瑞香狼毒提取物对试验动物急性毒性及活性的初步研究

采用急性经口、眼刺激、皮肤试验方法,研究了瑞香狼毒乙酸乙酯萃取物的急性毒性作用,同时以番茄晚疫病菌为供试菌,研究了瑞香狼毒提取物的抑菌活性.初步研究表明,瑞香狼毒乙酸乙酯萃取物对小白鼠经口急性毒性为低毒,对白兔的急性皮肤刺激属无刺激性,对白兔的眼刺激属轻度刺激性,对鲫鱼的毒性属于中毒级;瑞香狼毒乙酸乙酯萃取物及其分段物流分B、c、D对番茄晚疫病菌有较好的抑制活性,这为瑞香狼毒乙酸乙酯萃取物进一步开发为产品提供了毒理学依据.     

瑞香狼毒根提取物对山楂叶螨的生物活性

采用不同的生物活性测定方法比较了瑞香狼毒(Stellera chamaejasme L.)根部4种不同溶剂提取物的杀螨活性。结果表明,瑞香狼毒根提取物对山楂叶螨(Tetranychus viennensis Zacher)有很好的触杀和内吸活性。在触杀活性测试中,石油醚提取物和氯仿提取物的杀螨活性最高;在内吸作用中,乙醇、氯仿和石油醚提取物的杀螨活性均较高,杀螨效果显著。在对石油醚提取物的不同溶剂萃取物进行生物活性追踪测定中发现,石油醚萃取物和氯仿萃取物具有较高的生物活性,浓度为0.6 g.L-1,山楂叶螨的24 h校正死亡率分别达到93.22%和79.66%。     

小桐子提取物除草活性的生物测定

为全面了解小桐子(Jatropha curcas L. )提取物的除草活性,以萝卜(Raphanus sativus L. )、苋(Amaranthus tricolor L. )、苏丹草[Sorghum sudanense (Piper) Stapf]和黑麦草(Lolium perenne L. )为实验材料,对小桐子果壳和枝叶的水、乙醇(体积分数95%)、正丁醇、乙酸乙酯、氯仿和石油醚粗提物的除草活性进行了生物测定,并从中筛选出抑制作用最强的水粗提物进行进一步的活性组分分离及其除草活性的生物测定.测定结果显示,小桐子果壳和枝叶的6种溶剂提取物(10 g·L~(-1))对供试的4种植物幼苗的根长和茎高均有不同程度的抑制作用,其中水粗提物和乙醇(体积分数95%)粗提物的抑制作用较强,且水粗提物对供试的4种植物幼苗的根长和茎高的抑制作用均在75%以上,显著高于其他溶剂粗提物(P<0.05);石油醚粗提物的抑制作用最小,均在10%以下.小桐子果壳和枝叶水粗提物的石油醚、氯仿、乙酸乙酯、正丁醇和水萃取物(10 g·L~(-1))对萝卜和苏丹草幼苗的根长和茎高均有不同程度的抑制作用,其中水、正丁醇和乙酸乙酯萃取物的抑制作用显著高于氯仿和石油醚萃取物,抑制率均在70%以上;水萃取物的抑制作用最强,抑制率均在80%以上;石油醚萃取物的抑制作用最小,抑制率均在10%以下.研究结果表明,小桐子果壳和枝叶的水粗提物具有一定的除草活性,其有效成分为极性较大的组分.     

山芝麻提取物对10种植物病原真菌的抑菌活性初探

该文采用菌丝生长速率法,研究了山芝麻根、茎和叶不同溶剂萃取物在1.5 mg·mL~(-1)浓度下对10种植物病原真菌菌丝生长的抑制活性,用孢子萌发法测试了山芝麻根石油醚相和乙酸乙酯相萃取物对香蕉炭疽病菌分生孢子萌发的抑制作用,用离体法测试了山芝麻根石油醚相和乙酸乙酯相萃取物对香蕉炭疽病的防治效果,并通过气相与质谱联用技术(Gas Chromatography-Mass Spectrometer,GC-MS)分析了山芝麻根石油醚相和乙酸乙酯相萃取物的主要成分,测试了其中8种主要化合物对香蕉炭疽病菌菌丝生长的抑制活性。结果表明:山芝麻各部分萃取相对10种植物病原真菌菌丝生长均具有不同程度的抑制作用。其中:在1.5 mg·mL~(-1)浓度下,山芝麻根石油醚相和乙酸乙酯相萃取物对香蕉炭疽病菌菌丝生长的抑制率分别为87.00%和86.14%,其EC50分别为0.062 mg·mL~(-1)和0.052 mg·mL~(-1);浓度在2、4、8 mg·mL~(-1)时,山芝麻根石油醚相和乙酸乙酯相萃取物对香蕉炭疽病菌分生孢子萌发相对抑制率均在70%以上;在10 mg·mL~(-1)浓度下,山芝麻根石油醚相和乙酸乙酯相萃取物对香蕉炭疽病的防治效果分别为72.32%和59.77%。通过气相与质谱联用技术对山芝麻根石油醚相和乙酸乙酯相萃取物进行了分析,在山芝麻根石油醚相萃取物中共鉴定出36种主要化学成分,在山芝麻根乙酸乙酯相萃取物中共鉴定出17种主要化学成分。对选取的8种主要化合物,在100μg·mL~(-1)浓度下,邻苯二甲酸二异丁酯和邻苯二甲酸二丁酯对香蕉炭疽病菌菌丝生长显现出较高的抑制活性,抑制率分别为65.12%和68.07%,EC_(50)分别为56.66μg·mL~(-1)和37.04μg·mL~(-1)。     

Leukamenin E调节拟南芥幼苗生长发育的模式及其机制

研究对映-贝壳杉烷型二萜化合物Leukamenin E对拟南芥种子萌发、下胚轴伸长以及根生长发育的作用模式,并探讨植物激素生长素和乙烯可能介导Leukamenin E影响拟南芥主根生长、侧根和根毛发育的初步机制。结果表明:Leukamenin E浓度在10~160μmol·L~(-1)范围对拟南芥种子的萌发率无显著影响,但高浓度Leukamenin E(80~160μmol·L-1)显著抑制种子的萌发速率。Leukamenin E对拟南芥幼苗根生长的抑制作用明显高于对下胚轴的抑制效应。进一步研究表明,Leukamenin E通过阻滞根尖细胞有丝分裂和细胞伸长进而抑制主根的生长,并能促进侧根提前发生并影响其形成数量,同时减少根毛密度及降低根毛长度。Leukamenin E联合乙烯利(乙烯释放剂)处理可阻止乙烯利单独使用对拟南芥幼苗根毛生长的促进作用,与Ag+(乙烯竞争抑制剂)联合乙烯利的作用效果相一致,表明Leukamenin E可能通过干扰根细胞乙烯途径而抑制根毛发育。流动注射化学发光分析和酶联免疫检测的结果发现,Leukamenin E显著上调拟南芥幼苗根组织中生长素(IAA)水平,表明生长素可能作为主要因子介导了Leukamenin E对拟南芥幼苗根生长发育的调节作用。     

泥胡菜等8种草本植物提取物除草活性的生物测定

采用顺序提取法制备了泥胡菜（Hemistepta lyrata Bunge）等8种草本植物全草的石油醚、乙酸乙酯和乙醇提取物,并以高粱（Sorghum vulgare Pers．）、黄瓜（Cucumis sativus L．）、小麦（Triticum aestivum L．）和油菜（Brassica campestris L．）为供试对象,用种子萌发法对提取物的除草活性进行了生物测定。结果表明,所有提取物对4种作物幼苗根和茎的生长均有一定的抑制作用,但抑制率有一定差异。泥胡菜和獯草[Humulus scandens（Lour．）Merr．]的乙酸乙酯提取物对作物幼苗根和茎的抑制作用最强,抑制率随提取物浓度的提高逐渐增高,且对作物幼苗根生长的抑制强度高于茎。在低浓度（12．5g·L^-1）条件下,泥胡菜乙酸乙酯提取物对小麦幼苗根和茎生长的抑制作用最强;蓓草乙酸乙酯提取物对高粱幼苗根的生长及油菜幼苗根和茎的生长抑制作用最强。研究结果显示,泥胡菜及蓰草的乙酸乙酯提取物具有潜在的除草活性。     

瑞香狼毒根的抑菌活性研究（Ⅰ）

以苹果干腐病菌、小麦赤霉病菌、番茄早疫病菌、南瓜枯萎病菌、玉米大斑病菌、烟草赤星病菌和辣椒疫霉病菌为供试菌,采用生物活性跟踪法、生长速率测定法和系统溶剂提取法对瑞香狼毒根中的杀菌活性物质进行了筛选和分离。结果表明,杀菌活性物质主要集中在乙酸乙酯提取物和甲醇粗提物中。从乙酸乙酯提取物中分离出两种杀菌活性物质AF1-4和AF1-5,同时还发现瑞香狼毒根中还存在增菌物质。     

大量元素胁迫下南瓜化感作用研究

研究采用水培实验、生物测试及室内分析相结合的方法,研究在不同大量元素(N、P、K、Ca、S、Mg)营养胁迫下幼苗期南瓜根系分泌物及其提取物对南瓜幼苗生长的化感作用。结果表明：南瓜具有自毒作用,不同大量营养元素胁迫对其胚根和胚芽生长均产生了抑制作用。不同的营养条件对其根系分泌物的影响不同,营养元素的合理搭配可以减轻自身的自毒作用。南瓜根系分泌物经乙酸乙酯提取的活性有机物埘南瓜胚根牛长亦表现出抑制作用,且抑制作用程度较大。南瓜幼苗期根系十物质水浸液巾存在着抑制南瓜幼苗生长的化感物质：筛选出南瓜根系分泌物对自身幼苗生长产生抑制作用最弱的大量元素水平优化组合,为南瓜的营养胁迫机理提供依据。     

瑞香狼毒地上部分化学成分的研究

采用多种色谱技术,对瑞香狼毒(Stellera chamaejasme L.)地上部分脂溶性部位的化学成分进行了研究,分离得到11种化合物,结合理化性质和波谱分析,其结构分别鉴定为:1-亚油酸-棕榈酸-甘油酯(1),亚麻酸(2),亚油酸(3),β-谷甾醇(4),亚麻酸乙酯(5),西瑞香素(6),异新狼毒素A(7),丙二酸单乙酯(8),伞形花内酯(9),新狼毒素B(10)和龙胆酸(11)。其中,化合物1、8和11为首次从该植物中分离得到。     

青藏高原有毒植物瑞香狼毒根抑菌活性初步研究

以人体病原细菌大肠杆菌、金黄色葡萄球菌、深部真菌白色念珠菌、浅部真菌红色毛癣菌、石膏样毛癣菌、石膏样小孢子菌、絮状表皮癣菌为供试菌,采用药敏纸片法对瑞香狼毒活性成分的抑菌活性进行了初步研究。结果表明瑞香狼毒对人体常见病原细菌和真菌有抑制作用,乙酸乙酯萃取物在33．33g／L浓度下对细菌组的抑菌圈直径最高可达12．02mm,对真菌组最高可达9．04mm,并初测瑞香狼毒中的抑菌活性物质主要为中偏强极性成分。     

Phytotoxicity mechanisms of two coumarin allelochemicals from <Emphasis Type="Italic">Stellera chamaejasme</Emphasis> in lettuce seedlings

Stellera chamaejasme, a perennial weed which is an ecological threat, is widely distributed in some grasslands of Central and Eastern Asia. Our previous studies have identified several allelochemicals including two coumarins (umbelliferone and daphnoretin), from S. chamaejasme, and confirmed that allelopathy contributed to the competitive behavior of this weed. In this study, the inhibitory effects of umbelliferone and daphnoretin on lettuce seedlings and the mechanisms of their phytotoxicity were investigated. Results showed that shoot and root elongation and fresh weight of lettuce seedlings were effectively inhibited by umbelliferone in a concentration-dependent manner. Daphnoretin showed a weaker phytotoxicity. Both of the coumarins arrested the mitosis process in lettuce root tips and induced proline overproduction. Additionally, loss of cell viability and overproduction of reactive oxygen species in lettuce root cells were found after treatments with umbelliferone. Moreover, umbelliferone caused lipid peroxidation. These results suggested that umbelliferone displayed stronger phytotoxicity than daphnoretin on lettuce growth, and that the two coumarins had different mechanisms of phytotoxicity. That of daphnoretin was mainly dependent on its inhibitory effects on mitosis. Umbelliferone caused membrane lipid peroxide formation and cell death by inducing ROS overproduction, and impacted cell division, which resulted in growth inhibition of the receptor plant.     

Phytotoxic lignans of Leucophyllum frutescens.

Bioassay-guided fractionation of the hexane:ethyl acetate (1:1) extract of the leaves of Leucophyllum frutescens (Berl.) I.M.Johnst (Scrophulariaceae) led to the isolation of its phytotoxic constituents diayangambin (1), epiyangambin (2), diasesartemin (3) and epiashantin (4). Phytotoxicity was demonstrated as inhibition of seed germination of Agrostis stolonifera cv. penncross (Poaceae) and inhibition of development of Lactuca sativa L. (Asteraceae) seedlings in a microassay using 24-well plates. Compound 1 was the most phytotoxic to L. sativa, showing strong inhibitory activity at 110 microM. Compound 1 was more active than 2 and 3 in inhibiting the growth of A. stolonifera with I(50) values of 160, 670 and 930 microM, respectively. At a concentration of 500 microM, these compounds inhibited all phases of onion root cell division. This is the first demonstration of antimitotic activity of these furofuran lignans, and the first report of their isolation from this species.     

Changes in root development of Arabidopsis promoted by organic matter from oxisols

The presence of ramified and abundant lateral roots is fundamental to plant growth on highly weathered soils. In this work, the effects of humic acid (HA), fulvic acid and hexanic–methanolic (HM) extract, after alkaline extraction from topsoil of seven different oxisols, on the development of roots of Arabidopsis thaliana was evaluated. Furthermore, we used another emergent plant model, that is, micro‐tom (MT) tomatoes with size similar to that of Arabidopsis to test the effects of HA. It was observed that both humic fractions and the HM extract were able to change the root development, improving the number of lateral roots and their development in comparison to control plants. The promotion of root growth by the three organic matter fractions was higher than that observed by 10^?6 mol L^?1 indole acetic acid. The treatment of MT tomato mutant, less sensitive to auxin, with HA did not promote the emergence of lateral roots, being an additional indication of auxin‐like activities of HA. However, some organic matter fractions exhibited, besides promotion of lateral roots number, increase in the length of principal root, which is not a typical auxin effect, indicating that these substances could contain other physiologically active substances.     

Inhibition of Rust Diseases of Cereals by Metabolic Products of Verticillium chlamydosporium

Verticillium chlamydosporium produced in submers culture several antifungal and/or phytotoxic compounds which were detected in a bioassay by using the pathogen-host system Puccinia coronata and oat seedlings. The antifungal compounds were also tested against P. recondita on wheat and P. sorghi on corn seedlings. The production of the active metabolic compounds highly depended on the nutrient solution (peptone-Czapek [PC] and malt extract [ME]) and on the fermentation times. Cell-free filtrates of PC-cultures of the fungus were highly phytotoxic; the fungitoxic and phytotoxic compounds were heat-labile and dialyzable. The ethyl acetate extracts of the PC-culture filtrates contained only the antifungal active substances. The antifungal compounds in ME-culture filtrates proved to be heat-stable, could be dialyzed and extracted with ethyl acetate. Ethyl acetate extracts of PC- and ME-culture filtrates at concentrations of 500 μg/ml reduced rust disease incidence by up to 80 % compared to the control treatment. Further studies with extracts of ME-culture filtrates displayed a distinct protective but no systemic activity. The extract interfered with the development of several infection structures of the rust fungi, mostly with the growth of germ tubes as well as with the formation of the aappressoria and haustorial mother cells. Three rust-active fractions were obtained by preparative layer chromatography on silica gel. One of these fractions exhibited phytotoxic activity. The most active antifungal fraction is identical with the macrolid antibiotic monorden which caused a desorientated spiral growth in P. coronata germlings on oat leaves.     

Isolation and identification of antitumor promoters from the seeds of Cassia tora

A methanol extract of Cassia tora seeds was successively partitioned with diethyl ether, chloroform, ethyl acetate, and water, and the antitumor-promoting activity of the solvent fractions was determined by inhibition of Epstein- Barr virus early antigen (EBV-EA) activation induced by teleocidin B-4 in Raji cells. The diethyl ether (68.7%) and chloroform (91.2%) fractions and the hydrolysate (94.3%) of the ethyl acetate fraction had strong inhibitory activities. The chloroform and ethyl acetate fractions were chromatographed on silica gel and further purified by HPLC. Three active compounds, obtusifolin-2-glucoside (75.0%), chryso-obtusin-6-glucoside (56.8%), and norrubrofusarin- 6-glucoside (39.4%), were obtained from the ethyl acetate fraction, and two active compounds, questin (97.9%) and chryso-obtusin (53.8%), were isolated from the chloroform fraction.     

<Emphasis Type="Italic">Artemisia arborescens</Emphasis> L. leaf litter: phytotoxic activity and phytochemical characterization

Artemisia arborescens L. is a perennial fast-growing Mediterranean shrub, which releases abundant leaf litter upon soil surface throughout the year. The paper aimed to both evaluate the phytotoxic potential and identify major compounds occurring in the plant leaf litter. Following methanolic maceration of the leaf litter, the crude extract was then sequentially extracted with hexane, chloroform and ethyl acetate through a bio-guided fractionation method. The phytotoxic potential of the methanolic extract and its solvent fractions was assessed in vitro on germination and root growth of two sensitive (Lactuca sativa L., Raphanus sativus L.) and native (Amaranthus retroflexus L., Cynodon dactylon (L.) Pers.) species. Moreover, the most active fractions were chemically characterized by GC–MS and HPTLC analysis. In all species, the physiological processes were highly inhibited by both the methanolic extract and its solvent fractions. Several classes of biologically active phytochemicals such as terpenoids, fatty acids, lignans and phenolic compounds were identified in all fractions. Artemisia arborescens leaf litter could be considered an important source of biologically active phytochemicals, which may have a significant allelopathic impact towards neighbouring species once released into the environment.     

Auxin-induced inhibition of lateral root initiation contributes to root system shaping in Arabidopsis thaliana

The hormone auxin is known to inhibit root elongation and to promote initiation of lateral roots. Here we report complex effects of auxin on lateral root initiation in roots showing reduced cell elongation after auxin treatment. In Arabidopsis thaliana, the promotion of lateral root initiation by indole-3-acetic acid (IAA) was reduced as the IAA concentration was increased in the nanomolar range, and IAA became inhibitory at 25 nM. Detection of this unexpected inhibitory effect required evaluation of root portions that had newly formed during treatment, separately from root portions that existed prior to treatment. Lateral root initiation was also reduced in the iaaM-OX Arabidopsis line, which has an endogenously increased IAA level. The ethylene signaling mutants ein2-5 and etr1-3, the auxin transport mutants aux1-7 and eir1/pin2, and the auxin perception/response mutant tir1-1 were resistant to the inhibitory effect of IAA on lateral root initiation, consistent with a requirement for intact ethylene signaling, auxin transport and auxin perception/response for this effect. The pericycle cell length was less dramatically reduced than cortical cell length, suggesting that a reduction in the pericycle cell number relative to the cortex could occur with the increase of the IAA level. Expression of the DR5:GUS auxin reporter was also less effectively induced, and the AXR3 auxin repressor protein was less effectively eliminated in such root portions, suggesting that decreased auxin responsiveness may accompany the inhibition. Our study highlights a connection between auxin-regulated inhibition of parent root elongation and a decrease in lateral root initiation. This may be required to regulate the spacing of lateral roots and optimize root architecture to environmental demands.     

Trypanocidal and antimicrobial activities of Moquinia kingii.

A chloroform crude extract (aerial part) and two compounds, apigenin (1) and cynaropicrin (2), isolated from Moquinia kingii were evaluated against Trypanosoma cruzi trypomastigotes in vitro. Antimicrobial activity was also screened using twenty-two strains including gram-positive and gram-negative bacteria and the yeasts Candida albicans and C. tropicalis. The chloroform crude extract, fractions and isolated compounds from M. kingii were active for both activities. The IC50 values for trypanocidal activity obtained for cynaropicrin and apigenin were 93.5 microg/ml and 181 microg/ml, respectively, while the minimum inhibitory concentrations (MICs) varied from 100 microg/ml to 2500 microg/ml, against the strains of bacteria and yeasts evaluated.     

A mutation in protein phosphatase 2A regulatory subunit A affects auxin transport in Arabidopsis.

The phytohormone auxin controls processes such as cell elongation, root hair development and root branching. Tropisms, growth curvatures triggered by gravity, light and touch, are also auxin-mediated responses. Auxin is synthesized in the shoot apex and transported through the stem, but the molecular mechanism of auxin transport is not well understood. Naphthylphthalamic acid (NPA) and other inhibitors of auxin transport block tropic curvature responses and inhibit root and shoot elongation. We have isolated a novel Arabidopsis thaliana mutant designated roots curl in NPA (rcn1). Mutant seedlings exhibit altered responses to NPA in root curling and hypocotyl elongation. Auxin efflux in mutant seedlings displays increased sensitivity to NPA. The rcn1 mutation was transferred-DNA (T-DNA) tagged and sequences flanking the T-DNA insert were cloned. Analysis of the RCN1 cDNA reveals that the T-DNA insertion disrupts a gene for the regulatory A subunit of protein phosphatase 2A (PP2A-A). The RCN1 gene rescues the rcn1 mutant phenotype and also complements the temperature-sensitive phenotype of the Saccharomyces cerevisiae PP2A-A mutation, tpd3-1. These data implicate protein phosphatase 2A in the regulation of auxin transport in Arabidopsis.     

SIZ1 regulation of phosphate starvation-induced root architecture remodeling involves the control of auxin accumulation

Phosphate (Pi) limitation causes plants to modulate the architecture of their root systems to facilitate the acquisition of Pi. Previously, we reported that the Arabidopsis (Arabidopsis thaliana) SUMO E3 ligase SIZ1 regulates root architecture remodeling in response to Pi limitation; namely, the siz1 mutations cause the inhibition of primary root (PR) elongation and the promotion of lateral root (LR) formation. Here, we present evidence that SIZ1 is involved in the negative regulation of auxin patterning to modulate root system architecture in response to Pi starvation. The siz1 mutations caused greater PR growth inhibition and LR development of seedlings in response to Pi limitation. Similar root phenotypes occurred if Pi-deficient wild-type seedlings were supplemented with auxin. N-1-Naphthylphthalamic acid, an inhibitor of auxin efflux activity, reduced the Pi starvation-induced LR root formation of siz1 seedlings to a level equivalent to that seen in the wild type. Monitoring of the auxin-responsive reporter DR5::uidA indicated that auxin accumulates in PR tips at early stages of the Pi starvation response. Subsequently, DR5::uidA expression was observed in the LR primordia, which was associated with LR elongation. The time-sequential patterning of DR5::uidA expression occurred earlier in the roots of siz1 as compared with the wild type. In addition, microarray analysis revealed that several other auxin-responsive genes, including genes involved in cell wall loosening and biosynthesis, were up-regulated in siz1 relative to wild-type seedlings in response to Pi starvation. Together, these results suggest that SIZ1 negatively regulates Pi starvation-induced root architecture remodeling through the control of auxin patterning.