Dendrobium is a genus of flowering plants belonging to the Orchidaceae family with more than 1,400 species. Many Dendrobium species have been used as medicinal plants in several Asian countries for thousands of years. Alkaloids were reported as the major biological markers due to their complex chemical compositions and various types. In this review, we summarized the structural types of alkaloids, their pharmacological activities, as well as the mechanisms of biological activities. More than sixty alkaloids were isolated and identified from the Dendrobium genus. Moreover, the pharmacological effects of Dendrobium alkaloids as hepatic lipid and gluconeogenesis regulation, as neuroprotection, and as anti-tumor, anti-inflammatory, anti-diabetes, and anti-virus factors were described. Besides, the total chemical synthesis of dendrobine is provided, while the biosynthetic pathway of dendrobine has been proposed based on the functions of associated genes. For applications of these invaluable herbs, more researches on the extraction of biological markers from compounds are needed. Further confirmation of the proposed biosynthetic pathways is anticipated as well.

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Dendrobium represents one of the most important orchid genera, ornamentally and medicinally. Dendrobiums are sympodial epiphytic plants, which is a name they are worthy of, the name coming from Greek origin: "dendros", tree, and "bios", life. Dendrobium species have been used for a thousand years as first-rate herbs in traditional Chinese medicine (TCM). They are source of tonic, astringent, analgesic, antipyretic, and anti-inflammatory substances, and have been traditionally used as medicinal herbs in the treatment of a variety of disorders, such as, nourishing the stomach, enhancing production of body fluids or nourishing Yin. The Chinese consider Dendrobium as one of the fifty fundamental herbs used to treat all kinds of ailments and use Dendrobium tonic for longevity. This review is focused on main research conducted during the last decade (2006-2016) on Dendrobium plants and their constituents, which have been subjected to investigations of their pharmacological effects involving anticancer, anti-diabetic, neuroprotective and immunomodulating activities, to report their undeniable potential for treating age-related pathologies.

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Dendrobium is one of the largest genera in Orchidaceae, comprising about 800-1500 species mainly distributed in tropical Asia, Australasia, and Australia. There are 74 species and two varieties of this genus in China. Because of their ornamental and commercial value, Dendrobium orchids have been studied at low taxonomic levels. However, structural changes and effective mutational hotspots of Dendrobium plastomes have rarely been documented. Here, 30 Dendrobium plastomes were compared, comprising 25 newly sequenced in this study and five previously published. Except for their differences in NDH genes, these plastomes shared identical gene content and order. Comparative analyses revealed that the variation in size of Dendroubium plastomes was associated with dramatically changed length of InDels. Furthermore, ten loci were identified as the top-ten mutational hotspots, whose sequence variability was almost unchanged with more than 10 plastomes sampled, suggesting that they may be powerful markers for Dendrobium species. In addition, primer pairs of 47 polymorphic microsatellites were developed. After assessing the mean BS values of all combinations derived from the top-ten hotspots, we recommend that the combination of five hotspots-trnT-trnL, rpl32-trnL, clpP-psbB, trnL intron, and rps16-trnQ-should be used in the phylogenetic and identification studies of Dendrobium.

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A pair of racemic indolizidine enantiomers, (±)-homocrepidine A (1), and a piperidine derivative, homocrepidine B (2), were isolated from Dendrobium crepidatum along with the known alkaloid crepidine (3). The racemic mixture of 1 was separated into a pair of enantiomers, (+)-1 and (-)-1, by HPLC using a chiral chromatographic substrate, which represents the first successful example of resolving indolizidine racemic mixtures. The absolute configurations of (+)-1 and (-)-1 were assigned from single-crystal X-ray diffraction data. The evaluation of anti-inflammatory activity with LPS-induced RAW 264.7 macrophages revealed that (+)-1 strongly inhibited the production of nitric oxide (IC50, 3.6 μM) and significantly decreased the expression of inducible nitric oxide synthase, while (-)-1 and (±)-1 only had moderate inhibitory effects (IC50, 22.8 and 14.7 μM). Compound 2 showed moderate anti-inflammatory activity (IC50, 27.6 μM).

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Aim of the study This study was conducted in the Naban River Watershed National Nature Reserve to identify and analyse knowledge and use of wild plants for medicinal purposes by Hani ethnicity and to search out culturally as well as economically important plant species and land use types. Material and methods Ethnobotanical data was collected using freelisting interviews with randomly selected informants and semi-structured as well as field interviews. Plant specimens were collected, identified and deposited at the Herbarium of Xishuangbanna Tropical Botanical Garden, Mengla, Yunnan Province, China. Data were analysed by use-reports, in addition important indices like relative frequency of citation (RFC) and cultural importance index (CI) were calculated. Smith's salience index was assessed using Anthropac 4.08. Consensus analysis was applied to measure informant agreement on plants used in different medicinal use categories. Results A total of 199 medicinal plants belonging to 73 families were recorded. Dominant families are Asteraceae (5.5%), Piperaceae and Verbenaceae (4.5%), Fabaceae, Liliaceae (4.0%) and Euphorbiaceae, Lamiaceae and Solanaceae (3.5%). Most culturally salient species from freelisting analysis were Dendrobium crepidatum Lindl. ex Paxt. (Smith's SI=0.41), Aristolochia sp. (0.306), Microstegium ciliatum (Trin.) A. Camus (0.129), Eupatorium coelestinum L. (0.119), Litsea martabanica (Kurz) Hook. F. (0.116) and Psidium guajava L. (0.103). The majority of the utilised species were collected from forest (51.9%), followed by fallow land (22.52%), arable fields (14.5%), and homegardens (11.08%). Conclusions It became clear that the knowledge of medicinal plants is not homogenously distributed among Hani. Based on the percentage of collected medicinal plants from four habitat types, forest is the most important source of medicinal plants for Hani but when considering the cultural importance of species it seems that homegardens are slightly more important than other habitats.

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