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1.
J Agric Food Chem ; 70(40): 12784-12795, 2022 Oct 12.
Article in English | MEDLINE | ID: mdl-36170206

ABSTRACT

Banana Fusarium wilt caused by Fusarium oxysporum f. sp. cubense (Foc) is the most destructive soil-borne fungal disease. Tropical race 4 (Foc TR4), one of the strains of Foc, can infect many commercial cultivars, which represents a threat to global banana production. Currently, there are hardly any effective chemical fungicides to control the disease. To search for natural product-based fungicides for controlling banana Fusarium wilt, we identified a novel strain Streptomyces yongxingensis sp. nov. (JCM 34965) from a marine soft coral, from which a bioactive compound, niphimycin C, was isolated using an activity-guided method. Niphimycin C exhibited a strong antifungal activity against Foc TR4 with a value of 1.20 µg/mL for EC50 and obviously inhibited the mycelial growth and spore germination of Foc TR4. It caused the functional loss of mitochondria and the disorder of metabolism of Foc TR4 cells. Further study showed that niphimycin C reduced key enzyme activities of the tricarboxylic acid (TCA) cycle and the electron transport chain (ETC). It displayed broad-spectrum antifungal activities against the selected 12 phytopathogenic fungi. In pot experiments, niphimycin C reduced the disease indexes in banana plantlets and inhibited the infection of Foc TR4 in roots. Hence, niphimycin C could be a promising agrochemical fungicide for the management of fungal diseases.


Subject(s)
Biological Products , Fungicides, Industrial , Fusarium , Musa , Streptomyces , Agrochemicals , Antifungal Agents/pharmacology , Fungicides, Industrial/pharmacology , Fusarium/genetics , Gene Expression Profiling , Guanidines , Mitochondria , Musa/genetics , Plant Diseases/microbiology , Plant Diseases/prevention & control , Soil , Tricarboxylic Acids
2.
ACS Omega ; 6(1): 401-407, 2021 Jan 12.
Article in English | MEDLINE | ID: mdl-33458491

ABSTRACT

Bioassay-guided fractionation of the ethyl acetate extract of Amyris elemifera leaves was carried out to identify phytotoxic and antifungal constituents. A novel phytotoxic furanocoumarin 8-(3-methylbut-2-enyloxy)-marmesin acetate (1) and its deacyl analog 8-(3-methylbut-2-enyloxy)-marmesin (2) were isolated. The X-ray crystal structure determination is reported for the first time for 1. Both 1 and 2 have the S configuration at C-2' based on X-ray crystallographic data. Both these compounds inhibited the growth of the dicot Lactuca sativa (lettuce) and the monocot Agrostis stolonifera with a more pronounced inhibitory effect on the monocots at 330 µM by 1. In Lemna paucicostata Hegelm phytotoxicity bioassay, the IC50 value for 1 was 26 µM, whereas 2 had an IC50 value of 102 µM. Compounds 1 and 2 were weakly antifungal against Colletotrichum fragariae Brooks in TLC bioautography.

3.
J Agric Food Chem ; 68(28): 7324-7332, 2020 Jul 15.
Article in English | MEDLINE | ID: mdl-32530612

ABSTRACT

Natural products are a source of many novel compounds with biological activity for the discovery of new pesticides and pharmaceuticals. Quinoxaline is a fused N-heterocycle in many natural products and synthetic compounds, and seven novel quinoxaline derivatives were designed and synthesized via three steps. Pesticidal activities of title quinoxaline derivatives were bioassayed. Most of these compounds had herbicidal, fungicidal, and insecticidal activities. The compounds 2-(6-methoxy-2-oxo-3-phenylquinoxalin-1(2H)-yl)acetonitrile (3f) and 1-allyl-6-methoxy-3-phenylquinoxalin-2(1H)-one (3g) were the most active herbicides and fungicides. Mode-of-action studies indicated that 3f is a protoprophyrinogen oxidase-inhibiting herbicide. Compound 3f also possessed broad-spectrum fungicidal activity against the plant pathogen Colletotrichum species. Some of these compounds also had insecticidal activity. Molecular docking and DFT analysis can potentially be used to design more active compounds.


Subject(s)
Pesticides/chemical synthesis , Pesticides/pharmacology , Quinoxalines/chemistry , Animals , Colletotrichum/drug effects , Colletotrichum/growth & development , Fungicides, Industrial/chemical synthesis , Fungicides, Industrial/chemistry , Fungicides, Industrial/pharmacology , Herbicides/chemical synthesis , Herbicides/chemistry , Herbicides/pharmacology , Insecta/drug effects , Insecta/growth & development , Insecticides/chemical synthesis , Insecticides/chemistry , Insecticides/pharmacology , Molecular Docking Simulation , Pesticides/chemistry , Plant Weeds/drug effects , Quinoxalines/pharmacology , Structure-Activity Relationship
4.
Chem Biodivers ; 16(5): e1800618, 2019 May.
Article in English | MEDLINE | ID: mdl-30901146

ABSTRACT

Trifluoromethylphenyl amides (TFMPAs) were designed and synthesized as potential pesticides. Thirty-three structures were evaluated for fungicidal activity against three Colletotrichum species using direct bioautography assays. Active compounds were subsequently tested against C. fragariae, C. gloeosporioides, C. acutatum, Phomopsis obscurans, P. viticola, Botrytis cinerea and Fusarium oxysporum. The study identified 2-chloro-N-[2,6-dichloro-4-(trifluoromethyl)phenyl]acetamide (7a) as showing the strongest antifungal activity, and the broadest activity spectrum in this set against Colletotrichum acutatum (at 48 and 72 h) and Phomopsis viticola (at 144 h). The presence of triethylamine in its complex with N-[2,6-dichloro-4-(trifluoromethyl)phenyl]-2,2,3,3,3-pentafluoropropanamide (7b') played an important role in the bioactivity, and depending on the concentration or fungal species it showed higher or lower activity than the parent amide. X-Ray crystallography has shown that the complex (7b') is an ion pair, (C10 H2 Cl2 F8 NO)- (C6 H16 N)+ , where a proton is transferred from the amide nitrogen to the triethylamine nitrogen and then connected by hydrogen bonding to the acyl oxygen (N-H 0.893 Å; H⋅⋅⋅O 1.850 Å; N⋅⋅⋅O 2.711 Å; N-H⋅⋅⋅O 161.2(13)°). Although none of these compounds were better than standards, this work revealed some potential lead structures for further development of active novel compounds.


Subject(s)
Amides/chemistry , Antifungal Agents/chemistry , Amides/pharmacology , Antifungal Agents/pharmacology , Colletotrichum/drug effects , Colletotrichum/growth & development , Crystallography, X-Ray , Drug Design , Ethylamines/chemistry , Hydrogen Bonding , Microbial Sensitivity Tests , Molecular Conformation , Plants/microbiology , Structure-Activity Relationship
5.
Molecules ; 24(5)2019 Feb 26.
Article in English | MEDLINE | ID: mdl-30813648

ABSTRACT

The discovery of potent natural and ecofriendly pesticides is one of the focuses of the agrochemical industry, and plant species are a source of many potentially active compounds. We describe the bioassay-guided isolation of antifungal and phytotoxic compounds from the ethyl acetate extract of Ambrosia salsola twigs and leaves. With this methodology, we isolated and identified twelve compounds (four chalcones, six flavonols and two pseudoguaianolide sesquiterpene lactones). Three new chalcones were elucidated as (S)-ß-Hydroxy-2',3,4,6'-tetrahydroxy-5-methoxydihydrochalcone (salsolol A), (S)-ß-Hydroxy-2',4,4',6'-tetrahydroxy-3-methoxydihydrochalcone (salsolol B), and (R)-α, (R)-ß-Dihydroxy-2',3,4,4',6'- pentahydroxydihydrochalcone (salsolol C) together with nine known compounds: balanochalcone, six quercetin derivatives, confertin, and neoambrosin. Chemical structures were determined based on comprehensive direct analysis in real time-high resolution mass spectrometry (HR-DART-MS), as well as 1D and 2D NMR experiments: Cosy Double Quantum Filter (DQFCOSY), Heteronuclear Multiple Quantum Coherence (HMQC) and Heteronuclear Multiple Bond Coherence (HMBC), and the absolute configurations of the chalcones were confirmed by CD spectra analysis. Crystal structure of confertin was determined by X-ray diffraction. The phytotoxicity of purified compounds was evaluated, and neoambrosim was active against Agrostis stolonifera at 1 mM, while confertin was active against both, Lactuca sativa and A. stolonifera at 1 mM and 100 µM, respectively. Confertin and salsolol A and B had IC50 values of 261, 275, and 251 µM, respectively, against Lemna pausicotata (duckweed). The antifungal activity was also tested against Colletotrichum fragariae Brooks using a thin layer chromatography bioautography assay. Both confertin and neoambrosin were antifungal at 100 µM, with a higher confertin activity than that of neoambrosin at this concentration.


Subject(s)
Ambrosia/chemistry , Fungicides, Industrial/isolation & purification , Fungicides, Industrial/pharmacology , Herbicides/isolation & purification , Herbicides/pharmacology , Circular Dichroism , Colletotrichum/drug effects , Fungicides, Industrial/chemistry , Herbicides/chemistry , Lactuca/drug effects , Molecular Structure , Plant Extracts/analysis , Plant Leaves/chemistry , Sesquiterpenes/chemistry , Sesquiterpenes/isolation & purification , X-Ray Diffraction
6.
J Agric Food Chem ; 67(7): 1973-1981, 2019 Feb 20.
Article in English | MEDLINE | ID: mdl-30685966

ABSTRACT

Eragrostis plana (Nees) is an allelopathic plant with invasive potential in South American pastures. To isolate and identify phytotoxic compounds from leaves and roots of E. plana, a bioassay-directed isolation of the bioactive constituents was performed. This is the first report on a new diterpene carbon skeleton, neocassane, and of three new neocassane diterpenes, neocassa-1,12(13),15-triene-3,14-dione, 1; 19-norneocassa-1,12(13),15-triene-3,14-dione, 2; and 14-hydroxyneocassa-1,12(17),15-triene-3-one, 3, identified from the roots. Compounds 1, 2, and 3 inhibited the growth of duckweed by 50% at concentrations of 109 ± 28, 200 ± 37, and 59 ± 15 µM, respectively. Compound 2 was fungicidal to Colletotrichum fragariae, Colletotrichum acutatum, and Colletotrichum gloeosporioides. The compounds identified here could explain the allelopathy of E. plana. The description of the newly discovered compounds, besides contributing to the chemical characterization of the species, may be the first step in the study of the potential of these compounds as bioherbicides.


Subject(s)
Diterpenes/isolation & purification , Eragrostis/chemistry , Herbicides , Agrostis/drug effects , Biological Control Agents , Colletotrichum/drug effects , Diterpenes/chemistry , Diterpenes/pharmacology , Fungicides, Industrial/pharmacology , Herbicides/chemistry , Herbicides/isolation & purification , Herbicides/pharmacology , Lactuca/drug effects , Plant Extracts/chemistry , Plant Extracts/pharmacology , Plant Leaves/chemistry , Plant Roots/chemistry
7.
J Org Chem ; 84(2): 666-678, 2019 01 18.
Article in English | MEDLINE | ID: mdl-30550716

ABSTRACT

The phytotoxin diplopyrone is considered to be the main phytotoxin in a fungus that is responsible for cork oak decline. A carbohydrate-based synthesis of the enantiomer of the structure proposed for diplopyrone has been developed from a commercially available derivative of d-galactose. Key steps in the synthesis are a highly stereoselective pyranose chain-extension based on methyltitanium, preparation of a vinyl glycoside via Isobe C-alkynylation-rearrangement/reduction, and RCM-based pyranopyran construction. Crystallographic and NMR analysis confirms an earlier report that the structure originally proposed for diplopyrone may require revision. Structural analogues were prepared for biological evaluation, the most promising being a pyranopyran nitrile synthesized from tri- O-acetyl-d-galactal by Ferrier cyanoglycosidation, Wittig chain extension, and lactonization. Biological assays revealed potent antibacterial activity for the nitrile analogue against common bacterial pathogens Edwardsiella ictaluri and Flavobacterium columnare that cause enteric septicemia (ESC) and columnaris disease, respectively, in catfish. The IC50 value of 0.002 against E. ictaluri indicates approximately 100 times greater potency than the antibiotic florfenicol used commercially for this disease. Phytotoxic activity for all three target compounds against duckweed was also observed. The antibiotic and phytotoxic activities of the new pyranopyrans synthesized in this study demonstrate the potential of such compounds as antibiotics and herbicides.


Subject(s)
Anti-Bacterial Agents/pharmacology , Edwardsiella ictaluri/drug effects , Flavobacterium/drug effects , Pyrans/pharmacology , Pyrones/pharmacology , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Microbial Sensitivity Tests , Molecular Conformation , Pyrans/chemical synthesis , Pyrans/chemistry , Pyrones/chemistry , Stereoisomerism
8.
Mem. Inst. Oswaldo Cruz ; 112(10): 692-697, Oct. 2017. tab, graf
Article in English | LILACS | ID: biblio-894841

ABSTRACT

BACKGROUND Endophytic fungi, present mainly in the Ascomycota and Basidiomycota phyla, are associated with different plants and represent important producers of bioactive natural products. Brazil has a rich biodiversity of plant species, including those reported as being endemic. Among the endemic Brazilian plant species, Vellozia gigantea (Velloziaceae) is threatened by extinction and is a promising target to recover endophytic fungi. OBJECTIVE The present study focused on bioprospecting of bioactive compounds of the endophytic fungi associated with V. gigantea, an endemic, ancient, and endangered plant species that occurs only in the rupestrian grasslands of Brazil. METHODS The capability of 285 fungal isolates to produce antimicrobial and antimalarial activities was examined. Fungi were grown at solid-state fermentation to recover their crude extracts in dichloromethane. Bioactive extracts were analysed by chromatographic fractionation and NMR and displayed compounds with antimicrobial, antimycobacterial, and antimalarial activities. FINDINGS Five fungi produced antimicrobial and antimalarial compounds. Extracts of Diaporthe miriciae showed antifungal, antibacterial, and antimalarial activities; Trichoderma effusum displayed selective antibacterial activity against methicillin-resistant Staphylococcus aureus and Mycobacterium intracellulare; and three Penicillium species showed antibacterial activity. D. miriciae extract contained highly functionalised secondary metabolites, yielding the compound epoxycytochalasin H with high antimalarial activity against the chloroquine-resistant strain of Plasmodium falciparum, with an IC50 approximately 3.5-fold lower than that with chloroquine. MAIN CONCLUSION Our results indicate that V. gigantea may represent a microhabitat repository hotspot of potential fungi producers of bioactive compounds and suggest that endophytic fungal communities might be an important biological component contributing to the fitness of the plants living in the rupestrian grassland.


Subject(s)
Plasmodium/drug effects , Microbial Sensitivity Tests , Magnoliopsida/classification , Magnoliopsida/microbiology , Mitosporic Fungi/drug effects , Gram-Negative Aerobic Bacteria/drug effects , Gram-Positive Bacteria/drug effects , Anti-Bacterial Agents/isolation & purification , Anti-Bacterial Agents/pharmacology , Antifungal Agents/isolation & purification , Antifungal Agents/pharmacology , Antimalarials/isolation & purification , Antimalarials/pharmacology , Tropical Climate , Biological Assay , Candida/drug effects , Endophytes/chemistry
9.
Mem Inst Oswaldo Cruz ; 112(10): 692-697, 2017 Oct.
Article in English | MEDLINE | ID: mdl-28953997

ABSTRACT

BACKGROUND: Endophytic fungi, present mainly in the Ascomycota and Basidiomycota phyla, are associated with different plants and represent important producers of bioactive natural products. Brazil has a rich biodiversity of plant species, including those reported as being endemic. Among the endemic Brazilian plant species, Vellozia gigantea (Velloziaceae) is threatened by extinction and is a promising target to recover endophytic fungi. OBJECTIVE: The present study focused on bioprospecting of bioactive compounds of the endophytic fungi associated with V. gigantea, an endemic, ancient, and endangered plant species that occurs only in the rupestrian grasslands of Brazil. METHODS: The capability of 285 fungal isolates to produce antimicrobial and antimalarial activities was examined. Fungi were grown at solid-state fermentation to recover their crude extracts in dichloromethane. Bioactive extracts were analysed by chromatographic fractionation and NMR and displayed compounds with antimicrobial, antimycobacterial, and antimalarial activities. FINDINGS: Five fungi produced antimicrobial and antimalarial compounds. Extracts of Diaporthe miriciae showed antifungal, antibacterial, and antimalarial activities; Trichoderma effusum displayed selective antibacterial activity against methicillin-resistant Staphylococcus aureus and Mycobacterium intracellulare; and three Penicillium species showed antibacterial activity. D. miriciae extract contained highly functionalised secondary metabolites, yielding the compound epoxycytochalasin H with high antimalarial activity against the chloroquine-resistant strain of Plasmodium falciparum, with an IC50 approximately 3.5-fold lower than that with chloroquine. MAIN CONCLUSION: Our results indicate that V. gigantea may represent a microhabitat repository hotspot of potential fungi producers of bioactive compounds and suggest that endophytic fungal communities might be an important biological component contributing to the fitness of the plants living in the rupestrian grassland.


Subject(s)
Anti-Bacterial Agents/pharmacology , Antifungal Agents/pharmacology , Antimalarials/pharmacology , Endophytes/chemistry , Magnoliopsida/microbiology , Anti-Bacterial Agents/isolation & purification , Antifungal Agents/isolation & purification , Antimalarials/isolation & purification , Biological Assay , Candida/drug effects , Gram-Negative Bacteria/drug effects , Gram-Positive Bacteria/drug effects , Magnoliopsida/classification , Microbial Sensitivity Tests , Mitosporic Fungi/drug effects , Plasmodium/drug effects , Tropical Climate
10.
Pest Manag Sci ; 73(5): 953-959, 2017 May.
Article in English | MEDLINE | ID: mdl-27448764

ABSTRACT

BACKGROUND: Aedes aegypti is a major mosquito vector for the transmission of serious diseases, especially dengue and yellow fever. More than 1 billion people in developing countries are at risk. The widespread and continual use of pesticides can lead to resistant mosquitoes. In order to maintain mosquito control gains, it is critical to develop and evaluate novel bioactive molecules that differ in mode of action from currently used products. RESULTS: A series of novel pyrimidine derivatives were designed and synthesized. Their structures were elucidated by proton nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry. The biological activities of these compounds were tested against Ae. aegypti. Many of them exhibited insecticidal activity against adult and larval mosquitoes. Compound 4d displayed relatively good activity to reach 70% mortality at 2 µg mL-1 . Furthermore, density functional theory calculations were established to study the structure-activity relationship of these novel compounds. CONCLUSION: A practical synthetic route for pyrimidine derivatives is presented. This study suggests that these pyrimidine derivatives exhibit some activity against the yellow fever mosquito and, with further structure modification, could be novel lead compounds for the development of insecticides against mosquitoes. © 2016 Society of Chemical Industry.


Subject(s)
Aedes , Insecticides/chemistry , Insecticides/chemical synthesis , Pyrimidines/chemistry , Pyrimidines/chemical synthesis , Urea/chemistry , Animals , Larva/drug effects , Models, Molecular , Molecular Conformation , Mosquito Control , Quantum Theory , Structure-Activity Relationship
11.
Chem Biodivers ; 13(9): 1165-1177, 2016 Sep.
Article in English | MEDLINE | ID: mdl-27450661

ABSTRACT

In our continuing effort to discover natural product-based pest management agents, derivatives of 3,5-dimethoxystilbene were synthesized yielding 27 new and six known compounds. Compounds 11 and 12 showed strong Aedes aegypti larvicidal activity (LC50 45.31 and 49.93 µm, respectively). Furthermore, 11 and 12 exhibited high effectiveness against larvae of pesticide-susceptible and pyrethroid-resistant strains of Ae. aegypti; activity against the adult mosquitoes was low. Compounds 6f, 6g, and 6i at either 83.3 or 166.7 µg/ml reduced the mobility of second-stage juveniles (J2) of the root-knot nematode (Meloidogyne incognita) that hatched from eggs immersed in the test compounds for 7 days. However, there was little or no effect on J2 placed directly into these compounds, and none of the analogs suppressed M. incognita egg hatch. The compounds were tested for inhibition of some agriculturally important fungi; 6a, 7a, and 7e demonstrated strong inhibition of Colletotrichum species. Activity of the stilbenes against some human pathogens was also explored; 11, 12, and 16 showed moderate inhibitory activity against Cryptococcus neoformans, Staphylococcus aureus, methicillin-resistant S. aureus, and Mycobacterium intracellulare. Except for 11 and 12, which were active against mosquito larvae and some human pathogens, no single analog demonstrated activity in all the tests, indicating specific activities. Synthesis of the analogs and structure-activity relationships are discussed.


Subject(s)
Aedes/drug effects , Anti-Bacterial Agents/pharmacology , Antifungal Agents/pharmacology , Insecticides/pharmacology , Stilbenes/pharmacology , Animals , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Antifungal Agents/chemical synthesis , Antifungal Agents/chemistry , Bacteria/drug effects , Dose-Response Relationship, Drug , Fungi/drug effects , Insecticides/chemical synthesis , Insecticides/chemistry , Larva/drug effects , Microbial Sensitivity Tests , Molecular Structure , Stilbenes/chemical synthesis , Stilbenes/chemistry , Structure-Activity Relationship
12.
Chem Biodivers ; 13(7): 918-30, 2016 Jul.
Article in English | MEDLINE | ID: mdl-27273012

ABSTRACT

The endophytic fungal community associated with the ethnomedicinal plant Echinacea purpurea was investigated as well as its potential for providing antifungal compounds against plant pathogenic fungi. A total of 233 endophytic fungal isolates were obtained and classified into 42 different taxa of 16 genera, of which Alternaria alternata, Colletotrichum dematium, and Stagonosporopsis sp. 2 are the most frequent colonizers. The extracts of 29 endophytic fungi displayed activities against important phytopathogenic fungi. Eight antifungal extracts were selected for chemical analysis. Forty fatty acids were identified by gas chromatography-flame-ionization detection (GC-FID) analysis. The compounds (-)-5-methylmellein and (-)-(3R)-8-hydroxy-6-methoxy-3,5-dimethyl-3,4-dihydroisocoumarin were isolated from Biscogniauxia mediterraneaEPU38CA crude extract. (-)-5-Methylmellein showed weak activity against Phomopsis obscurans, P. viticola, and Fusarium oxysporum, and caused growth stimulation of C. fragariae, C. acutatum, C. gloeosporioides, and Botrytis cinerea. (-)-(3R)-8-Hydroxy-6-methoxy-3,5-dimethyl-3,4-dihydroisocoumarin appeared slightly more active in the microtiter environment than 5-methylmellein. Our results indicate that E. purpurea lives symbiotically with different endophytic fungi, which are able to produce bioactive fatty acids and aromatic compounds active against important phytopathogenic fungi. The detection of the different fatty acids and aromatic compounds produced by the endophytic community associated with wild E. purpurea suggests that it may have intrinsic mutualistic resistance against phytopathogen attacks in its natural environment.


Subject(s)
Antifungal Agents/analysis , Antifungal Agents/pharmacology , Asteraceae/microbiology , Bioprospecting , Endophytes/chemistry , Mitosporic Fungi/drug effects , Phylogeny , Antifungal Agents/chemistry , Dose-Response Relationship, Drug , Endophytes/isolation & purification , Fatty Acids/analysis , Fatty Acids/chemistry , Fatty Acids/pharmacology , Medicine, Traditional , Microbial Sensitivity Tests , Mitosporic Fungi/classification , Molecular Conformation , Structure-Activity Relationship
13.
Nat Prod Res ; 30(4): 478-81, 2016.
Article in English | MEDLINE | ID: mdl-25812930

ABSTRACT

Endophytic fungi represent ubiquitous microbial organisms able to live in the tissues of different plants around the world and represent a prolific source of bioactive metabolites. In the present study, the endophytic fungus Aspergillus calidoustus was isolated from the medicinal plant Acanthospermum australe (Asteraceae), and identified using molecular, physiological and morphological methods. A methylene chloride crude extract of A. calidoustus has been produced and subjected to antifungal bioassay-directed fractionation which resulted in the isolation of the two bioactive compounds: ophiobolin K and 6-epi-ophiobolin K. These pure compounds displayed antifungal activity against fungal plant pathogens, protozoal activity against Trypanosoma cruzi, and cytotoxic activity against human tumoral cell lines. The results show that A. calidoustus was able to produce the antifungal and cytotoxic metabolites ophiobolin K and 6-epi-ophiobolin K, which may help the fungus to colonise and occupy the substratum as well as survive in natural environments.


Subject(s)
Antifungal Agents/chemistry , Antimalarials/chemistry , Antineoplastic Agents/chemistry , Aspergillus/chemistry , Sesterterpenes/chemistry , Antifungal Agents/isolation & purification , Antimalarials/isolation & purification , Antineoplastic Agents/isolation & purification , Asteraceae/microbiology , Cell Line, Tumor , Humans
14.
Environ Microbiol ; 18(1): 232-45, 2016 Jan.
Article in English | MEDLINE | ID: mdl-26235221

ABSTRACT

This study assessed the diversity of cultivable rock-associated fungi from Atacama Desert. A total of 81 fungal isolates obtained were identified as 29 Ascomycota taxa by sequencing different regions of DNA. Cladosporium halotolerans, Penicillium chrysogenum and Penicillium cf. citrinum were the most frequent species, which occur at least in four different altitudes. The diversity and similarity indices ranged in the fungal communities across the latitudinal gradient. The Fisher-α index displayed the higher values for the fungal communities obtained from the siltstone and fine matrix of pyroclastic rocks with finer grain size, which are more degraded. A total of 23 fungal extracts displayed activity against the different targets screened. The extract of P. chrysogenum afforded the compounds α-linolenic acid and ergosterol endoperoxide, which were active against Cryptococcus neoformans and methicillin-resistance Staphylococcus aureus respectively. Our study represents the first report of a new habitat of fungi associated with rocks of the Atacama Desert and indicated the presence of interesting fungal community, including species related with saprobes, parasite/pathogen and mycotoxigenic taxa. The geological characteristics of the rocks, associated with the presence of rich resident/resilient fungal communities suggests that the rocks may provide a favourable microenvironment fungal colonization, survival and dispersal in extreme conditions.


Subject(s)
Ascomycota/metabolism , Cladosporium/metabolism , Cryptococcus neoformans/drug effects , Geologic Sediments/microbiology , Methicillin-Resistant Staphylococcus aureus/drug effects , Penicillium/metabolism , Ascomycota/classification , Ascomycota/genetics , Ascomycota/isolation & purification , Chile , Cladosporium/classification , Cladosporium/genetics , Cladosporium/isolation & purification , Desert Climate , Ecology , Ecosystem , Molecular Sequence Data , Penicillium/classification , Penicillium/genetics , Penicillium/isolation & purification
15.
Nat Prod Commun ; 11(10): 1595-1600, 2016 Oct.
Article in English | MEDLINE | ID: mdl-30549627

ABSTRACT

. Natural antifungal agents are generally broad-spectrum compounds with low mammalian and environmental toxicity. Cladosporin is a naturally occurring fungal metabolite mainly isolated from the endophytic fungus Cladosporium cladosporioides. This review article summarizes the chemistry and biological - properties of cladosporin covering references published from 1971-2016, including the source, phytochemical characterization, biosynthesis, total synthesis, structure and activity (SAR), and biological activity of cladosporin. Cladosporin exhibited potent antibacterial, antifungal, insecticidal, and anti-inflammatory activities, as well as plant growth regulatory effects. More importantly, cladosporin was identified as having potent, nanomolar, antiparasitic activity against both Plasmodiumfalciparum blood and liver stages via specific inhibition of protein synthesis. This provides a new approach for the design of isocoumarin- based compounds for the treatment of malaria. Herbicidal activity and antifungal activity against Cryptococcus neoformans (C50 value of 17.7 µg/mL) of cladosporin are also described here in the review for the first time. Cladosporin selectively inhibited the growth of a monocot (agostis) and showed no activity against a dicot (lettuce), which indicates its great potential as a selective herbicide for monocots in agriculture use. The above data suggest that cladosporin has great potential utility as a lead compound in the development of agrochemicals against certain plant pathogens and pharmaceuticals against drug-resistant bacteria and parasites.


Subject(s)
Antifungal Agents/pharmacology , Isocoumarins/pharmacology , Animals , Antifungal Agents/chemistry , Cladosporium/chemistry , Cladosporium/metabolism , Herbicides , Humans , Isocoumarins/chemistry
16.
Nat Prod Commun ; 11(7): 931-934, 2016 Jul.
Article in English | MEDLINE | ID: mdl-30452165

ABSTRACT

Phytochemical investigation of the roots and rhizomes of Pileostegia viburnoides var. glabrescens led to the isolation and identification of 31 compounds (1-31), 25 of which (1-2, 4-7, 9-12, 15-18, 21-31) were isolated from the Pileostegia genus for the first time. 7α-Hydroxyfriedelan-3-one-26-ol-29-oic acid (1) is a new friedelane-type triterpene. The structure of n-butyl-ß-D-fructopyranoside (2) was determined by single-crystal X-ray diffraction. Compounds 4 and 12 displayed marginal cytotoxicity against the P388 murine leukemia cell line with IC50 values of 13.4 µM and 25.0 µM, respectively. Compound 23 exhibited marginal anti-inflammatory activity by the inhibition of lipopolysaccharide induced nitric oxide production in RAW 264.7 macrophage cells, with an IC50 value of 32.0 µM. Compounds 3, 8-10, 25, and 27 were phytotoxic to the dicot Lactuca sativa (lettuce) and/or the monocot Agrostis stolonifera (bentgrass).


Subject(s)
Plant Roots/chemistry , Rhizome/chemistry , Saxifragaceae/chemistry , Triterpenes/chemistry , Animals , Anti-Inflammatory Agents/chemistry , Anti-Inflammatory Agents/pharmacology , Antineoplastic Agents, Phytogenic/chemistry , Antineoplastic Agents, Phytogenic/pharmacology , Cell Line, Tumor , Cell Survival , Computational Biology , Herbicides/chemistry , Herbicides/pharmacology , Lactuca/drug effects , Mice , Molecular Structure , Seeds/drug effects , Triterpenes/pharmacology
17.
J Chem Ecol ; 41(7): 602-12, 2015 Jul.
Article in English | MEDLINE | ID: mdl-26133676

ABSTRACT

Zinnia elegans Jacq. plants are infected by a fungus that causes dark red spots with necrosis on leaves, particularly in late spring to the middle of summer in the Mid-South of the United States. This fungal disease causes the leaves to wilt and eventually kills the plant. The fungus was isolated, cultured in potato dextrose broth, and identified as Nigrospora sphaerica by molecular techniques. Two major lactone metabolites (phomalactone and catenioblin A) were isolated from liquid culture of N. sphaerica isolated from Z. elegans. When injected into leaves of Z. elegans, phomalactone caused lesions similar to those of the fungus. The lesion sizes were proportional to the concentration of the phomalactone. Phomalactone, but not catenioblin A, was phytotoxic to Z. elegans and other plant species by inhibition of seedling growth and by causing electrolyte leakage from photosynthetic tissues of both Z. elegans leaves and cucumber cotyledons. This latter effect may be related to the wilting caused by the fungus in mature Z. elegans plants. Phomalactone was moderately fungicidal to Coletotrichum fragariae and two Phomopsis species, indicating that the compound may keep certain other fungi from encroaching into plant tissue that N. sphaerica has infected. Production of large amounts of phomalactone by N. sphaerica contributes to the pathogenic behavior of this fungus, and may have other ecological functions in the interaction of N. sphaerica with other fungi. This is the first report of isolation of catenioblin A from a plant pathogenic fungus. The function of catenioblin A is unclear, as it was neither significantly phyto- nor fungitoxic.


Subject(s)
Ascomycota/metabolism , Asteraceae/microbiology , Plant Diseases/microbiology , Plant Leaves/microbiology , Pyrones/isolation & purification , Pyrones/metabolism , Ascomycota/chemistry , Ascomycota/isolation & purification , Asteraceae/growth & development , Lactones/chemistry , Lactones/isolation & purification , Lactones/metabolism , Plant Leaves/growth & development , Pyrones/chemistry
18.
Nat Prod Commun ; 10(6): 1071-4, 2015 Jun.
Article in English | MEDLINE | ID: mdl-26197554

ABSTRACT

The Himalayan region is very rich in a great variety of medicinal plants. In this investigation the essential oils of two selected species are described for their antimicrobial and larvicidal as well as biting deterrent activities. Additionally, the odors are characterized. Analyzed by simultaneous GC-MS and GC-FID, the essential oils' chemical compositions are given. The main components of Skimmia laureola oil were linalool and linalyl acetate whereas sabinene was found as the main compound for Juniperus macropoda essential oil. Antibacterial testing by agar dilution assay revealed highest activity of S. laureola oil against all tested bacteria, followed by J. macropoda oil. Antifungal activity was evaluated against the strawberry anthracnose causing plant pathogens Colletotrichum acutatum, C. fragariae and C. gloeosporioides. Juniperus macropoda essential oil indicated higher antifungal activity against all three pathogens than S. laureola oil. Both essential oils showed biting deterrent activity above solvent control but low larvicidal activity.


Subject(s)
Anti-Infective Agents/chemistry , Anti-Infective Agents/pharmacology , Juniperus/chemistry , Oils, Volatile/chemistry , Oils, Volatile/pharmacology , Plant Oils/chemistry , Plant Oils/pharmacology , Rutaceae/chemistry , Bacteria/drug effects , Candida/drug effects , Microbial Sensitivity Tests
19.
Nat Prod Commun ; 10(1): 133-8, 2015 Jan.
Article in English | MEDLINE | ID: mdl-25920235

ABSTRACT

The essential oils of two representatives of the Lamiaceae, Dracocephalum heterophyllum Benth. and Hyssopus officinalis L., are described for their antifungal, antibacterial, larvicidal and inect biting deterrent activities. Additionally, the chemical compositions of the essential oils, analyzed by simultaneous GC-MS and GC-FID, and odor descriptions are given. The main components of H. officinalis oil were pinocarvone, cis-pinocamphone, and ß-pinene. Citronellol was found as the main compound of D. heterophyllum essential oil. Antibacterial testing by agar dilution assay revealed greater activity of D. heterophyllum against Staphylococcus aureus compared with H. officinalis. D. heterophyllum essential oil also showed promising antifungal activity against Colletotrichum species and was more toxic to Aedes aegypti larvae in a larvicial bioassay. Both essential oils showed high activity in the biting deterrent bioassay.


Subject(s)
Anti-Bacterial Agents/analysis , Antifungal Agents/analysis , Insect Repellents/analysis , Lamiaceae/chemistry , Oils, Volatile/chemistry , Aedes , Animals , Asia , Microbial Sensitivity Tests
20.
Nat Prod Commun ; 10(1): 143-8, 2015 Jan.
Article in English | MEDLINE | ID: mdl-25920237

ABSTRACT

Nerolidol and its derivatives, namely cis-nerolidol, O-methyl-nerolidol, O-ethyl-nerolidol, (-)-α-bisabolol, trans,trans-farnesol and its main natural source cabreuva essential oil, were tested for their antimicrobial activity against airborne microbes and antifungal properties against plant pathogens. Among the tested compounds, α-bisabolol was the most effective antimicrobial agent and trans,trans-farnesol showed the best antifungal activity.


Subject(s)
Air Microbiology , Anti-Infective Agents/analysis , Sesquiterpenes/chemistry , Fabaceae , Microbial Sensitivity Tests , Oils, Volatile
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