<Superscript>1</Superscript>H NMR-based metabolomics combined with HPLC-PDA-MS-SPE-NMR for investigation of standardized <Emphasis Type="Italic">Ginkgo biloba</Emphasis> preparations

Commercial preparations of Ginkgo biloba are very complex mixtures prepared from raw leaf extracts by a series of extraction and prepurification steps. The pharmacological activity is attributed to a number of flavonoid glycosides and unique terpene trilactones (TTLs), with largely uncharacterized pharmacological profiles on targets involved in neurological disorders. It is therefore important to complement existing targeted analytical methods for analysis of Ginkgo biloba preparations with alternative technology platforms for their comprehensive and global characterization. In this work, ¹H NMR-based metabolomics and hyphenation of high-performance liquid chromatography, photo-diode array detection, mass spectrometry, solid-phase extraction, and nuclear magnetic resonance spectroscopy (HPLC-PDA-MS-SPE-NMR) were used for investigation of 16 commercially available preparations of Ginkgo biloba. The standardized extracts originated from Denmark, Italy, Sweden, and United Kingdom, and the results show that ¹H NMR spectra allow simultaneous assessment of the content as well as identity of flavonoid glycosides and TTLs based on a very simple sample-preparation procedure consisting of extraction, evaporation and reconstitution in acetone-d ₆. Unexpected or unwanted extract constituents were also easily identified in the ¹H NMR spectra, which contrasts traditional methods that depend on UV absorption or MS ionizability and usually require availability of reference standards. Automated integration of ¹H NMR spectral segments (buckets or bins of 0.02 ppm width) provides relative distribution plots of TTLs based on their H-12 resonances. The present study shows that ¹H NMR-based metabolomics is an attractive method for non-selective and comprehensive analysis of Ginkgo extracts.     

中国北方草地植被物候变化及其对气候变化的响应

研究草地物候变化对揭示草地生态系统随全球气候变化的响应机制具有重要的科学意义.本研究基于1983—2015年的GIMMS NDVI 3g、气候和数字高程模型(DEM)数据,采用动态阈值法提取北方草地的物候信息[生长季始期(SOS)、生长季末期(EOS)、生长季长度(LOS)],分析北方草地物候的时空变化及LOS对气候的响应.结果表明: 88.9%的像元SOS发生在3月下旬到5月下旬(日序第90～150天),其中,68.1%的像元表现为提前,速率为-1.5～0 d·(32 a)^-1;79.7%的像元EOS发生在10月上旬到10月下旬(日序第270～300天),其中,70.3％的像元表现为推迟,速率为0～1.5 d·(32 a)^-1;LOS持续在100～140 d,其中,LOS变长的像元占73.7%,速率为0～1.5 d·(32 a)^-1.LOS与气温呈显著正相关(R=0.628),与降水呈弱负相关(R=-0.091),并存在明显的空间差异.以海拔2000 m为分界线,低于2000 m时,LOS与海拔呈弱正相关(R=0.235),高于2000 m时,LOS与海拔呈显著负相关(R=-0.861);海拔高于3000 m时,海拔每升高1000 m, LOS缩短约10 d.     

Morphological diversity of Ethiopian barley (Hordeum vulgare L.) in relation to geographic regions and altitudes

A total of 199 germplasm accessions collected from 10 administrative regions of Ethiopia and four released cultivars, which were used for estimating of error variance, of barley in Ethiopia were field evaluated for nine agronomic traits at Holetta and Bekoji Agricultural Research Centers of Ethiopia during the 2006 main cropping season using non-replicated augmented design plots consisting of four incomplete blocks. The objectives were to assess the extent and pattern of morphological variation in the barley accessions with respect to regions and altitude of collection, to classify the genotypes tested into relatively homogenous groups and to identify the major traits contributing to the overall observed diversity in the germplasm. Genotype variance estimate of regions and altitudes indicated wide variation among accessions depending on the traits involved. The presence of high morphological variation within regions and altitudes particularly above 2000 m a.s.l. indicated the potential of each region and high altitude zones for barley improvement and conservation in the country. The clustering of accessions did not show grouping on the basis of regions of origin. Traits like thousand kernel weight, plant height, days to head and days to maturity accounted for most of the gross variance among the barley accessions and played role in differentiating accessions collected from different regions and altitude classes into principal components. In general because of environmental factors on the observed morphological variation future germplasm collection should consider to explore wide geographical and climatic differences within the country.     

Lack of altitudinal trends in phytochemical constituents of Swertia franchetiana (Gentianaceae)

Diverse biological characters commonly vary with altitude in species that have a wide altitudinal distribution, partly at least as a result of adaptation to differences in aridity, but whether such variation exists for phytochemical constituents remains unknown. Therefore, levels of seven important phytochemical constituents of Swertia franchetiana (swertiamarin, oleanolic acid, swertisin, mangiferin, 1,5,8-trihydroxy-3-methoxyxanthone, 1,8-dihydroxy-3,7-dimethoxyxanthone and 1,8-dihydroxy-3,5-dimethoxyxanthone) were studied and statistically compared, using materials collected from sites ranging from 2200 to 3960 m in altitude. Swertiamarin was the most abundant in all samples, then mangiferin, oleanolic acid and the other three xanthones. Throughout the distributional range of this species, no altitudinal trend was detected for other constituents except 1,8-dihydroxy-3,7-dimethoxyxanthone, which showed a negative correlation with altitude. However, the concentration of 1,8-dihydroxy-3,7-dimethoxyxanthone and mangiferin showed a significantly latitudinal and longitudinal correlation.     

Bioactive constituents in Prunus africana: Geographical variation throughout Africa and associations with environmental and genetic parameters

Prunus africana – an evergreen tree found in Afromontane forests – is used in traditional medicine to cure benign prostate hyperplasia. Different bioactive constituents derived from bark extracts from 20 tree populations sampled throughout the species’ natural range in Africa were studied by means of GC–MSD. The average concentration [mg/kg w/w] in increasing order was: lauric acid (18), myristic acid (22), n-docosanol (25), ferulic acid (49), β-sitostenone (198), β-sitosterol (490), and ursolic acid (743). The concentrations of many bark constituents were significantly correlated and concentration of n-docosanol was highly significantly correlated with all other analytes. Estimates of variance components revealed the highest variation among populations for ursolic acid (66%) and the lowest for β-sitosterol (20%). In general, environmental parameters recorded (temperature, precipitation, altitude) for the samples sites were not correlated with the concentration of most constituents; however, concentration of ferulic acid was significantly correlated with annual precipitation. Because the concentration of compounds in bark extracts may be affected by tree size, the diameter of sampled plants at 1.3 m tree height (as proxy of age) was recorded. The only relationship with tree diameter was a negative correlation with ursolic acid. Under the assumption that genetically less variable populations have less variable concentrations of bark compounds, correlations between variation parameters of the concentration and the respective genetic composition based on chloroplast and nuclear DNA markers were assessed. Only variation of β-sitosterol concentration was significantly correlated with haplotypic diversity. The fixation index (F_IS) was positively correlated with the variation in concentration of ferulic acid. Principal Components Analysis (PCA) indicated a weak geographic pattern. Mantel tests, however, revealed associations between the geographic patterns of bioactive constituents and the phylogenetic relationship among the populations sampled. This suggests an independent evolution of bark metabolism within different phylogeographical lineages, and the molecular phylogeographic pattern is partly reflected in the variation in concentration of bark constituents. The results have important implications for the design of strategies for the sustainable use and conservation of this important African tree species.     

Variation in invertebrate–bryophyte community structure at different spatial scales along altitudinal gradients

Aim This study assessed changes in diversity and assemblage composition in bryophytes and their associated invertebrates along altitudinal gradients in Australia and New Zealand. The importance of altitude in shaping these communities and for the diversity of both invertebrates and bryophytes was examined at different spatial scales, including local, altitudinal, regional and biogeographical. Location Samples were taken from four Australasian mountain ranges between 42° and 43°S: Mt Field and Mt Rufus, Tasmania, Australia, and Otira Valley and Seaward Kaikoura Mountains, South Island, New Zealand. Methods On both Tasmanian mountains, five altitudes were assessed (250, 500, 750, 1000 and 1250 m). At each location (mountain/altitude combination) two sites were chosen and six samples were taken. Six altitudes were assessed on New Zealand mountains (Otira: 250, 500, 750, 1000, 1250 and 1500 m; Kaikoura: 1130, 1225, 1325, 1425, 1525 and 2000 m). Bryophyte substrate was collected, and all samples were stored in 70% ethanol. Invertebrates were extracted from bryophytes using kerosene‐phase separation and all invertebrates were identified to family. At each location in Tasmania, all bryophyte species within six 25‐cm² grids per site were collected and identified to species. Bryophytes from New Zealand were identified to species from the invertebrate sample substrate because of sampling constraints. Results Altitude did have a significant effect on diversity, however, no general trend was found along the altitudinal gradient on the four mountains. There were distinct differences in diversity between biogeographical regions, mountains, altitudes and sites. In Tasmania, Mt Field had the highest diversity in invertebrates and bryophytes at 750 m. In contrast, Mt Rufus had consistent low invertebrate and bryophyte diversity along the entire altitudinal gradient. There were also distinctive differences between locations in the composition of invertebrate and bryophyte communities in Tasmania. Along the two altitudinal gradients in New Zealand, Otira had highest diversity for both invertebrates and bryophytes at low altitudes, whereas Kaikoura had highest invertebrate and lowest bryophyte diversity at the highest altitude. Main conclusions There was an effect of altitude, however, there were no consistent changes in diversity or composition on the four different mountains. There was considerable local and regional variation, and, despite a strong sampling design, no underlying altitudinal trends were detectable. This study demonstrates the importance of examining a range of spatial scales if patterns in community structure along altitudinal gradients are to be studied. The implications of this study are discussed with reference to survey design, taxonomic resolution, climate change and conservation of habitat.     

几种常用中草药抗氧化活性研究(英文)

当归、黄芪、银杏叶、益母草、野甘草是中国传统中药材,几千年来一直为中国人民所认可,在中国和世界都具有重要的科研和药用价值。本研究采用HO&#183;清除及对肝微粒体和亚油酸脂质过氧化抑制的方法,测定五种草药精油和水煮提取物的抗氧化活性;采用Folin—Ciocalteu试剂法测定它们的总酚含量;用肝细胞体外培养法测定它们的细胞毒性并对它们的作用机制进行分析。结果发现五种草药提取物都具有一定的抗氧化活性,尤其是益母草、野甘草、银杏叶的水煮提取物活性较强,其抗氧化活性与总酚含量存在较好的线形关系。此外,本论文还为研究这些草药的一些抗病机制提供参考依据。     

Evaluation of drying methods on nutritional constituents and antioxidant activities of Chlorella vulgaris cultivated in an outdoor open raceway pond

Chlorella vulgaris is known for its protein, growth factor, and nutritional constituents. Chlorella vulgaris was cultivated in a 1000-L outdoor open raceway pond with a maximum volumetric productivity of 130 mg L^-1 day^-1. The harvested biomass was dried through different methods, viz., sun drying (30 °C), oven drying (60 °C), lyophilization (?110 °C), drum drying (120 °C), and spray drying (100–150 °C). The effect of the drying method on proximate composition, pigments (chlorophyll, carotenoids), bioactive compounds (total phenolic content, flavonoid content), vitamin B₁₂, antioxidant properties (ferric reducing antioxidant power, DPPH, and total antioxidant activity), and the color quality of C. vulgaris biomass was evaluated. Surface characterization by scanning electron microscopy (SEM) and functional group characterization through Fourier transform infrared spectroscopy were also performed. The biomass dried through lyophilization and sun drying retained maximum bioactive compounds and antioxidant activities. In contrast, drum drying resulted in a loss of nutrients, viz., protein (up to 44%), lipid (up to 41%), vitamin B₁₂ (up to 40%), total phenolic content (> 50%), total flavonoid content (> 50%), and antioxidant activity (> 50%). Oven drying led to a loss of 30% in total flavonoid content and 17% in ferric reducing antioxidant power. SEM showed the destruction of cell wall integrity in the drum-dried sample and porous structure in the spray-dried sample. This study suggests that drying methods affect the nutrients and bioactive compounds of C. vulgaris biomass, and therefore a drying method should be selected carefully depending on the end use of the biomass.

     

Impact of Altitude on Power Output during Cycling Stage Racing

Purpose

The purpose of this study was to quantify the effects of moderate-high altitude on power output, cadence, speed and heart rate during a multi-day cycling tour.

Methods

Power output, heart rate, speed and cadence were collected from elite male road cyclists during maximal efforts of 5, 15, 30, 60, 240 and 600 s. The efforts were completed in a laboratory power-profile assessment, and spontaneously during a cycling race simulation near sea-level and an international cycling race at moderate-high altitude. Matched data from the laboratory power-profile and the highest maximal mean power output (MMP) and corresponding speed and heart rate recorded during the cycling race simulation and cycling race at moderate-high altitude were compared using paired t-tests. Additionally, all MMP and corresponding speeds and heart rates were binned per 1000m (<1000m, 1000–2000, 2000–3000 and >3000m) according to the average altitude of each ride. Mixed linear modelling was used to compare cycling performance data from each altitude bin.

Results

Power output was similar between the laboratory power-profile and the race simulation, however MMPs for 5–600 s and 15, 60, 240 and 600 s were lower (p ≤ 0.005) during the race at altitude compared with the laboratory power-profile and race simulation, respectively. Furthermore, peak power output and all MMPs were lower (≥ 11.7%, p ≤ 0.001) while racing >3000 m compared with rides completed near sea-level. However, speed associated with MMP 60 and 240 s was greater (p < 0.001) during racing at moderate-high altitude compared with the race simulation near sea-level.

Conclusion

A reduction in oxygen availability as altitude increases leads to attenuation of cycling power output during competition. Decrement in cycling power output at altitude does not seem to affect speed which tended to be greater at higher altitudes.     

Geographical variation in AdhF and alcoholic resource utilization in Indian populations of Drosophila melanogaster

Indian geographical populations of Drosophila melanogaster, collected at latitude 10–32.3 ^oN, longitude 76.1–80.1 ^oE and altitude 16–2050 m, were analysed for changes in Adh ¹ frequency and utilization potential of diverse alcoholic resources. Until now, there have been limited data on climatic association of correlated changes on these aspects in continental populations of D. melanogaster. Indian populations demonstrate an increase in Adh ^F frequency by 0.04 per degree latitude and significantly higher utilization of ethanol (9.0–15.2%), acetic acid (8.1–12.5%), n-propanol (2.55-4.25%), 2-propanol (1.5-3.5%), n-butanol (2.15 3.5%) and 2-butanol (0.68-1.2%). Data also revealed significant correlation with latitude as well as altitude. Regression analysis of climatic data from collection sites confirmed the observed clinal variation of Adh ^F as well as alcoholic utilization in D. melanogaster. On the Indian subcontinent, variation in Adh ^F frequency and alcoholic resource utilization along increasing latitude as well as altitude are due to climatic selection factors such as temperature and rainfall.     

Collection characteristics of a batch-type wetted wall bioaerosol sampling cyclone

The collection efficiency and sample retention of a batch-type wetted wall bioaerosol sampling cyclone (BWWC) were experimentally characterized. The BWWC is designed to sample air at 400 l/min and concentrate the particles into 12 ml of water. Aerosol is transported into a cylindrically-shaped axial flow cyclone through a tangential slot and the particles are impacted on the inner wall, which is wetted by air shear acting on a liquid pool at the base of the cyclone. The retention of collected particles and the aerosol collection efficiency of the BWWC were evaluated with polystyrene latex beads (PSL), sodium fluorescein/oleic acid droplets, and Bacillus atrophaeus (aka BG) spores. The retention of particles was determined by adding hydrosol directly into the device, running the BWWC for a pre-set period of time, and then determining the amount of particulate matter recovered relative to the initial amount. For 1-μm diameter PSL, 90% of the particles were recoverable from the cyclone body immediately after their introduction; however, only 10% were retained in the collection liquid after 8 h of operation. The aerosol sampling efficiency was determined by comparing the amount of particulate matter collected in the liquid with that collected by a reference filter. The collection efficiency was 50–60% for 1- and 3-μm polystyrene (PSL) particles, and 1.5% for 10-μm oleic acid particles. The efficiency for 3-μm oleic acid droplets was 35%. Explanations are provided for the difference between liquid and solid particle behavior, and for the low efficiency for the large liquid particles. The collection efficiency for single spore BG was slightly lower than that for 1-μm PSL.     

Effects of dose and timing of calcium supplementation on bone resorption in early menopausal women.

Bone resorption follows a circadian rhythm that peaks at night, reflecting the circadian rhythm of serum parathyroid hormone. Our previous studies in early postmenopausal women have established that 1000 mg of calcium given at 9 p. m. reduced bone resorption markers overnight, but not during the day. In contrast, 1000 mg given as a divided dose (500 mg doses at 9 a. m. and 9 p. m. each) reduced bone resorption markers during the day, but not during the night. We have now evaluated the effect of 1500 mg of calcium given as a divided dose of 500 mg in the morning and 1000 mg in the evening on bone resorption. We studied 26 healthy women (median age 56 years) whose menopause was less than five years before. On two days, urine was collected from 9 a. m. to 9 p. m. (day collection), and from 9 p. m. to 9 a. m. (night collection); a further fasting (spot) urine sample was obtained at 9 a. m. at the end of the night collection. On the second day, 500 mg of calcium in the carbonate form was taken at 9 a. m. (at the start of the collection) and a further 1000 mg at 9 p. m. (at the start of the second night collection). Calcium supplementation decreased urinary deoxypyridinoline (DPyr/Cr) during the day (p = 0.08) and night (p < 0.05), as well as urinary pyridinoline (Pyr/Cr) both by day (p < 0.05) and night (p < 0.001). There were also decreases in urine hydroxyproline. We conclude that the acute administration of 500 mg of calcium in the morning and 1000 mg in the evening to early postmenopausal women suppresses bone resorption markers during both the day and night.     

Microorganisms asssociated with Withania somnifera leaves.

Microorganisms including bacteria, actinomycetes and fungi were recovered from the leaves of Withania somnifera, which were collected from two altitudinal ranges (0–300 m and 1700–2000 m) in the Asir region, Saudi Arabia. Types and numbers of microorganisms varied according to the altitude and the month of collection. The number of microorganisms was higher on old leaves than that on young ones in most cases. Low altitude exhibited more microorganisms than high altitude. The relationship between meteorological factors and type and number of the recovered microorganisms is discussed. Inoculation of detached healthy leaves of Withania by all recovered fungal species revealed only Alternaria solani as a pathogen of this plant. To confirm pathogenicity, scanning and transmission electron microscopic examination revealed the colonization of this pathogen inside the leaf tissue. Penetration of Withania leaves by the fungus occurred only through stomata, and the invading hyphae were located in the intercellular spaces of leaf tissues. Ultrastructural changes noted in infected cells included changes in chloroplasts and the invagination of the host plasma membrane.     

Quantitative determination of the major saponin mixture bacoside A in Bacopa monnieri by HPLC

Bacoside A, the putative bioactive component of the Indian medicinal plant Bacopa monnieri, was found to be a mixture of saponins with bacoside A3 (1), bacopaside II (2), jujubogenin isomer of bacopasaponin C (3) and bacopasaponin C (4) as major constituents. An HPLC method together with an optimised extraction procedure was developed for the estimation of 1-4 in B. monnieri to enable standardisation of the latter. Concentration ranges of the analytes in samples of B. monnieri collected from different regions of India were 0.14-0.85% (w/w) (1), 0.12-0.69% (2), 0.05-0.72% (3) and 0.05-0.44% (4). The importance of using bacoside A, with known concentrations of 1-4, as a reference standard for the routine analysis of B. monnieri is highlighted. Two common flavonoids, luteolin and apigenin, were present in all samples of B. monnieri.     

Microorganisms asssociated with Withania somnifera leaves

Microorganisms including bacteria, actinomycetes and fungi were recovered from the leaves of Withania somnifera, which were collected from two altitudinal ranges (0–300 m and 1700–2000 m) in the Asir region, Saudi Arabia. Types and numbers of microorganisms varied according to the altitude and the month of collection. The number of microorganisms was higher on old leaves than that on young ones in most cases. Low altitude exhibited more microorganisms than high altitude. The relationship between meteorological factors and type and number of the recovered microorganisms is discussed. Inoculation of detached healthy leaves of Withania by all recovered fungal species revealed only Alternaria solani as a pathogen of this plant. To confirm pathogenicity, scanning and transmission electron microscopic examination revealed the colonization of this pathogen inside the leaf tissue. Penetration of Withania leaves by the fungus occurred only through stomata, and the invading hyphae were located in the intercellular spaces of leaf tissues. Ultrastructural changes noted in infected cells included changes in chloroplasts and the invagination of the host plasma membrane.     

Chemical composition and bioactivity of Boswellia serrata Roxb. essential oil in relation to geographical variation

Oleo–gum–resin of Boswellia serrata Roxb. (Burseraceae) was collected from Shivpuri forest situated in northwestern district of Madhya Pradesh, India. The commercial samples were purchased from Mandsaur and Neemuch districts (the major herbal markets of Madhya Pradesh) for comparative study of their essential oils. The average essential oil contents in the commercial Neemuch samples (11.1%) were much better as compared to the wild collection from Shivpuri (6.1%) as well as commercial collection from Mandsaur (6.9%). The commercial samples contained higher percentage of monoterpene hydrocarbons (81.9–88.1%) including α-thujene (61.4–69.8%) as the major compound. The wild habitat contained higher percentage of oxygenated monoterpenoids/benzenoids (15.7%) and sesquiterpenes (19.2%) including α-terpineol (7.8%), terpinyl isobutyrate (5.1%), and eudesmol (11.5%). Further, the antimicrobial activities of these collections showed remarkable variation among the essential oils. On the other hand, wild habitat contained improved percentage of semi-polar compounds (34.9%) which might be responsible for enhanced antibacterial activity. Similarly, the winter collection from Neemuch (BS-N2) showed significant antioxidant activity, whereas the wild habitat did not show any antioxidant activity. The higher percentage of monoterpene hydrocarbons in commercial samples, especially δ-3-carene, α-pinene, and α-thujene, might be responsible for enhanced antifungal and antioxidant activities. The Pearson correlation values justify the bioactivity relationship of the major compounds with different microbial strains. It also justified the interaction among the major individual compounds.     

区域气温和降水对关帝山不同海拔华北落叶松径向生长的耦合效应

为揭示区域气温和降水在不同海拔对山地林区林木径向生长的耦合效应,在关帝山林区孝文林场和庞泉沟国家自然保护区外围4个不同海拔选取立地条件相似的华北落叶松(Larix principis-rupprechtii Mayr.)人工林设置调查样地,采集典型样木样芯,采用建立年表的方法,获取年轮宽度指数,结合区域气温和降水进行相关性分析和单年分析。结果表明:在研究地区4个海拔上华北落叶松的径向生长均与区域气温和降水量有密切关系,但不同海拔响应机制不同;在1600 m海拔处,年轮宽度指数与当年4月气温极显著负相关,与当年9月降水量显著正相关;在1800 m海拔处,年轮宽度指数与上年6月气温显著负相关,降水量显著正相关;在2000 m海拔处,年轮宽度指数与当年9月气温和当年3月降水量显著负相关;在海拔2200 m处,年轮宽度指数与上年8月气温显著正相关,降水量显著负相关;随着海拔的升高,气温逐渐降低,降水量增加,两者对华北落叶松径向生长的耦合效应也发生变化,当海拔到达2000 m时,生长季降水量的增加使耦合效应关系发生转换。     

Biflavones from Ginkgo biloba as inhibitors of human thrombin

Ginkgo Biloba leaf extract has been widely used for the prevention and treatment of thrombosis and cardiovascular disease in both eastern and western countries, but the bioactive constituents and the underlying mechanism of anti-thrombosis have not been fully characterized. The purpose of this study was to investigate the inhibitory effects of major constituents in Ginkgo biloba on human thrombin, a key serine protease regulating the blood coagulation cascade and the processes of thrombosis. To this end, a fluorescence-based biochemical assay was used to assay the inhibitory effects of sixteen major constituents from Ginkgo biloba on human thrombin. Among all tested natural compounds, four biflavones (ginkgetin, isoginkgetin, bilobetin and amentoflavone), and five flavonoids (luteolin, apigenin, quercetin, kaempferol and isorhamnetin) were found with thrombin inhibition activity, with the IC₅₀ values ranging from 8.05 μM to 82.08 μM. Inhibition kinetic analyses demonstrated that four biflavones were mixed inhibitors against thrombin-mediated Z-GGRAMC acetate hydrolysis, with the K_i values ranging from 4.12 μM to 11.01 μM. Molecular docking method showed that the four biflavones could occupy the active cavity with strong interactions of salt bridges and hydrogen bonds. In addition, mass spectrometry-based lysine labeling reactivity assay suggested that the biflavones could bind on human thrombin at exosite I rather than exosite II. All these findings suggested that the biflavones in Ginkgo biloba were naturally occurring inhibitors of human thrombin, and these compounds could be used as lead compounds for the development of novel thrombin inhibitors with improved efficacy and high safety profiles.     

江西官山常绿阔叶林土壤有机碳组分沿海拔的变化

对江西官山国家级自然保护区不同海拔(400、600、800、1000、1200 m)常绿阔叶林土壤总有机碳、惰性有机碳和活性有机碳进行分析,研究土壤有机碳的海拔分布特征。结果表明: 土壤总有机碳、惰性有机碳及活性有机碳含量在土壤表层最高,随土层加深而逐渐下降。随海拔升高,土壤总有机碳、惰性有机碳、易氧化有机碳、微生物生物量碳及0～20 cm土层土壤颗粒有机碳含量均出现先增后降的趋势, 且在海拔1000 m达到峰值,而土壤水溶性有机碳及20～40 cm土层土壤颗粒有机碳含量无明显变化。在0～10 cm土层,土壤惰性有机碳占总有机碳的比例在海拔800和1200 m显著高于海拔400和1000 m,而土壤活性有机碳占总有机碳的比例在海拔400 m最高;土壤惰性有机碳和活性有机碳占总有机碳的比例在10～40 cm土层随海拔的增加均呈先增加后降低的趋势,峰值分别在1000和600 m处。各组分有机碳与土壤湿度、微生物生物量氮、可溶性有机氮均呈显著正相关,而且活性有机碳与铵态氮呈显著正相关。海拔显著影响常绿阔叶林土壤有机碳组分的分布,惰性有机碳、易氧化有机碳和微生物生物量碳对海拔变化的响应更敏感。高海拔土壤惰性有机碳和活性有机碳在水分和氮素充足条件下易发生分解与转化,降低土壤碳库的稳定性。在全球气温持续升高背景下,要加强高海拔地区森林土壤有机碳的动态变化研究。     

Effect of dietary supplementation of grape seed extract on the growth performance,lipid profile,antioxidant status and immune response of broiler chickens

Grape seed extracts (GSE) contain several beneficial bioactive constituents; therefore, can be utilized as a potential feed additive in broiler chickens. An experiment was conducted to investigate the effect of supplementation of broiler chicken diets with GSE as a natural antioxidant at levels of 125, 250, 500, 1000 and 2000 ppm on the growth performance, serum lipid profile, liver glutathione-reduced, thigh muscle malondialdehyde and humoral immune response against Newcastle disease virus vaccines. This experiment was performed during the life-span of chickens from 0 to 42 days of age. The results of broilers fed on diet supplemented by GSE were compared with those fed on the basal diet (control) or the basal diet supplemented by butylated hydroxytoluene as a synthetic antioxidant (BHT, 125 ppm). No significant differences were observed in the growth performance, percent livability, total lipid, high and very low-density lipoprotein cholesterols when the use of GSE or BHT were compared with the control. Total cholesterol and low-density lipoprotein cholesterol were significantly decreased after intake of GSE compared with BHT in the feed diet. The glutathione-reduced level in liver tissues was significantly increased by inclusion of GSE, but not by BHT. Inclusion of GSE or BHT decreased significantly the malondialdehyde level found in meat tissue. The antibody titer against Newcastle disease virus vaccines was significantly elevated in 28 and 35-day-old broiler chickens fed with a diet supplemented with GSE or BHT, the former providing a higher response. It can be concluded that GSE can be used as an effective natural antioxidant and immunostimulant agent in broiler chicken diets, and that 125 to 250 ppm can be considered as the optimum dosage.