Dioscorea Research Articles

Evaluación cualitativa de extractos macerados con diferentes solventes para la extracción de glicoalcaloides y flavonoides de Dioscórea bulbifera en condiciones estándar obtenidos en los llanos orientales de Colombia

Se evaluaron cualitativamente diferentes solventes para la extracción de núcleos esteroides y flavonoides en bulbos de Dioscorea bulbifera Salv. Se analizó el bulbo crudo y macerados en agua, aceite y alcohol 40%. La triangulación de las observaciones en las RxSh y RxL-B con un patrón químico definido, un blanco y la prueba experimental evaluó la presencia del núcleo químico. Se estableció por matriz de relaciones que el alcohol tuvo mayor afinidad a compuestos flavonoides y alcaloides detectándose que el 100% de ensayos realizados fue positivo para cada núcleo. Se detectó en un 83% compuestos alcaloides en muestras de bulbo crudo y superior al 70% para flavonoides. El aceite mineral presentó características conservantes del bulbo y resultados negativos para ambos núcleos. Se concluye que el alcoholato con bulbos de D. bulbifera extrae compuestos de núcleos flavonoides y esteroides para emplearse como ingrediente bioactivo para aplicación en diferentes áreas industriales.

Genome analyses reveal the hybrid origin of the staple crop white Guinea yam (Dioscorea rotundata)

White Guinea yam (Dioscorea rotundata) is an important staple tuber crop in West Africa. However, its origin remains unclear. In this study, we resequenced 336 accessions of white Guinea yam and compared them with the sequences of wild Dioscorea species using an improved reference genome sequence of D. rotundata In contrast to a previous study suggesting that D. rotundata originated from a subgroup of Dioscorea praehensilis, our results suggest a hybrid origin of white Guinea yam from crosses between the wild rainforest species D. praehensilis and the savannah-adapted species Dioscorea abyssinica We identified a greater genomic contribution from D. abyssinica in the sex chromosome of Guinea yam and extensive introgression around the SWEETIE gene. Our findings point to a complex domestication scenario for Guinea yam and highlight the importance of wild species as gene donors for improving this crop through molecular breeding.

Interrelationship and Path analysis of Tuber yield and related traits in yam (Dioscorea spp.) from Ethiopia

Interrelationship and Path analysis of Tuber yield and related traits in yam (Dioscorea spp.) from Ethiopia

Diosgenin content is a novel criterion to assess memory enhancement effect of yam extracts.

Several studies have suggested that some kind of Dioscorea species (yam) or yam-contained herbal medicines have cognitive enhancement effect. However, it has been unknown what is a crucial factor for cognitive enhancement in each Dioscorea species. In this study, we aimed to investigate whether one of the main and brain-penetrating components in yams, diosgenin, can be a novel criterion to assess memory enhancement effect of yam extracts. Although our previous studies showed that administration of diosgenin or diosgenin-rich yam extract enhanced cognitive function in normal mice and healthy humans, we have never evaluated whether the effect depends on diosgenin content or not. Therefore, we compared memory enhancement effects of low diosgenin-contained general yam water extract with diosgenin-rich yam extract on cognitive function in normal mice. We found that unlike diosgenin-rich yam, administration of general yam water extract did not enhance object recognition memory in normal mice. LC-MS/MS analyses revealed that after administration of general yam, diosgenin concentration in the brain did not reach to the effective dose because of the low diosgenin content in the original yam extract. On the other hand, when diosgenin was artificially added into general yam, the extract showed memory enhancement in normal mice and promoted neurite outgrowth in neurons. Our study suggests that diosgenin is actually an active compound in yams for memory enhancement, and diosgenin content can be a criterion for predicting cognitive enhancement effect of yam extracts.

The Dioscorea Genus (Yam)-An Appraisal of Nutritional and Therapeutic Potentials.

The quest for a food secure and safe world has led to continuous effort toward improvements of global food and health systems. While the developed countries seem to have these systems stabilized, some parts of the world still face enormous challenges. Yam (Dioscorea species) is an orphan crop, widely distributed globally; and has contributed enormously to food security especially in sub-Saharan Africa because of its role in providing nutritional benefits and income. Additionally, yam has non-nutritional components called bioactive compounds, which offer numerous health benefits ranging from prevention to treatment of degenerative diseases. Pharmaceutical application of diosgenin and dioscorin, among other compounds isolated from yam, has shown more prospects recently. Despite the benefits embedded in yam, reports on the nutritional and therapeutic potentials of yam have been fragmented and the diversity within the genus has led to much confusion. An overview of the nutritional and health importance of yam will harness the crop to meet its potential towards combating hunger and malnutrition, while improving global health. This review makes a conscious attempt to provide an overview regarding the nutritional, bioactive compositions and therapeutic potentials of yam diversity. Insights on how to increase its utilization for a greater impact are elucidated.

For District IV director: Paul W. Jagodzinski

Northern Arizona University, Flagstaff, Arizona. Polytechnic Institute of Brooklyn, BS, chemistry, 1973; Texas AM Northern Arizona Univ...

Dynamics of Live Oil Droplets and Natural Gas Bubbles in Deep Water.

Explaining the dynamics of gas-saturated live petroleum in deep water remains a challenge. Recently, Pesch et al. [ Environ. Eng. Sci. 2018, 35 (4), 289-299] reported laboratory experiments on methane-saturated oil droplets under emulated deep-water conditions, providing an opportunity to elucidate the underlying dynamical processes. We explain these observations with the Texas A&M Oil spill/Outfall Calculator (TAMOC), which models the pressure-, temperature-, and composition-dependent interactions between oil-gas phase transfer; aqueous dissolution; and densities and volumes of liquid oil droplets, gas bubbles, and two-phase droplet-bubble pairs. TAMOC reveals that aqueous dissolution removed >95% of the methane from ∼3.5 mm live oil droplets within 14.5 min, prior to gas bubble formation, during the experiments of Pesch et al. Additional simulations indicate that aqueous dissolution, fluid density changes, and gas-oil phase transitions (ebullition, condensation) may all contribute to the fates of live oil and gas in deep water, depending on the release conditions. Illustrative model scenarios suggest that 5 mm diameter gas bubbles released at a <470 m water depth can transport methane, ethane, and propane to the water surface. Ethane and propane can reach the water surface from much deeper releases of 5 mm diameter live oil droplets, during which ebullition occurs at water depths of <70 m.

Rhizobium dioscoreae sp. nov., a plant growth-promoting bacterium isolated from yam (Dioscorea species).

This study investigated endophytic nitrogen-fixing bacteria isolated from two species of yam (water yam, Dioscorea alata L.; lesser yam, Dioscorea esculenta L.) grown in nutrient-poor alkaline soil conditions on Miyako Island, Okinawa, Japan. Two bacterial strains of the genus Rhizobium , S-93T and S-62, were isolated. The phylogenetic tree, based on the almost-complete 16S rRNA gene sequences (1476 bp for each strain), placed them in a distinct clade, with Rhizobium miluonense CCBAU 41251T, Rhizobium hainanense I66T, Rhizobium multihospitium HAMBI 2975T, Rhizobium freirei PRF 81T and Rhizobium tropici CIAT 899T being their closest species. Their bacterial fatty acid profile, with major components of C19 : 0 cyclo ω8c and summed feature 8, as well as other phenotypic characteristics and DNA G+C content (59.65 mol%) indicated that the novel strains belong to the genus Rhizobium . Pairwise average nucleotide identity analyses separated the novel strains from their most closely related species with similarity values of 90.5, 88.9, 88.5, 84.5 and 84.4 % for R. multihospitium HAMBI 2975T, R. tropici CIAT 899T, R. hainanense CCBAU 57015T, R. miluonense HAMBI 2971T and R. freirei PRF 81T, respectively; digital DNA–DNA hybridization values were in the range of 26–42 %. Considering the phenotypic characteristics as well as the genomic data, it is suggested that strains S-93T and S-62 represent a new species, for which the name Rhizobium dioscoreae is proposed. The type strain is S-93T (=NRIC 0988T=NBRC 114257T=DSM 110498T).

English

This study was conducted to characterize Dioscorea spp. in Kenya using morphological and molecular characteristics. Data on 22 morphological traits were subjected to cluster analysis and multivariate analysis using principal component (PCA). The dendrogram of cluster analysis revealed three main groups: Species distribution based on PC-1 and PC-2 showed the distantly related species in each quarter; D. alata L. (1st quarter), D. bulbifera L. (2nd quarter), D. cayenensis Lam. (3rd quarter) and D. minutiflora Engl. (4th quarter). In molecular characterization, one sub-cluster grouped D. minutiflora Engl. and D. burkilliana J. Miege as one genetic group. However not all D. minutiflora Engl. species were in one specific cluster showing that there may be variation within the species. D. alata L. and D. bulbifera were seen to be potentially related because they shared a common origin. D. bulbifera L. and D. cayenensis Lam. genotypes clustered together, indicating that the species might be closely related. Generally, the rbcL marker demonstrated the phylogeny of Kenyan Dioscorea spp L. Comparison of morphological and molecular data analysis gave almost similar results. From the study, the phylogenetic relationships of Kenyan Dioscorea spp. were established and morphological and molecular characterization was efficient in establishing species relatedness among Dioscorea spp. &nbsp; Key words: Dioscorea spp., rbcL, principal component analysis, molecular characterization, morphological characterization, yams.

Effect of harvest time on saponins in yam (Dioscorea pseudojaponica Yamamoto)

Steroidal saponins including furostanol and spirostanol glycosides are the important bioactive compounds in yams. In the study, the content of individual saponin in varied organs of yam (Dioscorea pseudojaponica Yamamoto) harvested from November to March of the next year (the harvest season) were determined. Results showed that total saponin levels in yam organs (except rhizophor) harvested at various time were in the order: January＞December＞February＞November＞March. Saponin contents in rhizophor gathered in December were higher than those obtained in January. The highest total amounts of saponins among various organs were in the order: tuber cortex (619.79μg/g dw)＞tuber flesh (247.84μg/g dw)＞rhizophor (32.19μg/g dw)＞leaf (26.57μg/g dw)＞vine (25.06μg/g dw).

Modulation of Proinflammatory Cytokines by Red Mold Dioscorea Ethanol Extract in Radioactive Cobalt-60 Exposure

Monascus-fermented products offer valuable therapeutic benefits and have been extensively used in East Asia. Secondary polyketide metabolites ofMonascus, including monacolin K (MK), ankaflavin (AK) and monascin (MS), have been reported to have antioxidation, antiinflammation and tumor metastasis suppression effects. This study investigated the attenuation of radiation-induced proinflammatory cytokines overexpression by ethanol extract of red mold dioscorea (RMDE). We used the B16-F0 melanoma cell line to establish an animal radiotherapy model and serum proinflammatory cytokines (i.e. TNF-a, IL-1b and IL-6) were analyzed. RAW 264.7 cells were pre-treated with different pure compounds [AK, MS and citrinin (CT)] of RMDE and irradiation of 2 Gy cobalt-60 g-radiation. The animal experiment results showed that oral administration of RMDE increased feed intake in C57BL/6 mice. Serum proinflammatory cytokine levels (i.e. TNF-α, IL-1β and IL-6) and profibrotic cytokine (TGF-b) were significantly reduced in the RMDE group compared to control group (p ＜0.01). For in vitro cell model, we evaluated the antiinflammative effects of AK, MS and CT in irradiated RAW 264.7 cells. Both AK and MS significantly reduced radiation-induced overexpression of proinflammatory cytokines and profibrotic cytokines. We have shown for the first time that Monascus-fermented products can attenuate ionizing radiation-induced inflammatory response. AK and MS are the main components of RMDE responsible for this effect.

Genetic identification of Chinese drug materials in yams (Dioscorea spp.) by RAPD analysis

The botanical origins of Chinese drug materials in yams were examined among eighteen cultivarities/ species of Dioscorea by randomly amplified polymorphic DNA (RAPD). DNA isolated from fresh leaves were used as a template in polymerase chain reactions (PCR) using thirty random decamer primers. Eighteen primers produced 237 polymorphic RAPD markers, which were scored for all the lines studied. Four primers including OPP-04, OPP-15, OPAP-04 and OPAP-10, could distinguish all tested samples. Genetic distances and similarities among eighteen cultivarities/species were calculated, and a cluster analysis was used to generate a dendrogram showing a phylogenetic relationship. The studied Dioscorea species could be divided into five subgroups by phylogenetic analysis. Genetic distance and similarity analysis showed that line 70W37 was distantly related to 70W47, and line 70W41 was closely related to 70W59. RAPD technique could be successfully applied for the rapid identification and differentiation of Dioscorea species.

A spirostanol glycoside from wild yam (Diosccorea villosa) extract and its cytostatic activity on three cancer cells

A spirostanol glycoside, (25R)-spirost-5-en-3β-ol 3-O-α-L-rhamnopyranosyl -(1→2)-O-[β-D-glucopyranosyl -(1→4)]-β-D-glucopyranoside, was isolated from wild yam (Dioscorea villosa) extract with reversed-phase preparative HPLC. This was the first time found in yams (Dioscorea species). The structure was identified by LC-MS, 1H- and 13C-NMR. Cytostatic activities of the isolated saponin on Hep G2, HEK293 and MCF7 cells were estimated. Growth of these cells was inhibited as higher concentration of the compound was used. The IC50 values of the isolated spirostanol glycoside and its aglycon, diosgenin, were 9.02 and 23.91 μM for Hep G2 cells, 13.21 and 27.31 μM for HEK293 cells, and 16.74 and 35.38 μM for MCF7 cells, respectively. The isolated compound had significantly higher active intensity than diosgenin.

Physicochemical, enzymatic and molecular characterisation of the storage protein of aerial tuber, Dioscorea bulbifera Linn.

BackgroundThe storage protein of the aerial tuber of Dioscorea bulbifera was purified and its physicochemical, enzymatic and molecular properties determined with a view to comparing its functionality and genetic relatedness with other storage proteins. ResultsThe purified protein had molecular weight of 21 kDa. The protein showed carbonic anhydrase, trypsin inhibitory, dehydroascorbate reductase and monodehydroascorbate reductase activities. Amplifications with polymerase chain reactions resulted in the detection of two genes encoding the storage protein. The deduced amino acid sequence of the shorter and larger genes had homologies with the storage proteins of members of the Dioscorea family. ConclusionThe study concluded that the storage protein of the aerial tuber of D. bulbifera had similar properties with those of other Dioscorea species and may be suitable for development as functional food.

Sample Preservation and Plant Sex Prediction in White Guinea yam (Dioscorea rotundata Poir.)

Introduction: Yam (Dioscorea spp.) is an economically important staple food in tropical regions, especially for people in West Africa. Understanding of the flowering behavior of the crop to determine potential manipulation available to accomplish crop improvement at early stage remain key challenge in the yam breeding. The methods that reliably yield quality DNA and distinguishing sex type at the early stage of growth have been a challenge in yam genetics and breeding studies. This study assessed the effect of sample preservation methods on DNA quantity and quality during extraction and potential of DNA marker to diagnose plant sex at the early seedling stage in white Guinea yam. Materials and Methods: Five sample preservation methods were assessed for quality DNA extraction during field leaf tissue collection, namely liquid nitrogen, dry ice, silica gel, 95% ethanol, and oven drying. The predicted sex at the seedling stage using the molecular marker was further validated with the visual score for the sex phenotype at the flowering stage. Results: According to the findings of the present study, the DNA extracted from leaf samples preserved in liquid nitrogen, silica gel, dry ice, and oven drying methods were higher in molecular weights than samples stored in ethanol solution. Yam plant sex diagnosis with the DNA marker (sp16) identified a higher proportion of ZW genotypes (female or monoecious phenotypes) than the ZZ genotypes (male phenotypes) in the studied materials with 74% prediction accuracy. Conclusions: The results from this study provided valuable insights on suitable sample preservation methods for quality DNA extraction and the potential of DNA marker sp16 to predict sex in white Guinea yam.

Nitrogen-Fixing Bacteria Associated with Yams ( Dioscorea spp.) Growth

Nitrogen-Fixing Bacteria Associated with Yams ( Dioscorea spp.) Growth

Physicochemical properties of free and immobilized tyrosinase from different species of yam (Dioscorea spp)

A shortened method of purification and immobilization of tyrosinase from different species of yam (Dioscorea spp) on insoluble supports is described. The enzyme was purified by aqueous two-phase partitioning (ATPS) followed by gel filtration chromatography. The purified enzyme was immobilized on Ca-alginate, polyacrylamide gel or as cross-linked enzyme aggregate (CLEA) to obtain a yield of between 51–64%, 33–46% and 52–65% respectively for all the yam species. The optimum pH obtained for tyrosinase immobilized on polyacrylamide gel and CLEA was equivalent to that of free enzyme (pH 6.5). In contrast, Ca-alginate entrapped tyrosinase exhibited a shift of optimum pH to 7.0. Entrapped Tyrosinase in polyacrylamide gel and Ca-alginate also retained the same optimum temperature as the free enzyme (50 °C). While the optimum temperature of CLEA shifted to 60 °C. When subjected to four repeated use cycles, tyrosinase entrapped in polyacrylamide gel, Ca-alginate and CLEA still retained close to 40, 35 and 45 % of their initial activities respectively after the fourth cycle. The overall result further suggests yam tyrosinase as a promising enzyme for biocatalysis and biotechnological applications.

Typification of seven names in Dioscorea (Dioscoreaceae) described by J.D. Hooker

Typification of seven names in Dioscorea (Dioscoreaceae) described by J.D. Hooker

The origin and evolution of the diosgenin biosynthetic pathway in yam

Diosgenin, mainly produced by Dioscorea species, is a traditional precursor of most hormonal drugs in the pharmaceutical industry. The mechanisms that underlie the origin and evolution of diosgenin biosynthesis in plants remain unclear. After sequencing the whole genome of Dioscorea zingiberensis, we revealed the evolutionary trajectory of the diosgenin biosynthetic pathway in Dioscorea and demonstrated the de novo biosynthesis of diosgenin in a yeast cell factory. First, we found that P450 gene duplication and neo-functionalization, driven by positive selection, played important roles in the origin of the diosgenin biosynthetic pathway. Subsequently, we found that the enrichment of diosgenin in the yam lineage was regulated by CpG islands, which evolved to regulate gene expression in the diosgenin pathway and balance the carbon flux between the biosynthesis of diosgenin and starch. Finally, by integrating genes from plants, animals, and yeast, we heterologously synthesized diosgenin to 10 mg/l in genetically-engineered yeast. Our study not only reveals the origin and evolutionary mechanisms of the diosgenin biosynthetic pathway in Dioscorea, but also introduces an alternative approach for the production of diosgenin through synthetic biology.

Constituents of Two Dioscorea Species That Potentiate Antibiotic Activity against MRSA.

The isolation of two diarylnonanoids from Dioscorea cotinifolia possessing antibiotic-potentiating activity against resistant strains of S.aureus are reported. The diarylnonanoids are a class of natural products similar in structure to the diarylheptanoids, which have a wide spectrum of reported biological activities. One of the diarylnonanoids (1) isolated possesses a chiral center, and to deduce its configuration, the modified Mosher ester method was used. Using both 1D and 2D NMR data, as many protons as possible were assigned to both the R- and S-MTPA esters, and the configuration of the chiral center in 1 was determined to be R. Both the chiral and achiral diarylnonanoid (2) exhibited potent antibiotic-potentiating activity with the chiral natural product showing a greater tetracycline-potentiating activity than 2. Interestingly, 2 gave a higher norfloxacin-potentiating activity with a resultant higher efflux pump inhibitory activity. Manipulation of the structure of the diarylnonanoids through synthesis could lead to improved biological activity.