Characterization and bioactive potentials of secondary metabolites from Fusarium chlamydosporum

Abstract

A search for bioactive secondary metabolites from the endophytic fungus Fusarium chlamydosporum, isolated from the root of Suaeda glauca, led to the isolation of three indole derivatives (1–3), three cyclohexadepsipeptides (4–6), and four pyrones (7–10). The structures of new (1) and known compounds (2–10) were elucidated on the basis of extensive spectroscopic analysis. All these compounds were evaluated for phytotoxic, antimicrobial activities, and brine shrimp lethality. Compound 1 showed significant phytotoxic activity against the radicle growth of Echinochloa crusgalli, even better than the positive control of 2,4-D. Cyclohexadepsipeptides (4–6) and pyrones (7–10) exhibited brine shrimp lethality, especially 4 and 7 with the LD₅₀ values of 2.78 and 7.40?μg mL^?1, respectively, better than the positive control.     

RP-HPTLC fingerprinting of secondary metabolites from Nephrolepis exaltata and Cycas revoluta

This study aims to develop a quantitative fingerprinting between two evolutionary close plant species Nephrolepis exaltata (L.) Schott and Cycas revoluta Thunb. The crude plant extracts were prepared in 1:1:1, v/v/v: Ethyl Acetate: n-Hexane: Methanol (AR) solvent system through cold extraction for 24 Hrs. The plant extracts were diluted (10 mg/mL) with a similar solvent system spotted (10 μL) on silica gel 60 F²⁵⁴ thin-layer chromatography plates. Five mobile phases (i) tetrahydrofuran (THF): toluene: formic acid: water (16:8:2:1) (ii) toluene: ethyl acetate: diethylamine (7:2:1) (iii) toluene: ethyl acetate: formic acid (7:3:0.1) (iv) n-hexane: ethyl acetate (7.2:2.9) (v) toluene: methanol (9:1) were used. The results were scanned at 254 nm, 366 nm, and in visible white light. This study gave minimum compact spots between Rf 0.06 to 0.051 corresponding to terpenoids, simultaneously for flavonoids spots were found between Rf 0.004 to 0.910. Total eight phenolic bands were found in Cycas revoluta among which five was found in leaf extract with Max RF of 0.033, 0.093, 0.273, 0.901 and 0.964 whereas three bands were found in stem extract with Max Rf of 0.007, 0.897 and 0.954. The presence of fifteen different types of flavonoids was determined by the flavonoids profile at Rf 0.004, 0.027, 0.047, 0.073, 0.134, 0.230, 0.303, 0.369, 0.369, 0.427, 0.514, 0.631, 0.703, 0.757, 0.846 and 0.910 for Nephrolepis exaltata. HPTLC fingerprint has shown several peaks with different Rf for different mobile phases. The fingerprinting would be helpful in the identification, and authentication of these species ecologically and therapeutically.     

Potential bioactive secondary metabolites of Actinomycetes sp. isolated from rocky soils of the heritage village Rijal Alma,Saudi Arabia

The present study was designed to discover novel secondary antibiotic metabolites from Actinomycetes species from the soil of Rijal Almaa, Saudi Arabia. A laboratory-scale benchtop fermentation was utilized for the demonstration of antibiotics from the soil actinomycetes. Fourier transform-infrared spectroscopy (FT-IR) spectroscopy analysis of the fermented product (FP) was carried out, which showed unique fingerprint regions indicating the presence of phenolic hydroxyl groups, aliphatic compounds, carboxylic groups, esters, isothiocyanate, etc. GC-MS analysis of the FP depicted the unique structures of secondary metabolites, such as cyclononasiloxane octadecamethyl, cercosporin, ethyl iso-allocholate, octadecane, 3-ethyl-5-(2-ethylbutyl), dasycarpidan-1-methanol (acetate), heptadecane, 9-hexyl-, phthalic acid-butyl, and octadecane, 3-ethyl-5-(2-ethylbutyl). The TGA analysis showed the thermal stability of FP and the initial weight loss in FP was observed at 277.29 °C. The ¹H NMR and ¹³C NMR spectra of FP analysis demonstrated the various characteristic peaks presence of secondary metabolites. The XRD analysis at 2θ revealed distinct particles based on specific diffraction peaks. A set of six human bacterial pathogens, namely, the Gram-positive bacteria Staphylococcus aureus (S. aureus), Streptococcus pyogenes (S. pyogenes), and Bacillus subtilis (B. subtilis) and Gram-negative bacteria Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa), and Klebsiella pneumoniae (K. pneumoniae), were utilized for screening. The FP exhibited promising antibacterial effects against both Gram-positive and Gram-negative bacterial organisms. The antibacterial spectrum of activity was greater for E. coli and B. subtilis than for K. pneumoniae.     

Typology of secondary cyanobacterial metabolites from minimum spanning tree analysis

Recently, two main events have spurred a rapid increase in cyanobacteria chemical, toxicological, and ecological research. The first deals with the interest in isolating compounds from these organisms as source of active products with potential therapeutic applications. The second pertains the crucial problem of harmful cyanobacterial blooms in the aquatic environments.

In this context, 594 secondary metabolites belonging to more than 30 genera of cyanobacteria were retrieved from literature. In order to perform their typology, they were first associated with 87 different molecular archetypes and two orphan classes. These 89 groups of molecular structures were then confronted to minimum spanning tree analysis. Attempts were made to graphically derive chemotaxonomical relationships. The interest of QSAR models for estimating the potential pharmacological interest of the cyanobacterial secondary metabolites was also discussed.     

Antifungal and cytotoxic substances from the stem barks of Desmos chinensis

Isounonal-7-methyl ether（1） and chinendihydrochalcone（2） together with 8 known compounds were isolated from the stem barks of Desmos chinensis.Their structures were determined on the basis of spectroscopic data.Compound 2 exhibited cytotoxic activity against MOLT-3 cancer cell line(IC₅₀ 7.16μg/mL) and antifungal activity against Pyricularia oryzae and Rhizoctonia solani with MIC values of 15.6 and 31.2μg/mL,respectively.     

Antifungal Ursene‐Type Triterpene from the Roots of Alhagi camelorum

A new ursene‐type triterpene, (3β)‐30‐norurs‐11‐en‐3‐ol ( 1 ), was isolated from the MeOH extract of the roots of Alhagi camelorum. Its structure was elucidated on the basis of extensive spectroscopic investigations by 1D‐ and 2D‐NMR studies. In addition, 1 was evaluated for antifungal activities. Its application on prepared cultures of two fungi, i.e., Aspergillus niger and Saccharomyces cerevisiae, showed noticeable antifungal activity, suggesting that 1 could be used as a new promising agent in antifungal drug formulations.     

Temporal variations of137Cs concentrations in the surface seawater and marine organisms collected from the Japanese coast during the 1980's

The surface seawater and marine organisms were collected on the Japanese coast and analyzed for their¹³⁷Cs concentrations during the 1980's. The¹³⁷Cs concentrations in surface seawater decreased almost exponentially with time and the¹³⁷Cs removal rate constant was estimated to be 0.0445 y⁻¹. The¹³⁷Cs concentrations in marine organisms also decreased almost exponentially with time. The environmental half-lives of¹³⁷Cs in muscle and viscera of fish, crustacea, and seaweed were estimated from the measured decreases of¹³⁷Cs concentrations.     

Indolic metabolites from the new marine bacterium Roseivirga echinicomitans KMM 6058T

N-Acetyl-(1) and N,N-diacetyl-(2) tryptamines were isolated from the butanol extract of culture medium of the new marine bacterium Roseivirga echinicomitans KMM 6058^T. The structures of the compounds were proved using mass spectrometry, UV, PMR, and ¹³C NMR spectroscopy and by comparing these data with mass and NMR spectra of synthetic samples of 1 and 2. Compound 2 was isolated from a natural source and synthesized for the first time. The cytotoxic activity of the compounds was studied using Erlich carcinoma tumor cells, murine erythrocytes, and sperm and egg cells of the sea urchin Strongylocentrotus intermedius. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 581–584, November–December, 2006.     

Antimicrobial evaluation of selected naturally occurring oxyprenylated secondary metabolites

This study tested the antimicrobial activity of eight selected naturally occurring oxyprenylated secondary metabolites against Staphylococcus aureus ATCC 29213, S. epidermidis ATCC 35984, Escherichia coli ATCC 8739, Pseudomonas aeruginosa ATCC 9027 and Candida albicans ATCC 10231. Results showed a moderate antimicrobial activity. The most active compounds were 3-(4-geranyloxyphenyl)-1-ethanol (4) and 3-(4-isopentenyloxyphenyl)-1-propanol (5) that were tested on mature and in-formation biofilms of all micro-organisms, moreover the cytotoxic activity was evaluated. Except for S. epidermidis, both compounds reduced significantly (p < 0.05) the microbial biofilm formation at 1/2 MIC and 1/4 MIC, in particular, compounds 4 and 5 at each concentration, inhibited E. coli biofilm formation to a greater extent, the biofilm formation was never more than 44% in respect to the control, moreover both compounds showed a low cytotoxic effect. Oxyprenylated derivatives may be of great interest for the development of novel antimicrobial therapeutic strategies and the synthesis of semi-synthetic analogues with anti-biofilm efficacy.     

Antifungal variant bis(bibenzyl)s from the liverwort Asterella angusta

Bioassay-guided fractionation of the diethyl ether extract of the liverwort Asterella angusta led to the isolation of two antifungal bis(bibenzyl)s,riccardin I(1),and angustatin A(2).Their structures were established by spectroscopic analysis(1D NMR and 2D NMR,IR,MS).Compound 1 is a novel variant riccardin-type bis(bibenzyl),while compound 2 is the first nonheteratom-containing variant bis(bibenzyl)possessing a bibenzyl-phenanthrene skeleton.     

Polyoxygenated dihydropyrano[2,3-c]pyrrole-4,5-dione derivatives from the marine mangrove-derived endophytic fungus Penicillium brocae MA-231 and their antimicrobial activity

A new polyoxygenated dihydropyrano[2,3-c]pyrrole-4,5-dione derivative, pyranonigrin F (1), together with a related known compound, pyranonigrin A (2), were isolated and identified from Penicillium brocae MA-231, an endophytic fungus obtained from the fresh tissue of the marine mangrove plant Avicennia marina. The structures of these metabolites were determined based on comprehensive spectral interpretation and the absolute configuration of compound 1 was established by X-ray crystallographic analysis. Compounds 1, and 2 showed potent activity against a broad spectrum of human-, aqua-, and plant-pathogens.     

Bioactive DOPA melanin isolated and characterised from a marine actinobacterium Streptomyces sp. MVCS6 from Versova coast

The melanin pigment produced from Streptomyces sp., MVCS6 was isolated and dihydroxyphenyalanine (DOPA) melanin compound was biochemically identified and spectroscopically characterised (ultraviolet and FT-IR). DOPA melanin showed a promising activity as an antibacterial natural product against 12 pathogenic bacteria from hospital isolations, particularly, against Pseudomonas aeruginosa RMMH7 (inhibition zone of 18 ± 0.02 at 30 μg/disc, and MIC of 10 ± 0.02 μg/mL) and Vibrio parahaemolytics RMMH12 (inhibition zone of 15 mm ± 0.03 at 30 μg/disc, and MIC of 14 ± 0.02 μg/mL). Moreover, in vitro evaluation of reducing power (Ascorbic Acid Equivalent (160 μg/mL)), DPPH radical-scavenging (89%), NO-scavenging (72%) and lipid peroxidation activities (89.6%) were determined. Cytotoxicity of DOPA melanin against cervical cancer cell line showed a dose–response activity, and IC₅₀ value was found to be 300 μg/mL. These results would open the way to propose Streptomyces sp. MVCS6 as a promising source of bioactive eumelanin with therapeutic potential in medicine.     

Antimicrobial activity of secondary metabolites from Streptomyces sp. K15, an endophyte in Houttuynia cordata Thunb

We isolated Streptomyces sp. K15 from the root tissue of Houttuynia cordata Thunb and found that some of its secondary metabolites exhibited significant antimicrobial activity against Botrytis cinerea. Moreover, we separated, purified and identified the major active ingredient to be 2-pyrrol formic acid by using silica gel column chromatography, high-performance liquid chromatography and NMR analysis of the spectral data. 2-Pyrrol formic acid critically inhibited the growth of some phytopathogenic bacteria. Therefore, it has potential value in agricultural applications.     

南海红树林内生真菌Cephalosporium sp．（2090#）次级代谢产物研究

海洋微生物是寻找海洋药物先导化合物的一个新的源泉,人们已经从海洋微生物的次级代谢产物中分离得到了很多结构新颖或强药理活性的化合物[1]。我们在对中国南海红树林内生真菌的研究中,发现了大量的生物活性化合物,这也揭示了我国南海海洋真菌具有极大的药用开发前景[2-5]。红     

Antimicrobial secondary metabolites of an endolichenic Aspergillus niger isolated from lichen thallus of Parmotrema ravum

Abstract

A new 6-benzyl-γ-pyrone (1), named aspergyllone was isolated from the culture filtrates of an endolichenic fungus Aspergillus niger Tiegh, obtained from lichen thallus Parmotrema ravum (Krog & Swinscow) Serus, collected in India. 1 was isolated for the first time from an endolichenic fungus together with six other known metabolites identified as aurasperones A (2) and D (3), asperpyrone A (4), fonsecinone A (5), carbonarone A (6) and pyrophen (7). The compounds were tested against a panel of human, plant, food borne and fish pathogens. Aspergyllone showed strong selective antifungal activity against Candida parapsilosis (Ashford) Langeron & Talice, with an IC₅₀ of 52?µg/mL. Aurasperone A and pyrophen showed moderate to strong antimicrobial activity inhibiting seven different test pathogens, being pyrophen active with IC₅₀ ranging from 35 to 97?µg/mL.

     

阿舒假囊酵母合成的精油及其抗真菌活性与机理

利用发酵法对阿舒假囊酵母进行发酵, 用萃取法和水蒸气蒸馏法从发酵液中提取精油; 通过气相色谱-质谱(GC-MS)法确定其成分; 分别利用抑菌圈和二倍稀释法实验法测定了精油的抗真菌能力、 最小抑菌浓度和最小杀菌浓度; 利用荧光标记法、 精油处理酵母后细胞内容物检测法及透射电子显微镜研究了精油的抗菌机理. 结果表明, 阿舒假囊酵母发酵法得到的精油产率为0.54 g/L. 用GC-MS法鉴定了22种化学成分, 占精油总量的98.82%. 精油主要由单萜、 倍半萜、 芳香醇和倍半萜烃类物质组成. 精油对白色念珠菌、 光滑念珠菌、 热带念珠菌、 季也蒙念珠菌、 新型隐球菌和酿酒酵母具有良好的抗菌活性, 其最小抑菌浓度分别为31.25, 31.25, 62.5, 31.25, 15.625和15.625 μg/mL; 最小杀菌浓度分别为62.5, 62.5, 125.0, 62.5, 31.25和31.25 μg/mL. 结果表明, 精油的抗菌机理可能是破坏真菌的细胞壁、 细胞膜, 使胞内物质外泄, 最终导致真菌死亡. 该研究结果为发酵法合成精油及其应用提供了新思路.     

Cebulactams A1 and A2, new macrolactams isolated from Saccharopolyspora cebuensis, the first obligate marine strain of the genus Saccharopolyspora

The new macrolactams cebulactams A1 and A2 were isolated from an extract of the first obligate marine strain of the genus Saccharopolyspora. Their constitutionally identical structures, each bearing a six-membered cyclic ether as part of the macrocycle, and their relative configurations were elucidated by MS methods and by 1D and 2D NMR techniques.     

Phytotoxic property of metabolites isolated from Garcinia gardneriana

Garcinia gardneriana is a medicinal tree species used in Brazil in the treatment of hepatitis and gastritis. This use is attributed to phenolic compounds, mainly 7-epiclusianone, guttiferone-A and fukugetin, which present several proven biological activities. However, to the best of our knowledge, no study on the phytotoxic activity of G. gardneriana extracts has been conducted until now. This research proposed to isolate and quantify by high-performance liquid chromatography (HPLC) the major compounds from G. gardneriana seed extracts in ethyl acetate and to evaluate their phytotoxic activities. The natural products 7-epiclusianone, guttiferone-A and fukugetin were quantified at concentrations varying from 0.46 to 1.13 mg mL⁻¹ and were isolated with yields ranging from 7% to 23% (w/w). The phytotoxic assay indicated that the crude extract showed no action on the dry matter of Sorghum bicolor plants, but the isolated compounds fukugetin and 7-epiclusianone had moderate activity. On the other hand, guttiferone-A displayed a greater herbicide activity than glyphosate, a positive control, even in almost three times lower concentrations, causing severe intoxication in the plants. This work is the first report on this activity by the extract of G. gardneriana and its isolated compounds. Besides that, guttiferone-A showed up as a scaffold for the development of new agrochemicals. Complementing these findings, computational studies suggested that this benzophenone can interact effectively with transferase enzymes type, in special caffeic acid O-methyltransferase from S. bicolor (PDB code: 4PGH), indicating a possible mechanism of action in this plant.     

qNMR for profiling the production of fungal secondary metabolites

Analysis of complex mixtures is a common challenge in natural products research. Quantitative nuclear magnetic resonance spectroscopy offers analysis of complex mixtures at early stages and with benefits that are orthogonal to more common methods of quantitation, including ultraviolet absorption spectroscopy and mass spectrometry. Several experiments were conducted to construct a methodology for use in analysis of extracts of fungal cultures. A broadly applicable method was sought for analysis of both pure and complex samples through use of an externally calibrated method. This method has the benefit of not contaminating valuable samples with the calibrant, and it passed scrutiny for line fitting and reproducibility. The method was implemented to measure the yield of griseofulvin and dechlorogriseofulvin from three fungal isolates. An isolate of Xylaria cubensis (coded MSX48662) was found to biosynthesize griseofulvin in the greatest yield, 149 ± 8 mg per fermentation, and was selected for further supply experiments. Copyright © 2016 John Wiley & Sons, Ltd.     

含嘧啶氨基的三氨基取代三嗪衍生物的设计、合成及抗苹果树腐烂病菌活性

依据三嗪和嘧啶衍生物的抗菌特性以及生物活性叠加原理, 以三聚氯氰为起始原料, 设计、合成了系列新的含嘧啶氨基的2,4,6-三氨基取代-1,3,5-三嗪化合物. 化合物的结构经1H NMR, ESI-MS和元素分析等表征. 化合物的抗苹果树腐烂病菌活性测试结果表明, 大部分化合物对苹果树腐烂病菌具有显著的抑制作用, 如化合物2aa, 2ba, 2ca, 2da, 3ba和3ea在200 μg/mL浓度下的抑制率分别为96.33%, 98.17%, 97.25%, 97.71%, 98.39%和94.50%, 在100 μg/mL浓度下的抑制率也均在74%以上.