Structural characterization and improves cognitive disorder in ageing mice of a glucomannan from Dendrobium huoshanense

In the present work, a neutral polysaccharide (DHP-2W) with attenuating cognitive disorder was identified from Dendrobium huoshanense and its structure was clarified. The polysaccharide was successfully purified from D. huoshanense by column chromatography and its activity was evaluated. With a molecular weight of 508.934kDa, this polysaccharide is composed of mannose and glucose at a molar ratio of 75.81: 24.19. Structural characterization revealed that DHP-2W has a backbone consisting of 4)-β-D-Manp-(1 and 4)-β-D-Glcp-(1. In vivo experiments revealed that DHP-2W improved cognitive disorder in D-galactose treated mice and relieved oxidative stress and inflammation. DHP-2W attenuates D-galactose-induced cognitive disorder by inhibiting the BCL2/BAX/CASP3 pathway and activating the AMPK/SIRT pathway, thereby inhibiting apoptosis. Furthermore, DHP-2W had a significant effect on regulating the serum levels of Flavin adenine dinucleotide, Shikimic acid, and Kynurenic acid in aged mice. These, in turn, had a positive impact on AMPK/SIRT1 and BCL2/BAX/CASP3, resulting in protective effects against cognitive disorder.

Identification of Dof transcription factors in Dendrobium huoshanense and expression pattern under abiotic stresses

Introduction: DNA-binding with one finger (Dof) transcription factors (TFs) are a unique family of TFs found in higher plants that regulate plant responses to light, hormones, and abiotic stresses. The specific involvement of Dof genes in the response to environmental stresses remains unknown in D. huoshanense. Methods: A total of 22 Dof family genes were identified from the D. huoshanense genome. Results: Chromosome location analysis showed that DhDof genes were distributed on 12 chromosomes, with the largest number of Dof genes located on chromosome 8. The phylogenetic tree revealed that DhDofs could be categorized into 11 distinct subgroups. In addition to the common groups, DhDof4, DhDof5, DhDof17, and the AtDof1.4 ortholog were clustered into the B3 subgroup. Group E was a newly identified branch, among which DhDof6, DhDof7, DhDof8, and DhDof9 were in an independent branch. The conserved motifs and gene structure revealed the differences in motif number and composition of DhDofs. The dof domain near the N-terminus was highly conserved and contained a C2-C2-type zinc finger structure linked with four cysteines. Microsynteny and interspecies collinearity revealed gene duplication events and phylogenetic tree among DhDofs. Large-scale gene duplication had not occurred among the DhDofs genes and only in one pair of genes on chromosome 13. Synteny blocks were found more often between D. huoshanense and its relatives and less often between Oryza sativa and Arabidopsis thaliana. Selection pressure analysis indicated that DhDof genes were subject to purifying selection. Expression profiles and correlation analyses revealed that the Dof gene under hormone treatments showed several different expression patterns. DhDof20 and DhDof21 had the highest expression levels and were co-expressed under MeJA induction. The cis-acting element analysis revealed that each DhDof had several regulatory elements involved in plant growth as well as abiotic stresses. qRT-PCR analysis demonstrated that DhDof2 was the main ABA-responsive gene and DhDof7 was the main cold stress-related gene. IAA suppressed the expression of some Dof candidates, and SA inhibited most of the candidate genes. Discussion: Our results may provide new insights for the further investigation of the Dof genes and the screening of the core stress-resistance genes.

Genome-wide identification and expression analysis of TIFY genes under MeJA, cold and PEG-induced drought stress treatment in Dendrobium huoshanense

The TIFY family consists of plant-specific genes that regulates multiple plant functions, including developmental and defense responses. Here, we performed a comprehensive genomic analysis of TIFY genes in Dendrobium huoshanense. Our analysis encompassed their phylogenetic relationships, gene structures, chromosomal distributions, promoter regions, and patterns of collinearity. A total of 16 DhTIFY genes were identified, and classified into distinct clusters named JAZ, PPD, ZIM, and TIFY based on their phylogenetic relationship. These DhTIFYs exhibited an uneven distribution across 7 chromosomes. The expansion of the DhTIFY gene family appears to have been significantly influenced by whole-genome and segmental duplication events. The ratio of non-synonymous to synonymous substitutions (Ka/Ks) implies that the purifying selection has been predominant, maintaining a constrained functional diversification after duplication events. Gene structure analysis indicated that DhTIFYs exhibited significant structural variation, particularly in terms of gene organization and intron numbers. Moreover, numerous cis-acting elements related to hormone signaling, developmental processes, and stress responses were identified within the promoter regions. Subsequently, qRT-PCR experiments demonstrated that the expression of DhTIFYs is modulated in response to MeJA (Methyl jasmonate), cold, and drought treatment. Collectively, these results enhance our understanding of the functional dynamics of TIFY genes in D. huoshanense and may pinpoint potential candidates for detailed examination of the biological roles of TIFY genes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-024-01442-9.

Data notes on the proteomics of Dendrobium huoshanense under pb treatment

OBJECTIVES

Pb stress has a negative impact on plant growth by interfering with photosynthesis and releasing reactive oxygen species, causing major risks such as heavy metal ion accumulation in the soil matrix. A proteomics experiment was conducted to determine whether protein levels of Dendrobium huoshanense changed in response to Pb stress seven to fifteen days after being sprayed with a 200 mg/L Pb (NO3)2 solution. The proteomic data we gathered provides a model for investigations into the mechanisms underlying Dendrobium plant resistance to heavy metal stress.

DATA DESCRIPTION

A label-free quantitative proteomics approach was employed to examine the variations in protein expression levels of D. huoshanense at different times of Pb(NO3)2 treatment. We submitted the raw data obtained from these proteomics sequencing experiments to the ProteomeXchange database with the accession number PXD047050. 63,194 mass spectra in total were compared after being imported into the Proteome Discoverer software for database search. A total of 12,402 spectral peptides were identified with a confidence level exceeding 99%, which resulted in the identification of 2,449 significantly differential proteins. These proteins can be utilized for screening, functional annotation, and enrichment analysis of differentially expressed proteins before and after heavy metal treatment experiments.

Phytochemical Profile of Alkaloid Extract from Dendrobium huoshanense and Inhibitory Effects against Oxidative Stress in H2 O2 -Induced PC12 Cells

This study aimed to explore the alkaloid profile of Dendrobium huoshanense and determine the potential protective effect against oxidative damage. The crude D. huoshanense alkaloid extract (DHAE) was obtained by 70 % ethanol extraction and liquid-liquid partition. DHAE contained specific alkaloid components with abundant 6-hydroxynobiline (58.15 %) and trace dendrobine (3.23 %) in the preliminary HPLC fingerprint and GC-MS analysis, which was distinguished from D. officinale or D. nobile. Subsequently, six alkaloids including 6-hydroxynobiline, 2-hydroxy dendrobine, nobilonine, dendrobine, Findlayines D and trans-dendrochrysanine were identified in the purified DHAE (namely DHSAE-3, DHSAE-3') via further solid phase extraction coupled with UPLC-MS/MS analysis. Meanwhile, pretreatment with DHAE or DHSAE (0.5, 5 μg/mL) increased cell viability by 14.0-57.4 % compared to that of H2 O2 -induced PC12 Model cells. Among them, 5 μg/mL DHSAE-3-treated cells displayed a pronounced reversion than the positive vitamin E (p<0.01). Furthermore, a clear cellular morphological restoration and 38.4 % reduction in intracellular reactive oxidative species level were achieved. Our findings suggest that D. huoshanense has a characteristic alkaloid profile represented by abundant 6-hydroxynobiline, and DHAEs exhibit obvious protection against oxidative neuronal damage. Overall, this study indicates that DHAEs might be used to inhibit oxidative stress and provide a source to develop novel neuroprotective drugs.

[Cloning and functional analysis of flavanone synthase Ⅱ from Dendrobium huoshanense]

Flavonoid C-glycosides are a class of natural products that are widely involved in plant defense responses and have diverse pharmacological activities. They are also important active ingredients of Dendrobium huoshanense. Flavanone synthase Ⅱ has been proven to be a key enzyme in the synthesis pathway of flavonoid C-glycosides in plants, and their catalytic product 2-hydroxyflavanone is the precursor compound for the synthesis of various reported flavonoid C-glycosides. In this study, based on the reported amino acid sequence of flavanone synthase Ⅱ, a flavanone synthase Ⅱ gene(DhuFNSⅡ) was screened and verified from the constructed D. huoshanense genome localization database. Functional validation of the enzyme showed that it could in vitro catalyze naringenin and pinocembrin to produce apigenin and chrysin, respectively. The open reading frame(ORF) of DhuFNSⅡ was 1 644 bp in length, encoding 547 amino acids. Subcellular localization showed that the protein was localized on the endoplasmic reticulum. RT-qPCR results showed that DhuFNSⅡ had the highest expression in stems, followed by leaves and roots. The expression levels of DhuFNSⅡ and other target genes in various tissues of D. huoshanense were significantly up-regulated after four kinds of abiotic stresses commonly encountered in the growth process, but the extent of up-regulation varied among treatment groups, with drought and cold stress having more significant effects on gene expression levels. Through the identification and functional analysis of DhuFNSⅡ, this study is expected to contribute to the elucidation of the molecular mechanism of the formation of quality metabolites of D. huoshanense, flavonoid C-glycosides, and provide a reference for its quality formation and scientific cultivation.

The potential roles of acid invertase family in Dendrobium huoshanense: Identification, evolution, and expression analyses under abiotic stress

Dendrobium huoshanense, a traditional Chinese medicine prized for its horticultural and medicinal properties, thrives in an unfavorable climate and is exposed to several adverse environmental conditions. Acid invertase (AINV), a widely distributed enzyme that has been demonstrated to play a significant role in response to environmental stresses. However, the identification of the AINV gene family in D. huoshanense, the collinearity between relative species, and the expression pattern under external stress have yet to be resolved. We systematically retrieved the D. huoshanense genome and screened out four DhAINV genes, which were further classified into two subfamilies by the phylogenetic analysis. The evolutionary history of AINV genes in D. huoshanense was uncovered by comparative genomics investigations. The subcellular localization predicted that the DhVINV genes may be located in the vacuole, while the DhCWINV genes may be located in the cell wall. The exon/intron structures and conserved motifs of DhAINV genes were found to be highly conserved in two subclades. The conserved amino acids and catalytic motifs in DhAINV proteins were determined to be critical to their function. Notably, the cis-acting elements in all DhAINV genes were mainly relevant to abiotic stresses and light response. In addition, the expression profile coupled with qRT-PCR revealed the typical expression patterns of DhAINV in response to diverse abiotic stresses. Our findings could be beneficial to the characterization and further investigation of AINV functions in Dendrobium plants.

Optimization of Three Extraction Methods and Their Effect on the Structure and Antioxidant Activity of Polysaccharides in Dendrobium huoshanense

Dendrobium huoshanense is a famous edible and medicinal herb, and polysaccharides are the main bioactive component in it. In this study, response surface methodology (RSM) combined with a Box-Behnken design (BBD) was used to optimize the enzyme-assisted extraction (EAE), ultrasound-microwave-assisted extraction (UMAE), and hot water extraction (HWE) conditions and obtain the polysaccharides named DHP-E, DHP-UM, and DHP-H. The effects of different extraction methods on the physicochemical properties, structure characteristics, and bioactivity of polysaccharides were compared. The differential thermogravimetric curves indicated that DHP-E showed a broader temperature range during thermal degradation compared with DHP-UM and DHP-H. The SEM results showed that DHP-E displayed an irregular granular structure, but DHP-UM and DHP-H were sponge-like. The results of absolute molecular weight indicated that polysaccharides with higher molecular weight detected in DHP-H and DHP-UM did not appear in DHP-E due to enzymatic degradation. The monosaccharide composition showed that DHPs were all composed of Man, Glc, and Gal but with different proportions. Finally, the glycosidic bond types, which have a significant effect on bioactivity, were decoded with methylation analysis. The results showed that DHPs contained four glycosidic bond types, including Glcp-(1→, →4)-Manp-(1→, →4)-Glcp-(1→, and →4,6)-Manp-(1→ with different ratios. Furthermore, DHP-E exhibited better DPPH and ABTS radical scavenging activities. These findings could provide scientific foundations for selecting appropriate extraction methods to obtain desired bioactivities for applications in the pharmaceutical and functional food industries.

Cheng

Dendrobium huoshanense C.Z. Tang et S.J. Cheng is a perennial epiphytic herb of the family Orchidaceae. The main metabolites of D. huoshanense include polysaccharides and flavonoids. Low temperature is the main environmental factor that limits the growth and development of plants. However, changes that occur at the molecular level in response to low temperatures in D. huoshanense are poorly understood. We performed a transcriptome analysis at two time points of 0 d (control group) and 7 d (cold stress group) under culture of D. huoshanense at 4 °C. A total of 37.63 Gb transcriptomic data were generated using the MGI 2000 platform. These reads were assembled into 170,754 transcripts and 23,724 differentially expressed genes (DEGs) were obtained. Pathway analysis indicated that "flavonoid biosynthesis," "anthocyanin biosynthesis," "flavone and flavonol biosynthesis," and "plant hormone signal transduction" might play a vital role in the response of D. huoshanense to cold stress. Several important pathway genes were identified to be altered under cold stress, such as genes encoding polysaccharides, flavonoids, and plant hormone-signaling transduction kinase. In addition, the content of mannose and total flavonoids increased under cold stress. Twelve DEGs related to polysaccharides, flavonoid, and hormone pathways were selected from the transcriptome data for validation with real-time quantitative PCR (RT-qPCR). Our results provide a transcriptome database and candidate genes for further study of the response of D. huoshanense to cold stress.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-023-01385-7.

The spatiotemporal profile of Dendrobium huoshanense and functional identification of bHLH genes under exogenous MeJA using comparative transcriptomics and genomics

Introduction

Alkaloids are one of the main medicinal components of Dendrobium species. Dendrobium alkaloids are mainly composed of terpene alkaloids. Jasmonic acid (JA) induce the biosynthesis of such alkaloids, mainly by enhancing the expression of JA-responsive genes to increase plant resistance and increase the content of alkaloids. Many JA-responsive genes are the target genes of bHLH transcription factors (TFs), especially the MYC2 transcription factor.

Methods

In this study, the differentially expressed genes involved in the JA signaling pathway were screened out from Dendrobium huoshanense using comparative transcriptomics approaches, revealing the critical roles of basic helix-loop-helix (bHLH) family, particularly the MYC2 subfamily.

Results and discussion

Microsynteny-based comparative genomics demonstrated that whole genome duplication (WGD) and segmental duplication events drove bHLH genes expansion and functional divergence. Tandem duplication accelerated the generation of bHLH paralogs. Multiple sequence alignments showed that all bHLH proteins included bHLH-zip and ACT-like conserved domains. The MYC2 subfamily had a typical bHLH-MYC_N domain. The phylogenetic tree revealed the classification and putative roles of bHLHs. The analysis of cis-acting elements revealed that promoter of the majority of bHLH genes contain multiple regulatory elements relevant to light response, hormone responses, and abiotic stresses, and the bHLH genes could be activated by binding these elements. The expression profiling and qRT-PCR results indicated that bHLH subgroups IIIe and IIId may have an antagonistic role in JA-mediated expression of stress-related genes. DhbHLH20 and DhbHLH21 were considered to be the positive regulators in the early response of JA signaling, while DhbHLH24 and DhbHLH25 might be the negative regulators. Our findings may provide a practical reference for the functional study of DhbHLH genes and the regulation of secondary metabolites.

ICP-MS based metallomics and GC-MS based metabolomics reveals the physiological and metabolic responses of Dendrobium huoshanense plants exposed to Fe3O4 nanoparticles

It is found that the growth of Dendrobium huoshanense was dependent on Fe3O4, while the bioavailability of plants to ordinary Fe3O4 was low on the earth. In order to improve the growth, quality and yield of D. huoshanense, we used Fe3O4 NPs (100 or 200 mg/L) that was easily absorbed by plants as nano-fertilizer to hydroponically treat seedlings of D. huoshanense for 3 weeks. Fe3O4 NPs induced not only earlier flowering and increased sugar content and photosynthesis, but also stressed to plants, increased MDA content and related antioxidant enzymes activities. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) revealed that Fe3O4 NPs caused a significant accumulation of Fe and some other nutrient elements (Mn, Co, B, Mo) in stems of D. huoshanense. Metabolomics revealed that the metabolites were reprogrammed in D. huoshanense when under Fe3O4 NPs exposure. Fe3O4 NPs inhibited antioxidant defense-related pathways, demonstrating that Fe3O4 NPs have antioxidant capacity to protect D. huoshanense from damage. As the first study associating Fe3O4 NPs with the quality of D. huoshanense, it provided vital insights into the molecular mechanisms of how D. huoshanense responds to Fe3O4 NPs, ensuring the reasonable use of Fe3O4 NPs as nano-fertilizer.

Selection of Suitable Reference Genes for Gene Expression Normalization Studies in Dendrobium huoshanense

Dendrobium huoshanense is a kind of precious herb with important medicinal and edible value in China, which is widely used in traditional Chinese medicine for various diseases. Recent studies have paid close attention to the genetic expression of the biosynthetic pathway of the main active components (polysaccharides, alkaloids, and flavonoids), and real-time polymerase chain reaction (qPCR) is one of the most widely used methods for doing so. However, so far, no reference gene selections have been reported in D. huoshanense. In this study, 15 reference gene candidates (GAPDH, eIF, EF-1α, PP2A, UBCE, RPL5, TBP, APT1, MDH, PTBP3, PEPC, CYP71, NCBP2, TIP41, and F-box) were selected and evaluated for their expression stability in D. huoshanense under various experimental conditions, including in different tissues (root, stem, and leaf), abiotic stresses (oxidative, drought, cold, and UV), and hormone treatment (methyl jasmonate) using three statistical programs (geNorm, NormFinder, and BestKeeper). Then, the RefFinder program was employed to comprehensively validate the stability of the selected reference genes. Finally, the expression profiles of the CESA and GMPP genes were further analyzed, and these results indicated that TBP, NCBP2, and CYP71 were the top three most stable reference genes after comprehensive comparison, which could be used as stable reference genes for normalizing the genes expression in D. huoshanense. This study described here provides the first data regarding on reference gene selection in D. huoshanense, which will be extremely beneficial for future research on the gene expression normalization in D. huoshanense.

Comparative Proteome and Phosphoproteome Analyses Reveal Different Molecular Mechanism Between Stone Planting Under the Forest and Greenhouse Planting of Dendrobium huoshanense

The highly esteemed Chinese herb, Dendrobium huoshanense, whose major metabolites are polysaccharides and alkaloids, is on the verge of extinction. The stone planting under the forest (SPUF) and greenhouse planting (GP) of D. huoshanense are two different cultivation methods of pharmaceutical Dendrobium with significantly differences in morphology, metabolites content and composition, and medication efficacy. Here, we conducted proteomics and phosphoproteomics analyses to reveal differences in molecular mechanisms between SPUF and GP. We identified 237 differentially expressed proteins (DEPs) between the two proteomes, and 291 modification sites belonging to 215 phosphoproteins with a phosphorylation level significantly changed (PLSC) were observed. GO, KEGG pathway, protein domain, and cluster analyses revealed that these DEPs were mainly localized in the chloroplast; involved in processes such as posttranslational modification, carbohydrate transport and metabolism, and secondary metabolite biosynthesis; and enriched in pathways mainly including linoleic acid metabolism, plant-pathogen interactions, and phenylpropanoid, cutin, suberin, and wax biosynthesis. PLSC phosphoproteins were mainly located in the chloroplast, and highly enriched in responses to different stresses and signal transduction mechanisms through protein kinase and phosphotransferase activities. Significant differences between SPUF and GP were observed by mapping the DEPs and phosphorylated proteins to photosynthesis and polysaccharide and alkaloid biosynthesis pathways. Phosphorylation characteristics and kinase categories in D. huoshanense were also clarified in this study. We analyzed different molecular mechanisms between SPUF and GP at proteomic and phosphoproteomic levels, providing valuable information for the development and utilization of D. huoshanense.

Structural characterization of a mannoglucan polysaccharide from Dendrobium huoshanense and evaluation of its osteogenesis promotion activities

Dendrobium huoshanense, a valuable traditional Chinese herb, is widely used to prolong life in China. Our study aims to characterize the structure and osteogenesis-promotion effects of a heteropolysaccharide component isolated from Dendrobium huoshanense (DHPW1). The structure of DHPW1 was characterized using gas chromatography-mass spectrometry and nuclear magnetic resonance, while its osteogenic activity was evaluated using MG-63 cells and zebrafish skulls. The results showed that the molecular weight of DHPW1 was 230 kDa and it was mainly composed of mannose and glucose. In addition, the DHPW1 backbone consisted of (1 → 4)-linked-β-D-Mannopyranosyl and (1 → 4)-linked-β-d-Glucopyranosyl. Furthermore, DHPW1 significantly increased ALP activity and mineralized nodule formation in MG-63 cells. DHPW1 in zebrafish skull models significantly enhanced the relative fluorescence intensity of bone mass and increased the degree of bone mineralization. These results suggested that the DHPW1 component in D. huoshanense has potential to promote osteogenesis.

Structure and Bioactivities of a Novel Polysaccharide Extracted From Dendrobium huoshanense by Subcritical Water

In this study, the polysaccharide was extracted by subcritical water from Dendrobium huoshanense. A novel polysaccharide (DHPs-1) was obtained through several purification steps and its structure and bioactivity were investigated. Structural analysis indicated that the weight-average molecular weight of DHPs-1 was 5.0 × 10⁴ Da and it was mainly composed of glucose (65.04%), mannose (14.23%), galactose (8.17%), galacturonic acid (6.41%), rhamnose (2.34%), and xylose (1.25%). 1,4-Glcp, and 1,4,6-Galp were existed in the backbone of DHPs-1. The residues of 1,3,4-Galp, 1,4-Manp, 1,4-Galp, and 1,3,4,6-Galp could be in the backbone or the side chains with the non-reducing terminal of α-Manp. Bioactivity tests indicated that DHPs-1 had immunomodulatory activity in that it significantly enhanced transcript levels of cytokines [Tumor necrosis factor-α (TNF-α), Interleukin-6 (IL-6), Interleukin-1β (IL-1β), and Interleukin-10 (IL-10)]. DPPH and hydroxyl radical scavenging tests showed that it had good antioxidant activity. These results reveal that DHPs-1 could be developed as a safe immunomodulatory agent and antioxidant for pharmacological or functional food applications.

Qualitative Proteome-Wide Analysis Reveals the Diverse Functions of Lysine Crotonylation in Dendrobium huoshanense

The lysine crotonylation of histone proteins is a newly identified posttranslational modification with diversified cellular functions. However, there are few reports on lysine crotonylation of non-histone proteins in medicinal plant cells. By using high-resolution liquid chromatography-mass spectrometry (LC-MS) coupled with highly sensitive-specific immune-affinity antibody analysis, a whole crotonylation proteome analysis of Dendrobium huoshanense was performed. In total, 1,591 proteins with 4,726 lysine crotonylation sites were identified; among them, 11 conserved motifs were identified. Bioinformatic analyses linked crotonylated proteins to the drought stress response and multiple metabolic pathways, including secondary metabolite biosynthesis, transport and catabolism, energy production and conversion, carbohydrate transport and metabolism, translation, and ribosomal structure and biogenesis. This study contributes toward understanding the regulatory mechanism of polysaccharide biosynthesis at the crotonylation level even under abiotic stress.

Comparative analysis of chemical constituents by HPLC-ESI-MSn and antioxidant activities of Dendrobium huoshanense and Dendrobium officinale

Dendrobium huoshanense is a Chinese medicinal herb that has high quality and excellent efficacy. However, the chemical basis of its activity is still unclear. Of note, Dendrobium officinale is the most widely utilized among the Dendrobium species. Therefore, the current study systematically investigated the chemical constituents of methanolic extracts and different polar fractions of aqueous extracts from the two herbs by HPLC-ESI-MSⁿ , and then compared in vitro antioxidant activities of their five different polar extracts. Consequently, 61 and 49 compounds were identified from D. huoshanense and D. officinale, respectively, of which 43 compounds were common to both species. In addition, 17 out of 22 different compounds were identified only in D. huoshanense. Moreover, the peak areas of some shared identical compounds of D. huoshanense were significantly larger than that of D. officinale. In vitro antioxidant evaluation results showed that the n-BuOH-soluble fraction of the two herbs exhibited remarkable antioxidant activities. Furthermore, the antioxidant activities of different fractions of D. huoshanense were separately superior to that of D. officinale, which may be attributed to its variable and high contents of flavonoids, bibenzyls and phenanthrenes. These results provide the evidence for the high quality and efficacy of D. huoshanense.

Detection of Mercury Ion with High Sensitivity and Selectivity Using a DNA/Graphene Oxide Hybrid Immobilized on Glass Slides

Excessive mercury ions (Hg²⁺) cause great pollution to soil/water and pose a major threat to human health. The high sensitivity and high selectivity in the Hg²⁺ detection demonstrated herein are significant for the research areas of analytical chemistry, chemical biology, physical chemistry, drug discovery, and clinical diagnosis. In this study, a series of simple, low-cost, and highly sensitive biochips based on a graphene oxide (GO)/DNA hybrid was developed. Hg²⁺ is detected with high sensitivity and selectivity by GO/DNA hybrid biochips immobilized on glass slides. The performance of the biosensors can be improved by introducing more phosphorothioate sites and complementary bases. The best limit of detection of the biochips is 0.38 nM with selectivity of over 10:1. This sensor was also used for Hg²⁺ detection in Dendrobium. The results show this biochip is promising for Hg²⁺ detection.

Genome-Wide Analysis of PEBP Genes in Dendrobium huoshanense: Unveiling the Antagonistic Functions of FT/TFL1 in Flowering Time

Dendrobium is a semi-shade epiphytic Orchidaceae herb with important ornamental and medicinal value. Parts of the cultivation of Dendrobium germplasm resources, as well as the identification of medicinal components, are more studied, but the functional characterization of the flowering regulation in Dendrobium plants is less reported. Here, six PEBP family genes (DhFT3, DhFT1, DhMFT, DhTFL1b, DhFT2, and DhTFL1a) were identified from the Dendrobium huoshanense genome. The chromosome-level mapping showed that these genes were sequentially distributed on chromosomes 6, 9, 15, and 17. The paralogous gene DhTFL1b corresponded to DhTFL1a, which was determined through tandem duplication. The gene structure and conserved motif of DhPEBP indicated five PEBP genes apart from DhMFT contained four exons and three introns entirely. The phylogeny analysis showed that the PEBP gene family in A. thaliana, O. sativa, Z. mays, S. lycopersicum, and P. equestris were classified into three subclades, FT, TFL, and MFT, which maintained a high homology with D. huoshanense. The conserved domain of the amino acid demonstrated that two highly conserved short motifs (DPDXP and GXHR) embed in DhPEBPs, which may contribute to the conformation of the ligand binding bag. The 86th position of DhFTs was tyrosine (Y), while the 83th and 87th of DhTFL1s belonged to histidine (H), suggesting they should have distinct functions in flowering regulation. The promoter of six DhPEBPs contained several cis-elements related to hormone induction, light response, and abiotic stress, which indicated they could be regulated by the environmental stress and endogenous signaling pathways. The qRT-PCR analysis of DhPEBPs in short-term days induced by GA indicated the gene expressions of all DhFTs were gradually increased, whereas the expression of DhTFL1 was decreased. The results implied that DhPEBPs have various regulatory functions in modulating flowering, which will provide a scientific reference for the flowering regulation of Dendrobium plants.

Carbonized biosorbent assisted matrix solid-phase dispersion microextraction for active compounds from functional food

In this study, mangosteen peel based activated carbon was prepared and first applied as adsorbent in matrix solid-phase dispersion (MSPD) for simultaneously extraction of flavonoids from Dendrobium huoshanense prior to their separation and determination by ultra-high performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UHPLC-Q-TOF/MS). The MSPD-UHPLC-Q-TOF/MS method was validated exhaustively. Good linearities (r² ≥ 0.9929) were obtained for all target analytes. The limits of detection was in the range of 0.00387-0.159 μg/g. Satisfactory recoveries of six target compounds were between 80.02 and 99.49% and 85.32-99.86% for the low and high spiked level, respectively. Furthermore, relative to other common sorbent, the prepared mangosteen peel based activated carbon was less expensive and more environmentally-friendly. Consequently, the proposed method was a simple, efficient, low-cost, eco-friendly, time-saving and sensitive approach that could be successfully applied to the extraction and determination of flavonoids compounds in complex matrix.

Dendrobium huoshanense Polysaccharides Prevent Inflammatory Response of Ulcerative Colitis Rat through Inhibiting the NF-κB Signaling Pathway

The polysaccharides of the Chinese herbal medicine Dendrobium huoshanense exhibit anti-inflammatory effects in multiple organs through regulating the immune responses. In the present study, we constructed ulcerative colitis (UC) model rats using dextran sulfate sodium to investigate the anti-inflammatory effects of D. huoshanense polysaccharides (DHP). After oral administration of DHP for two weeks, the indices of UC symptoms, including the ratio of colon weight to length, Disease Activity Index (DAI), and Colon Mucosal Damage Index (CMDI), all decreased significantly compared with the UC model group. The histological sections also revealed better cell orders in DHP treatments than in the UC model rats. Moreover, in treatment with high dose of DHP (200 mg/kg), the treatment efficacy arrived the similar levels to those in the treatment with 300 mg/kg sulfasalazine, which is a typical medicine to treat UC. These results indicated that DHP has a high efficacy to treat UC in model rats. Furthermore, serum levels of interleukin-1β, tumor necrosis factor-α, interleukin-17, and transforming growth factor-β were assessed using the enzyme linked immunosorbent assay (ELISA) method, and the levels of nuclear factor-κB in colon tissue sections were determined using the immunohistochemical method. The results showed that all these indices decreased significantly after administration of DHP in UC model rats, which might be the mechanisms underlying the DHP-suppressed UC inflammation. Overall, this study indicated that DHP might be directly used to treat UC and is a promising source to develop novel drugs against UC.

[Comparison of planting modes of Dendrobium huoshanense and analysis of advantages of simulated cultivation]

Dendrobium huoshanense is a precious medicinal plant belonging to Dendrobium of Orchidaceae. It is a special medicinal material and extremely scarce in Huoshan county, Anhui province. At present, D. huoshanense has been greatly protected, which also makes it possible to industrialize relying on tissue culture and artificial cultivation technology. Three main planting methods were utilized for cultivating D. huoshanense including facility cultivation, under forest cultivation and simulative habitat cultivation. Firstly, the three cultivation modes and technical characteristics of D. huoshanense were compared and analyzed, and it was found that the ecological environment of D. huoshanense cultivated in the simulated environment was closer to that of wild D. huoshanense. Secondly, based on comparing the characters and quality of three cultivation modes, the results showed that the shape of D. huoshanense cultivated in simulated environment was more similar to that of &quot;grasshopper thigh&quot; recorded in Bencao Jing Jizhu, and its quality was better than that of facilities and under forest cultivation. The comprehensive benefit comparison of three modes showed that the simulated cultivation had high income, the lowest input-output ratio and significant economic benefit. The quality of cultivated D. huoshanense was further evaluated from four aspects of &quot;excellent environment&quot; &quot;excellent shape&quot; &quot;high quality&quot; &quot;excellent effect&quot;, which summarized the comprehensive advantages of simulative habitat cultivation of D. huoshanense as follows: the original habitat and site environment of simulated wild D. huoshanense, the closer shape to the wild, the more content of main medicinal components, and higher economic benefit and better efficacy. The quality of D. huoshanense was improved by the use of simulative habitat cultivation, which has practical significance to guide its large-scale cultivation.

Simultaneous determination of 16 important biologically active phytohormones in Dendrobium huoshanese by pressurized capillary electrochromatography

A rapid pressurized capillary electrochromatography (pCEC) method has been successfully developed for the simultaneous determination of 16 phytohormones in Dendrobium huoshanense. Effects of wavelength, mobile phase, the flow rate, pH value, concentration of buffer and applied voltage were investigated, respectively. The results showed that the 16 phytohormones could be baseline-separated rapidly in less than 21 min on a reversed-phase EP-100-20/45-3-C18 capillary column (total length of 45 cm, effective length of 20 cm, diameter of 100 μm, ODS packing inside for 3 μm) with ACN/5.0 mM ammonium acetate (containing 0.05% formic acid, pH = 3) as the mobile phase using gradient elution mode as follows: 0.1-10.0 min 40%ACN,10-15.0 min 70%ACN, 15.0-20 min 80% ACN, 20-21.0 min 80% ACN at a flow rate of 0.12 mL/min, applied voltage of -5 kV and a UV detection wavelength of 210 nm. The method validation howed that the established method is precise and stability, and the RSDs of intra- and inter-day precision based retention time and peak area were all below 5%. Employed the established method, in our experimental conditions, total 6 endogenous hormones including IAA, IBA, NAA, GA, ABA, t-Z were detected in D. huoshense. However, a relative larger amount of exogenous hormone 2,4-D (25.3 ~ 4.2 μg/kg) and 6-BA (79.5 ~ 35.4 μg/kg) were detected in 1 ~ 4 year old cultivated D. huoshense, suggesting there were still a certain amount of exogenous hormone residue in tissue-cultured D. huoshanese though they had been transplanted to field cultivation from the test-tube plantlets for several years.

Dendrobium huoshanense stem polysaccharide ameliorates rheumatoid arthritis in mice via inhibition of inflammatory signaling pathways

The present study explored the beneficial effect of Dendrobium huoshanense stem polysaccharide (cDHPS) after oral administration on rheumatoid arthritis (RA) using type Ⅱ collagen-induced arthritis (CIA) mouse model. It was found that cDHPS effectively alleviated joint swelling, synovial hyperplasia, pannus formation, cartilage erosion and bone destruction in CIA mice. Concurrently, cDHPS remodeled the balance of Th17 and regulatory T cells, reduced the secretion of pro-inflammatory mediators related to fibroblast-like synoviocyte activation, angiogenesis, articular cartilage degradation and osteoclast differentiation, inhibited HIF-1α expression and promoted anti-inflammatory mediator release in the joint tissues and serum of CIA mice. Western blot of joint tissues showed that cDHPS significantly inhibited the phosphorylation of IκB, p65, JNK, p38, ERK1/2, AKT, PI3K, JAK1 and STAT3 in CIA mice. These results suggest that cDHPS possesses the potential of ameliorating RA and its anti-RA effect may be attributed to the inhibition of inflammatory signaling pathways.

[Comparison of active ingredients and protective effects of Dendrobium huoshanense of different growth years on acute liver injury]

The differences of the active ingredients in Dendrobium huoshanense of different growth years and their protective effects on acute liver injury were studied to provide evidence for optimizing harvest time. The contents of polysaccharides, total flavonoids and total alkaloids in D. huoshanense of different growth years were determined by UV spectrophotometry, and the contents of gigantol in D. huoshanense were determined by HPLC. C57 BL/6 mice were randomly divided into blank control group(saline), modeling group(saline), high-dose(7.5 g·kg~(-1)) and low-dose(1.25 g·kg~(-1)) groups of D. huoshanense of different growth years. Each group was intragastrically administered every day for 2 weeks. 500 mg·kg~(-1) paracetamol was injected intraperitoneally 2 h after last treatment except the control group. After 12 hours, the serum and liver tissues were collected to detect the activities of ALT and AST, and the levels of SOD and MDA. The hepatic histopathological examination was performed. The results showed that the chemical constituents of D. huo-shanense of different growth years were significantly different(P&lt;0.05). The contents of polysaccharide and gigantol of D. huoshanense of 2 growth years were the highest. The contents of flavonoids and alkaloids of D. huoshanense of 3 growth years were the hig-hest, followed by the D. huoshanense of 2 growth years, and the lowest were that of 1 growth year. Compared with the modeling group, D. huoshanense of different growth years could decrease the activities of ALT and AST in serum. Meanwhile, the levels of MDA reduced significantly, while those of SOD increased markedly. Histopathological results suggested that all D. huoshanense samples were effective in the reduction of the necrosis of hepatocytes in different degrees. The results of the multi-component SPSS paired tests showed that polysaccharide and gigantol probably played a leading role in the liver protection effects, while D. huoshanense of 2 growth years showed the best efficacy. The optimal harvesting time of D. huoshanense is 2 growth years.

[Comparative analysis of active components and transcriptome between autotetraploid and diploid of Dendrobium huoshanense]

In this study, the roots, stems and leaves of diploid and autotetraploid Dendrobium huoshanense were used as materials to compare their contents of polysaccharides and alkaloids, and the transcriptome sequencing analysis was carried out. The results showed that the contents of polysaccharides and alkaloids in the roots, stems and leaves of tetraploid were 7.6%, 34.5%, 17.2%, 0.01%, 0.024% and 0.035% higher than those of diploid D. huoshanense, respectively. The contents of active components in different tissues were significantly different. There were 3 687 differentially expressed genes in diploid and tetraploid D. huoshanense, of which 2 346 genes were up-regulated and 1 341 down regulated. Go functional analysis showed that these genes were mainly involved in growth and development, stress resistance and other related functions. KEGG pathway analysis showed that most of the differential genes were concentrated in the processes of carbon metabolism, signal transduction, carbohydrate metabolism, amino acid metabolism and energy metabolism. The differential expression of key genes involved in the metabolism of polysaccharides, terpenes and polyketones, amino acid metabolism, hormone synthesis and signal transduction in diploid and tetraploid plants may be the main reason for the high energy content, the increase of active components and the growth potential of tetraploid plants.

[Study on chemical constituents of Dendrobium huoshanense stems and their anti-inflammatory activity]

Three bibenzyls 1-3 and six other compounds 4-9 were firstly isolated from Dendrobium huoshanense stems. They were identified as 3',4-dihydroxy-3,5'-dimethoxybibenzyl(1), batatasin Ⅲ(2), 3,4'-dihydroxy-5-methoxy bibenzyl(3), dihydroconiferyl dihydro-p-coumarate(4), syringaresinol(5), 3-(4-hydroxyphenyl)-propionic acid ethyl ester(6),(3-ethylphenyl)-1,2-ethanediol(7),(S)-5-hydroxy-3,4-dimethyl-5-pentylfuran-2(5H)-one(8) and loliolide(9). Anti-inflammation assay showed that bibenzyls 1-3 could significantly inhibit the production of nitric oxide(NO) and the expression of tumor necrosis factor α(TNF-α) and interleukin 1β(IL-1β) mRNA in LPS-induced RAW264.7 macrophages. Mechanism study exhibited that the phosphorylation of nuclear factor kappa B(NF-κB) p65, inhibitor of κB(IκB), extracellular regulatedprotein kinase(ERK), c-Jun N-terminalkinase(JNK), p38 and Akt of LPS-induced RAW264.7 macrophages could be remarkably reduced by 1. These results suggested that the inflammatory response of LPS-induced RAW264.7 macrophages could be significantly inhibited by 1-3. Additionally, the anti-inflammatory effect of 1 might be contributed to its ability on the regulation of NF-κB, MAPKs and Akt signaling pathways.

A comparative plastomics approach reveals available molecular markers for the phylogeographic study of Dendrobium huoshanense, an endangered orchid with extremely small populations

Comparative plastomics approaches have been used to identify available molecular markers for different taxonomic level studies of orchid species. However, the adoption of such methods has been largely limited in phylogeographic studies. Therefore, in this study, Dendrobium huoshanense, an endangered species with extremely small populations, was used as a model system to test whether the comparative plastomic approaches could screen available molecular markers for the phylogeographic study. We sequenced two more plastomes of D. huoshanense and compared them with our previously published one. A total of 27 mutational hotspot regions and six polymorphic cpSSRs have been screened for the phylogeographic studies of D. huoshanense. The cpDNA haplotype data revealed that the existence of haplotype distribution center was located in Dabieshan Mts. (Huoshan). The genetic diversity and phylogenetic analyses showed that the populations of D. huoshanense have been isolated and evolved independently for long period. On the contrary, based on cpSSR data, the genetic structure analysis revealed a mixed structure among the populations in Anhui and Jiangxi province, which suggested that the hybridization or introgression events have occurred among the populations of D. huoshanense. These results indicated that human activities have played key roles in shaping the genetic diversity and distributional patterns of D. huoshanense. According to our results, both two markers showed a high resolution for the phylogeographic studies of D. huoshanense. Therefore, we put forth that comparative plastomic approaches could revealed available molecular markers for phylogeographic study, especially for the species with extremely small populations.

[Therapeutic effect and mechanism of three kinds of Dendrobium on constipation in rats with spleen Yin deficiency]

Books on Chinese herbal medicines have shown that Dendrobium has the effect of nourishing Yin and reinforcing Yin,usually used for constipation induced by spleen Yin deficiency in clinical application. D. huoshanense,as an independent species among many species of Dendrobium,has no experimental studies about its effects on spleen Yin deficiency-type constipation. The purpose of this experiment was to illustrate the therapeutic effect of D. huoshanense on the constipation of spleen Yin deficiency type in rats,investigate its preliminary mechanism,and compare it with the D. officinale and D. nobile contained in the Chinese Pharmacopoeia to clarify its characteristics. The spleen Yin deficiency model was replicated in 70 rats by the composite factor method,and then the model rats were randomly divided into 7 groups: model group,Liuwei Dihuang Pills group( LWDHP),D. huoshanense high( DHS-H),medium( DHS-M),low( DHS-L) dose groups,D. nobile group( DNS),and D. officinale group( DOS),and another 10 rats were used as normal group( Normal). After 7 continuous days of administration,the fecal water content and intestine propulsion rate of each group were detected. HE staining was used to observe the pathological damage of ileum and colon in each group. Immunohistochemistry and Western blot were used to detect aquaporin 3( AQP3) expressions,while the expression levels of the somatostatin( SS) and motilin( MTL) in the ileum of each group were detected by enzyme-linked immunosorbent assay. The results showed that as compared with the model group,the rats in each drug-administered group had increased number of fecal pellets,increased fecal water content,and the increased intestinal propulsion rate( P<0. 01),while the pathological damage of the ileum and colon was significantly reduced; the expression of AQP3 protein was significantly decreased( P<0. 01); the level of MTL was significantly increased and the level of SS was decreased( P<0. 01). All DHS groups showed a good dose-effect relationship,and the same dose treatment effect was equivalent to that of DOS,but it was superior to DNS. Therefore,DHS has a significant therapeutic effect on constipation of spleen Yin deficiency type,and its mechanism may be related to intestinal motility and water-liquid metabolism,with a good therapeutic effect.

[Diversity and difference of endophytes in Dendrobium huoshanense with different growth years]

In order to explore endophytes diversity and difference in Dendrobium huoshanense,in this paper,the metagenomics method was used to analyze the endophytic bacteria and fungi community of 5 groups include 30 samples in different growth years. The results indicate that 3 540 bacterial OTUs were identified from D. huoshanense,and there are 138 OTUs in 5 groups simultaneously;2 168 fungal OTUs were identified,and 143 OTUs exist in 5 groups simultaneously. The dominate endophytic bacteria community are Sphingomonas sp.,Acinetobacter sp.,Burkholderia sp.,Methylobacterium sp.,Enterococcus sp.,Bacillus sp.,the difference endophytic bacteria community are Oceanobacillusd sp.,Actinomycetospora sp.,Paenibacillus sp.. The dominate endophytic fungi community are Zasmidium sp.,Zymoseptoria sp.,Alternaria sp.,Cladosporium sp.,Fusarium sp.,the difference endophytic fungi community are Cyphellophore sp.,Fusarium sp.. The results of clustering revealed that both the endophytic bacteria and the endophytic fungi,ⅢY2 and ⅢY3 are complete clustered,and ⅡY1 and ⅢY1 are also cluster completely. These enriched the species and resources of endophytic bacteria and fungi in D. huoshanense,and provided a theoretical reference for the reasonable harvest of D. huoshanense.

[Cloning and quantitative expression analysis of GMPP gene from Dendrobium huoshanense]

In order to understand the function of GDP-mannose pyrophosphorylase(GMPP) function and its regulation in polysaccharide biosynthesis mechanism in Dendrobium. D. huoshanense was used to clone GMPP gene. GMPP gene expression in D. huoshanense,D. officinale and D. moniliforme was also determined by qPCR. The results showed that the length of D. huoshanense GMPP gene c DNA sequence is 1 867 bp,containing 1 245 bp open reading frame(ORF),encoding 415 amino acids. Phylogenetic tree analysis showed that D. huoshanense,D. officinale and D. moniliforme are closely related with GMPP taken into consideration. Bioinformatics analysis demonstrated that GMPP sequence similarity among the three species reached as high as 99%. qPCR results indicated that GMPP genes was highly expressed in stem of D. huoshanense compared with its leaf,flower and root. According to GMPP gene expression profile in D. huoshanense,D. officinale and D. moniliforme grown in Huoshan area,it was clear that GMPP in D. huoshanense showed the highest expression level. Furthermore,our findings of GMPP gene expression profile will facilitate future researches into its polysaccharide biosynthetic mechanism.

Morphological and microscopic identification of three major medicinal Dendrobium species in Ta-pieh Mountains area

Dendrobium is an important medicinal material in China. It has the effect of nourishing the stomach, nourishing yin and clearing heat. In China, there are many types of Dendrobium, and different Dendrobium species have different efficacy. The present study is aimed at distinguishing three major Dendrobium species from morphological and microscopic identification in Ta-pieh mountains area. In this article, the roots, stems and leaves of Dendrobium huoshanense, Dendrobium officinale, and Dendrobium moniliforme are used as materials to compare the differences of tissues of these three Dendrobium species by morphological indexes and microscopic identification of different Dendrobium. The stem morphology of these three Dendrobium species was significantly different except for stem internodes number and the middle part of the stem diameter by measuring the stems of Dendrobium. To ensure the safe use of Dendrobium, we built a fast and convenient method combining normal and fluorescence microscopy was applied in the present study to distinguish D. huoshanense, D. officinale, and D. moniliforme. The microscopic results show that different types of Dendrobium exhibit different states that can be distinguished under normal light normal and fluorescence microscopy. This comparative study of morphology and microscopy contributes to the development of identification and quality evaluation of Dendrobium.

Analysis of Dendrobium huoshanense transcriptome unveils putative genes associated with active ingredients synthesis

BACKGROUND

Dendrobium huoshanense C.Z. Tang et S.J. Cheng is a traditional Chinese herbal medicine with high medicinal value in China. Polysaccharides and alkaloids are its main active ingredients. To understand the difference of main active ingredients in different tissues, we determined the contents of polysaccharides and alkaloids in the roots, stems and leaves of D. huoshanense. In order to explore the reasons for the differences of active ingredients at the level of transcription, we selected roots, stems and leaves of D. huoshanenese for transcriptome sequencing and pathway mining.

RESULTS

The contents of polysaccharides and alkaloids of D. huoshanense were determined and it was found that there were significant differences in different tissues. A total of 716,634,006 clean reads were obtained and 478,361 unigenes were assembled by the Illumina platform sequencing. We identified 1407 carbohydrate-active related unigenes against CAZy database including 447 glycosyltransferase genes (GTs), 818 glycoside hydrolases (GHs), 60 carbohydrate esterases (CEs), 62 carbohydrate-binding modules (CBMs), and 20 polysaccharide lyases (PLs). In the glycosyltransferases (GTs) family, 315 differential expression genes (DEGs) were identified. In total, 124 and 58 DEGs were associated with the biosynthesis of alkaloids in Dh_L vs. Dh_S and Dh_R vs. Dh_L, respectively. A total of 62 DEGs associated with the terpenoid pathway were identified between Dh_R and Dh_S. Five key enzyme genes involved in the terpenoids pathway were identified, and their expression patterns in different tissues was validated using quantitative real-time PCR.

CONCLUSIONS

In summary, our study presents a transcriptome profile of D. huoshanense. These data contribute to our deeper relevant researches on active ingredients and provide useful insights into the molecular mechanisms regulating polysaccharides and alkaloids in Dendrobium.

Analysis of Dendrobium huoshanense transcriptome unveils putative genes associated with active ingredients synthesis

Background

Dendrobium huoshanense C.Z. Tang et S.J. Cheng is a traditional Chinese herbal medicine with high medicinal value in China. Polysaccharides and alkaloids are its main active ingredients. To understand the difference of main active ingredients in different tissues, we determined the contents of polysaccharides and alkaloids in the roots, stems and leaves of D. huoshanense. In order to explore the reasons for the differences of active ingredients at the level of transcription, we selected roots, stems and leaves of D. huoshanenese for transcriptome sequencing and pathway mining.

Results

The contents of polysaccharides and alkaloids of D. huoshanense were determined and it was found that there were significant differences in different tissues. A total of 716,634,006 clean reads were obtained and 478,361 unigenes were assembled by the Illumina platform sequencing. We identified 1407 carbohydrate-active related unigenes against CAZy database including 447 glycosyltransferase genes (GTs), 818 glycoside hydrolases (GHs), 60 carbohydrate esterases (CEs), 62 carbohydrate-binding modules (CBMs), and 20 polysaccharide lyases (PLs). In the glycosyltransferases (GTs) family, 315 differential expression genes (DEGs) were identified. In total, 124 and 58 DEGs were associated with the biosynthesis of alkaloids in Dh_L vs. Dh_S and Dh_R vs. Dh_L, respectively. A total of 62 DEGs associated with the terpenoid pathway were identified between Dh_R and Dh_S. Five key enzyme genes involved in the terpenoids pathway were identified, and their expression patterns in different tissues was validated using quantitative real-time PCR.

Conclusions

In summary, our study presents a transcriptome profile of D. huoshanense. These data contribute to our deeper relevant researches on active ingredients and provide useful insights into the molecular mechanisms regulating polysaccharides and alkaloids in Dendrobium.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5305-6) contains supplementary material, which is available to authorized users.

[Effects of Dendrobium huoshanense on expressions and activities of hepatic microsomal cytochrome P450s in mice]

This study was carried out to investigate the effect of oral administration of Dendrobium huoshanense on the expressions and activities of hepatic microsomal cytochrome P450s in mice, and to provide a reference for the evaluation of drug-drug interactions between D. huoshanense and clinical drugs. The C57BL/6 mice were randomly divided into blank control group, D. huoshanense low dose group (crude drug 1.25 g·kg⁻¹), D. huoshanense high dose group (crude drug 7.5 g·kg⁻¹), and phenobarbital positive control group (0.08 g·kg⁻¹). Each group was intragastrically administered with drugs for 2 weeks. The mice were sacrificed and their liver microsomes were prepared. The expressions of major subtypes of P450 enzyme were determined by Western blot and the probe drugs were used to detect the enzyme activities of P450 subtypes with protein expression changes. Western blot analysis showed that the protein expressions of CYP1A1, CYP1A2 and CYP2B in liver tissues were up-regulated in D. huoshanense-treated group. In vitro enzyme activity tests showed that there were no significant difference in metabolism of 7-ethoxyresorufin (a probe drug for CYP1A1) and bupropion (a probe drug for CYP2B) between D. huoshanense group and control group. The metabolism of phenacetin (a probe drug for CYP1A2) showed a statistical difference in rate Vmax, and it was significantly increased by approximately 20% in D. huoshanense group as compared with the blank control group, and the clearance CLint in treated group was also increased by about 32%. Therefore, oral administration of D. huoshanense had no effects on the activities of most hepatic P450 enzymes in mice, with no drug-drug interaction related to the P450 enzyme system in most clinical drugs theoretically. However, oral administration of D. huoshanense may accelerate the metabolism of CYP1A2-catalyzed drugs, which needs to be considered in clinical practice.

[Purification and cytotoxicity of glycoprotein isolated from Dendrobium huoshanense]

Dendrobium huoshanense is a rare traditional Chinese medicinal herb, and the anti-tumor activity of its polysaccharides is a research hotspot in traditional Chinese medicine resources domain. This study aims to explore the material basis for the anti-tumor activity of polysaccharide. D. huoshanense was used as raw material in the experiment, and the different protein components were obtained through low salt solution extraction and ammonium sulfate fractional precipitation. Then glycoprotein components were determined by SDS-PAGE electrophoresis staining, and were further isolated and purified by DEAE ion column and Sephadex gel column. At the same time, MTT assay was used in detecting the cytotoxicity of different products on HepG2 cells in vitro. As a result, three kinds of glycoprotein components RG1, RG2, RG3 with relative molecular mass of 22.5, 19.8, 15.6 kDa were gained, and the IC₅₀ of three compounds on human liver cancer cell HepG2 was 534.23 mg•L⁻¹, meanwhile IC₅₀ of single glycoprotein component RG1, RG2 was 432.96, 413.91 mg•L⁻¹ respectively, and glycoprotein component RG3 had no cytotoxicity on HepG2 cells. All in all, the experiment results suggested that two kinds of glycoproteins components with relative molecular mass of 22.5, 19.8 kDa may be one of the material basis for anti-tumor activity of D. huoshanense polysaccharide, and they had a synergistic effect.

Plastome-wide comparison reveals new SNV resources for the authentication of Dendrobium huoshanense and its corresponding medicinal slice (Huoshan Fengdou)

Dendrobium species and their corresponding medicinal slices have been extensively used as traditional Chinese medicine (TCM) in many Asian countries. However, it is extremely difficult to identify Dendrobium species based on their morphological and chemical features. In this study, the plastomes of D. huoshanense were used as a model system to investigate the hypothesis that plastomic mutational hotspot regions could provide a useful single nucleotide variants (SNVs) resource for authentication studies. We surveyed the plastomes of 17 Dendrobium species, including the newly sequenced plastome of D. huoshanense. A total of 19 SNVs that could be used for the authentication of D. huoshanense were detected. On the basis of this comprehensive comparison, we identified the four most informative hotspot regions in the Dendrobium plastome that encompass ccsA to ndhF, matK to 3'trnG, rpoB to psbD, and trnT to rbcL. Furthermore, to established a simple and accurate method for the authentication of D. huoshanense and its medicinal slices, a total of 127 samples from 20 Dendrobium species including their corresponding medicinal slices (Fengdous) were used in this study. Our results suggest that D. huoshanense and its medicinal slices can be rapidly and unequivocally identified using this method that combines real-time PCR with the amplification refractory mutation system (ARMS).

A comparative study of three tissue-cultured Dendrobium species and their wild correspondences by headspace gas chromatography-mass spectrometry combined with chemometric methods

Plant tissue culture technique is widely used in the conservation and utilization of rare and endangered medicinal plants and it is crucial for tissue culture stocks to obtain the ability to produce similar bioactive components as their wild correspondences. In this paper, a headspace gas chromatography–mass spectrometry method combined with chemometric methods was applied to analyze and evaluate the volatile compounds in tissue-cultured and wild Dendrobium huoshanense Cheng and Tang, Dendrobium officinale Kimura et Migo and Dendrobium moniliforme (Linn.) Sw. In total, 63 volatile compounds were separated, with 53 being identified from the three Dendrobium spp. samples. Different provenances of Dendrobiums had characteristic chemicals and showed remarkable quantity discrepancy of common compositions. The similarity evaluation disclosed that the accumulation of volatile compounds in Dendrobium samples might be affected by their provenance. Principal component analysis showed that the first three components explained 85.9% of data variance, demonstrating a good discrimination between samples. Gas chromatography–mass spectrometry techniques, combined with chemometrics, might be an effective strategy for identifying the species and their provenance, especially in the assessment of tissue-cultured Dendrobium quality for use in raw herbal medicines.

Qualitative and quantitative analysis of specific polysaccharides in Dendrobium huoshanense by using saccharide mapping and chromatographic methods

Qualitative and quantitative analysis of specific polysaccharides from ten batches of Dendrobium huoshanense were performed using high performance size exclusion chromatography coupled with multi-angle laser light scattering and refractive index detector (HPSEC-MALLS-RID), gas chromatography-mass spectrometry (GC-MS), nuclear magnetic resonance (NMR) and saccharide mapping based on polysaccharides analysis by using carbohydrate gel electrophoresis (PACE) and high performance thin layer chromatography (HPTLC). Results showed that molecular weights, the radius of gyrations, and contents of specific polysaccharides in D. huoshanense were ranging from 1.16×10(5) to 2.17×10(5)Da, 38.8 to 52.1nm, and 9.9% to 19.9%, respectively. Furthermore, the main monosaccharide compositions were Man and Glc. Indeed, the main glycosidic linkages were β-1,4-Manp and β-1,4-Glcp, and substituted with acetyl groups at O-2 and O-3 of 1,4-linked Manp. Moreover, results showed that PACE and HPTLC fingerprints of partial acidic and enzymatic hydrolysates of specific polysaccharides were similar, which are helpful to better understand the specific polysaccharides in D. huoshanense and beneficial to improve their quality control. These approaches could also be routinely used for quality control of polysaccharides in other medicinal plants.

A polysaccharide from Dendrobium huoshanense prevents hepatic inflammatory response caused by carbon tetrachloride

Dendrobium huoshanense is a precious herbal medicine in China, which exhibits a variety of restorative and therapeutic effects. This study aimed at investigating the hepatoprotective effects of a polysaccharide (DHP1A) isolated from D. huoshanense via water extraction, diethylaminoethyl (DEAE) cellulose anion exchange and size exclusion chromatography. The animal experiment indicated that the oral administration of DHP1A obviously reduced the levels of alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase and 8-hydroxy-2'-deoxyguanosine in the serum of mice treated with carbon tetrachloride (CCl₄), suggesting the hepatoprotective potential of this polysaccharide. Moreover, DHP1A decreased the expressions of tumor necrosis factor-α, interleukin-1β, monocyte chemoattractant protein-1, macrophage inflammatory protein-2, CD68 and phosphorylated IκBα (p-IκBα) in the CCl₄-treated mice. These results revealed that the hepatoprotective effect of DHP1A was partly attributed to its anti-inflammatory action.

Immunoregulatory activities of Dendrobium huoshanense polysaccharides in mouse intestine, spleen and liver

To evaluate the immunomodulating responses in intestine, spleen and liver, 50-200mg/kg of DHP was orally administrated to mice without or with methotrexate. The proliferation of marrow cells, which was performed with the addition of the supernatant of small intestinal lymphocytes isolated from the mice administrated orally with DHP, showed that the intestinal immune response was significantly enhanced in all DHP-treated groups. For the immune response in spleen, all tested doses of DHP remarkably promoted the proliferation of splenic cells and increased the secretion of interferon-γ (IFN-γ). For the immune responses in liver, DHP not only significantly stimulated the proliferation of hepatic cells and the secretion of IFN-γ at all tested doses of DHP, but also significantly elevated the secretion interleukin-4 (IL-4) at the doses of 100 and 200mg/kg. Moreover, DHP could recover methotrexate-injured small intestinal immune function (100 and 200mg/kg) and promoted cell proliferation and IFN-γ production (200mg/kg) in spleen and liver of methotrexate-treated mice. These results suggested that DHP after oral administration possessed immunomodulating effects both in small intestine immune system and in systemic immune system, which were further proved by the mRNA expression of IFN-γ and IL-4.

Structural characterization and antioxidant activity of a low-molecular polysaccharide from Dendrobium huoshanense

The present study aimed at investigating the structural features and antioxidant activities of a polysaccharide fraction (DHP1A) obtained from Dendrobium huoshanense, a precious herb medicine in China. DHP1A mainly consisted of mannose (Man), glucose (Glc) and a trace of galactose (Gal), with a molecular weight of 6700Da. Its backbone contained (1→4)-linked α-D-Glcp, (1→6)-linked α-D-Glcp and (1→4)-linked β-D-Manp, with a branch of terminal β-D-Galp. The in vitro antioxidant evaluation revealed that DHP1A had a remarkable inhibition effect on the FeCl2-induced lipid peroxidation. Furthermore, DHP1A pretreatment decreased the production of malondialdehyde (MDA), and restored the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), as well as the level of glutathione (GSH) in the livers of CCl4-treated mice. These results suggested that DHP1A was a potential antioxidant component in D. huoshanense.