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PubMed2006

Anti-HIV-1 protease- and HIV-1 integrase activities of Thai medicinal plants known as Hua-Khao-Yen.

Ethanolic- and water extracts from five species of Thai medicinal plants known as Hua-Khao-Yen were tested for their inhibitory effects against HIV-1 protease (HIV-PR) and HIV-1 integrase (HIV-1 IN). The result revealed that the ethanolic (EtOH) extract of Smilax corbularia exhibited anti-HIV-1 IN activity with an IC50 value of 1.9 microg/ml, followed by the water extract of Dioscorea birmanica (IC50 = 4.5 microg/ml), the EtOH extract of Dioscorea birmanica (IC50 = 4.7 microg/ml), the water extract of Smilax corbularia (IC50 = 5.4 microg/ml), the EtOH extract of Smilax glabra (IC50 = 6.7 microg/ml) and the water extract of Smilax glabra (IC50 = 8.5 microg/ml). The extracts of Pygmaeopremna herbacea and Dioscorea membranacea were apparently inactive (IC50 > 100 microg/ml). Interestingly, only the EtOH extract of Dioscorea membranacea showed appreciable activity (IC50 = 48 microg/ml) against HIV-1 PR, while the other extracts possessed mild activity. This result strongly supported the basis for the use of Smilax corbularia and Dioscorea membranacea for AIDS treatment by Thai traditional doctors.

Base Sequence↗
PubMed2000

High genetic diversity, distant phylogenetic relationships and intraspecies recombination events among natural populations of Yam mosaic virus: a contribution to understanding potyvirus evolution.

To evaluate the genetic diversity and understand the evolution of Yam mosaic virus (YMV), a highly destructive pathogen of yam (Dioscorea sp.), sequencing was carried out of the C-terminal part of the replicase (NIb), the coat protein (CP) and the 3'-untranslated region (3'-UTR) of 27 YMV isolates collected from the three main cultivated species (Dioscorea alata, the complex Dioscorea cayenensis-Dioscorea rotundata and Dioscorea trifida). YMV showed the most variable CP relative to eight other potyviruses. This high variability was structured into nine distant molecular groups, as revealed by phylogenetic analyses and validated by assessment of the molecular evolutionary noise. No correlation was observed between the CP and 3'-UTR diversities and phylogenies. The most diversified and divergent groups included isolates from Africa. The remaining groups clustered in a single clade and a geographical distinction between isolates from the Caribbean, South America and Africa was observed. The role of the host in the selection of particular isolates was illustrated by the case of a divergent cultivar from Burkina Faso. Phylogenetic topological incongruence and complementary statistical tests highlighted the fact that recombination events, with single and multiple crossover sites, largely contributed to the evolution of YMV. We hypothesise an African origin of YMV from the yam complex D. cayenensis-D. rotundata, followed by independent transfers to D. alata and D. trifida during virus evolution.

3' Untranslated Regions↗
PubMed2006

Food processing methods influence the glycaemic indices of some commonly eaten West Indian carbohydrate-rich foods.

Glycaemic index (GI) values for fourteen commonly eaten carbohydrate-rich foods processed by various methods were determined using ten healthy subjects. The foods studied were round leaf yellow yam (Dioscorea cayenensis), negro and lucea yams (Dioscorea rotundata), white and sweet yams (Dioscorea alata), sweet potato (Solanum tuberosum), Irish potato (Ipomoea batatas), coco yam (Xanthosoma spp.), dasheen (Colocasia esculenta), pumpkin (Cucurbita moschata), breadfruit (Artocarpus altilis), green banana (Musa sapientum), and green and ripe plantain (Musa paradisiaca). The foods were processed by boiling, frying, baking and roasting where applicable. Pure glucose was used as the standard with a GI value of 100. The results revealed marked differences in GI among the different foods studied ranging from 35 (se 3) to 94 (se 8). The area under the glucose response curve and GI value of some of the roasted and baked foods were significantly higher than foods boiled or fried (P<0.05). The results indicate that foods processed by roasting or baking may result in higher GI. Conversely, boiling of foods may contribute to a lower GI diet.

Adolescent↗
PubMed1995

Enzyme inhibitors in tuber crops and their thermal stability.

Tubers of Cassava (Manihot esculenta), yams (Dioscorea esculenta), aroids (Amorphophallus campanulatus, Colocasia esculenta, Xanthosoma sagittfolium) and Coleus (Solenostemon rotundifolius) were screened for inhibitory activities against amylase, trypsin and chymotrypsin. Coleus tuber possessed the highest anti-amylase activity, whereas Colocasia tuber was the most potent source of anti-tryptic and anti-chymotryptic activity. Xanthosoma tubers exhibited amylase inhibitory activity and Amorphophallus tubers antiprotease activity. Dioscorea esculenta had low levels of amylase and chymotrypsin inhibitors, while Cassava tubers were totally free of inhibitors. When tubers were processed by pressure cooking, there was significant reduction/complete elimination in inhibitory activity. Partial retention of inhibition was observed in the case of amylase inhibitor in Dioscorea, chymotrypsin inhibitor in Colocasia and trypsin inhibitor in Colocasia, Coleus and Amorphophallus. In vitro experiments on heat stability of the different inhibitors revealed almost similar pattern of inactivation.

Amylases↗
PubMed2004

Compositional and conformational analysis of yam proteins by near infrared fourier transform Raman spectroscopy.

Fourier transform (FT)-Raman spectroscopy was employed to study the molecular structure of yam proteins isolated from three commonly consumed yam species including Dioscorea alata L., D. alata L. var. purpurea, and Dioscorea japonica. Although D. alata L. and D. alata L. var. purpurea consisted of similar amino acid residues, they still exhibited significant differences in conformational arrangement. The secondary structure of D. alata L. was mainly an alpha-helix, while D. alata L. var. purpurea was mostly in antiparallel beta-sheets. In contrast, D. japonica, which belongs to a different species, exhibited explicit differences in amino acid compositions and molecular structures of which the conformation was a mixed form of alpha-helices and antiparallel beta-sheets. FT-Raman directly proved the existence of S-S in yam proteins, implying that oligomer formation in yam proteins might be due to disulfide linking of dioscorin (32 kDa). The microenvironment of aromatic amino acids and the state of S-S in yam proteins were also discussed.

Amino Acids↗
PubMed2005

Estrogenic effect of yam ingestion in healthy postmenopausal women.

OBJECTIVE: Yam (Dioscorea) has been used to treat menopausal symptom folklorically. This study was to investigate the effects of yam ingestion on lipids, antioxidant status, and sex hormones in postmenopausal women. METHODS: Twenty-four apparently healthy postmenopausal women were recruited to replace their staple food (rice for the most part) with 390 g of yam (Dioscorea alata) in 2 of 3 meals per day for 30 days and 22 completed the study. Fasting blood and first morning urine samples were collected before and after yam intervention for the analyses of blood lipids, sex hormones, urinary estrogen metabolites and oxidant stress biomarker. The design was a one arm, pre-post study. A similar study of postmenopausal women (n = 19) fed 240 g of sweet potato for 41 days was included as a control study. Serum levels of estrone, estradiol and SHBG were analyzed for this control group. RESULTS: After yam ingestion, there were significant increases in serum concentrations of estrone (26%), sex hormone binding globulin (SHBG) (9.5%), and near significant increase in estradiol (27%). No significant changes were observed in serum concentrations of dehydroepiandrosterone sulfate, androstenedione, testosterone, follicular stimulating hormone, and luteinizing hormone. Free androgen index estimated from the ratio of serum concentrations of total testosterone to SHBG decreased. Urinary concentrations of the genotoxic metabolite of estrogen, 16alpha-hydroxyestrone decreased significantly by 37%. Plasma cholesterol concentration decreased significantly by 5.9%. Lag time of low-density lipoprotein oxidation prolonged significantly by 5.8% and urinary isoprostane levels decreased significantly by 42%. For the control subjects fed with sweet potato, all three hormone parameters measured were not changed after intervention. CONCLUSION: Although the exact mechanism is not clear, replacing two thirds of staple food with yam for 30 days improves the status of sex hormones, lipids, and antioxidants. These effects might reduce the risk of breast cancer and cardiovascular diseases in postmenopausal women.

Aged↗
PubMed2004

In vitro cytotoxic activity of Thai medicinal plants used traditionally to treat cancer.

The SRB assay was used to test cytotoxicity against three human cancer cell lines and one normal cell line of 11 Thai medicinal plant species used by traditional doctors in treating cancer patients. The extraction procedures used were similar to those practised by Thai traditional doctors (ethanolic and water extracts). Extracts were tested against the human large cell lung carcinoma cell line COR-L23, the human breast adenocarcinoma cell line MCF-7 and human colon adenocarcinoma cell line LS-174T and normal human keratinocytes SVK-14. The results showed that three plants; Dioscorea membranacea Pierre ex Prain & Burkill, Dioscorea birmanica Prain & Burkill (Dioscoreaceae) and Siphonodon celastrineus Griff. (Celastraceae), exhibited high cytotoxic activity showing a certain degree of selectivity against the different cell types.

Cell Line, Tumor↗
PubMed2000

Zulu medicinal plants with antibacterial activity.

Aqueous, methanolic and ethyl acetate extracts of 14 plants used in traditional Zulu medicine for treatment of ailments of an infectious nature were screened for antibacterial activity. Most of the activity detected was against gram-positive bacteria. Tuber bark extracts of Dioscorea sylvatica had activity against gram-negative Escherichia coli and extracts of Dioscorea dregeana, Cheilanthes viridis and Vernonia colorata were active against Pseudomonas aeruginosa. The highest antibacterial activity was found in extracts of C. viridis, D. dregeana, D. silvatica, Melianthus comosus and V. colorata. In general, methanolic extracts exhibited higher activity than aqueous and ethyl acetate extracts.

Anti-Bacterial Agents↗
PubMed2004

Corni fructus as the major herb of Die-Huang-Wan for lowering plasma glucose in Wistar rats.

Die-Huang-Wan is a mixture of six herbs used to lower plasma glucose by increasing insulin secretion in normal rats. Die-Huang-Wan contains the herbs dioscorea (Dioscoreae rhizoma), cornus (Corni fructus), alisma (Rhizoma alismatis), holelen (Poria), rehmannia (Rehmanniae radix) and tree peony bark (Moutan radicis cortex). The present study was designed to clarify the major herb contributing to the plasma glucose-lowering action of Die-Huang-Wan in rats. A decrease in plasma glucose was not observed in Wistar rats treated with the cornus-deleted formula of Die-Huang-Wan; however, the action was retained in the other herb-deleted formulas containing cornus. In normal rats, the decrease in plasma glucose and increase in plasma insulin concentrations were dependent on the dose of cornus and were similar to those produced by Die-Huang-Wan. Treatment of Wistar rats with each of the other five herbs separately did not result in a decrease in plasma glucose. Moreover, the increase in plasma insulin or reduction in plasma glucose resulting from cornus treatment was blocked by atropine or 4-diphenylacetoxy-N-methylpiperidine methiodide mustard, indicating mediation of muscarinic M(3) receptors similar to that caused by Die-Huang-Wan. These results suggest that cornus is the major contributor to the plasma glucose-lowering action in Die-Huang-Wan in normal rats.

Animals↗
PubMed1996

Biochemical changes occurring during growth and storage of two yam species.

The biochemical changes occurring during growth and storage of two yam cultivars (Dioscorea rotundata cv. Oshei and Dioscorea dumetorum cv. Jakri) were studied. Tubers were harvested at monthly intervals from the fourth to the tenth month after 50% emergence of the planted yam sets. For storage studies, Oshei and Jakri tubers were harvested 9.5 and 9 months post-emergence, respectively. These were stored under prevailing tropical ambient conditions (18-31 degrees C, 62-100% RH) for 1,2,3 and 4 months. All samples were analysed for dry matter, crude protein, carbohydrate, essential amino acids and mineral contents. The maximum dry matter was reached in both cultivars 9 months post-emergence, being 40.4 and 26.4%, respectively for Oshei and Jakri tubers. This was judged to be the optimum time for harvesting. Starch reached maximum values of 86.7 and 78.3 g/100g, respectively after 6 months. Ethanol-soluble sugars declined from 9.4 to 2.3 g/100g in Oshei but remained constant at over 6.0 g/100g in Jakri tubers during growth. Crude protein values increased slightly to a maximum of 5.4 and 8.0 g/100g, respectively for Oshei and Jakri tubers. During storage, weight losses reached 31% in Oshei tubers and 35% in Jakri after 110 days due to sprouting and dehydration. Starch decreased by approximately 3.5-4.5 g/100g while sugars and fibre values increased slightly in both cultivars.

Amino Acids, Essential↗
PubMed1997

[Studies on X-ray diffraction pattern of traditional Chinese medicinal materials].

Traditional Chinese medicine(TCM) as prescribed by Chinese traditional physicians is usually available as "decoction slices" which calls for a ready method for assessment of quantity or even genuineness. Three groups of TCM drugs (radix Rubiae, bulbus Fritillariae and rhizoma Dioscoreae) were selected by using powder X-ray diffraction analysis with complete absorption profile. Topological regularity and characteristic peaks of the absorption profile were obtained as fingerprint in X-ray diffraction diagrams of the pertinent medicinal materials. We have discovered the similarities of 3 radix Rubiae samples gathered from different localities and their differences with Rubia tinctorum, the similarities and differences between 7 species belonging to Fritillaria Genus, the similarities of 2 rhizoma Dioscoreae samples from different localities and their differences with 2 counterfeits. The result points to a promising prospect in achieving an objective assessment of genuineness at TCM drugs.

Drugs, Chinese Herbal↗
PubMed1979

[Role of the digestive microflora and of the crystalline structure of starch in digestion and dietary efficiency in the chicken. Study of tropical tubers].

The influence of microflora in the utilization of starches, the X ray pattern which was of A or B type, was studied by balances and carcasses analysis with growing axenic or holoxenic chickens, put in isolators. Five tropical tubers were used : Manihot utilissima and Dioscorea dumetorum of A-type, Dioscorea cayenensis and alata and Canna edulis of B-type. They were introduced in isoenergetic (4,460 Kcal/g D.M.) and isoproteic (18 p. 100) diets. The A-type starches are entirely digested (95 p. 100) and the B-type are poorly digested (40-60 p. 100). The first ones induced a better growth than the second. The influence of digestive microflora changes with the two types of tubers used. With A-type starches the microflora lowered the feed intake, the growth and the energy and protein efficiency respectively--25 and--10 p. 100. When the diet included tubers with B-type starches, the low digestibility of starch and the low metabolisable energy in the diets induced poor growth and retentions. The results are discussed in relation with the starch breakdown into glucose, lactic acid and volatile fatty acids.

Animals↗
PubMed2002

Electrophoretic identification of new genomic profiles with a modified selective amplification of microsatellite polymorphic loci technique based on AT/AAT polymorphic repeats.

The present paper introduces improvements of the conventional selective amplification of microsatellite polymorphic loci (SAMPL) technique, that exploit AT-rich microsatellite primers. Generally, AT/AAT microsatellites are frequent components of eukaryotic genomes, but their ubiquity and polymorphic information content (PIC) could not be exploited yet, because standard SAMPL conditions did not allow amplifications. Here we report (i) on the design of new versatile AT-rich microsatellite primers, that are combined with (ii) a modified SAMPL adapter primer (called EcoRI-Short), and (iii) special polymerase chain reaction (PCR) amplification regimes. The novel SAMPL procedure expands the range of useful microsatellite primers to AT-rich sequences and produces a high number of bands and a clear banding pattern, and detects polymorphisms in otherwise nonpolymorphic genomes of plants (Dioscorea alata, D. rotundata) and a fungus (Mycosphaerella fijiensis).

AT Rich Sequence↗
PubMed2006

In vitro availability of some essential minerals in commonly eaten processed and unprocessed Caribbean tuber crops.

The levels of three essential minerals Ca, Fe and Mg and the extent of their availability were assessed in four commonly eaten Caribbean tuber crops [dasheen (Xanthosoma spp.), Irish potato (Solanum tuberosum), sweet potato (Ipomoea batatas) and yellow yam (Dioscorea cayenensis)] in their processed and unprocessed states. Calcium was highest in cooked dasheen (5150+/-50 mg/kg) while Magnesium was highest in uncooked Irish potato (3600+/-200 mg/kg). There was no significant loss of calcium from the food samples upon cooking. All the uncooked food samples displayed higher levels minerals assessed compared to the cooked samples except for cooked Irish potato that recorded the level of iron (182.25+/-8.75 mg/kg). Availability of these minerals in the cooked and uncooked tubers crops upon digestion also showed a similar pattern. In conclusion, the consumption of these tuber crops in the Caribbean may not be responsible for the reported cases of iron deficiency in the region. However, the availability of minerals from these tuber crops when consumed with other foods (the usual practice in the Caribbean) needs further investigation.

Calcium↗
PubMed2002

Enhancement of oxidative response and cytokine production by yam mucopolysaccharide in murine peritoneal macrophage.

Yam (Dioscorea batatas) mucopolysaccharide (YMP) was examined for the ability to induce secretory and cellular responses in murine peritoneal macrophages. When macrophages were treated with various doses (10-100 microg/ml) of YMP for 48 h, a significant cytotoxicity against B 16 cells was observed. YMP also increased the myeloperoxidase activity and the production of H(2)O(2), O(2)(-), nitric oxide (NO) and tumor necrosis factor (TNF-alpha). However, there was a little alteration on the production of IFN-gamma. These results indicate that reactive oxygen intermediates (ROI), reactive nitrogen intermediates (RNI) and TNF-alpha are likely major mediators of cytotoxic activity of YMP-treated macrophages.

Animals↗
PubMed2003

Origin, world-wide dispersion, bio-geographical diversification, radiation and recombination: an evolutionary history of Yam mild mosaic virus (YMMV).

We developed an evolutionary epidemiological approach to understand the regional and world-wide dispersion of Yam mild mosaic virus (YMMV) by retracing its evolutionary history. Analyses of the distribution and the prevalence of YMMV in the Caribbean islands of Guadeloupe and Martinique, and in French Guyana revealed that YMMV has a wide repartition and different prevalence on Dioscorea alata L. (Asian and Oceanic origin), on D. cayenensis Lam.-D. rotundata Poir. (African origin) and on D. trifida L. (Amazon and the Caribbean origin) in this region. Considering the data on the current dispersion of the virus and the evolution and the history of the yams, the phylogenetic analysis of the 3' terminal part of the YMMV genome gave a consistent support of the Asian-Pacific origin of YMMV from D. alata species. The YMMV phylogenetic tree is star-like, suggesting an early split of the genetic lineages. An important part of the clades is constituted by a single lineage arisen by recombination. The largest emerging monophyletic group illustrates well YMMV geographical dispersion. This evolutionary pattern contrasts with the one revealed by the African distinct lineages and by the second significant monophyletic group, for which a host adaptation to D. trifida is suggested. The analysis of the pattern of nucleotide substitutions in the CP gene revealed that purifying selection dominates the evolution of the CP of potyviruses and strongly operates on the YMMV. Switching events, radiation, host and geographical adaptation and recombination events are proposed as major traits of YMMV evolutionary history.

3' Flanking Region↗
PubMed2001

Screening of cassava and yam cultivars for resistance to anthracnose using toxic metabolites of colletotrichum species.

Collectotrichum gloeosporioides f. sp. manihotis and C. gloeosporioides, causal agents of cassava (Manihot spp.) and yam (Dioscorea spp.) anthracnose diseases, respectively, produce toxic metabolites in culture that fluoresce at 254 nm and 366 nm, producing bands with Rf of 0.65 and 7.0, respectively. Symptoms induced on yam and cassava by the extracted metabolites were similar to those induced by the pathogens. Twenty-four clones of tropical D. rotundata (TDr), D. alata (TDa), D. esculenta (TDe), and D. cavenensis (TDc) were screened by applying toxic metabolites of C. gloeosporioides to their leaves and stems. Only TDr131, TDe179 and TDc750 were resistant. Other clones were susceptible to varying degrees. Nineteen of the 45 clones of M. esculenta were resistant to varying degrees of toxic metabolites of C. gloeosporioides f. sp. manihotis. Results from in vitro screening of' cassava and yam clones using toxic metabolites compared favourably with field screening based on natural epidemics. Using toxic metabolites appears to be a more effective technique for screening for disease resistance than conventional inoculation with plant pathogens.

Biological Assay↗
PubMed2002

Protodioscin (NSC-698 796): its spectrum of cytotoxicity against sixty human cancer cell lines in an anticancer drug screen panel.

Protodioscin (NSC-698 796) is a furostanol saponin isolated from the rhizome of Dioscorea collettii var. hypoglauca (Dioscoreaceae), a Chinese herbal remedy for the treatment of cervical carcinoma, carcinoma of urinary bladder and renal tumor for centuries. To systematically evaluate its potential anticancer activity, protodioscin was tested for cytotoxicity in vitro against 60 human cancer cell lines in the NCI's (National Cancer Institute, USA) anticancer drug screen. As a result, protodioscin was cytotoxic against most cell lines from leukemia and solid tumors in the NCI's human cancer panel, especially selectively against one leukemia line (MOLT-4), one NSCLC line (A549/ATCC), two colon cancer lines (HCT-116 and SW-620), one CNS cancer line (SNB-75), one melanoma line (LOX IMVI), and one renal cancer line (786 - 0) with GI50 < or = 2.0 microM. In the general view of mean graphs, leukemia, colon cancer and prostate cancer are the most sensitive subpanels, while ovarian cancer is the least sensitive subpanel. Based on an analysis of COMPARE computer program with protodioscin as a seed compound, no compounds in the NCI's anticancer drug screen database have cytotoxicity patterns (mean graphs) similar to those of protodioscin, indicating that a potential novel mechanism of anticancer action is involved.

Antineoplastic Agents, Phytogenic↗