三种药用植物内生真菌抗真菌活性的研究

从雪上一枝蒿(Aconitumbrachypodum)、刺五加(Acanthopanaxsenticosus)和大血藤(Sargentodoxacuneata)分离获得的162株内生真菌进行抗真菌活性检测,结果具有抗菌活性菌株有74株,雪上一枝蒿15株,刺五加23株,大血藤36株,分别占3种植物各自内生真菌的44.12%,48.94%和44.44%。将具有抗菌活性的菌株进行分类鉴定,分属于6目、7科、23属。     

三种水生植物内生真菌多样性及其抗真菌活性

从华凤仙(Impatiens chinensis L.)、问荆(Equisetum arvense L.)和轮叶狐尾藻(Myriophyllum verticillatum L.) 3种植物中共分离到内生真菌155株。经鉴定, 它们分属于26个不同的分类单元。以杨桃炭疽菌(Colletotrichum gloeosporioides)、香蕉疫霉(Phytophthora nicotianae)和腐皮镰刀菌(Fusarium solani)等6种植物病原真菌为指示菌, 对3种水生植物内生真菌代谢产物进行抗菌活性研究。结果表明, 有37株内生真菌(占分离菌株总数的23.9%)显示出对一种或多种病原菌的抑菌活性。来自华凤仙、问荆和轮叶狐尾藻的抗菌活性菌株比例分别为29.2%、13.9%及37.1%, 都远低于已报道的陆生植物内生真菌中活性菌株的比例。抗菌活性菌株主要分布于枝孢属(Cladosporium)、木霉属(Trichoderma)和地霉属(Geotrichum)等5个属中。     

川乌植物内生真菌抗菌活性的研究

从川乌（Radix aconiti）植物的根和茎中分离获得内生真菌61株,经显微形态观察进行内生真菌的分类鉴定,同时采用纸片法进行抗菌活性筛选。结果有29株内生真菌显示抗菌活性,占菌株数的47．54％;毛壳菌属是抗菌活性菌株的优势种属;活性高且抗菌谱广的菌株有3株,主要分布在毛壳菌属和束丝菌属。结果表明：川乌植物内生真菌中广泛分布着有抗菌活性的菌株。     

元江印楝植物内生真菌及其抗菌活性筛选的研究

通过抗菌活性初步筛选,从采自云南元江县的印楝(Azadirachta indica A.Juss)植物茎和果实中已分离到的372株内生真菌中筛选出80株作为复筛菌株,经显微形态特征观察鉴定为5目、6科、29个属。选择16种病原微生物作为指示菌检测复筛菌株发酵产物的抗菌活性,结果表明,其中29株内生真菌对细菌、植物病原真菌和皮肤致病真菌中的一种或多种病原微生物有抑制生长作用,活性菌株比例占复筛菌株的36.25%,并显示种群多样性,其中7株内生真菌显示较强的广谱抗菌作用,活性较好的菌株主要分布在曲霉属和交链孢属。     

中国新疆柳叶藓科、青藓科和灰藓科植物区系研究

通过对新疆柳叶藓科(Amblystegiaceae)、青藓科(Brachytheciaceae)和灰藓科(Hypnaceae)植物标本的野外采集和室内鉴定,报道了中国新疆地区柳叶藓科15属33种,青藓科12属51种,灰藓科11属30种,共计38属114种。其中,中国青藓科新记录种2种,新疆新记录4属37种。优势属10个,且以青藓属(Brachythecium BrushSchimp.)为代表的北温带成分为主;单种属19个,体现了新疆藓类植物区系的古老性和多样性。新疆3科藓类植物区系成分可划分为9种类型,其中北温带成分居主导地位,占中国新疆3科藓类植物总种数的52.08%,东亚成分次之,占25.01%,热带成分甚微。对中国新疆与中国内蒙古、中国西藏以及俄罗斯、蒙古、哈萨克斯坦、巴基斯坦和印度7个邻近地区的区系比较发现,印度物种丰富度最高,俄罗斯和中国新疆次之;中国新疆与中国内蒙古、俄罗斯在物种组成上相似度最高。地理成分区系谱及聚类分析结果表明,中国新疆与中国内蒙古地区的植物区系关系最为接近,而且与俄罗斯密切相关。     

新疆野核桃自然保护区植物区系和地理成分

根据野外实地调查,采集植物标本鉴定,借鉴文献资料,对新疆野核桃自然保护区植物进行了植物区系和地理成分分析。研究表明:自然保护区内共有植物56科182属329种,其中蕨类植物6科7属17种,裸子植物3科4属9种,被子植物47科171属303种。平均种密度27.88种·km-2。菊科、蔷薇科、禾本科等14科为优势科,毛茛科、豆科、紫草科等8科为表征科;优势属和表征属分别为17属和5属。保护区植物不存在真正意义上的单种科,但有6个单种属。中国特有属1属(鸦葱属),中国特有种14种,其中新疆特有种9种。在地理成分中温带分布型有14科140属299种,分别占(不含广布型)科、属、种总数的60.87%、94.59%和96.78%;保护区植物与中亚、地中海交流较多,与热带和东亚交流较少,具有强烈的温带性质。     

巴音布鲁克大尤尔都斯盆地野生种子植物区系研究

基于野外实地调查,采集植物标本鉴定并结合相关文献资料整理,构建新疆巴音布鲁克大尤尔都斯盆地野生种子植物名录,在此基础上对该地区野生种子植物区系进行研究.结果表明:(1)巴音布鲁克大尤尔都斯盆地共有野生种子植物60科261属770种.(2)优势科有禾本科、菊科、豆科、石竹科、蔷薇科、十字花科、莎草科、毛茛科等11个科,表征科有豆科、龙胆科、石竹科、禾本科4个科.(3)区系地理成分以温带分布型为主,其中在科级水平上,温带分布型所属科共有30科,占到总科数(不含世界广布科)的88.24％;在属级水平上,温带性质分布型的属有220属,占总属数(不含世界广布属)的97.78％;同时该地区植物物种与地中海、中亚、西亚交流相对较多,而与东亚和热带交流很少.(1)本地区无中国特有属,但有中国特有种55个,其中新疆特有种32个.     

红树植物内生真菌的分离鉴定及抗菌活性菌株的筛选

本文对厦门集美红树植物无瓣海桑(Sonneratia apetala),海马齿(Sesuvium portulacastrum)和秋茄(Kan-delia candel)的多个部位进行内生真菌的分离和形态鉴定,并采用菌饼法对分离到的内生真菌进行抗菌活性筛选。结果显示,从3种红树植物的根、茎、叶中分离得到25株内生真菌,分别隶属8个类群,以链格孢属和曲霉属为主,分别占菌株总数的28.0%和24.0%;有19株菌株对至少一种指示菌有抑制作用,占菌株总数的76.0%。研究结果表明,红树植物来源的内生真菌数量多,种属丰富,同时具有良好的抗菌活性,是研究抗菌活性化合物的重要资源。     

云南重楼植物内生真菌的分离及抗菌活性筛选

从云南重楼[Paris polyphylla Smithvar.yunnnanensis(Franch.)Hand.Mazz.]块状茎中分离出166株内生真菌,对其进行形态分类鉴定归于4目,6科,20个属,体现了云南重楼植物内生真菌的生物多样性特征。同时,选择与人类和植物相关的37株病原微生物作为抗菌活性筛选指示菌,进行了云南重楼植物内生真菌抗菌活性的初步研究。结果表明,4株内生真菌对细菌、植物致病真菌、皮肤致病真菌多种病原微生物具有显著抑制生长的作用。     

虎杖内生真菌的分离及产抗菌活性物质的筛选

从植物虎杖(Polygonum cuspidatum Sieb.et Zucc.)的根状茎中分离出24株内生真菌,分别对其液体发酵液进行抗菌活性检测,结果筛选出3株内生真菌具有抗菌活性,它们分别属于曲霉属、青霉属和无孢菌类。     

Antimicrobial Peptides from Plants

Peptides with antimicrobial properties are present in most if not all plant species. All plant antimicrobial peptides isolated so far contain even numbers of cysteines (4, 6, or 8), which are all pairwise connected by disulfide bridges, thus providing high stability to the peptides. Based on homologies at the primary structure level, plant antimicrobial peptides can be classified into distinct families including thionins, plant defensins, lipid transfer proteins, and he vein- and knottin-type antimicrobial peptides. Detailed three-dimensional structure information has been obtained for one or more members of these peptide families. All antimicrobial peptides studied thus far appear to exert their antimicrobial effect at the level of the plasma membrane of the target microorganism, but the different peptide types are likely to act via different mechanisms. Antimicrobial peptides can occur in all plant organs. In unstressed organs, antimicrobial peptides are usually most abundant in the outer cell layer lining the organ, which is consistent with a role for the antimicrobial peptides in constitutive host defense against microbial invaders attacking from the outside. Thionins are predominantly located intracellularly but are also found in the extracellular space, whereas most plant defensins and lipid transfer proteins are deposited exclusively in the extracellular space. In a number of plant species, a strong induction of genes expressing either thionins, plant defensins, or lipid transfer proteins has been observed on infection of the leaves by microbial pathogens. Hence, antimicrobial peptides can also take part in the inducible defense response of plants. Constitutive expression in transgenic plants of heterologous antimicrobial peptide genes has been achieved, which in some cases has led to enhanced resistance to particular microbial plant pathogens.     

Plant antimicrobial peptides

Plant antimicrobial peptides (AMPs) are a component of barrier defense system of plants. They have been isolated from roots, seeds, flowers, stems, and leaves of a wide variety of species and have activities towards phytopathogens, as well as against bacteria pathogenic to humans. Thus, plant AMPs are considered as promising antibiotic compounds with important biotechnological applications. Plant AMPs are grouped into several families and share general features such as positive charge, the presence of disulfide bonds (which stabilize the structure), and the mechanism of action targeting outer membrane structures.     

Novel chemistry of invasive exotic plants

Of the many exotic plants that have become naturalized in North America, only a small proportion are pests capable of invading and dominating intact natural communities. In the present study, we tested the hypothesis that the most invasive plants are phytochemically unique in their new habitats. A comparison of exotic plant species that are highly invasive in North America with exotics that are widespread, but non-invasive revealed that the invasive plants were more likely to have potent secondary compounds that have not been reported from North American native plants. On average, the compounds found in the invasive plants were reported from fewer species, fewer genera and fewer families than those from non-invasive plants. Many of the unique phytochemicals from invasive plants have been reported to have multiple activities, including antiherbivore, antifungal, antimicrobial and allelopathic (phytotoxic) effects, which may provide the plants with several advantages in their new environments.     

Antibacterial plant compounds,extracts and essential oils: An updated review on their effects and putative mechanisms of action

Background: Antibiotic-resistant bacteria pose a global health threat. Traditional antibiotics can lose their effectiveness, and the development of novel effective antimicrobials has become a priority in recent years. In this area, plants represent an invaluable source of antimicrobial compounds with vast therapeutic potential.Purpose: To review the full possible spectrum of plant antimicrobial agents (plant compounds, extracts and essential oils) discovered from 2016 to 2021 and their potential to decrease bacterial resistance. Their activities against bacteria, with special emphasis on multidrug resistant bacteria, mechanisms of action, possible combinations with traditional antibiotics, roles in current medicine and future perspectives are discussed.Methods: Studies focusing on the antimicrobial activity of compounds of plant origin and their mechanism of action against bacteria were identified and summarized, including contributions from January 2016 until January 2021. Articles were extracted from the Medline database using PubMed search engine with relevant keywords and operators.Results: The search yielded 11,689 articles from 149 countries, of which 101 articles were included in this review. Reports from 41 phytochemicals belonging to 20 families were included. Reports from plant extracts and essential oils from 39 plant species belonging to 17 families were also included. Polyphenols and terpenes were the most active phytochemicals studied, either alone or as a part of plant extracts or essential oils. Plasma membrane disruption was the most common mechanism of antimicrobial action. Number and position of phenolic hydroxyl groups, double bonds, delocalized electrons and conjugation with sugars in the case of flavonoids seemed to be crucial for antimicrobial capacity. Combinations of phytochemicals with beta-lactam antibiotics were the most studied, and the inhibition of efflux pumps was the most common synergistic mechanism.Conclusion: In recent years, terpenes, flavones, flavonols and some alkaloids and phenylpropanoids, either isolated or as a part of extracts, have shown promising antimicrobial activity, being membrane disruption their most common mechanism. However, their utilization as appropriate antimicrobials need to be boosted by means of new omics technologies and network pharmacology to find the most effective combinations among them or in combination with antibiotics.     

蜘蛛抱蛋属植物内生细菌的多样性及其抗菌活性筛选

【背景】药用植物中蕴含多样性丰富的内生菌资源,这些微生物产生的多种新型物质在制药领域表现出较好的应用前景。【目的】研究蜘蛛抱蛋属(Aspidistra Ker-Gawl.)植物内生细菌的多样性,探索药用植物内生细菌在药用活性产物方面的开发潜力,以期发现具有抗菌活性的次级代谢产物。【方法】对9种13株新鲜的蜘蛛抱蛋植物进行表面消毒,采用5种分离培养基分离内生细菌;根据菌落形态特征排除重复菌株,并测定其16S rRNA基因序列,构建系统进化树分析内生细菌多样性;将菌株分别用2种培养基发酵,使用耻垢分枝杆菌(Mycobacterium smegmatis ATCC 700044)、水稻白叶枯菌(Xanthomonas oryzae PXO99A)、白色念珠菌(Candidaalbicans ATCC 10231)、肺炎雷伯菌(Klebsiella pneumoniae ATCC 700603)和耐药粪肠球菌HH22(Enterococcus faecalis HH22)5种检定菌对分离菌株的发酵液进行抑菌活性筛选。【结果】从植物组织中分离得到了234株内生细菌,根据形态初步排重得到156株植物内生细菌;基于16S rRNA基因序列构建的系统进化树显示它们分属于3门10目22科29属,其中链霉菌属(Streptomyces)、芽孢杆菌属(Bacillus)、微杆菌属(Microbacterium)、类芽孢杆菌属(Paenibacillus)和根瘤菌属(Rhizobium)的菌株广泛地分布在不同种的蜘蛛抱蛋植株中,且占据一定优势;发现可能的潜在新分类单元6个;156株内生细菌中38株菌的发酵液具有抑菌活性,初筛阳性率为23.7%。【结论】蜘蛛抱蛋植物组织中含有种类多样的内生细菌,它们可能是抗菌生物活性次级代谢产物的有效来源。     

灯台树内生放线菌多样性及抗菌活性评价

从云南西双版纳采集7份灯台树样品,经过表面消毒,用4种分离培养基分离得到105株内生放线菌。经16S rRNA基因序列分析鉴定,分布于7个科9个属。利用5种植物病原真菌指示菌对所有菌株的发酵液进行抗菌活性检测。结果显示,有12.4%、14.3%、11.4%、12.4%、8.6%的菌株分别对镰刀霉、疫霉、赤星霉、苹果炭疽、白色念珠菌有抗性。对3株具有广谱抗菌活性的菌株进行再次发酵和抗菌活性复筛,结果显示这3株的抗菌活性稳定,并可能含有生物碱类化合物。     

Death by proteases in plants: whodunit

Several studies have shown that protease inhibitors can suppress programmed cell death in various plant species and plant tissues. This is especially true of caspase inhibitors that can block programmed cell death and its marker DNA laddering. There are up to six different caspase-like activities that can be measured in plant extracts, the most prominent being caspase1-like and caspase3-like. These activities can be located in vacuoles and also in the nucleus or the cytoplasm. This represents a striking apparent similarity with animal programmed cell death. Because there are no caspase orthologue in plant genomes, a major challenge is to identify these proteases. Recently two proteases with caspase-like activities have been recognized as belonging to two different protease families that are not closely related to animal caspases. Various other protease families have been implicated and this suggests that complex protease networks have been recruited for the plant cell demise.     

Human antimicrobial peptides: analysis and application

Antimicrobial peptides are innate host defense molecules that have a direct effect on bacteria, fungi and enveloped viruses. They are found in evolutionarily diverse species ranging from prokaryotes and plants to invertebrate and vertebrate animals. Humans express several families of antimicrobial peptides in myeloid cells and on various epithelial surfaces where they are poised to defend against pathogens. Recently, antimicrobial peptides from animals and plants have served as templates for the design of new therapeutic antibiotics. This review provides an introduction to the biology of human antimicrobial peptides, followed by a more detailed discussion of their isolation from tissues and biological fluids, their purification by gel electrophoresis and chromatography and assays of their antimicrobial activities.     

Structural characterization of plant defensin protein superfamily

Plant defensins represent a major innate immune protein superfamily with strong inhibitory effects on infectious diseases of humans, antifungal/antibacterial activities, proteinase and insect amylase inhibitory activities. They are generally defined by their conserved cysteine scaffold with α-helix and triple strand anti parallel β-sheet connected to the scaffold. With the genome of more plant species being fully sequenced, significant information about newly sequenced defensin proteins has been revealed. In this paper, we identify members of defensin protein families across plant species and use protein-modeling-based structural reconstitution to reveal specific three dimensional hidden features of plant defensins mediating defense responses and other interesting biological activities in plants. Our data revealed that plant defensins are structurally similar to their insect counterparts despite the low amino acid sequence similarity between these two organisms. The molecular and structural relationship among plant defensins and defensins from other species is discussed.