Metabolic and transcriptomic analyses elucidate a novel insight into the network for biosynthesis of carbohydrate and secondary metabolites in the stems of a medicinal orchid Dendrobium nobile

Dendrobium nobile is an important medicinal and nutraceutical herb.Although the ingredients of D.nobile have been identified as polysaccharides,alkaloids,amino acids,flavonoids and bibenzyls,our understanding of the metabolic pathways that regulate the synthesis of these compounds is limited.Here,we used transcriptomic and metabolic analyses to elucidate the genes and metabolites involved in the biosynthesis of carbohydrate and several secondary metabolites in the stems of D.nobile.A total of 1005 metabolites and 31,745 genes were detected in the stems of D.nobile.The majority of these metabolites and genes were involved in the metabolism of carbohydrates(fructose,mannose,glucose,xylulose and starch),while some were involved in the metabolism of secondary metabolites(alkaloids,β-tyrosine,ferulic acid,4-hydroxybenzoate and chrysin).Our predicted regulatory network indicated that five genes(AROG,PYK,DXS,ACEE and HMGCR) might play vital roles in the transition from carbohydrate to alkaloid synthesis.Correlation analysis identified that six genes(ALDO,PMM,BGLX,EGLC,XYLB and GLGA) were involved in carbohydrate metabolism,and two genes(ADT and CYP73A) were involved in secondary metabolite biosynthesis.Our analyses also indicated that phosphoenol-pyruvate(PEP) was a crucial bridge that connected carbohydrate to alkaloid biosynthesis.The regulatory network between carbohydrate and secondary metabolite biosynthesis established will provide important insights into the regulation of metabolites and biological systems in Dendrobium species.

Protective effects of Dendrobium nobile Lindl. alkaloids on amyloid beta(25–35)-induced neuronal injury

Dendrobium nobile Lindl.alkaloids（DNLA）,the active ingredients of a traditional Chinese medicine Dendrobium,have been shown to have anti-oxidative effects,anti-inflammatory action,and protective effect on neurons against oxygen-glucose deprivation.However,it is not clear whether DNLA reduces amyloid-beta（Aβ）-induced neuronal injury.In this study,cortical neurons were treated with DNLA at different concentrations（0.025,0.25,and 2.5 mg/L）for 24 hours,followed by administration of Aβ（25-35）（10μM）.Aβ（25-35） treatments increased cell injury as determined by the leakage of lactate dehydrogenase,which was accompanied by chromatin condensation and mitochondrial tumefaction.The damage caused by Aβ（25-35） on these cellular properties was markedly attenuated when cells were pretreated with DNLA.Treatment with Aβ（25-35）down-regulated the expressions of postsynaptic density-95 mRNA and decreased the protein expression of synaptophysin and postsynaptic density-95,all changes were significantly reduced by pretreatment of cells with DNLA.These findings suggest that DNLA reduces the cytotoxicity induced by Aβ（25-35） in rat primary cultured neurons.The protective mechanism that DNLA confers on the synaptic integrity of cultured neurons might be mediated,at least in part,through the upregulation of neurogenesis related proteins synaptophysin and postsynaptic density-95.

A New Dendrobine-Type Alkaloid from Dendrobium nobile

A new dendrobine-type alkaloid has been isolated from stems of Dendrobium nobile lindl.. Its structure has been identified on the basis of spectroscopic method.

Influence of light intensity and water content of medium on total dendrobine of Dendrobium nobile Lindl

Objective: To ascertain the influence of light intensity and water content of medium on the total dendrobine of Dendrobium nobile(D. nobile).Method: The principal component analysis combined with total dendrobine accumulation was conducted to assess the yield and quality of D. nobile in all treatments. In the experiment, D. nobile plants were cultivated in greenhouse as tested materials, and complete test of 9 treatments was adopted with relative light intensities 75.02%, 39.74%,29.93% and relative water content of medium 50%, 65%, 80%. The plants were treated in June and harvested till December. Indexes including agronomic traits, fresh weight and dry weight of stem and leaf, ash content, extract, and dendrobine were measured.Results: Under the light intensity treatments of 75.02% with 50%, 65%, 80% water content of medium, the basal stems of plants were comparatively thicker with more leaves, and the fresh weight and dry weight of stems and leaves were significantly higher than other 6 treatments.Leaves in all treatments contained dendrobine. Under the light intensity treatments of 75.02%with 50%, 65%, 80% water content of medium, dendrobine content of leaves was lower while dendrobine contents of other treatments were more than 0.60%. After comprehensive assessment through the principal component analysis and total dendrobine accumulation, the results showed that 3 treatments with relative light intensity of 75.02% ranked the top three.Conclusions: In brief, the moderately strong light intensity and water content of medium from low to medium can facilitate the growth and yield of D. nobile plants, while light intensity from moderately weak to weak can enhance the dendrobine content.

Extraction Process Optimization and Anti-oxidant Activity of Total Flavonoids in Dendrobium nobile Lindl.

[Objectives]To improve the yield of flavonoids from Dendrobium nobile Lindl.[Methods]On the basis of four single-factor experiments of solid/liquid ratio,extraction temperature,extraction time and ethanol volume fraction,the ultrasonic-assisted extraction process of total flavonoids from D.nobile Lindl.was optimized using quadratic general rotary unitized design,and the in-vitro anti-oxidant activity of the flavonoids extracted was evaluated preliminarily.[Results]The optimized extraction process for flavonoids in D.nobile Lindl.was as follows:extraction time 10 min,solid/liquid ratio 1∶15(g∶mL),extraction temperature 75℃and ethanol volume fraction 90%.According to the revised optimal process,6 repeated experiments were carried out,and the average yield of flavonoids was(0.5515±0.0004)mg/g,consistent with the predicted value of the model.The results of anti-oxidation experiment show that the flavonoids extracted from D.nobile Lindl.have better scavenging effect on ABTS and DPPH free radicals,and the scavenging activity is proportional to the mass concentration of the extract.[Conclusions]The optimized extraction process for flavonoids from D.nobile Lindl.is reasonable and feasible,and the flavonoids in D.nobile Lindl.have strong antioxidant activity.

Dendrobium nobile Lindl:A Review on Its Chemical Constituents and Pharmacological Effects

Dendrobium nobile Lindl (D. nobile), a well-known precious herb, has a long history of use as a medicine and health food in China. Phytochemically, D. nobile has been found to contain various bioactive compounds, such as alkaloids, bibenzyl, phenanthrene, phenylpropanoids, and polysaccharides. Its medicinal applications are closely correlated to its diverse pharmacological activities, including antitumor, anti-inflammatory, nervous system protective, antifatigue, hypoglycemic, and hypolipidemic actions. In this review, we provide a comprehensive summary of the main chemical constituents and pharmacological activities of D. nobile, as well as the underlying molecular mechanisms for its bioactivities. It is expected that this review will provide a helpful scientific reference for the development and use of D. nobile.

Dendrobium nobile protects against ovalbumin-induced allergic rhinitis by regulating intestinal flora and suppressing lung inflammation

Antibiotic exposure-induced dysbiosis of the intestinal flora increases the risk of developing allergic rhinitis.Hence,regulating the balance of intestinal flora may be useful for preventing and treating allergic rhinitis.However,the underlying mechanism is unclear.Dendrobium nobile(Shihu)exhibits anti-inflammatory and immune activities.Hence,in this study,we investigated the mechanism via which Shihu may improve allergic rhinitis.Mouse models of allergic rhinitis with intestinal flora dysbiosis(Model-D,antibiotics induce intestinal flora dysbiosis with ovalbumin-induced allergy)and normal intestinal flora with allergic rhinitis(Model-N,ovalbumin-induced allergy)were established.The effect of Shihu on intestinal flora and inflammation caused during allergic rhinitis were analyzed.Allergic symptoms,infiltration of hematoxylin and eosin in the lungs and nose,and the release of various factors[interleukin(IL)-2,IL-4,IFN-y,IL-6,IL-10,and IL-17]in the lungs were evaluated.The results indicate that intestinal flora dysbiosis exacerbated lung and nose inflammation in allergic rhinitis.However,treatment with the Shihu extract effectively reversed these symp-toms.Besides,the Shihu extract inhibited the PI3K/AXT/mTOR pathway and increased the level of Forkhead box protein in the lungs.Additionally,the Shihu extract reversed intestinal flora dysbiosis at the phylum and genus levels and improved regulator T cell differentiation.Furthermore,in the Model-D group,the Shihu extract inhibited the decrease in the diversity and abundance of the intestinal flora.Screening was performed to determine which intestinal flora was positively correlated with Treg differentiation using Spearman5 s correlation analysis.In conclusion,we showed that Shihu extract restored the balance in intestinal flora and ameliorated inflammation in the lungs of allergic rhinitis mice and predicted a therapeutic new approach using Traditional Chinese Medicine to improve allergic rhinitis.

Interaction between a Dark Septate Endophytic Isolate from Dendrobium sp. and Roots of D. nobile Seedlings

Interactions between an isolate of dark septate endophytes （DSE） and roots of Dendrobium nobile Lindl. seedlings are reported in this paper. The isolate was obtained from orchid mycorrhizas on Dendrobium sp. in subtropical forest. The fungus formed typical orchid mycorrhiza in aseptic co-culture with D. nobile seedlings on modified Murashige-Skoog （MMS） medium. Anatomic observations of the infected roots showed that the DSE hyphae invaded the velamen layer, passed through passage cells in exodermis, entered the cortex cells, and then formed fungal pelotons of orchid mycorrhiza. D. nobile seedlings＇ plant height, stem diameter, new roots number and biomass were greatly enhanced by inoculating the fungus to seedlings. The fungus was identified as Leptodontidium by sequencing the polymerase chain reaction-amplified rDNA ITS1-5,8S-ITS2 （internal transcribed spacer （ITS）） regions and comparison with similar taxa.

不同施肥处理对金钗石斛光合特性的影响

以贵州省赤水市金钗石斛(Dendrobium nobile Lindl)苗为试验材料,通过不同施肥处理进行单因素分析和正交试验,采用Li-6400型便携式光合作用测量系统(Li-Cor,USA),对金钗石斛光合特性的有关参数进行测试。结果表明,施用Hoaglan营养液能有效改善金钗石斛的净光合速率,光合速率的快慢与金钗石斛气孔导度呈正相关,气孔导度日变化与蒸腾速率日变化有直接关系,所有因子中钾肥对净光合速率、蒸腾速率影响较大,均达显著水平,而影响气孔导度的是氮肥,生产中应合理施用钾肥、氮肥。