A steroidal glycoside from Polygonatum odoratum (Mill.) Druce. improves insulin resistance but does not alter insulin secretion in 90% pancreatectomized rats.
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The aim of this study was to investigate the effects of three steroidal glycosides (SG-100, SG-280, and SG-460) obtained from Polygonatum odoratum (Mill.) Druce. on insulin secretion, insulin action, and relative glucose uptake in various tissues of 90% pancreatectomized male Sprague-Dawley rats. One of the compounds (30 mg/kg body weight daily) with a 40%-fat diet was orally administered to a group of such rats for 13 weeks. On the day after a hyperglycemic clamp, euglycemic hyperinsulinemic clamp with 1 microCi of [1-(14)C]2-deoxyglucose per 100 g body weight was used. Serum glucose levels were lowest in the rats receiving SG-100. Insulin secretion from pancreatic beta-cells did not change with SG administration. Whole-body glucose disposal rates increased with SG-100 administration by 39%. SG-100 increased the glycogen contents and glycogen synthase activity in the soleus muscle of pancreatectomized rats. Uptake of [1-(14)C]2-deoxyglucose into the soleus muscle was higher in such rats receiving SG-100 than in rats receiving other compounds. In conclusion, SG-100 has an antihyperglycemic effect by promoting peripheral insulin sensitivity without changing insulin secretion. (+info)
Variation in floral sex allocation in Polygonatum odoratum (Liliaceae).
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BACKGROUND AND AIMS: It is well known that resource allocation to male and female functions can be highly variable in hermaphroditic plants. The purpose of this study was to investigate variations in sexual investment at different levels (flower, plant and population) in Polygonatum odoratum, a plant with sequentially opening flowers. METHODS: Pollen and ovule production in base, middle and top flowers of P. odoratum flowering shoots from two natural populations were quantified. Plant measurements of phenotypic and functional gender were calculated in both populations. Total leaf number was used to investigate the relationship between gender assessments and plant size. KEY RESULTS: Pollen and ovule production varied depending on flower position, although the precise pattern differed between both studied populations; only investment in female floral function decreased markedly from base to top flowers in both populations. The frequency distribution of phenotypic gender and their relationship with plant size differed between populations. Phenotypic and functional gender were correlated in both populations. CONCLUSIONS: Sexual investment in P. odoratum has shown a marked variability within plants, among plants, and between populations, which confirms the importance of analysing sex expression in plants of this type. Differences in relative investment in male and female components (phenotypic gender) are reflected in the functional gender and it would be expected that the evolution of sexual specialization in Polygonatum odoratum would be promoted. (+info)
Furostanol saponins from the fresh rhizomes of Polygonatum kingianum.
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Ten furostanol saponins were isolated as five pairs of 25R and 25S epimers from the fresh rhizomes of Polygonatum kingianum. Seven of them were identified as new compounds, (25S)-kingianoside D (2), (25S)-kingiano-side C (4), (25R,22)-hydroxylwattinoside C (5), kingianoside E (7), (25S)-kingianoside E (8), kingianoside F (9) and (25S)-kingianoside F (10), together with three known saponins, kingianoside C (1), kingianoside D (3), and 22-hydroxylwattinoside C (6). The structures of the new saponins were determinded by detailed analysis of their 1D and 2D NMR spectra, and by comparison of the spectral data with those reported. (+info)
Apoptosis-inducing effect and structural basis of Polygonatum cyrtonema lectin and chemical modification properties on its mannose-binding sites.
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Polygonatum cyrtonema Lectin (PCL), which is classified as a monocot mannose-binding lectin, has received great regards for its uniquely biological activities and potentially medical applications in cancer cells. This paper was initially aimed to study apoptosis of PCL on Hela cells. Thus, 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) method was carried out. Through observation of cell morphologic changes and Lactate dehydrogenase (LDH) activity-based cytotoxicity assays, PCL induced HeLa cell apoptosis in a dose-dependent manner. To further gain structural basis, multiple alignments, homology modeling and docking experiments were performed to analyze the correlation between its biological activities and mannose-binding sites. Eventually, considering docking data, chemical modification properties on the three mannose-binding sites were analyzed by a series of biological experiments (e.g., hemagglutinating and mitogenic activity assays, fluorescence and Circular Dichrosim (CD) spectroscopy) to profoundly identify the role of some key amino acids in the structure-function relationship of PCL. (+info)
Three new saponins from the fresh rhizomes of Polygonatum kingianum.
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Further studies on the fresh rhizomes of Polygonatum kingianum led to the isolation of one new spirostanol saponin (25R)-kingianoside G (1), and two pairs mixture of 25R and 25S stereoisomeric spirostanol saponins (25R, S)-pratioside D1 (2a, 2b) and (25R, S)-kingianoside A (3a, 3b), among them 2b and 3b were new spirostanol saponins, together with another two known compounds, disporopsin (4) and daucosterol (5). The structures of the new saponins were determined by detailed analysis of their 1D and 2D NMR spectra, and chemical evidences. (+info)
Molecular mechanisms of Polygonatum cyrtonema lectin-induced apoptosis and autophagy in cancer cells.
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Polygonatum cyrtonema lectin (PCL), a mannose/sialic acid-binding lectin, has been reported to display remarkable inhibitory and cytotoxic activity toward cancer cells. However, the precise mechanism by which PCL induces tumor cell death is still only rudimentarily understood. In the present study, PCL was shown to markedly inhibit the growth of human melanoma A375 cells with concomitant low toxicity to the normal melanocytes. Subsequently, PCL was found to simultaneously induce A375 cell apoptosis and autophagy. The mechanism of apoptosis following treatment with PCL involved regulation of Bax, Bcl-x(L) and Bcl-2 proteins, which then caused collapse of the mitochondrial membrane potential, leading to cytochrome c release and caspase activation. The treatment with PCL also abrogated the glutathione antioxidant system, and induced mitochondria to generate massive ROS accumulation, which subsequently resulted in p38 and p53 activation. Further experimental data confirmed that the ROS-p38-p53 pathway could be involved in the stimulation of autophagy, suggesting that autophagy may play a death-promoting role via the above-mentioned apoptotic pathway. In conclusion, these findings indicate that PCL induces both apoptosis and autophagy in cancer cells through a mitochondria-mediated ROS-p38-p53 pathway. (+info)
Induction of apoptosis by Polygonatum odoratum lectin and its molecular mechanisms in murine fibrosarcoma L929 cells.
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Saponins from the processed rhizomes of Polygonatum kingianum.
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Two new spirostanol saponins, named kingianoside H (1) and kingianoside I (2), were isolated from the processed rhizomes of Polygonatum kingianum, along with a known triterpenoid saponin ginsenoside-Rc (3), four known spirostanol saponins Tg (4), (5), polygonatoside C(1) (6) and ophiopogonin C' (7). The structures of the new compounds were elucidated by detailed spectroscopic analyses, including 1D and 2D NMR techniques and chemical methods. Compounds 3 and 5 were first reported from the genus Polygonatum. Compounds 4, 6 and 7 are reported for the first time from the processed Polygonatum kingianum. (+info)