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PubMed1999

Effect of steam pressure treatment on the physicochemical properties of Dioscorea starches.

Dioscorea alata and Dioscorea rotundata starches were subjected to steam pressure treatments (0.35, 0.7, and 1.05 kg cm(-)(2)) for different periods. The total amylose content in the treated starches was not significantly affected, but the soluble amylose content decreased 3-5-fold. Reducing values and lambda(max) of the iodine complexes were unaffected. Viscosity of the starch paste was reduced by the treatments, and at higher pressures and longer time of treatments, the peak viscosity values were reduced to very low values. Pasting temperatures were enhanced considerably. Swelling volumes underwent reduction, but no change in solubility occurred. Clarity and paste stability were markedly lowered. The results suggest that starch granules are compressed by the steam pressure treatment, leading to vast changes in physicochemical properties.

Amylose↗
PubMed1992

Identification of Endogenous Gibberellins in Dormant Bulbils of Chinese Yam, Dioscorea opposita.

It is known that dormancy of the genus Dioscorea is induced by application of gibberellin (GA) A(3). To understand the role of GAs in dormancy induction, endogenous GAs have been identified by Kovats retention indices and full mass spectra from capillary gas chromatography-mass spectrometry analysis of purified extract from dormant bulbils of Dioscorea opposita Thunb. These include GA(4), GA(9), GA(12), GA(19), GA(20), GA(24), GA(36), and GA(53); their presence suggests the occurrence of two biosynthetic pathways in D. opposita bulbils, the early 13-hydroxylation pathway and the non-13-hydroxylation pathway.

Journal Article↗
PubMed1977

Dormancy in Dioscorea: Gibberellin-Induced Inhibition or Promotion in Seed Germination of D. tokoro and D. tenuipes in Relation to Light Quality.

Effects of light and gibberellic acid (GA(3)) application on the germination of Dioscorea tokoro Makino and Dioscorea tenuipes Franch. et Savat. were observed. For complete germination, seeds of both species required prechilling in moist condition before incubation at a higher temperature. Red light irradiation during the incubation after the prechilling promoted germination; blue, green, or far red light markedly inhibited the germination of both species.Application of GA(3) induced complicated changes in the germination of both species in relation to light quality. In the germination of D. tokoro, GA(3) inhibited in the dark and red; however, it promoted germination in blue and far red light. GA(3) promoted germination of D. tenuipes in the dark and in blue, green, or far red light. These phenomena are explainable by assuming two counteractive reactions (germination-promoting and germination-inhibiting) which are both activated by applied GA(3).

Journal Article↗
PubMed2006

ESI-QqTOF-MS/MS and APCI-IT-MS/MS analysis of steroid saponins from the rhizomes of Dioscorea panthaica.

Using high-resolution quadrupole time-of-flight mass spectrometry along with an electrospray ionization source (ESI-QqTOF-MS), accurate molecular weights of 13 steroid saponins extracted from the rhizomes of Dioscorea panthaica were acquired and the corresponding molecular formulae obtained. In order to elucidate the fragmentation pathways of steroid saponins in D. panthaica, 10 authentic samples were investigated using ESI-QqTOF-MS/MS. In addition, atmospheric pressure chemical ionization mass spectrometry combined with ion trap tandem mass spectrometry (APCI-IT-MS/MS) was used to analyze the structures of 13 steroid saponins in D. panthaica. Through the analysis of their tandem mass data, diagnostic fragment ions of the spirostanol and furostanol steroid saponins in D. panthaica were detected as m/z 271.2056 and 253.1951. In addition, four pairs of isomers were detected and the possible structures of four unknown steroid saponins in D. panthaica speculated. ESI-TOF and APCI-MS(n) have proved to be effective tools for research on fragmentation mechanism of steroid saponins and the rapid determination of native steroid saponins in extract mixture, thereby avoiding tedious derivation and separation steps.

Carbohydrate Sequence↗
PubMed2003

The cytotoxicity of methyl protoneogracillin (NSC-698793) and gracillin (NSC-698787), two steroidal saponins from the rhizomes of Dioscorea collettii var. hypoglauca, against human cancer cells in vitro.

In our continuous studies of anticancer activity of steroidal saponins from the rhizomes of Dioscorea collettii var. hypoglauca (Dioscoreaceae), methyl protoneogracillin (NSC-698793) and gracillin (NSC-698787) were tested for cytotoxicity against human cancer cell lines from leukemia and eight solid tumor diseases. As a result, methyl protoneogracillin was cytotoxic against all the test cell lines with GI(50) < 100 micro M, especially selectively against two leukemia lines (CCRF-CEM and RPMT-8226), one colon cancer line (KM12), two central nervous system (CNS) cancer lines (SF-539 and U251), one melanoma line (M14), one renal cancer line (786-0), one prostate cancer line (DU-145), and one breast cancer line (MDA-MB-435), with GI(50) < or = 2.0 micro M. Leukemia, CNS cancer, and prostate cancer were the most sensitive subpanels, while ovarian cancer was the least sensitive subpanels. The preliminary toxicity studies showed that the maximum tolerant dose was 600 mg/kg for methyl protoneogracillin to mice. Gracillin was cytotoxic against most cell lines with GI(50), TGI and LC(50) at micromolar levels, but no activity against EKVX (non-small cell lung cancer), HT29 (colon cancer), OVCAR-5 (ovarian cancer), and SN12C (renal cancer). Based on structure-activity relationship, C-25 R/S con fi guration was critical for leukemia selectivity between methyl protoneogracillin and methyl protogracillin. F-ring was critical to selectivity between furostanol (methyl protoneogracillin and methyl protogracillin) and spirostanol (gracillin) saponins in this study. By an analysis of COMPARE software, no compounds in the NCI's database had similar mean graphs to those of methyl protoneogracillin and gracillin, respectively, indicating potential novel mechanism(s) of action involved. Put all in together, methyl protoneogracillin has been selected as a potential anticancer candidate for hollow fi ber assay to nude mice, but gracillin will not be pursued due to lack of selectivity against human cancer diseases.

Animals↗
PubMed2006

Effect of ethanol extract of dried Chinese yam (Dioscorea batatas) flour containing dioscin on gastrointestinal function in rat model.

In this study, a 40% ethanol extract of Chinese yam flour (Dioscoreae rhizoma), containing 177 +/- 58 microg/mL of dioscin, was tested in order to evaluate its pharmacological effects on the gastrointestinal tracts of Sprague-Dawley rats. Via the ingestion of the Chinese yam extract, the secretion of gastric acid was suppressed in the rats, and gastrointestinal motility increased by as much as 10%. The fecal quantity of rats fed on the Chinese yam extract also increased, by more than 40% as compared with that of the controls. The Chinese yam extract was found not to affect the growth of normal intestinal bacteria. However, a great deal of lactose-fermenting bacteria was observed in the fecal samples of rats fed for 6 weeks on 2% Chinese yam extract. This finding would appear to suggest that Chinese yam extract not only induces an improvement in digestive capability, but also affects the conversion of some intestinal flora to helpful bacteria. Our serochemical analyses indicated that serum glucose, neutral lipid, and total cholesterol levels were reduced to some degree by long-term feeding on Chinese yam extract. This finding bolsters the notion that Chinese yam extract may prove helpful as a digestion-aiding agent for patients suffering from hyperglycemia or hyperlipidemia.

Animals↗
PubMed2005

Segregation patterns of isozyme loci and microsatellite markers show the diploidy of African yam Dioscorea rotundata (2n = 40).

The cultivated yam species Dioscorea rotundata (2n = 40) has been considered by most authors as a tetraploid species with a basic chromosome number of ten. In this paper, we analysed the segregation of two isozyme loci and six microsatellite markers in the progeny of a self-fertilised monoecious plant. For the eight markers, segregation patterns could be explained by only two genetic models: diploidy or tetraploidy with two null alleles. Given the nature of studied markers, the most parsimonious hypothesis was that the parental plant was diploid. These results, data from a diversity survey and results of other authors led to the conclusion that D. rotundata is a diploid species.

Africa↗
PubMed2003

Investigating a new cryopreservation protocol for yams ( Dioscorea spp.).

Experiments were initiated to develop protocols for four species of Dioscorea, namely D. bulbifera L., D. oppositifolia L., D. alata L. and D. cayenensis Lam., and to assess the effects of various factors on the survival and regrowth of explants after rewarming. The treatments consisted of three different methods-vitrification, droplet and a modified droplet method-as well as the following variables-cryoprotective solution, sucrose concentration in the preadaptation medium and cold acclimation. While most of the protocols resulted in low to zero survival and regrowth rates, maximum survival rates of 100% and 75% were obtained for D. oppositifolia L. and D. cayenensis Lam., respectively, using two different protocols of the modified droplet method. A higher average survival rate was obtained using the droplet and modified droplet techniques than for the original vitrification methods. When the average of all the experiments was taken, more than one-half (52%) of the surviving explants developed further within 1 month with the modified droplet method compared to zero regrowth with the two other methods. The optimum protocol for cryopreservation is specific for each genotype.

Cryopreservation↗
PubMed2005

Abiotic metal stress enhances diosgenin yield in Dioscorea bulbifera L. cultures.

Lower concentrations of CuSO(4) (25-75 microM) in the MS medium supplemented with 0.1 mg l(-1) IAA+5.0 mg l(-1) Kn+500 mg l(-1) CH+10 mg l(-1) Cyst hyd enhanced the growth of regenerants of Dioscorea bulbifera L. CuSO(4) (75 microM) induced an appreciable diosgenin yield in the regenerants compared to those obtained on media without Cu. The presence of Cu thus seems to stimulate diosgenin production. The regenerants also differentiated bulbils on lower concentrations of Cu. At CuSO(4) (100 microM), however, cultures showed poor growth as well as a low diosgenin yield. Increased proline and protein contents were recorded in cultures grown on Cu-enriched media.

Copper Sulfate↗
PubMed2005

Dioscorin isolated from Dioscorea alata activates TLR4-signaling pathways and induces cytokine expression in macrophages.

The Toll-like receptor 4 (TLR4)-signaling pathway is crucial for activating both innate and adaptive immunity. TLR4 is a promising molecular target for immune-modulating drugs, and TLR4 agonists are of therapeutic potential for treating immune diseases and cancers. Several medicinal herb-derived components have recently been reported to act via TLR4-dependent pathways, suggesting that medicinal plants are potential resources for identifying TLR4 activators. We have applied a screening procedure to systematically identify herbal constituents that activate TLR4. To exclude possible LPS contamination in these plant-derived components, a LPS inhibitor, polymyxin B, was added during screening. One of the plant components we identified from the screening was dioscorin, the glycoprotein isolated from Dioscorea alata. It induced TLR4-downstream cytokine expression in bone marrow cells isolated from TLR4-functional C3H/HeN mice but not from TLR4-defective C3H/HeJ mice. Dioscorin also stimulated multiple signaling molecules (NF-kappaB, ERK, JNK, and p38) and induced the expression of cytokines (TNF-alpha, IL-1beta, and IL-6) in murine RAW 264.7 macrophages. Furthermore, the ERK, p38, JNK, and NF-kappaB-mediated pathways are all involved in dioscorin-mediated TNF-alpha production. In summary, our results demonstrate that dioscorin is a novel TLR4 activator and induces macrophage activation via typical TLR4-signaling pathways.

Animals↗
PubMed2006

Anti-allergic substances from the rhizomes of Dioscorea membranacea.

Extracts of five species of Thai medicinal plants, locally known as Hua-Khao-Yen, were screened for anti-allergic activities using RBL-2H3 cells. Of the five species studied, the ethanolic extract of Dioscorea membranacea exhibited potent inhibitory activity against beta-hexosaminidase release as a marker of degranulation in RBL-2H3 cells, with an IC(50) value of 37.5microg/mL. Eight compounds were isolated from this crude ethanolic extract, [two naphthofuranoxepins (1,2), one phenanthraquinone (3), three steroids (4-6), and two steroidal saponins (7,8)], and tested for their anti-allergic activities. The results showed that dioscorealide B (2) possessed the highest activity with an IC(50) value of 5.7microM, followed by dioscoreanone (3, IC(50)=7.7microM), dioscorealide A (1, IC(50)=27.9microM), and diosgenin (9, IC(50)=29.9microM). Structure-activity relationship studies of naphthofuranoxepins on anti-allergic activity revealed that the hydroxylation at position 8 conferred higher activity than methoxylation. For diosgenin derivatives, the aglycone was found to possess higher activity than the diglucosylated molecule; whereas substitution with rhamnoglucosides apparently results in loss of activity. Furthermore, effects of dioscorealide A, dioscorealide B, and dioscoreanone on antigen-induced release of TNF-alpha and IL-4 in the late phase reaction were also examined.

Animals↗
PubMed2005

New starches from traditional Chinese medicine (TCM)--Chinese yam (Dioscorea opposita Thunb.) cultivars.

The starches separated from two different Dioscorea opposita Thunb. cultivars were investigated for morphological, thermal and crystal properties. The shape of starch granules separated from different D. opposita Thunb. cultivars varied from round to oval or irregular. The surface of the starch granules appeared to be smooth without any fissures. The average particle diameter of starches from different D. opposita Thunb. cultivars was 40.3 and 38.7mum for D. 47 and D. SXY starch, respectively. The transition temperatures (T(o), T(p) and T(c)) and enthalpy of gelatinization (DeltaH(gel)) were determined using differential scanning calorimetry (DSC). The D. SXY starch showed the lower T(o) (74.2 degrees C) and the broader R (12.4). T(p) and T(c) of starch from D. 47 were higher than that of D. SXY starch. DeltaH(gel) values (11.37J/g) of D. 47 was higher than that of D. SXY starch (10.78J/g). The crystal type of starches separated from two different D. opposita cultivars was a typical C-type pattern. The degree of crystallinity of two D. opposita cultivars starches was about 45.9% and 31.5%, respectively.

Dioscorea↗
PubMed2005

Hypoglycemic effects of steroidal sapogenins isolated from Jamaican bitter yam, Dioscorea polygonoides.

In this study, three steroidal sapogenins (Delta3 diosgenin, diosgenin, and pennogenin) and the phytosterols, stigmasterol and beta-sitosterol were isolated from Jamaican bitter yam, Dioscorea polygonoides. Their effects on fasting blood glucose and intestinal amylase and ATPases in streptozotocin-induced diabetic rats were studied. The diabetic rats (fed supplemented and unsupplemented diets) lost weight significantly compared to the normal group. There was a significant increase in the activity of alpha-amylase in the proximal region of the small intestinal mucosa of diabetic rats fed sapogenin extract or commercial diosgenin. However, this did not result in increased fasting blood glucose. Instead, supplementation of the diet with bitter yam sapogenin extract significantly decreased fasting blood glucose compared to the diabetic group. Supplementation of the diet with bitter yam sapogenin extract or commercial diosgenin significantly reduced Na+-K+-ATPase activity in all three regions compared to the diabetic control group. Commercial diosgenin supplementation resulted in a significant increase in Ca2+ ATPase activity in proximal region compared to the diabetic control and bitter yam sapogenin extract groups. The effect of bitter yam sapogenin extract or commercial diosgenin on intestinal Na+-K+-ATPase activity could account for their hypoglycemic properties. However, there was adverse effect on the body weight.

Adenosine Triphosphatases↗
PubMed2005

Elicitation of diosgenin production in Dioscorea floribunda by ethylene-generating agent.

Dioscorea floribunda cells aggregates were cultured in liquid modified MS medium supplemented with 2,4-D (2 mg/l) and kinetine (0.1 mg/l). The cells were treated with different concentrations of ethylene-generating-agent 2-chloroethylphosphonic acid (2-CEPA). 2-CEPA at concentrations of 50 mg/l, 100 mg/l elicited production of diosgenin. The level of diosgenin increased to 72-fold higher than those of non-treated cells with 100 mg/l of 2-CEPA.

Culture Techniques↗
PubMed2006

Dioscorea opposita reverses dexamethasone induced insulin resistance.

The effects of Dioscorea opposita (huai shan yao, HSY) on dexamethasone-induced insulin resistance were investigated in vitro and in vivo. D. opposita extract reduced significantly the blood insulin and glucose levels in dexamethasone-induced diabetic rats. In vitro, HSY significantly enhanced insulin-stimulated glucose uptake in 3T3-L1 adipocytes. Moreover, HSY increase the mRNA expression of GLUT4 glucose transporter in 3T3-L1 adipocytes. These data suggest that D. opposita has insulin sensitivity that is associated with the regulation of GLUT4 expression.

Adipocytes↗
PubMed2004

Immune cell stimulating activity of mucopolysaccharide isolated from yam (Dioscorea batatas).

Mucopolysaccharide (YMP) of yam (Dioscorea batatas Decne) was tested for immunomodulatory activity in vitro. We examined the effect of YMP on the viability, cell-mediated cytotoxicity and IFN-gamma secretion of splenic lymphocytes. The cytotoxic activity of mouse splenocyte against leukemia cell was increased in the presence of YMP (10 microg/ml). However, YMP (10 microg/ml) did not affect the viability of splenocytes. The production of IFN-gamma was significantly increased in the YMP treated splenocytes, suggesting that YMP may induce cell-mediated immune responses. The effects of YMP on phagocytic activity were studied in relation to uptaking capacity and lysosomal phosphatase activity of the mouse peritoneal macrophages in vitro. YMP (50 microg/ml) was found to increase uptaking capacity and lysosomal phosphatase activity of peritoneal macrophages. In addition, YMP (10-100 microg/ml) significantly increased the viability of peritoneal macrophages (P<0.05). The data obtained demonstrate that the YMP may be used as sources of immunoactive polysaccharides.

Animals↗
PubMed2006

Bafoudiosbulbins A, and B, two anti-salmonellal clerodane diterpenoids from Dioscorea bulbifera L. var sativa.

Two clerodane diterpenoids, Bafoudiosbulbins A 1, and B 2, together with five known compounds: tetracosanoic acid, 1-(tetracosanoyl)-glycerol, trans-tetracosanylferulate, beta-sitosterol and 3-O-beta-D-glucopyranosyl-beta-sitosterol were isolated from the tubers of Dioscorea bulbifera L. var sativa. Their structures were established by spectroscopic methods (1D and 2D-NMR, MS) and X-ray crystallographic diffraction analysis of compound 1. The CH2Cl2-soluble portion of the crude extract and the two clerodanes were screened for anti-bacterial activity using both agar diffusion and broth dilution techniques against Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Salmonella typhi, Salmonella paratyphi A and Salmonella paratyphi B. They both showed significant activities against P. aeruginosa, S. typhi, S. paratyphi A and S. paratyphi B.

Bacteria↗
PubMedDate not supplied

Effects of Taiwanese yam (Dioscorea japonica Thunb var. pseudojaponica Yamamoto) on upper gut function and lipid metabolism in Balb/c mice.

OBJECTIVE: This study investigated the effects of a Taiwanese yam, Dioscorea japonica Thunb var. pseudojaponica Yamamoto, on upper gut function and lipid metabolism in adult Balb/c mice. METHODS: Mice were randomly allocated to consume the control, 25%, or 50% yam diet in which yam in an uncooked lyophilized form was incorporated into the diet for 21 d. RESULTS: Growth rates were similar among groups, even though the apparent protein absorption rate was decreased by the 50% yam diet. Both yam diets decreased gastric villous width but did not significantly modulate other morphologic and proliferative indices. Brush-border leucine aminopeptidase activities in the small intestine were increased approximately 30% by the 25% and 50% yam diets, respectively. In contrast, sucrase activity was decreased 40% by the 25% yam diet and 50% by the 50% yam diet. The 50% yam diet consistently improved the cholesterol profile in the plasma and liver, whereas the 25% yam diet reduced only the level of low-density lipoprotein cholesterol in plasma. Changes in blood lipid levels were associated with reduced fat absorption. CONCLUSION: A 25% uncooked yam diet may benefit upper gut function and prevent hypercholesterolemia in humans, but the 50% yam diet negatively affected protein absorption.

Aminopeptidases↗