Dioscorea Oppositifolia Research Articles

Evaluation of freeze-dried pregelatinized Chinese yam (Dioscorea oppositifolia) starch as a polymer in floating gastroretentive metformin microbeads

Pregelatinized Chinese yam (Dioscorea oppositifolia) starch has been evaluated as a polymer for the formulation of floating gastroretentive beads for the controlled delivery of metformin hydrochloride. Floating microbeads were prepared by the ionotropic gelation method using a blend of modified Chinese yam starch and sodium alginate at different ratios. Sodium bicarbonate was added as a gas-generating agent. The floating microbeads were characterized by SEM, DSC, FTIR analyses and the drug entrapment efficiency and floating ability was evaluated. Drug release was investigated using in vitro dissolution test and the results were fitted to various kinetic models to determine the mechanism(s) of release. Spherical, discrete and free flowing microbeads were obtained from the modified starch-alginate blends. Minimum lag time (

Evaluation of the material and tablet formation properties of modified forms of Dioscorea starches

Starches obtained from four different Dioscorea species—namely, White yam (Dioscorea rotundata), Bitter yam (Dioscorea dumetorum), Chinese yam (Dioscorea oppositifolia), and Water yam (Dioscorea alata)—were modified by cross-linking, hydroxypropylation, and dual modification—cross-linking followed by hydroxypropylation. The physicochemical, material, and tablet properties of the modified starches were investigated with the aim of understanding their properties to determine their potential use for different applications. The tablet formation properties were assessed using 3D modeling, the Heckel equation, and force-displacement profiles. The analyzed tablet properties were elastic recovery, compactibility, and disintegration. The result indicates that the modifications generally increased the swelling power for all the starches in the rank order hydroxypropyl > hydroxypropylated cross-linked > cross-linked (CL) while the solubility did not show a clear-cut pattern. This indicates that hydroxypropylation generally showed the strongest effects on swelling. Furthermore, hydroxypropylation improved the hot water swelling of the CL starches. The modifications did not cause any detectable morphological change in the starch granules shape or size although slight rupture was observed in some granules. CL starch had the lowest water sorption capacity and hydroxypropylation increased the sorption capacity of the CL starches. The material property results indicate that hydroxypropylation and cross-linking did not significantly improve the flowability and compressibility but improved bonding, which resulted in an increased compaction and higher tablet crushing force even though they all disintegrated rapidly. Thus, the modified Dioscorea starches showed potentials for development as new excipients in solid dosage form design, and they could be useful as disintegrants or for Soft tableting.

English

In vitro propagation of two wild yams, Dioscorea oppositifolia and Dioscorea pentaphylla, is reported. Multiple shoots were initiated from nodal explants on Murashige and Skoog (MS) medium supplemented with 8.8 iM 6-benzylaminopurine (BAP) and 0.3% (w/v) activated charcoal. Root induction was also achieved simultaneously from the base of the shoots in the same medium. Individual shoots with a minimum of one node were excised and rooted in vitro on MS medium with 2.67 iM
-naphthaleneacetic acid (NAA) or ex vitro rooted on by treatment with 49 iM indole-3-butyric acid (IBA) for 30 min. Regenerants acclimatized in soil-rite showed vigorous shoot growth (within 2 weeks) and after 5 - 6 months were suitable for planting. Plantlets also developed tubers on MS medium with 8.8 iM 6-benzylaminopurine (BAP).

Biological control of invasive plants through collaboration between China and the United States of America: a perspective

For more than 100 years, classical biological control of invasive plants through screening, introducing and releasing of host-specific natural enemies from native regions has been regarded as one of the promising approaches to the management of invasive plants. Many invasive plants in the United States of America are native to China, and vice versa. China and the USA also share a number of invasive plant species, including water hyacinth (Eichhornia crassipes), alligator weed (Alternanthera philoxeroides) and cordgrass (Spartina spp.). Collaboration between the two countries on biological control benefits both the nations by reciprocal opportunities to research and exchange natural enemies, by exchanging information on common invasive species, and by providing training for students and professionals. Here we review the history of collaboration between China and the US on biological control of more than 20 invasive plants. Current collaborative projects associated with four plant species, Polygonum perfoliatum L., Trapa natans L. Pueraria montana (Lour.) Merr. var. lobata and Ailanthus altissima (Mill.) Swingle, are also covered. We prioritize 14 invasive plants as targets for future collaborative biological control based on information on their importance in introduced areas, natural enemy records, and their potential biocontrol risk to introduced ecosystems. They are: Ampelopsis brevipendunculata, Celastrus orbiculatus, Dioscorea oppositifolia, Euonymus alata, Euonymus fortunei, Ligustrum sinense, Melia azedarach, Paulownia tomentosa, Sapium sebiferum and Ulmus pumila for the US, as well as Spartina alterniflora, Ambrosia artemisiifolia, Ambrosia trifida and Solidago canadensis for China. In addition, we emphasize that we must very carefully consider any potential non-target effect when we intend to introduce and release new natural enemies. We anticipate that the high priority both countries have placed on control of invasive plants will stimulate increasing collaboration on biological control.

A Landscape Perspective of the Stream Corridor Invasion and Habitat Characteristics of an Exotic (Dioscorea oppositifolia) in a Pristine Watershed in Illinois

The spatial distribution of exotics across riparian landscapes is not uniform, and research elaborating the environmental constraints and dispersal behavior that underlie these patterns of distribution is warranted. This study examined the spatial distribution, growth patterns, and habitat constraints of populations of the invasive Dioscorea oppositifolia in a forested stream corridor of a tributary of Drury Creek in Giant City State Park, IL. The distribution of D. oppositifolia was determined at the watershed scale mainly by floodplain structure and connectivity. Populations of D. oppositifolia were confined to the floodplain, with overbank flooding from the stream. Dioscorea oppositifolia probably originates in disturbed areas upstream of natural corridors, and subsequently, the species disperses downstream into pristine canyons or ravines via bulbils dispersing in the water. In Giant City State Park, populations of D. oppositifolia were distributed on the floodplain across broad gradients of soil texture, light, slope, and potential radiation. The study also examined the longevity of bulbils in various micro-environments to illuminate strategies for the management of the species in invaded watersheds. After 1 year, the highest percentages of bulbils were viable under leaves, and much lower percentages were viable over leaves, in soil, and in the creek (76.0±6.8, 21.2±9.6, 21.6±3.6, and 5.2±5.2%), respectively. This study suggests that management procedures that reduce leaf litter on the forest floor (e.g., prescribed burning) could reduce the number of bulbils of D. oppositifolia stored in the watershed.

Water dispersal of vegetative bulbils of the invasive exotic Dioscorea oppositifolia L. in southern Illinois1

Thomas, J. R., D. J. Gibson (Department of Plant Biology, Southern Illinois University, Carbondale, IL 62901-6509), and B.A. Middleton (National Wetlands Research Center, Lafayette, LA 70506) . Water dispersal of vegetative bulbils of the invasive exotic Dioscorea oppositifolia L. in southern Illinois. J. Torrey Bot. Soc. 132: 187–196. 2005.—Riparian corridors promote dispersal of several species of exotic invasives worldwide. Dispersal plays a role in the colonization of exotic invasive species into new areas and this study was conducted to determine if the invasiveness of Dioscorea oppositifolia L. (Chinese yam) is facilitated by secondary dispersal of vegetative diaspores (bulbils) by water. Since seed production of this plant has not been observed in the United States, bulbils represent the only means of dispersal to new habitats. Dispersal was monitored by placing aquatic traps, tethered bulbils, and painted bulbil caches in a tributary of Drury Creek, Giant City State Park, Illinois. Results indicate that high-energy flow in the creek accelerated secondary dispersal of bulbils downstream and onto the floodplain. The longest recorded dispersal distance was 206.2 m downstream. Dispersal distance of tethered bulbils was not related to rainfall or flow velocity in the creek; however the total number of bulbils trapped was positively related to flow velocity. We conclude that secondary dispersal by water in streams can facilitate dispersal of vegetative bulbils of this exotic species.

Dioscorea oppositifolia L. Phenotypic Evaluations and Comparison of Control Strategies1

Dioscorea oppositifolia (Chinese yam) is an exotic perennial vine invading natural areas in the temperate regions of the eastern United States. Rapid early-season growth of D. oppositifolia is facilitated by an extensive tuber system. Plants can reach heights greater than 370 cm, as the plants climb trees and other vegetation. Shoot length increased 3.6 cm/d from late May to mid-August under field conditions, and primary and secondary tuber length increased 0.28 and 0.2 cm/d, respectively. This indicated rapid vegetative growth and substantial food reserves to form new plants in subsequent years. Dioscorea oppositifolia plants also formed aerial bulbils of 0.8- to 1.2-cm diameter, which are important in dissemination of the species over geographical areas. A field study indicated incomplete control from manual removal, clipping by hand, or glyphosate (2% v/v) application to control D. oppositifolia, although glyphosate was the most effective. Additionally, the use of herbicides was more efficient from a time-utilization perspective than either manual removal or clipping. In a separate study, glyphosate application at flowering was more effective in reducing D. oppositifolia growth the year after application as compared with glyphosate applications soon after emergence. Under greenhouse conditions, however, glyphosate at 0.84 kg ae/ha provided <15% control. The ester formulation of triclopyr at 2.5 kg ai/ha provided >90% D. oppositifolia control. Metsulfuron provided 31% control, and mesotrione provided 36% control and at higher rates may reduce D. oppositifolia growth. Several other herbicides having diverse modes of action provided minimal control of D. oppositifolia.Nomenclature: Glyphosate, triclopyr; Dioscorea oppositifolia.Additional index words: Chinese yam, cinnamon vine, Dioscorea batatas, exotic plants, invasive plants, natural areas.Abbreviation: NIS, nonionic surfactant.