植物中抗病原真菌的活性物质

综述了近十年国内外公开报道的部分植物抗病原真菌的活性物质,这些物质主要包括萜类、生物碱类、黄酮类、酚类、醌类、苯丙素类、香豆素类和木脂素类等.侧重介绍了禾本科、豆科、蔷薇科、菊科和十字花科植物中抗病原真菌的活性物质的特点.提出了一些看法与建议.     

植物内生真菌抗菌活性物质的研究进展

植物内生真菌是一种新的微生物资源,具有潜在的应用前景,能产生生物碱类、肽类、甾体类、萜类、酚类、醌类、脂肪族类、异香豆素类等多种类型的抗菌活性物质.本文简要综述了植物内生真菌的抗菌活性物质的研究方法、提取物的抗菌活性、抗菌活性成分等方面的研究进展.     

药用植物内生真菌研究进展

药用植物内生真菌具有抗肿瘤、抗菌、抗病毒、抗氧化等活性,能够产生植物生长素、细胞激动素、赤霉素等促植物生长物质促进植物生长,从而使研究药用植物内生真菌成为寻找新型拮抗菌、抗肿瘤、抗氧化活性药物的重要资源。本文对药用植物内生真菌的多样性、分离鉴定、产生的次生代谢产物及其功能等做一综述。     

植物内生真菌抗肿瘤药物研究进展

癌症已经严重威胁人类的健康。从自然界中筛选更新的、更有效的抗癌药物已成为了该领域的研究重点。作为新型抗癌药物的潜在来源,众多从植物内生真菌分离的代谢产物被证明具有抗肿瘤的生物活性。这些内生真菌通常具有特殊的代谢途径,可以在其培养物中积累抗癌活性物质,如紫杉烷类、生物碱类、细胞松弛素、鬼臼毒素、布雷菲德菌素A等。将系统的介绍已分离自植物内生真菌的抗癌药物的研究进展,同时对内生真菌的抗癌药物筛选的策略和发展前景进行简要的展望。     

植物内生真菌及其活性代谢产物研究进展

植物内生真菌是一大类未被充分研究过的真菌,其物种及代谢产物均具有生物多样性,现今从植物内生真菌中得到的活性物质种类远比从土壤微生物中得到的多。对植物内生真菌的研究具有重要的生态学意义和经济学意义,在各个领域中应用前景广泛。作者主要综述了植物内生真菌及其活性物质研究的最新进展。     

植物抗病的分子生物学基础

随着分子生物学的不断发展,人们已逐步了解植物寄主与病原之间的相互作用及植物抗病的分子机理。植物受病原侵染后出现两种类型的卫反应：局部防卫反应（过敏反应）和系统获得性防卫反应。本质素、植保素、活性氧、水杨酸等物质已被证明了在植物抗病中起了重要作用。抗病基因和防卫基因的诱导表达构成了防卫反应的遗传基础。本文综述了近年来抗病的分子生物学研究进展,并对其发展和应用前景作了展望。     

三类重要真菌生物活性物质及其研究方法概述

对高等真菌、内生真菌和海洋真菌活性物质的研究现状进行了概述,并对活性物质的筛选和分离方法等进行了介绍。     

网络药理学和分子对接技术研究桑黄类真菌对疾病的潜在作用机制

桑黄类真菌是一类极具研究价值的药用真菌。近年来,对于桑黄类真菌的研究,多集中于对某一个物种的成分及药理活性的研究,系统比较桑黄类真菌中成分及药理活性的研究较少。本研究利用网络药理学和分子对接技术从理论上初步探讨了5种桑黄类真菌中化合物与疾病之间的分子作用机制。研究结果表明5种桑黄类真菌(栎木桑黄Sanghuangporus quercicola、鲍姆桑黄Sanghuangporus baumii、粗毛纤孔菌Inonotus hispidus、裂蹄木层孔菌Tropicorus linteus、黑盖木层孔菌Phellinus nigrians)中的39种有效成分,对应潜在靶点588个。KEGG通路富集筛选得到165条通路,分析结果发现这39种化合物的靶点主要分布在与炎症、糖尿病、肝癌、阿尔茨海默病和衰老相关的信号通路上。筛选出桑黄类真菌中抗病的潜在靶点共486个,构建抗病靶点的蛋白互作(PPI)网络,并筛选出LCK、STAT3、PTPN11、STAT1、STAT5B、MAPK1、JAK1、MAPK3、JAK3和JAK2作为关键靶点,构建5种桑黄类真菌-化合物-关键靶点-5种疾病的网络互作图,并进行分子对接验证。筛选出的桑黄类真菌中的12个有效成分均可与这些关键靶点产生相互作用,其中酚类化合物居多,此外二萜类化合物异海松酸与MAPK1结合能力最强。因此,5种桑黄类真菌可以通过多种化合物、多种靶点和多种途径起到抗病的作用,本研究为探索桑黄类真菌治疗和预防疾病潜在机制提供了理论基础。     

弯孢聚壳属真菌次级代谢产物及其生物活性

本文对弯孢聚壳属真菌的化学成分和生物活性进行综述。目前从弯孢聚壳属真菌中发现的次级代谢产物类型主要包括二萜、细胞松弛素类、倍半萜、单萜、甾体、内酯类等。这些化学成分显示出抗肿瘤、抗菌、免疫抑制的活性。     

白僵菌天然产物及其药理活性和生物合成研究进展

白僵菌是重要的昆虫病原真菌,能产生多肽类、聚酮类、生物碱类、苯丙素类、萜类、核苷类等多种结构类型的天然产物,其中很多天然产物显示出优良的抗肿瘤、抗菌、抗病毒和杀虫等活性,具有极大的应用开发潜力。随着白僵菌基因组测序的完成,白僵菌素、白僵菌交酯、球孢交酯、卵孢素及纤细素等活性分子的生物合成基因簇及其生物合成机制已得到阐明,这些研究将大大促进白僵菌来源的新结构活性天然产物的基因组挖掘和发现以及已知重要活性分子的开发应用。本文对已知白僵菌产生的天然产物、药理活性及重要活性分子的生物合成途径进行了概括总结,为系统开发白僵菌天然产物资源提供参考。     

铜绿假单胞菌生防菌株抑菌代谢产物及其生防应用研究进展

微生物次生代谢产物的研究对开发微生物源农药具有重要意义。近年来一系列根际来源的铜绿假单胞菌被分离和鉴定,因其产生抑菌次生代谢产物,具有很好的生物防治效果。本文将系统综述铜绿假单胞菌生防菌株的种类及其抑菌代谢产物的多样性,并进一步介绍铜绿假单胞菌生防菌株的抑菌代谢产物合成机制及其遗传改造,简要讨论铜绿假单胞菌生防菌株抑菌代谢产物在生物防治上的应用和前景。     

Isolation and partial characterization of antifungal metabolites of Bacillus pumilus

Antifungal metabolites produced by Bacillus pumilus in Potato Dextrose Broth (PDB) were isolated from culture supernatant fluid by precipitation with ammonium sulphate. The antifungal metabolites inhibited mycelial growth of many species of Aspergillus , Penicillium and Fusarium . They also inhibited production of aflatoxins, cyclopiazonic acid, ochratoxin A and patulin. The metabolites were heat-stable and remained active after sterilization at 121 °C for 15 min. Their activity was stable over a wide range of pH (2–10). The metabolites were resistant to hydrolysis by various proteases, peptidases and other enzymes. They were also resistant to denaturation by many protein-denaturing detergents except Nonidet P-40. The metabolites were soluble in water and relatively polar organic solvents. Chromatographic bioassay revealed that a crude precipitate of the metabolites contained only one compound with antifungal activity. The active compound did not form a fluorescent derivative with fluorescamine suggesting that the compound is either a cyclic polypeptide or a non-peptidic compound.     

水葫芦内生拟枝孢镰刀菌SC1608的次生代谢产物

研究了一株水生植物水葫芦内生拟枝孢镰刀菌Fusarium sporotrichioides SC1608大米发酵物的抗真菌活性次生代谢产物,从中共分离获得6个化合物,经高分辨质谱、三重四极杆质谱和核磁共振谱分析,分别鉴定为4个鞘糖脂类化合物：asperamide B (1)、asperamide D (2)、asperamide E (3)、cerebrosides A (4),以及2个环酯肽类化合物acuminatum A (5)和acuminatum B (6),其中化合物2和化合物3是新的鞘糖脂类化合物。通过滤纸片琼脂扩散法评价了单体化合物的抗真菌活性,证实化合物5和6对柑橘绿霉和玉米小斑病菌均具有较强的体外抑制活性。研究结果初步揭示了F. sporotrichioides SC1608发酵物的抗真菌活性物质基础,丰富了拟枝孢镰刀菌次生代谢产物的化学多样性。     

Novel sample preparation method facilitating identification of urinary drug metabolites by liquid chromatography–tandem mass spectrometry

A simple, efficient procedure was developed for the preparation of urine samples, which greatly facilitated the identification of the urinary metabolites of a new antifungal agent SYN-2836. The urine samples following dilution with acetonitrile (ACN) formed distinct upper (ACN) and lower (aqueous) solution phases. The SYN-2836 metabolites were concentrated in the upper solution except that two glucuronides were concentrated in the lower solution. The upper solutions, containing concentrated metabolites and significantly reduced endogenous polar species, were ideally suitable for the metabolite identification. This novel sample preparation procedure would be applicable in identification of urinary metabolites of other drugs and drug candidates.     

Antifungal activity of <Emphasis Type="Italic">Bacillus subtilis</Emphasis> 355 against wood-surface contaminant fungi

A strain of Bacillus subtilis was examined for antifungal activity against phytopathogenic and wood-surface contaminant fungi. The bacterium was grown in five culture media with different incubation times in order to study cell development, sporulation, and the production of metabolites with antifungal activity. The anti-sapstain and anti-mould activity of the bacterium grown in yeast extract glucose broth (YGB) medium in wood was also evaluated. In YGB, the bacterium inhibited the growth of several fungi and displayed a broader spectrum of activity than in the other media tested. A relationship between bacterial spore production and the formation of metabolites with antifungal activity was detected. YGB medium displayed effective control in wood block tests. YGB medium was extracted with solvents of increasing polarity and the dry residues were applied to silicagel plates, resolved with the appropriate solvent and sprayed with different solutions, detecting the presence, of amines, and higher alcohols. The bioautographic method revealed the presence of at least two active compounds against the blue-stain fungus Cladosporium cucumerinum.     

Characterization of fungal antagonistic bacilli isolated from aerial roots of banyan (Ficus benghalensis) using intact‐cell MALDI‐TOF mass spectrometry (ICMS)

Aims

To characterize fungal antagonistic bacilli isolated from aerial roots of banyan tree and identify the metabolites responsible for their antifungal activity.

Methods and Results

Seven gram positive, endospore‐forming, rod‐shaped endophytic bacterial strains exhibiting a broad‐spectrum antifungal activity were isolated from the surface‐sterilized aerial roots of banyan tree. The isolates designated as K1, A2, A4 and A12 were identified as Bacillus subtilis, whereas isolates A11 and A13 were identified as Bacillus amyloliquefaciens using Biolog Microbial Identification System. The antifungal lipopeptides, surfactins, iturins and fengycins with masses varying in the range from m/z 900 to m/z 1550 could be detected using intact‐cell MALDI‐TOF mass spectrometry (ICMS). On the basis of mass spectral and carbon source utilization profile, all seven endophytes could be distinguished from each other. Furthermore, ICMS analysis revealed higher extent of heterogeneity among iturins and fengycins produced by B. subtilis K1, correlating well with its higher antifungal activity in comparison with other isolates.

Conclusion

Seven fungal antagonistic bacilli were isolated from aerial roots of banyan tree, exhibiting broad spectrum of antifungal activity, among which B. subtilis K1 isolate was found to be most potent. The ICMS analysis revealed that all these isolates produced cyclic lipopeptides belonging to surfactin, iturin and fengycin families and exhibited varying degree of heterogeneity.

Significance and Impact of the study

The endophytes are considered as a potential source of novel bioactive metabolites, and this study describes the potent fungal antagonistic bacilli from aerial roots of banyan tree. The isolates described in this study have a prospective application as biocontrol agents. Also ICMS analysis described in this study for characterization of antifungal metabolites produced by banyan endophytic bacilli may be used as a high throughput tool for screening of microbes producing novel cyclic lipopeptides.     

Cyclosporin A and C

Summary Cyclosporin A and C are new antifungal antibiotics fromTrichoderma polysporum (Link ex Pers.) Rifai. The metabolites are produced in submerged culture and are extracted therefrom by organic solvents. Cyclosporin A is a nonpolar cyclic peptide with a molecular weight of 1202.6. The cyclosporins exhibit a narrow spectrum of antifungal activity and in addition have immunosuppressive properties.     

Metabolite profiles of lactic acid bacteria in grass silage

The metabolite production of lactic acid bacteria (LAB) on silage was investigated. The aim was to compare the production of antifungal metabolites in silage with the production in liquid cultures previously studied in our laboratory. The following metabolites were found to be present at elevated concentrations in silos inoculated with LAB strains: 3-hydroxydecanoic acid, 2-hydroxy-4-methylpentanoic acid, benzoic acid, catechol, hydrocinnamic acid, salicylic acid, 3-phenyllactic acid, 4-hydroxybenzoic acid, (trans, trans)-3,4-dihydroxycyclohexane-1-carboxylic acid, p-hydrocoumaric acid, vanillic acid, azelaic acid, hydroferulic acid, p-coumaric acid, hydrocaffeic acid, ferulic acid, and caffeic acid. Among these metabolites, the antifungal compounds 3-phenyllactic acid and 3-hydroxydecanoic acid were previously isolated in our laboratory from liquid cultures of the same LAB strains by bioassay-guided fractionation. It was concluded that other metabolites, e.g., p-hydrocoumaric acid, hydroferulic acid, and p-coumaric acid, were released from the grass by the added LAB strains. The antifungal activities of the identified metabolites in 100 mM lactic acid were investigated. The MICs against Pichia anomala, Penicillium roqueforti, and Aspergillus fumigatus were determined, and 3-hydroxydecanoic acid showed the lowest MIC (0.1 mg ml(-1) for two of the three test organisms).     

The production of antifungal metabolites by Pseudomonas chlororaphis grown on different nutrient sources

It was found that the antifungal activity of Pseudomonas chlororaphis SPB1217 is due to phenazine-1-carboxylic acid, phenazine-1-carboxamide, and two unidentified exometabolites. The carbon source used for the growth of this bacterial strain and iron ions present in the medium considerably influenced the proportion between the antifungal metabolites. The maximum production of phenazines was observed in the media enriched in amino acids and iron ions. The absence of correlation between the production of phenazines and antifungal activity indicates that phenazines are not the only antifungal metabolites of the strain. Organic acids as nutrient sources provide for more intense production of exometabolites and for a higher level of antifungal activity than do sugars.