Glycyrrhizin Production in Licorice Hairy Roots Based on Metabolic Redirection of Triterpenoid Biosynthetic Pathway by Genome Editing

Glycyrrhizin, a type of the triterpenoid saponin, is a major active ingredient contained in the roots of the medicinal plant licorice (Glycyrrhiza uralensis, G. glabra and G. inflata), and is used worldwide in diverse applications, such as herbal medicines and sweeteners. The growing demand for licorice threatens wild resources and therefore a sustainable method of supplying glycyrrhizin is required. With the goal of establishing an alternative glycyrrhizin supply method not dependent on wild plants, we attempted to produce glycyrrhizin using hairy root culture. We tried to promote glycyrrhizin production by blocking competing pathways using CRISPR/Cas9-based gene editing. CYP93E3 CYP72A566 double-knockout (KO) and CYP93E3 CYP72A566 CYP716A179 LUS1 quadruple-KO variants were generated, and a substantial amount of glycyrrhizin accumulation was confirmed in both types of hairy root. Furthermore, we evaluated the potential for promoting further glycyrrhizin production by simultaneous CYP93E3 CYP72A566 double-KO and CYP88D6-overexpression. This strategy resulted in a 3-fold increase (∼1.4 mg/g) in glycyrrhizin accumulation in double-KO/CYP88D6-overexpression hairy roots, on average, compared with that of double-KO hairy roots. These findings demonstrate that the combination of blocking competing pathways and overexpression of the biosynthetic gene is important for enhancing glycyrrhizin production in G. uralensis hairy roots. Our findings provide the foundation for sustainable glycyrrhizin production using hairy root culture. Given the widespread use of genome editing technology in hairy roots, this combined with gene knockout and overexpression could be widely applied to the production of valuable substances contained in various plant roots.

Disruption of a licorice cellulose synthase-derived glycosyltransferase gene demonstrates its in planta role in soyasaponin biosynthesis

KEY MESSAGE

CRISPR-Cas9-mediated disruption of a licorice cellulose synthase-derived glycosyltransferase gene, GuCSyGT, demonstrated the in planta role of GuCSyGT as the enzyme catalyzing 3-O-glucuronosylation of triterpenoid aglycones in soyasaponin biosynthesis. Triterpenoid glycosides (saponins) are a large, structurally diverse group of specialized metabolites in plants, including the sweet saponin glycyrrhizin produced by licorice (Glycyrrhiza uralensis) and soyasaponins that occur widely in legumes, with various bioactivities. The triterpenoid saponin biosynthetic pathway involves the glycosylation of triterpenoid sapogenins (the non-sugar part of triterpenoid saponins) by glycosyltransferases (GTs), leading to diverse saponin structures. Previously, we identified a cellulose synthase-derived GT (CSyGT), as a newly discovered class of triterpenoid GT from G. uralensis. GuCSyGT expressed in yeast, which could transfer the sugar glucuronic acid to the C3 position of glycyrrhetinic acid and soyasapogenol B, which are the sapogenins of glycyrrhizin and soyasaponin I, respectively. This suggested that GuCSyGT is involved in the biosynthesis of glycyrrhizin and soyasaponin I. However, the in planta role of GuCSyGT in saponin biosynthesis remains unclear. In this study, we generated GuCSyGT-disrupted licorice hairy roots using CRISPR-Cas9-mediated genome editing and analyzed the saponin content. This revealed that soyasaponin I was completely absent in GuCSyGT-disrupted lines, demonstrating the in planta role of GuCSyGT in saponin biosynthesis.

Hyperdioxanes, dibenzo-1,4-dioxane derivatives from the roots of Hypericum ascyron

Six dibenzo-1,4-dioxane derivatives (1-6) were isolated from the roots of a Hypericaceous plant Hypericum ascyron. Spectroscopic analyses revealed 2 and 4-6 to be new compounds. The partial racemic natures of 1-3 were concluded by chiral HPLC analyses, while 5 was confirmed to be a racemate. The absolute configurations 1-4 were deduced on the basis of ECD calculations. Biological activity evaluation of the dibenzo-1,4-dioxane derivatives along with two related compounds: hyperdioxanes A (7) and B (8), previously isolated from the same plant material by our group demonstrated that 7 exhibit an anti-HIV activity (IC₅₀ 5.3 μM, TI 7.2) while 8 showed an inhibitory effect on IL-1β production (inhibition rate: 72.3% at 6.3 μM) from LPS-stimulated microglial cells.

Effect of Fucoxanthinol on Pancreatic Ductal Adenocarcinoma Cells from an N-Nitrosobis(2-oxopropyl)amine-initiated Syrian Golden Hamster Pancreatic Carcinogenesis Model

BACKGROUND/AIM

Fucoxanthinol (FxOH) is a marine carotenoid metabolite with potent anti-cancer activity. However, little is known about the efficacy of FxOH in pancreatic cancer. In the present study, we investigated the inhibitory effect of FxOH on six types of cells cloned from N-nitrosobis(2-oxopropyl)amine (BOP)-induced hamster pancreatic cancer (HaPC) cells.

MATERIALS AND METHODS

FxOH action and its molecular mechanisms were investigated in HaPC cells using flow-cytometry, comprehensive gene array, and western blotting analyses.

RESULTS

FxOH (5.0 μM) significantly suppressed the growth of four out of six types of HaPC cells. Moreover, FxOH significantly suppressed cell cycle, chemokine, integrin, actin polymerization, microtubule organization and PI3K/AKT and TGF-β signals, and activated caspase-3 followed by apoptosis and anoikis induction in HaPC-5 cells.

CONCLUSION

FxOH may have a high potential as a cancer chemopreventive agent in a hamster pancreatic carcinogenesis model.

Mesorhizobium sp. J8 can establish symbiosis with Glycyrrhiza uralensis, increasing glycyrrhizin production

Licorice (Glycyrrhiza uralensis) is a medicinal plant that contains glycyrrhizin (GL), which has various pharmacological activities. Because licorice is a legume, it can establish a symbiotic relationship with nitrogen-fixing rhizobial bacteria. However, the effect of this symbiosis on GL production is unknown. Rhizobia were isolated from root nodules of Glycyrrhiza glabra, and a rhizobium that can form root nodules in G. uralensis was selected. Whole-genome analysis revealed a single circular chromosome of 6.7 Mbp. This rhizobium was classified as Mesorhizobium by phylogenetic analysis and was designated Mesorhizobium sp. J8. When G. uralensis plants grown from cuttings were inoculated with J8, root nodules formed. Shoot biomass and SPAD values of inoculated plants were significantly higher than those of uninoculated controls, and the GL content of the roots was 3.2 times that of controls. Because uninoculated plants from cuttings showed slight nodule formation, we grew plants from seeds in plant boxes filled with sterilized vermiculite, inoculated half of the seedlings with J8, and grew them with or without 100 µM KNO₃. The SPAD values of inoculated plants were significantly higher than those of uninoculated plants. Furthermore, the expression level of the CYP88D6 gene, which is a marker of GL synthesis, was 2.5 times higher than in inoculated plants. These results indicate that rhizobial symbiosis promotes both biomass and GL production in G. uralensis.

A Fucoxanthinol Induces Apoptosis in a Pancreatic Intraepithelial Neoplasia Cell

BACKGROUND/AIM

Fucoxanthinol (FxOH), a predominant metabolite from fucoxanthin (Fx), can exert potential anti-cancer effects in various cancers. However, limited data are available on the effect of FxOH or Fx on pancreatic cancer. The present study investigated the effect of FxOH on a cell line derived from pancreatic cancer tissue developed in Ptf1aCre/+; LSL-k-rasG12D/+ mice.

MATERIALS AND METHODS

Using flow-cytometric, microarrays, and western blotting analyses, alterations in FxOH-induced apoptosis-related gene expression and protein levels were evaluated in a mice pancreatic cancer cell line, KMPC44.

RESULTS

FxOH significantly arrested the cells at S phase along with suppression of many gene sets, such as cytokine- cytokine receptor interaction and cell adhesion molecule CAMS. Moreover, attenuated protein levels for cytokine receptors, adhesion, phosphatidylinositol-3 kinase/protein kinase B, and mitogen-activated protein kinase were observed.

CONCLUSION

FxOH may prevent pancreatic cancer development in a murine cancer model.

Agesasines A and B, Bromopyrrole Alkaloids from Marine Sponges Agelas spp

Exploration for specialized metabolites of Okinawan marine sponges Agelas spp. resulted in the isolation of five new bromopyrrole alkaloids, agesasines A (1) and B (2), 9-hydroxydihydrodispacamide (3), 9-hydroxydihydrooroidin (4), and 9E-keramadine (5). Their structures were elucidated on the basis of spectroscopic analyses. Agesasines A (1) and B (2) were assigned as rare bromopyrrole alkaloids lacking an aminoimidazole moiety, while 3-5 were elucidated to be linear bromopyrrole alkaloids with either aminoimidazolone, aminoimidazole, or N-methylated aminoimidazole moieties.

Linaburiosides A-D, acylated iridoid glucosides from Linaria buriatica

Four previously undescribed acylated iridoid glucosides, linaburiosides A‒D, one undescribed iridoid, 7-deoxyiridolactonic acid, and one known acylated iridoid glucoside, iridolinarin C, were isolated from the aerial parts of a Mongolian traditional herbal medicine, Linaria buriatica. Linaburiosides A‒D had an acyl moiety corresponding to 7-deoxyiridolactonic acid. Detailed spectroscopic analyses of linaburiosides A‒D and 7-deoxyiridolactonic acid led to the assignment of their structures. The absolute configuration of 7-deoxyiridolactonic acid was elucidated by application of the PGME method; those of linaburiosides A‒D were assigned on the basis of chemical conversions, as well as application of the modified Mosher's method. The absolute configuration of iridolinarin C was also elucidated in this study. Anti-inflammatory and antiproliferative activities of isolated compounds and their derivatives were evaluated.

Hyperdioxane A, a Conjugate of Dibenzo-1,4-dioxane and Sesquiterpene from Hypericum ascyron

Two new dibenzo-1,4-dioxane derivatives, hyperdioxanes A (1) and B (2), were isolated from the roots of a Hypericaceous plant, Hypericum ascyron. Hyperdioxane A (1) is a conjugate of dibenzo-1,4-dioxane and sesquiterpene with an unprecedented heptacyclic ring system. The structures of 1 and 2 were assigned by detailed spectroscopic analyses, including application of a modified Mosher's method. A possible biogenetic pathway of hyperdioxane A (1) from hyperdioxane B (2) and a sesquiterpene, eremophil-9,11(13)-dien-8β,12-olide (3), is presented.

The Basic Helix-Loop-Helix Transcription Factor GubHLH3 Positively Regulates Soyasaponin Biosynthetic Genes in Glycyrrhiza uralensis

Glycyrrhiza uralensis (licorice) is a widely used medicinal plant belonging to the Fabaceae. Its main active component, glycyrrhizin, is an oleanane-type triterpenoid saponin widely used as a medicine and as a natural sweetener. Licorice also produces other triterpenoids, including soyasaponins. Recent studies have revealed various oxidosqualene cyclases and cytochrome P450 monooxygenases (P450s) required for the biosynthesis of triterpenoids in licorice. Of these enzymes, β-amyrin synthase (bAS) and β-amyrin C-24 hydroxylase (CYP93E3) are involved in the biosynthesis of soyasapogenol B (an aglycone of soyasaponins) from 2,3-oxidosqualene. Although these biosynthetic enzyme genes are known to be temporally and spatially expressed in licorice, the regulatory mechanisms underlying their expression remain unknown. Here, we identified a basic helix-loop-helix (bHLH) transcription factor, GubHLH3, that positively regulates the expression of soyasaponin biosynthetic genes. GubHLH3 preferentially activates transcription from promoters of CYP93E3 and CYP72A566, the second P450 gene newly identified and shown to be responsible for C-22β hydroxylation in soyasapogenol B biosynthesis, in transient co-transfection assays of promoter-reporter constructs and transcription factors. Overexpression of GubHLH3 in transgenic hairy roots of G. uralensis enhanced the expression levels of bAS, CYP93E3 and CYP72A566. Moreover, soyasapogenol B and sophoradiol (22β-hydroxy-β-amyrin), an intermediate between β-amyrin and soyasapogenol B, were increased in transgenic hairy root lines overexpressing GubHLH3. We found that soyasaponin biosynthetic genes and GubHLH3 were co-ordinately up-regulated by methyl jasmonate (MeJA). These results suggest that GubHLH3 regulates MeJA-responsive expression of soyasaponin biosynthetic genes in G. uralensis. The regulatory mechanisms of triterpenoid biosynthesis in legumes are compared and discussed.

CYP716A179 functions as a triterpene C-28 oxidase in tissue-cultured stolons of Glycyrrhiza uralensis

CYP716A179, a cytochrome P450 monooxygenase expressed predominantly in tissue-cultured stolons of licorice ( Glycyrrhiza uralensis ), functions as a triterpene C-28 oxidase in the biosynthesis of oleanolic acid and betulinic acid. Cytochrome P450 monooxygenases (P450s) play key roles in the structural diversification of plant triterpenoids. Among these, the CYP716A subfamily, which functions mainly as a triterpene C-28 oxidase, is common in plants. Licorice (Glycyrrhiza uralensis) produces bioactive triterpenoids, such as glycyrrhizin and soyasaponins, and relevant P450s (CYP88D6, CYP72A154, and CYP93E3) have been identified; however, no CYP716A subfamily P450 has been isolated. Here, we identify CYP716A179, which functions as a triterpene C-28 oxidase, by RNA sequencing analysis of tissue-cultured stolons of G. uralensis. Heterologous expression of CYP716A179 in engineered yeast strains confirmed the production of oleanolic acid, ursolic acid, and betulinic acid from β-amyrin, α-amyrin, and lupeol, respectively. The transcript level of CYP716A179 was about 500 times higher in tissue-cultured stolons than in intact roots. Oleanolic acid and betulinic acid were consistently detected only in tissue-cultured stolons. The discovery of CYP716A179 helps increase our understanding of the mechanisms of tissue-type-dependent triterpenoid metabolism in licorice and provides an additional target gene for pathway engineering to increase the production of glycyrrhizin in licorice tissue cultures by disrupting competing pathways.

Hitorins A and B, Hexacyclic C25 Terpenoids from Chloranthus japonicus

Two novel C₂₅ terpenoids with a 6/5/5/5/5/3 hexacyclic skeleton including one γ-lactone ring and two tetrahydrofuran rings, hitorins A (1) and B (2), were isolated from the aerial parts of Chloranthus japonicus. The structures of 1 and 2 were elucidated on the basis of spectroscopic analyses as well as TDDFT ECD calculations. Hitorins A (1) and B (2) might be biogenetically derived from eudesmane sesquiterpene and thujane monoterpene.

RNA-seq Transcriptome Analysis of Panax japonicus, and Its Comparison with Other Panax Species to Identify Potential Genes Involved in the Saponins Biosynthesis

The Panax genus has been a source of natural medicine, benefitting human health over the ages, among which the Panax japonicus represents an important species. Our understanding of several key pathways and enzymes involved in the biosynthesis of ginsenosides, a pharmacologically active class of metabolites and a major chemical constituents of the rhizome extracts from the Panax species, are limited. Limited genomic information, and lack of studies on comparative transcriptomics across the Panax species have restricted our understanding of the biosynthetic mechanisms of these and many other important classes of phytochemicals. Herein, we describe Illumina based RNA sequencing analysis to characterize the transcriptome and expression profiles of genes expressed in the five tissues of P. japonicus, and its comparison with other Panax species. RNA sequencing and de novo transcriptome assembly for P. japonicus resulted in a total of 135,235 unigenes with 78,794 (58.24%) unigenes being annotated using NCBI-nr database. Transcriptome profiling, and gene ontology enrichment analysis for five tissues of P. japonicus showed that although overall processes were evenly conserved across all tissues. However, each tissue was characterized by several unique unigenes with the leaves showing the most unique unigenes among the tissues studied. A comparative analysis of the P. japonicus transcriptome assembly with publically available transcripts from other Panax species, namely, P. ginseng, P. notoginseng, and P. quinquefolius also displayed high sequence similarity across all Panax species, with P. japonicus showing highest similarity with P. ginseng. Annotation of P. japonicus transcriptome resulted in the identification of putative genes encoding all enzymes from the triterpene backbone biosynthetic pathways, and identified 24 and 48 unigenes annotated as cytochrome P450 (CYP) and glycosyltransferases (GT), respectively. These CYPs and GTs annotated unigenes were conserved across all Panax species and co-expressed with other the transcripts involved in the triterpenoid backbone biosynthesis pathways. Unigenes identified in this study represent strong candidates for being involved in the triterpenoid saponins biosynthesis, and can serve as a basis for future validation studies.

Prenylated benzophenones from Triadenum japonicum

Six new prenylated benzophenones, (-)-nemorosonol (1) and trijapins A-E (2-6), were isolated from the aerial parts of Triadenum japonicum. (-)-Nemorosonol (1) and trijapins A-C (2-4) have a common tricyclo[4.3.1.0(3,7)]decane skeleton, while 1 is an enantiomer of (+)-nemorosonol previously isolated from Clusia nemorosa. The absolute configuration of (-)-nemorosonol (1) was assigned by ECD spectroscopy. Trijapins A-C (2-4) are analogues of 1 possessing an additional tetrahydrofuran ring. Trijapins D (5) and E (6) are prenylated benzophenones with a 1,2-dioxane moiety and a hydroperoxy group, respectively. (-)-Nemorosonol (1) exhibited antimicrobial activity against Escherichia coli (MIC, 8 μg/mL), Staphylococcus aureus (MIC, 16 μg/mL), Bacillus subtilis (MIC, 16 μg/mL), Micrococcus luteus (MIC, 32 μg/mL), Aspergillus niger (IC50, 16 μg/mL), Trichophyton mentagrophytes (IC50, 8 μg/mL), and Candida albicans (IC50, 32 μg/mL), while trijapin D (5) showed antimicrobial activity against C. albicans (IC50, 8 μg/mL).

Variation of glycyrrhizin and liquiritin contents within a population of 5-year-old licorice (Glycyrrhiza uralensis) plants cultivated under the same conditions

Cultivated licorice plants (Glycyrrhiza uralensis FISCH.) contain smaller amounts of the triterpene saponin glycyrrhizin than wild licorice plants. To resolve this problem and to breed strains with high-glycyrrhizin content we determined the glycyrrhizin content of 100 samples of G. uralensis that were propagated from seed and grown under the same conditions in the field for 5 years. There was a 10.2-fold variation in glycyrrhizin content among these plants, ranging from 0.46 to 4.67% (average 2.11±0.90%). There was also a wide variation in liquiritin content, ranging from 0.11 to 2.65% (average 1.00±0.49%). The glycyrrhizin content was positively correlated with that of liquiritin in the taproots (r(2)=0.5525). Our results indicate that there are various genetic strains for glycyrrhizin and liquiritin synthesis within a population of plants propagated from seed. The selected high-glycyrrhizin and liquiritin strains will be useful for licorice production and studies on biosynthetic analysis of glycyrrhizin and liquiritin.

Atlantic cod trypsin-catalyzed peptide synthesis with inverse substrates as acyl donor components

Atlantic cod trypsin-catalyzed peptide synthesis has been studied by using p-amidino- and p-guanidinophenyl esters of N-(tert-butyloxycarbonyl)amino acid as acyl donor components. The reaction temperature was optimized at 0 degrees C. The method was shown to be successful as effectively for synthesizing the peptide and useful for preparing dipeptide between D-amino acid with D-amino acid and beta-amino acid with beta-amino acid, respectively. The enzymatic hydrolysis of the resulting products was negligible.

DNA polymorphisms in the tetrahydrocannabinolic acid (THCA) synthase gene in "drug-type" and "fiber-type" Cannabis sativa L

The cannabinoid content of 13 different strains of cannabis plant (Cannabis sativa L.) was analyzed. Six strains fell into the "drug-type" class, with high Delta-9-tetrahydrocannabinolic acid (THCA) content, and seven strains into the "fiber-type" class, with low THCA using HPLC analysis. Genomic DNA sequence polymorphisms in the THCA synthase gene from each strain were studied. A single PCR fragment of the THCA synthase gene was detected from six strains of "drug-type" plants. We could also detect the fragment from seven strains of "fiber-type" plants, although no or very low content of THCA were detected in these samples. These were 1638 bp from all 13 strains and no intron among the sequences obtained. There were two variants of the THCA synthase gene in the "drug-type" and "fiber-type" cannabis plants, respectively. Thirty-seven major substitutions were detected in the alignment of the deduced amino acid sequences from these variants. Furthermore, we identified a specific PCR marker for the THCA synthase gene for the "drug-type" strains. This PCR marker was not detected in the "fiber-type" strains.

Growth characteristics of Cannabis sativa L. cultivated in a phytotron and in the field

Growth characteristics of Cannabis saliva L. are indispensable factors to verify the statements by the criminals of illegal cannabis cultivation. To investigate growth characteristics of C. sativa, two varieties, cannabidiolic acid (CBDA)-rich (CBDA-type) which being cultivated for fiber production and delta9-tetrahydrocannabinolic acid (THCA)-rich (THCA-type) which is used for drug abuse, were cultivated from seeds under the same growth environment in a phytotron. THCA-type showed high germination rate (100%) whereas only 39% of the CBDA-type seeds germinated 6 days after sowing. Plant height, number of true leaves, number of nodes, number of axillary buds and flowering of these two varieties were periodically observed. THCA-type grew more rapidly (plant height: 125.8 cm for THCA-type, 84.7 cm for CBDA-type, 75 days after cultivation) demonstrating vigorous axillary bud formation and earlier male-flowering (63 days for THCA-type, 106 days for CBDA-type, after sowing). Propagation of THCA-type was tested using the axillary shoot cuttings of female plants either with or without the main stem. All the cuttings with the main stem rooted after 21 days and grew healthily in a phytotron. However, all the newly developed leaves were single instead of palmate. In the field, THCA-type male-flowered after 155 days of cultivation after sowing on March 31. The height of the field-cultivated plants reached 260.9 cm 163 days after sowing. Despite the great differences in final plant heights, the increases of plant height per day during the vegetative growth stage were similar in the field and in the phytotron. Thus estimating the starting time of illegal cannabis cultivation might be possible if the plant is in the vegetative growth stage.

DNA fingerprinting of Cannabis sativa using inter-simple sequence repeat (ISSR) amplification

Chemical analysis of cannabinoid, and Inter-Simple Sequence Repeat (ISSR) fingerprinting of DNA were used to identify different samples of Cannabis sativa L. for forensic purposes. Three samples were classified into two types, tetrahydrocannabinol (THC) and cannabidiol (CBD) chemo-types, by high performance liquid chromatography (HPLC). The two samples of the CBD type were not distinguished by their HPLC patterns. ISSR fingerprinting identified polymorphic DNA patterns between these samples. ISSR fingerprinting clearly differentiated between cannabis samples that could not be achieved by HPLC analysis.

Genetic identification of cinnamon (Cinnamomum spp.) based on the trnL-trnF chloroplast DNA

Genetic identification among cinnamon species was studied by analyzing nucleotide sequences of chloroplast DNA from four species (Cinnamomum cassia, C. zeylanicum, C. burmannii and C. sieboldii). The two regions studied were the intergenic spacer region between the trnL 3'exon and trnF exon (trnL -trnF IGS) and the trnL intron region. We found nucleotide variation at one site in the trnL-trnF IGS, and at three sites in the trnL intron. With the sequence data from analysis of these regions, the four Cinnamomum species used in this study were correctly identified. Furthermore, single-strand conformation polymorphism (SSCP) analysis of PCR products from the trnL-trnF IGS and the trnL intron resulted in different SSCP band patterns among C. cassia, C. zeylanicum and C. burmannii.