. It is a major component of several Chinese patent medicines certificated by National Medical Products Administration that possess great anticancer activities. Aim of the study To comprehensively summarize the anticancer activities of licorice flavonoids, explain the underlying molecular mechanisms, and assess their therapeutic potentials and side-effects. Methods PubMed, Research Gate, Web of Science, Google Scholar, academic journals, and Science Direct were used as information sources, with the key words of “anticancer”, “licorice”, “flavonoids”, and their combinations, mainly from 2000 to 2019. Results Sixteen licorice flavonoids are found to possess anticancer activities. These flavonoids inhibit cancer cells through blocking cell cycle and regulating multiple signaling pathways. The major pathways targeted by licorice flavonoids include: the MAPK pathway, PI3K/AKT pathway, NF-κB pathway, death receptor - dependent extrinsic signaling pathway, and mitochondrial apoptotic pathway. Conclusion Licorice flavonoids are a group of versatile molecules that have pleiotropic effects on cell growth, survival and cell signaling. Many of the flavonoids possess inhibitory activities toward cancer cell growth and hence have a great therapeutic potential in cancer treatment. However, additional preclinical studies are still needed to assess their in vivo efficacy and possible toxicities. It is also imperative to evaluate the effects of licorice flavonoids on the metabolism of other drugs and explore the potential synergistic mechanism.

Ethnopharmacological relevance A great deal of valuable experience has been accumulated in the traditional Chinese medicine (TCM) system for the treatment of “Xiaoke” disease which is known as diabetes mellitus now. As the most-commonly used Chinese herb, licorice has been used in TCM for more than two thousand years. It is often used in combination with other herbs to treat metabolic disorders, especially diabetes mellitus. Aim of the study To summarize the characteristics, mechanisms, and clinical use of licorice and its active components for treating diabetes mellitus. Methods PubMed, Web of Science, Research Gate, Science Direct, Google Scholar, and Academic Journals were used as information sources by the inclusion of the search terms ‘diabetes’, ‘licorice’, ‘licorice extracts’, ‘flavonoids’, ‘triterpenoids’, and their combinations, mainly from 2005 to 2019. Results Licorice extracts, five flavonoids and three triterpenoids isolated from licorice possess great antidiabetic activities in vivo and in vitro. This was done by several mechanisms such as increasing the appetency and sensitivity of insulin receptor site to insulin, enhancing the use of glucose in different tissues and organs, clearing away the free radicals and resist peroxidation, correcting the metabolic disorder of lipid and protein, and improving microcirculation in the body. Multiple signaling pathways, including the PI3K/Akt, AMPK, AGE-RAGE, MAPK, NF-кB, and NLRP3 signaling pathways, are targets of the licorice compounds. Conclusion Licorice and its metabolites have a great therapeutic potential for the treatment of diabetes mellitus. However, a better understanding of their pharmacological mechanisms is needed for evaluating its efficacy and safety.

The length of record (LOR) method is an evaluation method that provides quantitative advice for the amount of computational data required for use of the indicators of hydrological alteration (IHA). The use of multi-index hydrological indicators to reflect river hydrological–ecological characteristics is the essence of the IHA method, while the LOR evaluation result using a single index does not have practical application value in the absence of IHA data volume. In this paper, we expand the LOR method from single index version into multi-index version, apply it to comprehensively analyze the credibility of hydrological alteration (HA) multi-indicators under different data volumes, and explore the relationship between multi-index LOR results and data requirements. Combined with the hydrological–ecological relationship, the practical application criteria of LOR dimension reduction under the condition of multiple HA indicators is given. The results show that the LOR results corresponding to each group of indicators in IHA have different data requirements, so an in-depth understanding of the hydrological–ecological relationship is the key to LOR's application of IHA data dimension reduction. In addition, we discuss the limitations of the LOR method of multi-index dimension reduction and its application value in IHA calculations.

Licorice is a frequently-used medicinal plant worldwide. Two triterpenoids, 18α-glycyrrhizic acid (18α-GC) and 18β-glycyrrhizic acid (18β-GC), are the key medicinal components accumulated in licorice. Biosynthesis of triterpenoids is a complex process that involves many secondary metabolic pathways. In this study, we tried to identify the key enzymes and pathways for the triterpenoid biosynthesis in licorice by analyzing the gene expression patterns in samples containing different GC levels. Glycyrrhizia glabra (one of the original species used as licorice in Chinese Pharmacopoeia) seeds were irradiated by X-ray and cultivated for one year, and samples with different GC contents were selected by HPLC analysis. RNA-Seq was performed to determine the gene expression in three X-ray irradiated G. glabra samples (H1, H2, and H3) with the highest GC content and one control G. glabra sample (L1) with the lowest GC content. 28.44 Gb raw data was generated and 47.7 million, 45.4 million, 43.3 million, and 45.9 million clean reads were obtained in samples H1, H2, H3, and L1, respectively. Approximately 48.53% of genes were annotated searching against GO and KEGG databases. A total of 1376 core differentially expressed genes (DEGs) were identified, which mainly enriched in phenylpropanoid metabolism, glycometabolism, plant circadian rhythm, and terpenoid biosynthetic pathway. 15 core DEGs selected from the 1376 DEGs were further verified by qRT-PCR, which confirmed that the RNA-Seq results were accurate and reliable. This study provides a basis for future functional genes mining and molecular regulatory mechanism elucidation of triterpenoid biosynthesis in licorice.