Kiyokazu Kawada

In Vitro Antiproliferative Effect of Arthrocnemum indicum Extracts on Caco-2 Cancer Cells through Cell Cycle Control and Related Phenol LC-TOF-MS Identification

This study aimed to determinate phenolic contents and antioxidant activities of the halophyte Arthrocnemum indicum shoot extracts. Moreover, the anticancer effect of this plant on human colon cancer cells and the likely underlying mechanisms were also investigated, and the major phenols were identified by LC-ESI-TOF-MS. Results showed that shoot extracts had an antiproliferative effect of about 55% as compared to the control and were characterised by substantial total polyphenol content (19 mg GAE/g DW) and high antioxidant activity (IC50 = 40 μg/mL for DPPH test). DAPI staining revealed that these extracts decrease DNA synthesis and reduce the proliferation of Caco-2 cells which were stopped at the G2/M phase. The changes in the cell-cycle-associated proteins (cyclin B1, p38, Erk1/2, Chk1, and Chk2) correlate with the changes in cell cycle distribution. Eight phenolic compounds were also identified. In conclusion, A. indicum showed interesting antioxidant capacities associated with a significant antiproliferative effect explained by a cell cycle blocking at the G2/M phase. Taken together, these data suggest that A. indicum could be a promising candidate species as a source of anticancer molecules.

Land degradation of abandoned croplands in the Xilingol steppe region, Inner Mongolia, China

Abstract Steppe grasslands are distributed over vast areas in arid and semiarid regions of Eurasia. However, steppe grasslands face desertification or degradation caused by human over‐activity. In the last decades, steppe regions have seen increased areas of crop cultivation and subsequent abandonment due to inappropriate agricultural management. Land degradation of abandoned croplands has become a common problem in the Inner Mongolia Autonomous Region, China. A field survey was conducted in the Xilingol steppe, and vegetation was classified into three groups. Based on comparisons of species composition and soil characters, group 1 represents steppe grassland, group 2 represents abandoned croplands and group 3 represents yardangs. The typical indicator species of steppe, abandoned croplands and yardangs are Leymus chinensis, Cleistogenes squarrosa and Elymus dahuricus, respectively. Abandoned croplands are exposed to wind and rain, resulting in soil erosion, which not only increases coarse sand content but also decreases total carbon and total nitrogen in the soil. We found that soil condition is an important factor affecting the early stages of secondary succession in abandoned croplands and that farming in typical steppes might contribute to land degradation. We concluded that abandoned croplands can be converted to yardangs by erosion. The extension of yardangs might then lead to desertification in steppe regions. Land managers should be aware that farming in typical steppes is associated with a risk of desertification. The degree of degradation of steppe can be measured by monitoring these indicator species.

Identification of 6-octadecynoic acid from a methanol extract of Marrubium vulgare L. as a peroxisome proliferator-activated receptor γ agonist

6-Octadecynoic acid (6-ODA), a fatty acid with a triple bond, was identified in the methanol extract of Marrubium vulgare L. as an agonist of peroxisome proliferator-activated receptor γ (PPARγ). Fibrogenesis caused by hepatic stellate cells is inhibited by PPARγ whose ligands are clinically used for the treatment of diabetes. Plant extracts of Marrubium vulgare L., were screened for activity to inhibit fibrosis in the hepatic stellate cell line HSC-T6 using Oil Red-O staining, which detects lipids that typically accumulate in quiescent hepatic stellate cells. A methanol extract with activity to stimulate accumulation of lipids was obtained. This extract was found to have PPARγ agonist activity using a luciferase reporter assay. After purification using several chromatographic methods, 6-ODA, a fatty acid with a triple bond, was identified as a candidate of PPARγ agonist. Synthesized 6-ODA and its derivative 9-octadecynoic acid (9-ODA), which both have a triple bond but in different positions, activated PPARγ in a luciferase reporter assay and increased lipid accumulation in 3T3-L1 adipocytes in a PPARγ-dependent manner. There is little information about the biological activity of fatty acids with a triple bond, and to our knowledge, this is the first report that 6-ODA and 9-ODA function as PPARγ agonists.

Metabolomics Analysis of Cistus monspeliensis Leaf Extract on Energy Metabolism Activation in Human Intestinal Cells

Energy metabolism is a very important process to improve and maintain health from the point of view of physiology. It is well known that the intracellular ATP production is contributed to energy metabolism in cells. Cistus monspeliensis is widely used as tea, spices, and medical herb; however, it has not been focusing on the activation of energy metabolism. In this study, C. monspeliensis was investigated as the food resources by activation of energy metabolism in human intestinal epithelial cells. C. monspeliensis extract showed high antioxidant ability. In addition, the promotion of metabolites of glycolysis and TCA cycle was induced by C. monspeliensis treatment. These results suggest that C. monspeliensis extract has an ability to enhance the energy metabolism in human intestinal cells.

Grazing Effects on Floristic Composition and Above Ground Plant Biomass of the Grasslands in the Northeastern Mongolian Steppes

We describe plant biomass in the grasslands of the Mongolian steppe obtained using a quadrat sampling technique. Four sites were studied in the northeastern Mongolia located between and and and , which were typical grasslands of the steppe. Biomass, carbon and nitrogen content were determined for the plants collected from the grazed and ungarazed stands. With the measurements above, we expect to obtain information on grazing effects on the grasslands and carbon sequestration of the grassland from the air. In order to estimate the biomass without destroying the stands, we derived an equation to describe the relationship between plant biomass and v-value using plant height and species coverage within the stand. Estimated plant biomass in the ungrazed and grazed stands ranged between and and between and in late June 2005, respectively. Litter in the ungrazed and grazed stands ranged from to and from to , similarly. Average carbon and nitrogen contents in plants and in litter were 43.0% and 1.9% and 33.7% and 1.4%, respectively. In study sites at Baganuur, the carbon and nitrogen content of plant materials (plant plus litter) was and on 30 June 2005.

Floristic Composition, Grazing Effects and Above-ground Plant Biomass in the Hulunbeier Grasslands of Inner Mongolia, China

ABSTRACT : In order to assess the effect of grazing on grasslands using floristic composition, we studied the floristic composition and plant biomass of steppe vegetation in Hulunbeier, Inner Mongolia. The dominant species of the grasslands were Stipa krylovii, Stipa grandis and Leymus chinensis . Floristic composition changed according to grazing pressure, being light, heavy and moderate. Under heavy grazing conditions, the importance value of P. acaulis, C. korshinskyi and Cleistogenes squarrosa increased in the plant community. These species were indicators of heavily grazed stand. Plant biomass of the stands ranged within 11.6 g m -2 and 63.5 g m -2 and 69.5 g m -2 and 166.2 g m -2 to the west and east of Lake Hulun, respectively. These values are equivalent to ca. 450～1,000 kg of atmospheric carbon per hector, which is retained within the stand during the summer season. Key words : Floristic composition, Grassland, Inner Mongolia, Plant biomass* Corresponding author; Phone: +81-268-24-4344, e-mail: ihayashi@coral.ocn.ne.jp

Phylogenetic constraints to soil properties determine elevational diversity gradients of forest understory vegetation

Elevational diversity gradients (EDGs) of vegetation are shaped by the evolutionary histories of plants as well as by ecological factors. However, few studies of EDGs have focused on the roles of phylogenetic constraints and the effects of complicated interactions among environmental factors. Here, we examine the direct and indirect effects of environmental factors in forming EDGs of forest understory vegetation. The study plots were selected along elevational gradients in cool-temperate and sub-alpine forests in the University of Tokyo Chichibu Forest of central Japan. Tree seedlings and herbs were identified, and environmental factors (elevation, soil temperature, soil pH, soil CN ratio, forest type, basal area, canopy openness, and slope) were measured in these plots. Structural equation modeling (SEM) including taxonomic and phylogenetic diversity was used to consider the causal relationships between environmental conditions and the diversity of understory vegetation. In addition, phylogenetic signals in habitat requirements were tested. The taxonomic and phylogenetic diversities of tree seedlings increased monotonically with elevation, and the same pattern was found for the taxonomic diversity of herbs. The SEM indicated that both the taxonomic and phylogenetic diversity of tree seedlings were most affected by soil properties, although the phylogenetic diversity of herbs was determined by light conditions. These results highlight the importance of environmental filtering by soil properties in shaping EDGs of tree seedlings. This study implies that phylogenetic constraints in the adaptation to soil properties should be considered when predicting changes in EDGs under environmental fluctuations.