Nontraditional microbial bioactive metabolites

Microorganisms produce low-molar-mass secondary metabolites exhibiting different biological activities, which are used.e.g., in medicine as antimicrobial and antifungal agents, alkaloids and toxins. Some of these substances have highly diverse biological activities and unusual structures. They are produced by streptomycetes, fungi, and bacilli, but interesting products have also been obtained from microorganisms growing in extreme conditions. Several thousands of microbial products have so far been discovered and many other, which can be potentially useful, and/or prospective for human use, can still be in the offing.     

Basidiomycetes: A new source of secondary metabolites.

The area of natural products research is the most rapidly growing field of organic chemistry, due to the great technical developments in the isolation and identification techniques. Today, near to one million natural products -isolated from the most diverse living things- are known. Microorganisms are among the least-studied of these. Nevertheless, they offer large possibilities for the discovery of new structures and biological activities. Among the microorganisms, the Basidiomycetes present a production capacity and a range of biologically active metabolites, which have scarcely been investigated. The wide spectrum of natural products with biological activity produced by Basidiomycetes includes antimicrobial agents, antifungal, antiviral and cytotoxic activities, enzymes, plant growth regulators and flavors. These metabolites are generally grouped by their chemical origin, and the relationship between chemical structure and the different biological activities reported. The main objective of this review is to bring an updated revision of the numerous and interesting biosynthetic pathways from basidiomycetes.     

Some results and prospects of studies in the area of marine biochemistry and biotechnology]

Recent studies on bioactive metabolites from marine macro- and microorganisms are reviewed with 83 refs. Structures of new sulphated and glycosylated secondary metabolites, which have been reported to have antifungal, immunomodulatory, and cytotoxic properties, are given. Some peculiarities of biosynthesis of natural compounds in marine organisms are revealed. It was shown that some natural products, isolated earlier from sponges, are produced by microbial symbionts. Different physiological activities associated with 8000 marine microbial (mainly symbiotic) strains are discussed as well as some prospects of marine biochemistry and biotechnology development.     

Novel N‐Cycloalkylcarbonyl‐N′‐arylthioureas: Synthesis,Design, Antifungal Activity and Gene Toxicity

A synthesis method of novel N‐cycloalkylcarbonyl‐N′‐arylthioureas was developed. It consists of sequential addition of equimolecular amounts of ammonium isothiocyanate and substituted anilines to cycloalkylcarbonyl chlorides. The identity and purity of products were confirmed by LC/MS spectra, their structure by elemental analysis, IR and ¹H‐NMR spectra. Preliminary antimicrobial screening for standard microorganisms and molecular docking allowed to select several structures for antifungal and genetic toxicity studies. Conducted in vitro screening of 9 compounds for antifungal potential against 11 phytopathogenic fungi and three Phytophthora strains revealed that two N‐(arylcarbamothioyl) cyclopropanecarboxamides at a concentration of 50 μg/ml exhibited activities comparable to the standard antifungal agent ‘Cyproconazole’. Analysis of mutagenicity of novel thioureas using the Salmonella reverse mutagenicity assay (‘Ames Test’) showed a low gene‐toxicity profile.     

深海细菌及其活性物质防控植物病原真菌的研究进展

近年来,从天然产物中开发生物农药成为了研究者关注的热点,海洋微生物因其独特的生存环境,产生了许多从陆地微生物中未曾发现的生物活性物质,为新型生物农药开发带来了佳音。从微生物多样性、抑菌物质的种类与结构和抑菌机理3个方面阐述深海细菌防控植物病原真菌的研究进展,并对其发展前景进行了展望,以期为抗植物病原真菌的海洋微生物的开发利用提供参考。     

Differential modulation of the antifungal activity of amphotericin B by natural and ent-cholesterol

The addition of exogenous ent-cholesterol suppressed the antifungal activity of the amphotericin B when added to cultures of Candida albicans, but to a lesser extent than natural cholesterol. There were no detectable differences between added 2a or 2b on the antifungal activities of jaspamide or bengazole A, two unrelated antifungal natural products.     

微生物源挥发性物质防治采后果蔬病害的研究进展

随着化学杀菌剂弊端的日益凸显,生物防治已逐渐成为采后果蔬病害控制的研究和开发热点.其中,很多微生物产生的多种挥发性物质(volatile organic compounds,VOCs),能显著抑制多种病原菌的生长繁殖,有效控制采后果蔬病害.由于微生物源VOCs具有有效、安全、环保、易降解和无残留等优点,越来越受到各国研...     

Metabolic modelling and flux analysis of microorganisms from the Atacama Desert used in biotechnological processes

Metabolic modelling is a useful tool that enables the rational design of metabolic engineering experiments and the study of the unique capabilities of biotechnologically important microorganisms. The extreme abiotic conditions of the Atacama Desert have selected microbial diversity with exceptional characteristics that can be applied in the mining industry for bioleaching processes and for production of specialised metabolites with antimicrobial, antifungal, antiviral, antitumoral, among other activities. In this review we summarise the scientific data available of the use of metabolic modelling and flux analysis to improve the performance of Atacama Desert microorganisms in biotechnological applications.     

Screening of antimicrobial activities in red, green and brown macroalgae from Gran Canaria (Canary Islands, Spain)

Extracts from 44 species of seaweed from Gran Canaria (Canary Islands, Spain) were screened for the production of antibacterial and antifungal compounds against a panel of gram-negative and gram-positive bacteria, mycobacteria, yeasts and fungi. A total of 28 species displayed antibacterial activity, of which six also showed antifungal activity. Asparagopsis taxiformis and Cymopolia barbata were the species with the strongest activities against the broadest spectrum of target microorganisms. All the species with antibacterial activity were active against gram-positive bacteria, whereas only two species, A. taxiformis and Osmundea hybrida, were active against mycobacteria. The production of secondary metabolites with antimicrobial activities by the macroalgae was also studied under different conditions, although no common trend for bioactivity was observed.     

氮源和碳源对解淀粉芽孢杆菌Q-426抗菌脂肽合成的影响

微生物来源的环状脂肽在生物农药以及医学领域极具应用潜力。通过测量抑菌活性并利用反相高效液相色谱(RP-HPLC),液相质谱联用(HPLC-MS)和串联质谱(MS/MS)技术检测抗菌脂肽组分的变化研究了氮(N)源、碳(C)源和培养基中的初始pH值对解淀粉芽孢杆菌Q-426菌株中抗菌脂肽bacillomycin D和fengycins合成的影响,从而为进一步研究它们生物合成的基因调控以及更有目的性提高产量提供理论依据。结果表明:L-组氨酸、L-赖氨酸、甘油、山梨醇以及培养基中的[OH]-均能促进脂肽bacillomycin D的合成,但它们在该实验菌株抗菌脂肽bacillomycinD合成途径中的调控靶点有所不同。     

Pterocarpenes elicited by Aspergillus caelatus in peanut (Arachis hypogaea) seeds

The substituted pterocarpenes named aracarpene-1 (1) and aracarpene-2 (2) were isolated from wounded peanut seeds challenged by a strain of Aspergillus caelatus. The structures of these putative phytoalexins were determined by interpretation of NMR and MS data. The aracarpenes were investigated for their antifungal and antibacterial activities as well as antioxidant, anti-inflammatory, and cytotoxic activities in mammalian cells. Aracarpene-2 demonstrated high antibacterial properties against tested gram-positive and gram-negative bacteria, whereas aracarpene-1 displayed low antibacterial properties against the same bacteria. Both compounds had no antifungal activity against Aspergillus flavus. Together with peanut stilbenoids that are also produced in the challenged seeds, these compounds may represent a class of low-molecular weight peanut metabolites with a defensive role(s) against pathogenic microorganisms.     

Stereoselective synthesis of hexahydro-3-methyl-1-arylchromeno[3,4-b]pyrrole and its annulated heterocycles as potent antimicrobial agents for human pathogens

Synthesis of a series of novel hexahydrochromenopyrrole analogues has been accomplished through an intramolecular 1,3-dipolar cycloaddition (1,3-DC reaction) of azomethine ylides, generated by the aldehyde induced decarboxylation of secondary amino acids. These compounds were screened for antibacterial and antifungal activities against six human pathogenic bacteria and three human pathogenic fungi and found to have good antimicrobial properties against most of the microorganisms.     

Synthesis of antimicrobial 2,9,10-trisubstituted-6-oxo-7,12-dihydro-chromeno[3,4-b]quinoxalines

A new series of 2,9,10-trisubstituted-6-oxo-7,12-dihydro-chromeno[3,4-b]quinoxalines was synthesized and submitted to antibacterial and antifungal activities. Result of the antimicrobial screening showed the compound 4j being the most effective among the various treatments in antimicrobial screening. Compounds 4c, 4d, 4k, and 4l showed moderate activity against the microorganisms tested.     

Taxonomic distribution of <Emphasis Type="Italic">Streptomyces</Emphasis> species capable of producing bioactive compounds among strains preserved at NITE/NBRC

The taxonomic distribution of Streptomyces species capable of producing bioactive compounds was investigated. Nine hundred and six strains were tested for the following four biological activities: antimicrobial, anti-tyrosinase, antioxidant, and hemolytic. Approximately 30% of strains tested showed antimicrobial activities, except for anti-Escherichia coli activity, which was present in only a few strains, while the rates of positivity for the anti-tyrosinase, antioxidant, and hemolytic activities were much lower. The distribution of Streptomyces strains capable of producing bioactive compounds was analyzed by the taxonomy based on 16S rRNA gene sequences. Moreover, the strains of Streptomyces hygroscopicus tested were divided into two clades in the phylogenetic tree, and all of the strains belonging to one clade showed antibacterial and antifungal activities. For detection of polyenes, the UV-visible spectra of metabolic extracts in the strains showing antifungal activities were measured. It was suggested that Streptomyces strains produce universal active compounds under different growth conditions. Further information on the relationship between the microbial taxonomy and the bioactive compounds produced would be useful for the utilization of industrial microorganisms.     

Synthesis and antimicrobial activity of some new thiazolyl thiazolidine-2,4-dione derivatives

In this study, a series of thiazolyl thiazolidine-2,4-dione derivatives (Va-f and VIa-f) were synthesized and evaluated for their antibacterial and antifungal activities against Staphylococcus aureus (ATCC 25923), methicillin resistant S. aureus (MRSA ATCC 43300), methicillin resistant S. aureus (MRSA isolate), and Escherichia coli (ATCC 23556) and C. albicans (ATCC10145). All the compounds were found active against used microorganisms.     

Carboline derivatives based on natural pityriacitrin as potential antifungal agents

Carboline alkaloids are a class of important heterocyclic natural products, which usually present extensive bioactivities. During the course of our research for active compounds from natural products, the pityriacitrin and pityriacitrin B belonged carboline alkaloids have been isolated from a Chinese Burkholderia sp. NBF227, which indicated potential antifungal activities. So, in order to develop these carboline alkaloids as potential fungicidal agents, a series of pityriacitrin derivatives were investigated for their antifungal activities against Phytophthora capsici, Sclerotinia sclerotiorum, Botrytis cinerea and Rhizoctonia solani, and the results demonstrated that compounds 4, 10 and 19 displayed broad-spectrum antifungal activities. In addition, in vivo bioassay also indicated that compounds 4 and 10 could protect the pepper leaves and grape fruits against infection by P. capsici and B. cinerea, respectively. The possible mechanism of antifungal action for these compounds was also explored.     

天然化合物抗真菌活性研究进展

近年来,真菌感染患者的发病率和死亡率持续上升,但现有抗真菌药物种类依然非常少,并且耐药现象的出现使临床可选择的抗真菌药物变得更加有限.因此,对新的抗真菌药物的开发迫在眉睫,从天然产物中寻找新型高效的抗真菌药物成为目前的研究热点之一.从天然产物中筛选出具有抗真菌活性的天然化合物,有助于扩大治疗真菌感染疾病的可选药物种类,减少耐药的发生.该文归纳现有报道的具有抗真菌活性的化合物,根据其不同来源及不同化学结构进行分类,阐明不同类别天然化合物的抗真菌作用机制,为开发新型高效抗真菌药物提供前体结构及抗真菌新靶点.     

脂肽类抗生素及其作用机制

脂肽类抗生素是由微生物代谢产生的一类具有很强表面活性的生物活性物质,含有由亲水性氨基酸和疏水性脂肪酸链组成的特殊分子结构,表现出亲水、亲脂两亲性的特性,具有抗菌、抗肿瘤和抗病毒等多种生物学活性,作为抗菌药物和肿瘤抑制剂在医药和临床应用领域具有良好的应用潜力和前景。本文对脂肽类抗生素的结构、生物学功能和作用机制等最新研究进展进行综述。     

The effects of antifungal substances on some zoosporic fungi (Kingdom Fungi)

Zoosporic fungi constitute a large group of true fungi which inhabit freshwater, brackish, marine and soil ecosystems. In general, very little is known about the effects of antifungal substances on the growth and survival of most species. This review focuses on experimental research with those isolates which have been studied, especially in some species of Synchytrium, Olpidium, Batrachochytrium, Allomyces, Blastocladiella, Neocallimastix. These genera represent genetically diverse groups. Although the research discussed here is restricted to a small sample, some general conclusions can be reached about zoosporic fungi as a whole. Like many other eukaryotic microorganisms, zoosporic fungi are sensitive to a large number of antibiotics, fungicides, surfactants, bacterial metabolites, metabolic poisons, proteins, heavy metals and other antifungal substances. These include substances commonly released into the environment for the control of plant and animal diseases, for increasing production of domestic animals and in the form of waste products from industry. It is possible that the release of antifungal substances into the environment might cause significant changes in the community structure of zoosporic fungi as well as of other groups of microorganisms which play significant roles in food web dynamics and ecosystem complexity. However, this needs documentation by quantitative studies. For these reasons, extensive research on the effects of antifungal substances is much needed.     

Major bioactive metabolites from marine fungi: A Review

Biologists and chemists of the world have been attracted towards marine natural products for the last five decades. Approximately 16,000 marine natural products have been isolated from marine organisms which have been reported in approximately 6,800 publications, proving marine microorganisms to be a invaluable source for the production of novel antibiotic, anti tumor, and anti inflammatory agents. The marine fungi particularly those associated with marine alga, sponge, invertebrates, and sediments appear to be a rich source for secondary metabolites, possessing Antibiotic, antiviral, antifungal and antiyeast activities. Besides, a few growth stimulant properties which may be useful in studies on wound healing, carcinogenic properties, and in the study of cancers are reported. Recent investigations on marine filamentous fungi looking for biologically active secondary metabolites indicate the tremendous potential of them as a source of new medicines. The present study reviews about some important bioactive metabolites reported from marine fungal strains which are anti bacterial, anti tumour and anti inflammatory in action. It highlights the chemistry and biological activity of the major bioactive alkaloids, polyketides, terpenoids, isoprenoid and non-isoprenoid compounds, quinones, isolated from marine fungi.