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Objectives: To evaluate the ameliorative effect of Dendrobium officinale Kimura et Migo (DO) on a desiccated environment-induced experimental dry eye rat model and elucidate its underlying mechanisms. Materials and Methods: The Sprague-Dawley rats were kept in low-humidity environment and received constant airflow for 8 weeks to establish the experimental dry eye model. DO water extract (DOW, 372 mg/kg/day) was orally administered daily for 8 weeks. Schirmer's test was used to measure the tear fluid production at days 0, 14, 28, 42, and 56. At the end of experiment, lacrimal gland tissues and eyeballs were collected for hematoxylin and eosin staining, PAS staining, and immunohistochemical staining. Inflammatory cytokines in conjunctiva including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, and matrix metalloproteinase 9 were measured by real-time PCR. The aquaporin 5 (AQP5) expression in lacrimal gland was also determined using Western blot assay. Results: DOW treatment (DOWT) increased the tear production of rats significantly in the desiccated environment at day 42. Histological analysis revealed that DOW could reverse destruction of conjunctiva and increase goblet cell number and mucin expression in the experimental dry eye rats. In dry eye rats, desiccated environment and constant airflow induced TNF-α and IL-1β production in the conjunctiva, whereas DOWT reversed the upregulation of proinflammatory cytokines. Moreover, DOWT increased the expression of AQP5 at protein level in the lacrimal gland tissues in both desiccated and normal environmental conditions. Conclusion: The present study suggests that DO has therapeutic potential on dry eye symptoms through upregulating AQP5 expression, increasing tear production, inhibiting conjunctiva destruction and inflammation, as well as promoting mucin production. [ABSTRACT FROM AUTHOR]

Two new bibenzyl derivatives, dendrocandin T (1) and dendrocandin U (2), together with eight known bibenzyls, were isolated from the stems ofDendrobium officinale. Those compounds were sent for the first time for central nervous system-related bioassay and the results indicated that compounds3,4, and5have a certain degree of neurite outgrowth-promoting activity, and compounds1,2,6, and7also have weak activity. The results indicated thatD. officinaleused as health food and traditional Chinese medicine “Tiepi Shihu” has a health function of neurotrophic effects. [ABSTRACT FROM PUBLISHER]

The Dendrobium plants (members of the Orchidaceae family) are used as traditional Chinese medicinal herbs. Bibenzyl, one of the active compounds in Dendrobium officinale, occurs in low amounts among different tissues. However, market demands require a higher content of thes compounds to meet the threshold for drug production. There is, therefore, an immediate need to dissect the physiological and molecular mechanisms underlying how bibenzyl compounds are biosynthesized in D. officinale tissues. In this study, the accumulation of erianin and gigantol in tissues were studied as representative compounds of bibenzyl. Exogenous application of Methyl-Jasmonate (MeJA) promotes the biosynthesis of bibenzyl compounds; therefore, transcriptomic analyses were conducted between D. officinale-treated root tissues and a control. Our results show that the root tissues contained the highest content of bibenzyl (erianin and gigantol). We identified 1342 differentially expressed genes (DEGs) with 912 up-regulated and 430 down-regulated genes in our transcriptome dataset. Most of the identified DEGs are functionally involved in the JA signaling pathway and the biosynthesis of secondary metabolites. We also identified two candidate cytochrome P450 genes and nine other enzymatic genes functionally involved in bibenzyl biosynthesis. Our study provides insights on the identification of critical genes associated with bibenzyl biosynthesis and accumulation in Dendrobium plants, paving the way for future research on dissecting the physiological and molecular mechanisms of bibenzyl synthesis in plants as well as guide genetic engineering for the improvement of Dendrobium varieties through increasing bibenzyl content for drug production and industrialization. [ABSTRACT FROM AUTHOR]

2,3-O-acetylated-1,4-β-d-glucomannan (DOP-1-1) is a polysaccharide isolated from the stem of Dendrobium officinale. DOP-1-1 has been demonstrated to have remarkable immunomodulatory properties, but little is known about the influence of its structural diversity on bioactivity (and even less about the exact mechanism underlying its immune responses). First, DOP-1-1 was stabilized at different temperatures and pH conditions based on differential scanning calorimetry and size exclusion-chromatography–high-performance liquid chromatography. Then, a detailed study on the effects of DOP-1-1 on a human leukemia monocytic cell line (THP-1) under normal conditions was undertaken. DOP-1-1 promoted the translocation of nuclear factor-kappa B (NF-κB) and degradation of IκB proteins. The expression of genes and proteins closely associated with the immune, survival and apoptotic functions of NF-κB were analyzed by quantitative real-time RT-PCR. Furthermore, CCL4 and IP10 were confirmed to be the novel targets of the immune response stimulated by DOP-1-1. The phosphorylation of NF-кB was inhibited by treatment with a toll-like receptor 4 (TLR4) antagonist (TAK-242) and myeloid differentiation factor 88 (MyD88) inhibitor (ST2825). These data suggested: (i) the O-acetylated glucomannan DOP-1-1 is present in the steady state in low-pH solutions; (ii) DOP-1-1 can induce an immune response through NF-кB mediated by a TLR4 signaling pathway; and (iii) CCL4 and IP10 could be the novel targets of the immune response stimulated by O-acetylated glucomannan. [ABSTRACT FROM AUTHOR]

The traditional Chinese medicine (TCM) "Shihu" has a long history of medicinal use in China from some species of Dendrobium. D. officinale is a major source of "Shihu" and is widely cultivated in south of China and listed separately as "Tiepi Shihu" by the Chinese Pharmacopoeia in now time. Traditionally, D. officinale has been widely used in daily health care and the treatment of diabetes and gastrointestinal diseases. In order to better develop and utilize D. officinale , we conducted this systematic review of previous studies, showed clear structure of all isolates from D. officinale together with pharmacological progress, hoping to provide references for further research and utilization. In addition, specific display of the chemical components and the research progress of related activities can help to better understand the traditional records and modern pharmaceutical applications of the plant medicine. Information on phytochemistry and pharmacological studies of D. officinale was collected from various scientific databases including Web of Science, SciFinder, ACS, Springer, Scopus, PubMed, ScienceDirect, Google Scholar and CNKI. More than 180 compounds isolated from D. officinale , including bibenzyls, phenols, phenylpropanoids, lignans, flavonoids and polysaccharides are listed in this review. Furthermore, modern pharmacological researches such as hypoglycemia, immune regulation, antioxidant, cardiovascular regulation and gastrointestinal protection are summarized. Based on the summary of the research work of D. officinale , we systematically show the chemical composition of the plant, and concluded the relationship of those composition with plant habitat together with the relationship between the structure of chemical components and pharmacological activity. Moreover, we suggest that some of small molecule compounds could also be quality control of D. officinale besides polysaccharides. [Display omitted] • D. officinale is widely used in Asia as a precious folk herbal medicine or health food. • Traditional application of D. officinale and modern diseases, especially diabetes, were discussed. • Active ingredients and their action mechanism of D. officinale were systematically summarized. • The relationship between habitat and chemical composition of D. officinale was discussed. • This review intends to provide a comprehensive understanding and appraisal of D. officinale. [ABSTRACT FROM AUTHOR]

A neutral heteropolysaccharide (DOP-1-1) consisted by mannose and glucose (5.9:1) with an average molecular weight at about 1.78 × 10 5 Da was purified from Dendrobium officinale . Based on Fourier transform infrared spectrum (FT-IR) and nuclear magnetic resonance (NMR) spectra, it suggested that partial structure of DOP-1-1 is an O -acetylated glucomannan with β- d configuration in pyranose sugar forms. The immunomodulatory activity of DOP-1-1 was evaluated by secretion level of cytokine (interleukin (IL)-1β and IL-10) and tumor necrosis factor (TNF)- α in vitro . Our results suggested that DOP-1-1 could stimulate cytokine production (TNF- α , IL-1β) in cells. These findings demonstrated that the purified polysaccharide from D. officinale presented significant immune-modulating activities. Furthermore, by Western-blot we can found that the signaling pathways of DOP-1-1 induced immune activities involving ERK1/2 and NF-кB. As to antioxidant activity, DOP-1-1 hadn’t showed remarkable scavenging capacity of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) in contrast with other studies of polysaccharides from D. officinale . [ABSTRACT FROM AUTHOR]

• Structural characterization of two polysaccharides from Dendrobium officinale were described. • DOP performed the hypoglycemic activity via stimulating GLP-1 secretion in STZ-induced diabetic rats and STC-1 cells. • Ca2+/CaM/CaMKII and MAPK pathways might involve in the intracellular DOP-induced GLP-1 secretion. • The repeated unit of backbone of DOP-1 and DOP-2 might be the effective unit of DOP-induced GLP-1 secretion. Two polysaccharides, named DOP-1 and DOP-2, with molecular weights of 6.8 kDa and 14.3 kDa, respectively, were isolated and purified from the stems of Dendrobium officinale. Monosaccharide composition, Fourier-transform infrared spectroscopy, methylation, and nuclear magnetic resonance analyses indicated that DOP-1 and DOP-2 may have a backbone consisted of →4)- β - d -Glcp-(1→, →4)- β - d -Manp-(1→, →4)-2- O -acetyl- β - d -Manp-(1→ and →4)-3- O -acetyl- β - d -Manp-(1→. In vivo assays showed that D. officinale polysaccharides (DOPs) exerted significant hypoglycemic effects accompanying increased serum insulin and glucagon-like peptide-1 (GLP-1) levels in streptozotocin-induced diabetic rats. Further in vitro experiments showed that DOP-induced GLP-1 secretion was inhibited by an intracellular calcium chelator, a Ca2+/calmodulin-dependent protein kinase (CaMK) II inhibitor, a specific calcium-sensing receptor antagonist, and a p38-mitogen-activated protein kinases (MAPK) inhibitor. These results indicated that DOPs may decrease fasting blood sugar levels by stimulating GLP-1 secretion and that intracellular DOP-induced GLP-1 secretion involved the Ca2+/calmodulin/CaMKII and MAPK pathways. [ABSTRACT FROM AUTHOR]