[Research advances in chemical constituents and pharmacological activities of Dendrobium plants].

Dendrobii Caulis are commonly used tonic Chinese medicinal materials with a long history of application. As demonstrated by pharmacological results, the chemical constituents and the extracts of Dendrobii Caulis have anti-inflammatory, antibacte-rial, antioxidant, and anti-tumor effects, and can also regulate immunity, lower blood pressure, and regulate blood sugar. The active ingredients contained are widely concerned by scholars. This paper comprehensively summarized the chemical constituents and pharmacological activities of Dendrobium plants reported so far. The chemical constituents isolated from Dendrobium plants are mainly alkaloids, sesquiterpenoids, flavonoids, fluorenones, coumarins, bibenzyls, phenanthrenes, lignans, steroids, phenols, and polysaccharides. This paper is expected to provide a reference for further research, development, and utilization of Dendrobium plants.

Complete genome sequence of Paris mosaic necrosis virus, a distinct member of the genus Potyvirus.

The complete genomic sequence of a novel potyvirus was determined from Paris polyphylla var. yunnanensis. Its genomic RNA consists of 9,660 nucleotides (nt) excluding the 3'-terminal poly (A) tail, containing the typical open reading frame (ORF) of potyviruses and encoding a putative large polyprotein of 3030 amino acids. The virus shares 53.9-70.1% nt sequence identity and 43.9-73.2% amino acid sequence identity with other viruses classified within the genus Potyvirus. Proteolytic cleavage sites and conserved motifs of the potyviruses were identified in the polyprotein and within individual proteins. Phylogenetic analysis indicated that the virus is most closely related to members of the BCMV subgroup. The results suggest that the virus should be classified as a novel species within the genus Potyvirus, which we tentatively name "Paris mosaic necrosis virus".

Characterization and immunological activity of polysaccharides from two types of Dendrobium devonianum with different appearance.

Dendrobium devonianum, a precious species of Dendrobium, is also called "Zi-pi Shi-hu" in Chinese due to its purple-skinned appearance. In this study, polysaccharides from green (GDP) and purple (PDP) skin D. devonianum were isolated by homogenate assisted extraction, ethanol precipitation and ultrafiltration. Their difference in physicochemical properties and immunological activities were investigated and compared. The results suggested that both GDP and PDP mainly contained glycosidic linkages of ß-1,4-Manp and ß-1,4-Glcp, but their molecular weights, 2.044 × 105 (GDP) vs 3.563 × 105 (PDP), and compositional monosaccharides of mannose to glucose ratio, 16.46: 1.00 (GDP) vs 7.61: 1.00 (PDP), were significantly different. Especially, GDP showed stronger immunological potentiation activity in vitro. Although the extraction yield of GDP was lower than that of PDP, considering the production of raw material and immunological activity of its polysaccharides, green skin D. devonianum should be a good alternative of purple one. These findings are helpful to provide evidence for improving the cultivation and production of D. devonianum.

Phytochemical profiles of edible flowers of medicinal plants of Dendrobium officinale and Dendrobium devonianum.

The discovery of new edible flowers that are nontoxic, innocuous flowers having human health benefits, surveys of their phytochemicals and utilization are of great scientific and commercial interest. Dendrobium officinale and Dendrobium devonianum are precious Traditional Chinese Medicine. During the massive commercial cultivation, a lot of flowers were produced and certified as edible flowers, and the phytochemical profiles and bioactivities warrant evaluate. The present study aimed to investigate the phytochemicals and antioxidative activities in flowers of D. officinale (DOF) and D. devonianum (DDF). In total, 474 metabolites were identified using a widely targeted metabonomics method, 16 amino acids and 6 flavonoids were measured using high-performance liquid chromatography (HPLC), and 8 fatty acids were detected using gas chromatography-mass spectrometry (GC-MS). Both flowers contained various amino acids, including 7 essential amino acids, diverse flavonoids, especially quercetin, kaempferol and their derivatives, and high levels of methyl linoleate and methyl linolenate. The relative levels of quercetin, kaempferol and their glycosides were higher in DDF than in DOF, whereas the relative levels of several flavonoids C-glycosides were high in DOF. Ethanol extracts of both DOF and DDF showed antioxidative capacities including the scavenging of 1,1-diphenyl-2-picrylhydrazyl and hydroxyl radicals. Both edible flowers contained flavonoids, amino acids, and fatty acids and have antioxidative activities, which should be explored for use in functional foods and pharmaceuticals.

Four new compounds from Dendrobium devonianum.

Two new phenanthrenes dendrodevonin A and B, two new aliphatic acids dendrodevonic acid A and B, along with ten known compounds, were isolated from the stems of Dendrobium devonianum. The structures of new compounds were elucidated on the basis of MS and NMR spectroscopic data, and single-crystal X-ray diffraction analysis. The cytotoxicities of isolates towards HT-29 cell were discussed, and 4-methoxy-2,7-phenanthrenediol exhibited inhibitory activity compared with other studied compounds.