Altitudinal changes in secondary metabolite contents of Hypericum androsaemum and Hypericum polyphyllum

The genus Hypericum (Hypericaceae) has attracted scientific interest as its members have yielded many bioactive compounds. In the present study we investigated the content of hypericin, pseudohypericin, hyperforin, adhyperforin, chlorogenic acid, neochlorogenic acid, caffeic acid, 2,4-dihydroxybenzoic acid, 13,II8-biapigenin, hyperoside, isoquercitrin, quercitrin, quercetin, avicularin, rutin, (+)-catechin and (−)-epicatechin in aerial parts of plants from populations of H. androsaemum L. and H. polyphyllum Boiss. & Bal. from Turkey growing at different altitudes. The plant materials were dried and subsequently assayed for chemical content by HPLC. All the tested compounds were detected in both species at varying levels depending upon the altitude the plants were growing, except for hypercins and rutin which did not accumulate in H. androsaemum. It was observed that overall the compounds were more abundant in plants from higher altitudes. The differences in the levels of the compounds could contribute to the ability of the plants to deal with the abiotic stress of lower temperature and higher ultraviolet (UV)-B radiation which would be greater at higher altitudes compared to lower altitudes.     

Prebiotics and bioactive natural substances induce changes of composition and metabolic activities of the colonic microflora in cancerous rats

Prebiotics are defined as selectively fermented food ingredients that induce specific changes in the composition and/or activity in the gastrointestinal microbiota beneficial to the host well-being and health. The aim of the presented experiment was to investigate the effect of a prebiotic applied alone or in combination with Hyppocastani extractum siccum, and Lini oleum virginale in rats with dimethylhydrazine induced colon cancer. Wistar albino rats were fed high fat diet supplemented with the prebiotic alone or in combination with Horse chestnut and flaxseed oil. The activity of faecal glycolytic enzymes, lipid parameters, bile acids, short chain fatty acids and counts of coliforms and lactobacilli were determined. Treatment with the prebiotic alone and in combination with selected substances significantly decreased the activity of glycolytic bacterial enzyme β-glucuronidase (P<0.001) and increased activities of β-galactosidase and β-glucosidase. Bile acids concentration was significantly decreased (P<0.01) except for the combination of the prebiotic with Horse chestnut. The prebiotic alone decreased the lipid parameters (P<0.001) and enhanced production of short chain fatty acids. Application of prebiotic and bioactive natural substances significantly reduced number of coliforms (P<0.05). Prebiotic alone significantly increased the count of lactobacilli (P<0.05). These results show that prebiotics have a protective effect and may be the useful for colon cancer prevention and treatment.     

Secondary metabolites of Hypericum orientale L. growing in Turkey: variation among populations and plant parts

The present study was conducted to determine the variation in the content of several plant chemicals, namely hyperforin, hypericin, pseudohypericin, chlorogenic acid, rutin, hyperoside, isoquercetine, kaempferol, quercitrine and quercetine among ten Hypericum orientale L. populations from Northern Turkey. The aerial parts representing a total of 30 individuals were collected at full flowering and dissected into floral, leaf and stem tissues. After dried at room temperature, the plant materials were assayed for chemical contents by HPLC. The populations varied significantly in chemical contents. Among different plant parts, the flowers were found to be the principle organ for hyperforin, hypericin, pseudohypericin and rutin accumulations while the rest of the chemicals were accumulated mainly in leaves in all growing localities. The chemical variation among the populations and plant parts is discussed as being possibly the result of different genetic, environmental and morphological factors.     

Myxobacteria, producers of novel bioactive substances

Myxobacteria are soil bacteria that move by gliding and have an astonishing life cycle culminating in fruiting body formation. In a research program at the Gesellshaft für Biotechnologische Forschung over the past 25 years the organisms have been shown to be a rich source of potentially useful secondary metabolites. So far about 80 different basic compounds and 450 structural variants have been characterized. Many of those compounds were new. It is particularly remarkable that myxobacteria specialize in mechanisms of action that are very rare with other producers. Thus 20 new electron transport inhibitors, 10 substances that act on the cytoskeleton, four inhibitors of nucleic acid polymerases, and one inhibitor of fungal acetyl-CoA carboxylase, a novel mechanism of action, have been found. Journal of Industrial Microbiology & Biotechnology (2001) 27, 149–156. Received 21 September 1999/ Accepted in revised form 19 January 2000     

南极磷虾生物活性物质的研究进展

南极磷虾因其生活环境和方式的特殊性而具有产生新型生物活性物质的巨大潜力,也因其巨大的生物资源量和潜在的渔业价值而日益受到人们的重视。南极磷虾生物活性物质包括酶、脂质、甲壳素、生物活性肽和紫外吸收物质等。本文综述了南极磷虾生物活性物质的研究进展,并展望了南极磷虾生物资源开发利用的前景。     

The variability of the hypericin content in the regenerants of Hypericum perforatum

The hypericin content of in vitro regenerated plants of Hypericum perforatum L. was determined by spectrophotometry. A significant variability of some of the morphological characters, of the biomass production and the hypericin formation was found within the somaclones of the same genetic origin and among the regerants of different genotypes. The concentration of BAP which promoted the shoot differentiation did not affect the hypericin content and the gland density. New information on the ultrastructure of hypericin-containing multicellular glands is presented here.     

海参资源及其生物活性物质的研究

海参属棘皮动物门海参纲,是海洋中重要的食物和药物资源。全世界海参资源比较丰富,目前已知约有1000种,我国约有140多种。海参含有多种生物活性物质,如多糖、甾醇、皂苷、脂肪酸和毒素等,具有增加免疫力、抗肿瘤、抗凝血、保护神经组织、镇痛、抗真菌、降低血黏度等作用。本综述了国内外海参资源分布、海参生物活性物质组成及其药理作用。     

贡嘎山地区不同海拔冷杉比叶质量和非结构性碳水化合物含量变化

以贡嘎山地区磨西山谷东北坡和康定山谷西南坡为样地,研究了高山林线和低海拔冷杉休眠期和生长旺盛期针叶比叶质量和组织非结构性碳水化合物含量.结果表明:生长在温暖湿润的磨西山谷东北坡的冷杉针叶比叶质量和组织非结构性碳水化合物含量均高于炎热干燥的康定山谷西南坡;高山林线冷杉比叶质量大于低海拔冷杉;高山林线冷杉组织非结构性碳水化合物含量总体高于低海拔冷杉,且生长期比休眠期更为显著.研究结果不支持"碳供应不足导致高山林线形成"的假说.     

鼎湖山森林土壤活性碳及惰性碳沿海拔梯度的变化

对鼎湖山3个不同海拔高度下的沟谷雨林(LA)、低地常绿阔叶林(MA)和山地常绿阔叶林(UA)的土壤活性碳库和惰性碳库进行了研究。结果表明:(1)土壤总碳库仅在30—45 cm土层中存在显著差异且碳库大小随着海拔的增加而增加。(2)土壤微生物生物量碳(MBC)碳库在0—15 cm是LA和MA显著大于UA,在30—45 cm是MA和UA显著高于LA,在45—60 cm土层中MA最大。水溶性碳(WSOC)和颗粒碳(POC)碳库均不随海拔高度而改变。WSOC碳库占总碳库的百分比仅在30—45cm土层中存在差异且大小顺序为:LAUAMA,POC碳库占总碳库的百分比仅在土层15—30 cm上存在显著差异且MA比值最大。易氧化性碳(ROC)碳库及占总碳库百分比都是在表层土壤(0—15 cm)中产生显著变化,且UA极显著地大于LA和MA。(3)惰性碳(RC)碳库仅在深层土壤中存在显著差异且MA中RC碳库最大,UA次之,LA最小。RC碳库占总碳库比值仅在表层土壤0—15 cm存在显著差异且UA最大。表层土壤中ROC碳库和RC碳库占总碳库百分比的增加是导致中高海拔森林土壤总碳库最大的主要原因。(4)不同海拔高度上森林土壤理化性质与土壤碳库组成存在显著相关,土壤理化性质的改变是引起不同海拔高度森林土壤碳库组成变化的重要原因。     

Production and metabolic engineering of bioactive substances in plant hairy root culture

In the past three decades, hairy roots research for the production of valuable biological active substances has received a lot of attention. The addition of knowledge to enhance the yields of desired substances and the development of novel tools for biomass engineering offer new possibilities for large-scale cultivation of the plant hairy root. Hairy roots can also produce recombinant proteins through the transfer of Agrobacterium T-DNA into the plant genome, and thereby hold immense potential for the pharmaceutical industry. This review highlights some of the significant progress made in the past few years and outlines future prospects for exploiting the potential utility of hairy root cultures as “chemical factories” for producing bioactive substances.     

淡水真菌活性代谢产物的研究进展

结合研究工作,综述了国内外有关淡水真菌次生代谢产物化学结构及其生物活性方面的研究概况,为进一步开发利用我国淡水真菌资源和寻找新药提供参考。     

Antifouling activity of bioactive substances extracted from Holothuria scabra

Methanol extract of Holothuria scabrawas tested for antifouling activity using `mollusc foot adherence bioassay'. It was found that the secondary metabolites of H. scabraeffectively prevented foot adherence of P. vulgataat various concentrations. Based on the present findings it could be inferred that the bioassay guided purification and fractionation may give forth potent novel antifouling compounds.     

Altitudinal changes in temperature responses of net photosynthesis and dark respiration in tropical bryophytes

Background and Aims

There is a conspicuous increase of poikilohydric organisms (mosses, liverworts and macrolichens) with altitude in the tropics. This study addresses the hypothesis that the lack of bryophytes in the lowlands is due to high-temperature effects on the carbon balance. In particular, it is tested experimentally whether temperature responses of CO₂-exchange rates would lead to higher respiratory carbon losses at night, relative to potential daily gains, in lowland compared with lower montane forests.

Methods

Gas-exchange measurements were used to determine water-, light-, CO₂- and temperature-response curves of net photosynthesis and dark respiration of 18 tropical bryophyte species from three altitudes (sea level, 500 m and 1200 m) in Panama.

Key Results

Optimum temperatures of net photosynthesis were closely related to mean temperatures in the habitats in which the species grew at the different altitudes. The ratio of dark respiration to net photosynthesis at mean ambient night and day temperatures did not, as expected, decrease with altitude. Water-, light- and CO₂-responses varied between species but not systematically with altitude.

Conclusions

Drivers other than temperature-dependent metabolic rates must be more important in explaining the altitudinal gradient in bryophyte abundance. This does not discard near-zero carbon balances as a major problem for lowland species, but the main effect of temperature probably lies in increasing evaporation rates, thus restricting the time available for photosynthetic carbon gain, rather than in increasing nightly respiration rates. Since optimum temperatures for photosynthesis were so fine tuned to habitat temperatures we analysed published temperature responses of bryophyte species worldwide and found the same pattern on the large scale as we found along the tropical mountain slope we studied.     

Isolation and purification of series bioactive components from Hypericum perforatum L. by counter-current chromatography

Counter-current chromatography (CCC) combined with pre-separation by ultrasonic solvent extraction was successively used for the separation of series bioactive compounds from the crude extract of Hypericum perforatum L. The petroleum ether extract was separated by the solvent system of n-heptane-methanol-acetonitrile (1.5:0.5:0.5, v/v) and n-heptane-methanol (1.5:1, v/v) in gradient elution, yielding a phloroglucinol compound, hyperforin with HPLC purity over 98%. The ethyl acetate extract was separated by using the solvent system composed of hexane-ethyl acetate-methanol-water (1:1:1:1 and 1:3:1:3, v/v) in gradient through both reverse phase and normal phase elution mode, yielding a naphthodianthrone compound, hypericin with HPLC purity about 95%. The n-butanol extract was separated with the solvent system composed of n-butanol-ethyl acetate-water (1:4:5 and 1.5:3.5:5, v/v) in elution and back-extrusion mode, yielding two of flavones, rutin and hyperoside, with HPLC purity over 95%. HPLC-MS, reference sample and UV spectrum were selectively used in separation to search for target compounds from HPLC-DAD profiles of different sub-extracts. The structures of isolated compounds were further identified by ESI-MS, 1HNMR and 13CNMR.     

Intraspecific DNA content variability in Festuca pallens on different geographical scales and ploidy levels

BACKGROUND AND AIMS: Intraspecific genome size variability of Festuca pallens occurring on relict rocky steppes in Central Europe was studied on two ploidy levels and three geographical scales: (1) local scale of 24 populations, (2) landscape scale of three transects in river canyons or hill systems, and (3) global scale of 160 samples covering the whole distribution area. METHODS: DAPI flow cytometry of homogeneously cultivated samples (>or=1 year), measured randomly with two internal standards, Lycopersicon esculentum and Pisum sativum. Differences in DNA content were confirmed (1) by the double peaks of simultaneously measured samples, (2) based on measurements carried out in different seasons, and (3) by additional measurements with propidium iodide. KEY RESULTS: On a global scale, the relative DNA content ranged between 1.170-fold in diploids and 1.164-fold in tetraploids. A maximum difference of 1.088-fold between the mean relative DNA content of nearby populations was found. In 16 of 24 populations significant variability was shown (P<0.001, 1.121-fold as maximum). For both ploidy levels, the relative genome size had the same range and geographical pattern, correlated with geographical coordinates (P<0.01). Diploids with larger genomes occur on relict habitats (P<0.01), and in areas of periglacial steppes (20,000 years ago; P<0.02). In tetraploids, the relative DNA content differs among the three previously recognized geographical types (Alpine, Pannonian and Scabrifolia, P<0.001). Tetraploids have a relative DNA content smaller than twice that of the diploids (P<0.001). An influence of microhabitat on DNA content variation was not confirmed. CONCLUSIONS: Genome size variability occurs over all spatial scales: intrapopulation, landscape and global. Correlation between geographical coordinates and palaeovegetation type, concomitant with diploids and tetraploids, and no influence of microhabitat were found. Genome size decreases in tetraploids. Lower CVs, and thus higher accuracy, resolution and reproducibility, favour DAPI measurements for the study of intraspecific genome size variability.     

Altitudinal changes in humus form dynamics in a spruce forest at the montane level

An altitudinal transect was studied at the montane level in a spruce forest, in order to describe changes in humus form dynamics. Whatever the elevation, the periodicity of humus form changes is copied on forest dynamics. Spruce regeneration is restricted both in space and time to favourable micro-site conditions accompanying tree fall gaps. One of these conditions is a shift from moder to mull humus form. As a result, this forest ecosystem shows a space-time mosaic pattern. The recovery of mull humus form takes more time as elevation increases and thus the ratio mull:moder progressively decreases. Simultaneously, burrowing earthworms become scarce. Nevertheless mull humus form does not change basically at increased elevation. On the other hand, moder has little organic matter at the lower montane level. At the mid montane level, accumulation of holorganic faeces into OH horizon is maximum. A mor-moder (few faunal traces) is observed during tree growth phase at the upper montane level. Lack of nutrient availability was hypothesized to explain the observed shift from mull to moder or mor-moder during the phase of intense tree growth. An increased independancy between the building of a moder humus profile and the actual accumulation of organic matter was the main change occurring with elevation. The transition to the subalpine level may thus be defined as the highest elevation up to which the forest ecosystem is able to reverse the mor-building process produced by tree growth. The discoupling between primary producers, plant debris accumulation and decomposers observed in the subalpine spruce forest leads to a breaking point in the carrying capability of humus for spruce seedlings. At high elevation spruce seedlings are mainly observed on rotten wood.The influence of humus form dynamics upon forest sustainability was discussed. The lack of humus biological activity at higher elevation was found to be a reason for the weakness of the forest ecosystem faced to the bilberry heath. Forest sustainability depends both on mull and moder. It was observed that moder failed to recover after mull along the forest cycle and turned to mor in harsh climate conditions. Consequences of management practices on the issue of competition between forest and heath were also discussed.     

Correlation between hypericin content and the ploidy of somaclones of Hypericum perforatum L.

An altered ploidy level was observed in plants regenerated by adventitious shoot formation from seedlings of Hypericum prformatum L. (2n = 4x = 32). Among the somaclones of the R_o generation, the presence of diploids (2n = 2x = 16), triraploids (2n = 3x = 24), tetraploids (2n = 4x = 32) and mixoploids was detected. Cytogenetic analyses of the R₁ and R₂ progenies showed that the chromosomal instability of the R_o somaclones was transferred onto the next generation. While almost all the seed progeny of diploids (100% in R¹ and 94% in R₂) progenies showed that the chromosomal instability of the R_o somaclones was transferred onto the next generations. While almost all the seed progeny of diploids (100% in R¹ and 94% in R²) and more than 60% of tetraploids (61% in R₁ and 73% in R₂) retained their chromosome number, cytogenetic diversity was observed in the progeny of triploids, mixoploids and some tetraploids. Somaclones and their offspring were analyzed for hypericin content. Statistical evaluation showed a correlation between hypericin content and ploidy during a two-year cultivation of R₀ somaclones and in their R₁ and R₂ progenies.