[Release Characteristics of Mercury from Submersed Typical Herbaceous Plants in the Water-Level Fluctuation Zone of the Three Gorges Reservoir Area].

In suit inundation experiments of three typical herbaceous plants were conducted in field to investigate the mercury release characteristics of plants grown in the water-level fluctuation zone of the Three Gorges Reservoir after flooding by regulating the water level. To realize this objective, this study mainly focused on the dynamic change of total mercury (THg) concentrations in plants after inundation, the release rate and flux of THg from plants and its release load in this region. The results showed that the release process of THg in plants fitted exponential curve, suggesting that mercury release rate was quick in the initial inundation period and then flat afterwards as the decomposing plants. The THg release amounts (followed the order of Alternanthera philoxeroides > Polygonum lapathifolium > Cynodon dactylon) were probably influenced by initial C/N ratio and THg concentrations of plants. The decrement of THg concentrations in per unit mass of plants residue was found to be generally proportional to their initial C/N ratio, while the THg release amounts were generally proportional to the initial THg concentrations of plants. The total release loads of three plants (Alternanthera philoxeroides, Polygonum lapathifolium, Cynodon dactylon) were estimated to be 167.31, 78.13 and 88.33 mg·hm-2, respectively, according to their weight distribution and biomass in the water-level fluctuation zone of the Three Gorges Reservoir Area.

[Effect of Low Molecular Weight Organic Acids on the Chemical Speciation and Activity of Mercury in the Soils of the Water-Level-Fluctuating Zone of the Three Gorges Reservoir].

To investigate the effect of low molecular weight organic acids ( LMWOA) on the ability of migration and the species of mercury in the soil of the Water-Level-Fluctuating Zone of the Three Gorges Reservoir, citric acid, tartaric acid and oxalic acid were dded into the soil to conduct simulation experiments. The results showed that the percentage of exchangeable mercury increased with the increase of the concentration of citric acid, but the value declined slightly as the concentration of tartaric acid and oxalic acid increased. While all three acids elevated the bioavailability of mercury, which increased with the increase of the concentration of acids. Vhen the concentration of citric acid reached 15 mmol x L(-1), the activation effect was the best. But for oxalic acid and citric acid, 10 mmol x L(-1) was the optimal concentration. In general, the effect of three organic acids on the activation of mercury in the soil followed the trend of citric acid > tartaric acid > oxalic acid. In the soil supplemented with 15 mmol x L(-1) citric acid, the change of mercury pecies was more and more striking with the prolonged incubation, and the conversion did not stop until 14 d, at that time the stomach cid dissolved mercury increased obviously, which was mainly converted from elemental mercury.

[Spectral Characteristics of Dissolved Organic Matter (DOM) Releases from Soils of Typical Water-Level Fluctuation Zones of Three Gorges Reservoir Areas:Fluorescence Spectra].

As an important sources of dissolved organic matter (DOM) in aquatic system, DOM releases from flooding or submerged soils is a key process in water-level fluctuation zones. In this study, four typical sites in water-level fluctuation zones of Three Gorges Reservoir areas were selected to conduct simulated soil flooding experiments, under ambient (open air) and anoxic conditions. By using fluorescence spectrum technique, the dynamic and geochemical characteristics of DOM releases from flooding soils were investigated. Results showed that the trend or model of DOM releases observed by fluorescence spectrum in all soils from four sampling sites was similar to the observation by UV-Vis spectrum. Fluorescence property of DOM releases showed an important contribution to DOM fluorescence in overlying waters. The rapid releases at initial stage and removal mechanism for later dynamic equilibrium were crucial to explain the dynamic "source-sink" equilibrium in whole flooding period. Effect of inorganic mineral adsorption-desorption on humic-like components (A and C peaks) was significant. Also, impact of microbial utilization on protein-like components (B and T peaks) was confirmative. Additionally, all DOM samples had "autochthonousness plus allochthonousness" property. Except Shibaozhai (SB) site in Zhongxian county, during the whole flooding period, all three other sites didn't show any significant difference between ambient and anoxic conditions. They could be explained by the high heterogeneity of soil property including minerals and organic components. Meanwhile, both the UV-Vis and fluorescence spectra were complementary for each other, and they evidentially showed that the "source-sink" (release and removal) mechanism in DOM releases from submerged soils was the core to decide the dynamics of DOM in overlying waters. Importantly, DOM showed higher aromaticity and humification at the initial release stage when flooding occurred, as well as the greater terrestrial source characteristics, which further helped to explain the environmental fates of pollutants in these environmental sensitive areas. It would also be useful for unveiling the role of DOM in environmental system in future.

Bioactive components and pharmacological action of Wikstroemia indica (L.) C. A. Mey and its clinical application.

Wikstroemia indica (L.) C. A. Mey. is a member of family Thymelaeaceae and mainly distributes in middle and southeast part of China. As a traditional Chinese herb, this plant has long been employed as antipyretics, detoxicants, expectorants, vermifuges as well as aborticides in clinic practice. However, its use has mainly been based on empirical findings during hundreds and thousands of years. Recent studies indicated that W. indica contains abundant active components including flavonoids, biflavonoids, coumarins, lignans, volatile oils, polysaccharides etc. This paper provides a comprehensive review of pharmacological relevant compounds of W. indica that have been characterized to date, and introduce the research progresses supporting its pharmacological action and clinical application. Particular attention has been given to antibacterial, antiviral, anti-inflammatory, anti-tumor and antifertility effects. Some examples of clinical applications of prepared W. indica in treatment of various diseases are outlined. Finally, the trend and necessity of future research, such as quantification of individual constituents extracted from W. indica and the assessment of their pharmacological activities in human body are proposed.

[Experimental studies on hypoglycemic effects of total flavonoid from Toona sinensis].

OBJECTIVE: To study hypoglycemic effects of total flavonoid from Toona sinensis (TSTF) on diabetic mice model. METHODS: To confect alloxan 0.02 g/ml with NS and injected alloxan into abdominal cavity to induce diabetic model, and all rats were fed bid with glucose for 2 consecutive days, then the blood glucose was detected by glucose oxidizes, when hypoglycemic point >11.00 mmol/L the rats were successful model made. 100 model rats were divided into 5 groups as contrast groups (distilled water), model control control groups, hight doses group (0.12 g/kg) and low doses group (0.6 g/kg) of TSTF, positive control groups of phenformin (0.10 g/kg); In addition to set 20 natural rats (distilled water), and all groups were fed qd for 15 consecutive days, and then the blood glucose were detected by glucose oxidizes in the sixteenth day. RESULTS: The blood glucose levels of the diabetic rats in TSTF groups significantly decreased. CONCLUSION: TSTF can significantly decrease the blood glucose levels of diabetic mice induced by alloxan.

[Studies on the chemical constituents of essential oil of Hunan Artemisia annua].

The chemical constituents of the essential oil of Hunan wild Artemisia annua L. in Xuefeng mountain region have been studied by means of the GC-MS. The essential oil was extracted from Artemisia annua L. by steam distillation. The chemical constituents were separated and identified by GC-MS, and the relative contents of them in the oil were determined with area normalization method. Forty-five components were separated and identified which accounted for 90% of total essential oil. These components identified from the essential oil indicate that Hunan wild Artemisia annua L. in Xuefeng mountain region is a good medical plant, and worth to exploiting.

New anthraquinones from Gladiolus gandavensis.

Two new anthraquinones, methyl 8-hydroxy-3-methoxy-6,7-methylenedioxy-1-methylanthraquinone-2-carboxylate (gandavensin A, 1) and methyl 8-hydroxy-3,6,7-trimethoxy-1-methylanthraquinone-2-carboxylate (gandavensin B, 2), have been isolated from the light petroleum extract of the subterranean corm of Gladiolus gandavensis Van Houtt., along with methyl 8-hydroxy-3,6-dimethoxy-1-methylanthraquinone-2-carboxylate (3), methyl trans-p-methoxycinnamate (4), 5,7-dimethoxy-2-methylchromone (5), and 5-hydroxy-2-hydroxymethyl-7-methoxychromone (6). Their structures were elucidated on the basis of spectral data.

Two new xanthones from Premna microphylla.

Two new xanthones have been isolated from the EtOAc extract of the roots of Premna microphylla Turcz. Based on spectral and chemical evidences, their structures were elucidated as 1-hydroxy-2,3-methylenedioxy-6-methoxycarbonyl-7-acetylxanthone 1 and 1,3-dihydroxy-2-methoxy-6-methoxycarbonyl-7-acetylxanthone 2. This is the first report on isolation of xanthones from this plant.