漆树木材中漆黄素的分离及其抑制酪氨酸酶活性的研究

采用体积分数70%乙醇水溶液对漆树木材进行减压回流提取,经过乙酸乙酯萃取和中低压色谱快速分离得到纯度70%以上的化合物,并进一步采用高效液相色谱纯化,分离得到单体化合物。经过IR、MS和NMR鉴定,化合物为漆黄素。进一步研究了漆黄素对酪氨酸酶活性的抑制作用。结果表明,漆黄素对多巴色素的形成有较强的抑制作用,对酪氨酸酶单酚酶的半数抑制浓度(IC50)为69.46 mg/L。对酪氨酸酶单酚酶的抑制表现出迟滞效应,0.524 mmol/L的漆黄素能将迟滞效应由1 min延长至11.2 min。通过Lineweaver-Burk图显示漆黄素对二酚酶的抑制作用表现为竞争性抑制。     

巨尾桉树皮总多酚的提取分离及其生物活性研究

以巨尾桉树皮为原料提取按树皮中的总多酚,通过正交试验优化了酶处理与超声波辅助联合提取法及超声波辅助提取法的工艺条件,并对抗氧化活性较强的乙酸乙酯萃取物进一步分离,通过大孔吸附树脂分离纯化制备得到11个活性组分(Fr.1~Fr.11)及1个活性单体化合物(Pu1),同时对其进行了体外抗氧化活性实验,并对Pu1进行了结构表征。研究结果表明:超声波辅助提取法的最佳工艺条件为60%乙醇、提取温度60℃、超声波作用时间50 min、料液比为1∶12(g∶mL),总多酚得率为5.12%。酶处理与超声波辅助联合提取法中最佳酶处理工艺条件为:酶溶液质量浓度0.15 g/L、酶解温度50℃、酶解时间50 min、酶溶液pH值5.0,在此基础上再经超声波辅助提取,总多酚得率为6.23%。乙酸乙酯萃取物的分离活性组分中Fr.5、Fr.6、Fr.7和Fr.8在质量浓度为24 mg/L时对DPPH·清除率大于60%,具有较好抗氧化能力,Pu1的半数抑制质量浓度(IC_(50))值为8.99 mg/L,小于对照样Vc的IC_(50)值(10.46 mg/L),说明Pu1具有显著的体外抗氧化活性。活性组分的总多酚含量与其抗氧化活性有很好的相关性(R=0.944 8,P0.000 1)。通过UV、FT-IR、MS和NMR等分析表明:化合物Pu1的相对分子质量为498,分子式为C21H_22O14,确定化合物Pu1为2'-甲氧基-六羟基联苯二酸-4-O-α-L-鼠李糖苷。     

东北红豆杉枝叶总黄酮超声波辅助提取及其抗氧化活性

以东北红豆杉枝叶为原料,采用超声波辅助法提取红豆杉中总黄酮,在单因素试验基础上采用响应面法优化了提取工艺条件。结果表明:在乙醇体积分数60%,提取温度64℃,提取时间60 min,液料比14∶1(m L∶g),超声波功率168 W的最佳工艺条件下提取1次,总黄酮得率可达4.48%(提取率为69.14%)。东北红豆杉总黄酮粗提物经不同溶剂萃取后,在质量浓度0.01~0.20g/L范围内,不同萃取物的抗氧化能力与质量浓度均呈良好量效关系。乙酸乙酯萃取物具有较强的1,1-二苯基-2-苦肼基自由基(DPPH·)清除能力,其半数抑制质量浓度(IC_(50))值0.018 g/L,与Vc(0.012 g/L)相近。乙酸乙酯萃取物经大孔树脂AB-8纯化后得到16个组分,各组分的总黄酮含量与其DPPH·清除能力具有良好的相关性,相关系数(R)为0.958 1,显著性水平P0.000 1。     

黄连木叶的多酚提取和抗氧化研究

以黄连木叶为原料,比较了不同溶剂以及超声和微波辅助对多酚提取率的影响,在单因素实验的基础上采用正交实验对多酚提取工艺参数进行了优化。结果显示最佳提取条件为乙醇50%、超声时间20 min、提取温度70℃、料液比1∶20,多酚得率15.39%。滤液经乙酸乙酯萃取,减压蒸馏,低温干燥成粉末,多酚纯度达到78.96%。用DPPH清除法对提取物的自由基清除作用进行测定,其体外抗氧化活性高于维生素C(Vc),与纯度为98%的茶多酚相当。     

棕榈花苞抗氧化成分提取及体外抗氧化活性研究

为研究棕榈花苞中抗氧化成分的最佳提取工艺及体外抗氧化活性,在单因素试验的基础上,选取乙醇体积分数、液料比和提取时间为考察因素,以DPPH·自由基清除率和ABTS·+自由基阳离子清除率等抗氧化能力指标为衡量指标,采用Box-Behnken试验设计来优化提取工艺。在最佳提取工艺下得到提取物,测定其多酚和黄酮的含量,并以多项抗氧化指标综合评价其体外抗氧化能力。结果表明:当乙醇体积分数78%,液料比28∶1(m L∶g),提取时间64 min,提取温度80℃时,棕榈花苞提取物DPPH·清除率为92.05%,ABTS·+清除率为63.82%,提取物中总酚含量4.72%,得率为15.08 mg/g;总黄酮含量3.63%,得率为11.67 mg/g。本试验条件下每100 g棕榈花苞(以干质量计)的体外抗氧化能力相当于2 990~6 262 mg Vc,棕榈花苞的体外抗氧化能力IC50为0.115~5.795 mg/m L,具备一定的抗氧化能力。     

马缨丹提取物对黄胸散白蚁体内酶活性的影响

【目的】探究马缨丹氯仿提取物、乙酸乙酯和石油醚萃取物对黄胸散白蚁体内纤维素酶系及解毒酶系活性的影响,初步探讨其作用机制。【方法】采用滤纸片带毒饲喂,测定处理不同时间点其对黄胸散白蚁体内3种纤维素酶[内切-β-1,4-葡萄糖酶(EG)、外切-β-1,4-葡萄糖酶(CBH)、β-葡萄糖苷酶(BG)]和3种解毒酶[羧酸酯酶(Car E)、谷胱甘肽S-转移酶(GSTs)、多功能氧化酶(MFO)]酶活性的影响。【结果】马缨丹氯仿提取物、乙酸乙酯和石油醚萃取物在6~72 h对黄胸散白蚁体内6种酶活性的影响存在差异,主要表现为有一定的抑制作用。对3种纤维素酶活性的影响而言,氯仿提取物对EG酶活性无显著影响,但对CBH和BG酶有显著的抑制作用,尤其对CBH酶抑制作用较强,在72 h时抑制率最大,达17.61%;乙酸乙酯萃取物对3种酶均有抑制作用,对EG和BG酶活性抑制作用较强,在48 h时对EG的抑制率最大,为27.18%,在24 h时对BG酶活性抑制作用最大,为29.28%;石油醚萃取物对CBH酶活性无显著影响,但对其他2种酶抑制作用显著,对EG酶的抑制作用较强,在72 h时对此酶的抑制作用最大,为39.89%。对3种解毒酶活性影响而言,3种提取物对Car E酶的活性影响不大;对GSTs酶的影响主要在12~48 h,其中乙酸乙酯萃取物的抑制作用最强,36 h时抑制率最大,为39.54%;对FMO酶的抑制作用呈波动式变化,其中以12 h、36 h抑制作用较强。【结论】马缨丹氯仿提取物、乙酸乙酯和石油醚萃取物能抑制黄胸散白蚁体内的纤维素酶和解毒酶,扰乱其正常的生理代谢功能。     

青钱柳叶提取物对Caco-2细胞二糖酶活性的抑制作用

采用Caco-2细胞模型,分析了青钱柳Cyclocarya paliurus叶水提物、醇提后的水提物、95%醇提物、乙酸乙酯萃取物和正丁醇萃取物5种不同提取物对Caco-2细胞活力的影响及对Caco-2细胞上麦芽糖酶、蔗糖酶、乳糖酶3种二糖酶活性的抑制作用。结果表明,5种不同提取物中除95%醇提物对Caco-2细胞活力产生一定影响外,其余4种提取物对Caco-2细胞基本无毒性,在200 mg·L^-1浓度提取物范围内培养24～72 h后细胞仍能保持较高活力;对3种二糖酶活性抑制作用效果最好的为醇提后的水提物,尤其是对蔗糖酶和乳糖酶的抑制作用更为明显,最高的抑制率分别达到76.35%和60.13%,其次为乙酸乙酯萃取物,对乳糖酶的抑制率最高达54.41%。从青钱柳叶不同方法提取物的制备流程说明多糖类或中等极性的黄酮甙类有可能是青钱柳叶中抑制二糖酶活性的主要组成成分。     

红豆杉枝叶中总生物碱的提取及其抗肿瘤活性研究

以红豆杉枝叶为原料,通过单因素试验和响应面法优化了红豆杉枝叶中总生物碱的酶与超声波辅助耦合提取工艺,并对粗总生物碱进行了体外抗肿瘤活性实验。研究结果表明:酶与超声波辅助耦合提取总生物碱的最佳工艺条件为原料量3.00 g,pH值为3的19%乙醇溶液作溶剂、酶质量浓度0.10 g/L、液料比12∶1(mL∶g)、酶解时间52 min、酶解温度50℃和超声波功率150 W,在此条件下提取1次的总生物碱得率为0.126%。响应面模型显著性检验发现模型的P0.000 1,表明差异极显著,回归方程有效,模型具有统计学意义。粗总生物碱萃取物的体外抗肿瘤活性结果表明:红豆杉枝叶粗总生物碱萃取物对3种肿瘤细胞都有较好的抑制作用,特别是对人宫颈癌(Hela)细胞的抑制活性最强,其半数抑制浓度(IC_(50))值为22.18 mg/L,抑制效果与阳性对照依托泊苷相当(IC_(50)值为21.2 mg/L);其次对人乳腺癌(MCF7)细胞的抑制活性较强,其IC_(50)值为74.95 mg/L;而对人肝癌(HepG2)细胞有一定的抑制活性,其IC_(50)值为146.03 mg/L。     

神秘果叶多酚的超声波提取工艺及其抗氧化能力

利用响应面法找出超声波提取神秘果叶多酚的最佳提取工艺,并考察其抗氧化性。在单因素试验的基础上,建立神秘果叶多酚的二次多项数学模型,1.0 g神秘果叶粉末,在液料比30∶1(mL∶g)条件下,所得到最优提取工艺条件为:丙酮体积分数58%、超声波时间72 min、提取温度48℃,实测得率为6.84%,与预测值(6.82%)基本相符。神秘果叶多酚对ABTS、DPPH和·OH自由基的清除作用均呈现量效关系,半数抑制浓度(IC50)值分别为51.81、13.40和28.91 mg/L,表明神秘果叶多酚具有较强的抗氧化能力。     

盐肤木叶多酚提取及抗氧化活性初探

比较了热浸提、超声波辅助提取、微波辅助提取3种方法和水、乙醇、甲醇、丙酮4种不同溶剂对盐肤木叶多酚提取的影响.选择乙醇溶液和热浸提作为基本提取方法,在单因素试验基础上进行正交试验对提取工艺进行优化,结果显示盐肤木叶多酚的最佳提取条件是料液比1∶15(g∶mL),提取时间60 min,提取温度60℃,乙醇体积分数60％.提取的粗多酚溶液离心后直接干燥得到粗多酚粉末或经过乙酸乙酯萃取分离,烘干分别得到乙酸乙酯相干粉和水相粗多酚干粉,接着对获得的粗提物进行了多酚纯度测定和抗氧化等生物学功能检测.结果显示,3种粗多酚纯度分别为:直接干燥的37.53％,水相的为19.26％,乙酸乙酯相的为59.44％.提取物体外清除DPPH自由基能力大于维生素C,略小于商品化茶多酚.     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Growth of Mixed Birch-Coniferous Stands in Relation to Pure Coniferous Stands at Similar Sites in South-eastern Norway

Mean age, mean and top heights and yield were studied in 20 mixed stands of birch ( Betula pubescens Ehrh. and B. pendula Roth) and Picea abies (L.) Karst. and nine mixed stands of birch and Pinus sylvestris L. in south-eastern Norway. Each mixed stand and the adjacent pure coniferous stand (control) were growing under the same site conditions and had not been commercially thinned. There were no significant differences in mean age at breast height or in top heights between birch and conifers in the mixed stands, while mean height was significantly higher for birch than for spruce. A growth index was calculated based on total volume and age at breast height. For the spruce sites the growth in young mixed stands (birch < 17 m) was superior to that of pure spruce, while the difference was insignificant in older stands. The growth index correlated positively with the ratio between generatively and vegetatively regenerated birch trees, and negatively with the age of the oldest species in the mixture and with site quality. For the pine sites there was no significant difference in the growth index between mixed birch-pine and pure pine stands. A mixture effect of birch on the volume yield of spruce or pine could not be demonstrated.     

Defoliation by the Needle-shortening Pine Gall Midge,Thecodiplosis brachyntera,on Pines in Central Sweden

An outbreak of the needle-shortening pine gall midge, Thecodiplosis brachyntera , occurred on Scots pine, Pinus sylvestris (L.) and lodgepole pine, P. contorta (Dougl.) in central Sweden during 1995-1998. The larval feeding of T. brachyntera kills current-year needles and heavy infestation causes severe defoliation. A pattern of fluctuating defoliation among years and sites was found on both pine species. Defoliation was evenly distributed in the crown of P. sylvestris during years of high as well as low infestation; apical whorls had as much defoliation as basal whorls. In P. contorta , however, there was a tendency for defoliation to be concentrated on branches in the most apical whorls. Growth ring increments on P. sylvestris with high levels of defoliation (71%) did not differ from trees with moderate levels (26%) of defoliation. Shoot lengths were significantly shorter, however, on heavily infested trees the year after defoliation.