An Integrated-Omics/Chemistry Approach Unravels Enzymatic and Spontaneous Steps to Form Flavoalkaloidal Nudicaulin Pigments in Flowers of Papaver nudicaule L.

Flower colour is an important trait for plants to attract pollinators and ensure their reproductive success. Among yellow flower pigments, the nudicaulins in Papaver nudicaule L. (Iceland poppy) are unique due to their rarity and unparalleled flavoalkaloid structure. Nudicaulins are derived from pelargonidin glycoside and indole, products of the flavonoid and indole/tryptophan biosynthetic pathway, respectively. To gain insight into the molecular and chemical basis of nudicaulin biosynthesis, we combined transcriptome, differential gel electrophoresis (DIGE)-based proteome, and ultra-performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS)-based metabolome data of P. nudicaule petals with chemical investigations. We identified candidate genes and proteins for all biosynthetic steps as well as some key metabolites across five stages of petal development. Candidate genes of amino acid biosynthesis showed a relatively stable expression throughout petal development, whereas most candidate genes of flavonoid biosynthesis showed increasing expression during development followed by downregulation in the final stage. Notably, gene candidates of indole-3-glycerol-phosphate lyase (IGL), sharing characteristic sequence motifs with known plant IGL genes, were co-expressed with flavonoid biosynthesis genes, and are probably providing free indole. The fusion of indole with pelargonidin glycosides was retraced synthetically and promoted by high precursor concentrations, an excess of indole, and a specific glycosylation pattern of pelargonidin. Thus, nudicaulin biosynthesis combines the enzymatic steps of two different pathways with a spontaneous fusion of indole and pelargonidin glycoside under precisely tuned reaction conditions.

Molecular Network-Guided Alkaloid Profiling of Aerial Parts of Papaver nudicaule L. Using LC-HRMS.

Papaver nudicaule L. (Iceland poppy) is widely used for ornamental purposes. A previous study demonstrated the alleviation of lipopolysaccharide-induced inflammation mediated by P. nudicaule extract through nuclear factor-kappa B and signal transducer and activator of transcription 3 inactivation. As isoquinoline alkaloids are chemical markers and bioactive constituents of Papaver species, the present study investigated the alkaloid profile of aerial parts of five P. nudicaule cultivars with different flower colors and a P. rhoeas cropped for two years. A combination of liquid chromatography high-resolution mass spectrometry and molecular networking was used to cluster isoquinoline alkaloids in the species and highlight the possible metabolites. Aside from the 12 compounds, including rotundine, muramine, and allocryptopine, identified from Global Natural Products Social library and reported information, 46 structurally related metabolites were quantitatively investigated. Forty-two and 16 compounds were proposed for chemical profiles of P. nudicaule and P. rhoeas, respectively. Some species-specific metabolites showed similar fragmentation patterns. The alkaloid abundance of P. nudicaule differed depending on the flower color, and the possible chemical markers were proposed. These results show that molecular networking-guided dereplication allows investigation of unidentified metabolites. The derived chemical profile may facilitate evaluation of P. nudicaule quality for pharmacological applications.

Papaver nudicaule (Iceland poppy) alleviates lipopolysaccharide-induced inflammation through inactivating NF-κB and STAT3.

BACKGROUND: Papaver nudicaule belongs to the Papaveraceae family, which is planted as an annual herbaceous species generally for ornamental purpose. Papaver rhoeas in the same family has been reported to have various pharmacological activities such as antioxidant and analgesic effects. In contrast, little is known about the pharmacological activity of Papaver nudicaule. In this study, the anti-inflammatory activity of Papaver nudicaule extracts and the action mechanisms were investigated in RAW264.7 macrophage cells. METHODS: To investigate the anti-inflammatory activity of five cultivars of Papaver nudicaule with different flower color, samples were collected from their aerial parts at two growth stages (60 and 90 days) and their ethanol extracts were evaluated in the lipopolysaccharide (LPS)-treated RAW264.7 cells by measuring nitric oxide (NO) and prostaglandin E2 (PGE2) levels. Interleukin 1-beta (IL-1ß), Interleukin-6 (IL-6) and Tumor necrosis factor alpha (TNF-α) production were also analyzed by RT-PCR and multiplex assays. Nuclear Factor-kappa-light-chain-enhancer of activated B cells (NF-κB) and Signal transducer and activator of transcription 3 (STAT3) signaling pathways were examined using western blotting and luciferase reporter assays to reveal the action mechanism of Papaver nudicaule extracts in their anti-inflammatory activity. RESULTS: All of the Papaver nudicaule extracts were effective in reducing the LPS-induced NO, which is an important inflammatory mediator, and the extract of Papaver nudicaule with white flower collected at 90 days (NW90) was selected for further experiments because of the best effect on reducing the LPS-induced NO as well as no toxicity. NW90 lowered the LPS-induced PGE2 level and decreased the LPS-induced Nitric oxide synthase 2 (NOS2) and Cyclooxygenase 2 (COX2). In addition, NW90 reduced the LPS-induced inflammatory cytokines, IL-1ß and IL-6. Furthermore, NW90 inhibited the LPS-induced activation of NF-κB and STAT3. CONCLUSIONS: These results indicate that NW90 may restrain inflammation by inhibiting NF-κB and STAT3, suggesting the potential therapeutic properties of Papaver nudicaule against inflammatory disease.

Transcriptome Profiling of Two Ornamental and Medicinal Papaver Herbs.

The Papaver spp. (Papaver rhoeas (Corn poppy) and Papaver nudicaule (Iceland poppy)) genera are ornamental and medicinal plants that are used for the isolation of alkaloid drugs. In this study, we generated 700 Mb of transcriptome sequences with the PacBio platform. They were assembled into 120,926 contigs, and 1185 (82.2%) of the benchmarking universal single-copy orthologs (BUSCO) core genes were completely present in our assembled transcriptome. Furthermore, using 128 Gb of Illumina sequences, the transcript expression was assessed at three stages of Papaver plant development (30, 60, and 90 days), from which we identified 137 differentially expressed transcripts. Furthermore, three co-occurrence heat maps are generated from 51 different plant genomes along with the Papaver transcriptome, i.e., secondary metabolite biosynthesis, isoquinoline alkaloid biosynthesis (BIA) pathway, and cytochrome. Sixty-nine transcripts in the BIA pathway along with 22 different alkaloids (quantified with LC-QTOF-MS/MS) were mapped into the BIA KEGG map (map00950). Finally, we identified 39 full-length cytochrome transcripts and compared them with other genomes. Collectively, this transcriptome data, along with the expression and quantitative metabolite profiles, provides an initial recording of secondary metabolites and their expression related to Papaver plant development. Moreover, these profiles could help to further detail the functional characterization of the various secondary metabolite biosynthesis and Papaver plant development associated problems.

Biosynthesis of Nudicaulins: A (13) CO2 -pulse/chase labeling study with Papaver nudicaule.

Nudicaulins are unique alkaloids responsible for the yellow color of the petals of some papaveraceaous plants. To elucidate the unknown biosynthetic origin of the skeleton, a (13) CO2 -pulse/chase experiment was performed with growing Papaver nudicaule plants. (13) C NMR analysis revealed more than 20 multiple (13) C-enriched isotopologues in nudicaulins from the petals of (13) CO2 -labeled plants. The complex labeling pattern was compared with the isotopologue composition of a kaempferol derivative that was isolated from petals of the same (13) CO2 -labeled plants. The deconvolution of the labeling profiles indicated that the nudicaulin scaffold is assembled from products or intermediates of indole metabolism, the phenylpropanoid pathway, and the polyketide biosynthesis. Naringenin-type compounds and tryptophan/tryptamine are potential substrates for the condensation reaction finally generating the aglycone skeleton of nudicaulins.

Ethyl Acetate Fractions of Papaver rhoeas L. and Papaver nudicaule L. Exert Antioxidant and Anti-Inflammatory Activities.

Abnormal inflammation and oxidative stress are involved in various diseases. Papaver rhoeas L. possesses various pharmacological activities, and a previously reported analysis of the anti-inflammatory effect of P. nudicaule ethanol extracts and alkaloid profiles of the plants suggest isoquinoline alkaloids as potential pharmacologically active compounds. Here, we investigated anti-inflammatory and antioxidant activities of ethyl acetate (EtOAc) fractions of P. nudicaule and P. rhoeas extracts in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. EtOAc fractions of P. nudicaule and P. rhoeas compared to their ethanol extracts showed less toxicity but more inhibitory activity against LPS-induced nitric oxide production. Moreover, EtOAc fractions lowered the LPS-induced production of proinflammatory molecules and cytokines and inhibited LPS-activated STAT3 and NF-κB, and additionally showed significant free radical scavenging activity and decreased LPS-induced reactive oxygen species and oxidized glutathione. EtOAc fractions of P. nudicaule increased the expression of HO-1, GCLC, NQO-1, and Nrf2 in LPS-stimulated cells and that of P. rhoeas enhanced NQO-1. Furthermore, metabolomic and biochemometric analyses of ethanol extracts and EtOAc fractions indicated that EtOAc fractions of P. nudicaule and P. rhoeas have potent anti-inflammatory and antioxidant activities, further suggesting that alkaloids in EtOAc fractions are potent active molecules of tested plants.

The Occurrence of Flavonoids and Related Compounds in Flower Sections of Papaver nudicaule.

Flavonoids play an important role in the pigmentation of flowers; in addition, they protect petals and other flower parts from UV irradiation and oxidative stress. Nudicaulins, flavonoid-derived indole alkaloids, along with pelargonidin, kaempferol, and gossypetin glycosides, are responsible for the color of white, red, orange, and yellow petals of different Papaver nudicaule cultivars. The color of the petals is essential to attract pollinators. We investigated the occurrence of flavonoids in basal and apical petal areas, stamens, and capsules of four differently colored P. nudicaule cultivars by means of chromatographic and spectroscopic methods. The results reveal the specific occurrence of gossypetin glycosides in the basal spot of all cultivars and demonstrate that kaempferol glycosides are the major secondary metabolites in the capsules. Unlike previous reports, the yellow-colored stamens of all four P. nudicaule cultivars are shown to contain not nudicaulins but carotenoids. In addition, the presence of nudicaulins, pelargonidin, and kaempferol glycosides in the apical petal area was confirmed. The flavonoids and related compounds in the investigated flower parts and cultivars of P. nudicaule are profiled, and their potential ecological role is discussed.

Content determination of alkaloids in different parts of Papaver nudicaule from different populations / 中草药

Objective To determine the qualitities Papaver nudicaule from different populations, a total alkaloid and three main kinds of alkaloids (reframidine, nudicauline, and amurensinine) from different parts, in order to provide a scientific basis for rational utilization and quality evaluation of P. nudicaule. Methods The qualitative and quantitative analysis of P. nudicaule has been conducted based on the method of LCMS-IT-TOF, Bromocresol green acid dye colorimetry and UPLC-MS, respectively. Results From the quantitative analysis, 13 kinds of alkaloids have been analyzed, in which eight kinds of chemical structures have been identified, and the results of quantitative analysis showed that there were greater variabilities in total alkaloid and three main kinds of alkaloids. Comprehensively, the plants grown in WLBT, HGL, and DL were better than other populations, in which the plants grown in WLBT were the best. In addition, the contents of total alkaloid and three main kinds of alkaloids were highly existed in the entire plants and flowers. Conclusion Based on the evaluation of the quality characteristics of P. nudicaule, it is suggested that total alkaloid and nudicauline can be seen as main reference indexes. Additionally, the result suggests that WLBT, HGL, and DL can be chosen to select and breed excellent quality of P. nudicaule, develop the quality standard and make layout of source area. The best harvest time should be chosen in late July to early August, and harvest site should be chosen flowers and whole plants.

Studies on harvest period for Papaver nudicaule / 中草药

Object To study the content of nudicauline in Papaver nudicaule L.from different harvest period, so as to provide the basis for development of the plant.Methods The nudicauline content in P.nudicaule was determined by HPLC with Shim-Pack CLC-ODS (4.6 mm?250 mm), mobile phase was methanol-water-diethylamine (550∶450∶0.45), detection wavelength was at 261 nm.Results The contents of nudicauline in P.nudicaule were greatly different from different harvest period, the content of nudicauline is higher in both July and Augest.Conclusion The whole plant is best harvested during July and Augest.

Analgesic sites of total alkaloids in Papaver nudicaule / 中草药

Objective To study the analgesic sites and mechanism of total alkaloids in Papaver nudicaule (TAPN). Methods The sites of analgesic action of TAPN were observed by adopting Formalin test and two different routes of intracerebroventricular (icv), intrathecal (ith) in mice and rats and comparing ED 50 of TAPN in writhing reaction in mice induced by acetic acid by ip and iv administration. Results TAPN significantly lowered pain score of the early and late phase of Formalin response and was more sensitive in the late phase. Inhibition of TAPN at the same dose by ip administration in writhing reaction in mice induced by acetic acid was stronger than that by iv. The ED 50 value of TAPN at any time by ip administration was lower than that by iv administration. By means of central microinjection, TAPN by icv administration induced remarkable analgesic effect in mice, but TAPN by ith administration had no significant analgesic effect. Conclusion The sites of analgesic action of TAPN are mainly at periphery. TAPN has also central analgesic effect, and the site may be at the level above the spinal cord.

Relationship between analgesic effect of total alkaloids in Papaver nudicaule and prostaglandins with opium receptors / 中草药

Objective To study the relationship between analgesic effect of total alkaloids in Papaver nudicaule(TAPN) and prostaglandins(PGs) with opium receptors.Methods The analgesic effect of TAPN was studied by hot-plate, writhing,electric-evoked methods of mice.The analgesic mechanisms of TAPN and PGs with opium receptors were studied by the writhing numbers induced by different substances(Ach,AA,MgSO_4),the PGE_2 level in celiac fluid in mice after treated by AA writhing test and the antagonistic experiment of Naloxone.Results The inhibitory effect of TAPN on the writhing induced by Ach and AA in mice was stronger than that induced by MgSO_4.TAPN could also lower the PGE_2 level in celiac fluid.In the antagonistic experiment of Naloxone,no antagonism to the analgesic effect of TAPN had been found by ip or icv Naloxone.Conclusion It may be the mainly peripheral analgesic mechanism that TAPN could lower the PGE_2 level in celiac fluid.Its central analgesic mechanisms are not related to opium receptors.