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1.
Chemosphere ; 263: 127937, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32828056

RESUMO

The cyanobacterium Microcoleus autumnalis grows as thick benthic mats in rivers and is becoming increasingly prevalent around the world. M. autumnalis can produce high concentrations of anatoxins and ingestion of benthic mats has led to multiple dog deaths over the past two decades. M. autumnalis produces a suite of different anatoxin congeners including anatoxin-a (ATX), dihydroanatoxin-a, (dhATX), homoanatoxin-a and dihydrohomoanatoxin-a. Benthic mat samples often contain high levels of dhATX, but there is little toxicology information on this congener. In the present study, natural versions of dhATX and ATX were purified from cyanobacteria to determine the acute toxicity by different routes of administration using mice. Nuclear magnetic resonance spectroscopy was used to confirm the putative structure of dhATX. By intraperitoneal (ip) injection, the median lethal dose (LD50) for dhATX was 0.73 mg/kg, indicating a reduced toxicity compared to ATX (LD50 of 0.23 mg/kg). However, by oral administration (both gavage and feeding), dhATX was more toxic than ATX (gavage LD50 of 2.5 mg/kg for dhATX and 10.6 mg/kg for ATX; feeding LD50 of 8 mg/kg for dhATX and 25 mg/kg for ATX). The relative nicotinic acetylcholine receptor-binding affinities of ATX and dhATX were determined using the Torpedo electroplaque assay which showed consistency with the relative toxicity determined by ip injection. This work highlights that toxicity studies based solely on ip injection may not yield LD50 values that are relevant to those derived via oral administration, and hence, do not provide a good estimate of the risk posed to human and animal health in situations where oral ingestion is the likely route of exposure. The high acute oral toxicity of dhATX, and its abundance in M. autumnalis proliferations, demonstrates that it is an important environmental contaminant that warrants further investigation.


Assuntos
Cianobactérias/metabolismo , Prolina/análogos & derivados , Tropanos/toxicidade , Animais , Toxinas Bacterianas/toxicidade , Compostos Bicíclicos Heterocíclicos com Pontes/toxicidade , Cianobactérias/química , Cães , Humanos , Camundongos , Prolina/toxicidade , Rios/química
2.
Ecotoxicol Environ Saf ; 208: 111515, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33099142

RESUMO

In order to study the toxicity of the cyanobacterial non-protein amino acids (NPAAs) L-ß-N-methylamino-L-alanine (BMAA) and its structural isomer L-2,4-diaminobutyric acid (DAB) in the forage crop plant alfalfa (Medicago sativa), seedlings were exposed to NPAA-containing media for four days. Root growth was significantly inhibited by both treatments. The content of derivatised free and protein-bound BMAA and DAB in seedlings was then analysed by LC-MS/MS. Both NPAAs were detected in free and protein-bound fractions with higher levels detected in free fractions. Compared to shoots, there was approximately tenfold more BMAA and DAB in alfalfa roots. These results suggest that NPAAs might be taken up into crop plants from contaminated irrigation water and enter the food chain. This may present an exposure pathway for NPAAs in humans.


Assuntos
Diamino Aminoácidos/metabolismo , Aminobutiratos/metabolismo , Produtos Agrícolas/metabolismo , Diamino Aminoácidos/toxicidade , Aminobutiratos/toxicidade , Bioacumulação , Cromatografia Líquida , Produtos Agrícolas/efeitos dos fármacos , Cianobactérias/química , Humanos , Isomerismo , Neurotoxinas/análise , Plântula/química , Espectrometria de Massas em Tandem
3.
J Appl Microbiol ; 130(1): 50-60, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32594639

RESUMO

AIM: Emergence of extended antibiotic resistance among several human bacterial pathogens often leads to the failure of existing antibiotics to treat bacterial infections worldwide. Hence, the present study is aimed to explore antibacterial activity of marine cyanobacterium against MDR pathogens. METHODS AND RESULTS: The cyanobacterial samples were collected and isolated from Thondi Palk Strait region. The isolate was subjected to polarity based solvent extraction and checked for their antibacterial activity against test bacterial pathogens. The active principles from chloroform extract of Oxynema thaianum (CEOT) were partially purified through thin layer chromatography (TLC). The active principle with highest activity was further characterized by FTIR, high performance liquid chromatography (HPLC) and gas chromatography mass spectrometry (GC-MS) analysis. Among the eight extracts tested, CEOT showed effective zone of clearance against ESBL producing Escherichia coli and Klebsiella pneumoniae in disc diffusion method. In TLC, all the purified five fractions were eluted and tested for their antibacterial activity against test pathogens. The third fraction showing maximum activity was subjected to HPLC analysis for checking its purity. In GC-MS analysis, 9-octadecenoic acid, methyl ester and hexadecanoic acid were identified as the major chemical compounds. CONCLUSION: Hence, the present study was concluded that O. thaianum ALU PBC5 is a promising agent to treat ESBL producing MDR bacterial pathogens. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the pioneer study on screening and isolation of bioactive compounds from the marine cyanobacteria against MDR pathogens such as E. coli and K. pneumoniae. Here, 9-octadecenoic acid, methyl ester and hexadecanoic acid were identified as the major chemical compounds through TLC, FTIR, HPLC and GC-MS. From this screen, we identified the bioactive compounds against ESBL producing multidrug resistant pathogens such as E. coli and K. pneumoniae.


Assuntos
Antibacterianos/farmacologia , Cianobactérias/química , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Enterobacteriaceae/efeitos dos fármacos , Antibacterianos/química , Antibacterianos/isolamento & purificação , Clorofórmio/química , Enterobacteriaceae/enzimologia , Humanos , Testes de Sensibilidade Microbiana , beta-Lactamases/metabolismo
4.
Sci Rep ; 10(1): 15564, 2020 09 23.
Artigo em Inglês | MEDLINE | ID: mdl-32968135

RESUMO

The Orange Carotenoid Protein (OCP) is a water-soluble protein that governs photoprotection in many cyanobacteria. The 35 kDa OCP is structurally and functionally modular, consisting of an N-terminal effector domain (NTD) and a C-terminal regulatory domain (CTD); a carotenoid spans the two domains. The CTD is a member of the ubiquitous Nuclear Transport Factor-2 (NTF2) superfamily (pfam02136). With the increasing availability of cyanobacterial genomes, bioinformatic analysis has revealed the existence of a new family of proteins, homologs to the CTD, the C-terminal domain-like carotenoid proteins (CCPs). Here we purify holo-CCP2 directly from cyanobacteria and establish that it natively binds canthaxanthin (CAN). We use small-angle X-ray scattering (SAXS) to characterize the structure of this carotenoprotein in two distinct oligomeric states. A single carotenoid molecule spans the two CCPs in the dimer. Our analysis with X-ray footprinting-mass spectrometry (XFMS) identifies critical residues for carotenoid binding that likely contribute to the extreme red shift (ca. 80 nm) of the absorption maximum of the carotenoid bound by the CCP2 dimer and a further 10 nm shift in the tetramer form. These data provide the first structural description of carotenoid binding by a protein consisting of only an NTF2 domain.


Assuntos
Proteínas de Bactérias/ultraestrutura , Cantaxantina/química , Cianobactérias/ultraestrutura , Proteínas de Transporte Nucleocitoplasmático/ultraestrutura , Proteínas de Bactérias/química , Cristalografia por Raios X , Cianobactérias/química , Proteínas de Transporte Nucleocitoplasmático/química , Proteínas de Transporte Nucleocitoplasmático/genética , Ligação Proteica/efeitos dos fármacos , Domínios Proteicos/genética , Espalhamento a Baixo Ângulo
5.
Int J Nanomedicine ; 15: 6033-6066, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32884261

RESUMO

Green synthesis of nanoparticles (NPs) is a global ecofriendly method to develop and produce nanomaterials with unique biological, physical, and chemical properties. Recently, attention has shifted toward biological synthesis, owing to the disadvantages of physical and chemical synthesis, which include toxic yields, time and energy consumption, and high cost. Many natural sources are used in green fabrication processes, including yeasts, plants, fungi, actinomycetes, algae, and cyanobacteria. Cyanobacteria are among the most beneficial natural candidates used in the biosynthesis of NPs, due to their ability to accumulate heavy metals from their environment. They also contain a variety of bioactive compounds, such as pigments and enzymes, that may act as reducing and stabilizing agents. Cyanobacteria-mediated NPs have potential antibacterial, antifungal, antialgal, anticancer, and photocatalytic activities. The present review paper highlights the characteristics and applications in various fields of NPs produced by cyanobacteria-mediated synthesis.


Assuntos
Cianobactérias/metabolismo , Nanopartículas/química , Nanotecnologia/métodos , Animais , Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Antineoplásicos/química , Antineoplásicos/farmacologia , Antioxidantes/química , Antioxidantes/farmacologia , Cianobactérias/química , Química Verde , Humanos
6.
PLoS One ; 15(8): e0237258, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32756605

RESUMO

Aquatic weeds such as muskgrass (Chara spp.), water hyacinth (Eichhornia crassipes), water lettuce (Pistia stratiotes), hydrilla (Hydrilla verticillate), filamentous algae (Lyngbya wollei), and duckweed (Lemna minor) thrive in farm canals within the Everglades Agricultural Area of South Florida. Their presence, particularly during the summer months is an environmental concern with regards to water quality, in addition to being a nuisance because of their ability to multiply and spread rapidly in open waters causing restricted drainage/irrigation flow and low dissolved oxygen levels. Chemical control is effective but can have undesirable off-target effects, so reduced herbicide use is desirable. Hence, need exists to discover ways in which these weeds could be best managed or utilized. The objective of this research was to evaluate the allelopathic effect of these weeds to determine their use as potential biopesticides. Six aqueous extracts were tested against 100 bacterial strains isolated from plants and soil to evaluate their antimicrobial activity. These extracts were also used to determine their insecticidal and antifeedant effects on fall armyworm (FAW, Spodoptera frugiperda). Both extracts and powder form of the aquatic weeds were tested for their herbicidal activity towards seed germination and growth of three common terrestrial weed species. At a dilution of 1:100 and 1:1,000, none of the aquatic weeds inhibited in-vitro growth of the bacterial strains, with one exception (filamentous algae extract at 1:100 reduced growth of one bacterial isolate by 54%). Water lettuce reduced the survival rate of FAW by 14% while hydrilla and duckweed caused 11% and 9% reduction of FAW growth, respectively. Powdered duckweed inhibited the growth of nutsedge by 41%, whereas filamentous algae powder and extract reduced germination of amaranth by 20% and 28%, respectively. Harvesting these weeds and converting them into useable compounds could not only eliminate the in situ farm canal and water quality problems but also result in development of new soil amendments or biopesticides.


Assuntos
Antibacterianos/toxicidade , Agentes de Controle Biológico/toxicidade , Plantas Daninhas/química , Agricultura , Animais , Antibacterianos/química , Bactérias/efeitos dos fármacos , Agentes de Controle Biológico/química , Cianobactérias/química , Eichhornia/química , Hydrocharitaceae/química , Inseticidas/química , Inseticidas/toxicidade , Plantas/microbiologia , Microbiologia do Solo , Spodoptera/efeitos dos fármacos
7.
Proc Natl Acad Sci U S A ; 117(33): 19705-19712, 2020 08 18.
Artigo em Inglês | MEDLINE | ID: mdl-32747579

RESUMO

Photosystem II (PS II) captures solar energy and directs charge separation (CS) across the thylakoid membrane during photosynthesis. The highly oxidizing, charge-separated state generated within its reaction center (RC) drives water oxidation. Spectroscopic studies on PS II RCs are difficult to interpret due to large spectral congestion, necessitating modeling to elucidate key spectral features. Herein, we present results from time-dependent density functional theory (TDDFT) calculations on the largest PS II RC model reported to date. This model explicitly includes six RC chromophores and both the chlorin phytol chains and the amino acid residues <6 Å from the pigments' porphyrin ring centers. Comparing our wild-type model results with calculations on mutant D1-His-198-Ala and D2-His-197-Ala RCs, our simulated absorption-difference spectra reproduce experimentally observed shifts in known chlorophyll absorption bands, demonstrating the predictive capabilities of this model. We find that inclusion of both nearby residues and phytol chains is necessary to reproduce this behavior. Our calculations provide a unique opportunity to observe the molecular orbitals that contribute to the excited states that are precursors to CS. Strikingly, we observe two high oscillator strength, low-lying states, in which molecular orbitals are delocalized over ChlD1 and PheD1 as well as one weaker oscillator strength state with molecular orbitals delocalized over the P chlorophylls. Both these configurations are a match for previously identified exciton-charge transfer states (ChlD1 +PheD1 -)* and (PD2 +PD1 -)*. Our results demonstrate the power of TDDFT as a tool, for studies of natural photosynthesis, or indeed future studies of artificial photosynthetic complexes.


Assuntos
Proteínas de Bactérias/química , Cianobactérias/metabolismo , Complexo de Proteína do Fotossistema II/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Clorofila/química , Clorofila/metabolismo , Cianobactérias/química , Cianobactérias/genética , Cinética , Modelos Moleculares , Fotossíntese , Complexo de Proteína do Fotossistema II/genética , Complexo de Proteína do Fotossistema II/metabolismo
8.
Proc Natl Acad Sci U S A ; 117(33): 19731-19736, 2020 08 18.
Artigo em Inglês | MEDLINE | ID: mdl-32759207

RESUMO

Cyanobacteriochromes are photoreceptors in cyanobacteria that exhibit a wide spectral coverage and unique photophysical properties from the photoinduced isomerization of a linear tetrapyrrole chromophore. Here, we integrate femtosecond-resolved fluorescence and transient-absorption methods and unambiguously showed the significant solvation dynamics occurring at the active site from a few to hundreds of picoseconds. These motions of local water molecules and polar side chains are continuously convoluted with the isomerization reaction, leading to a nonequilibrium processes with continuous active-site motions. By mutations of critical residues at the active site, the modified local structures become looser, resulting in faster solvation relaxations and isomerization reaction. The observation of solvation dynamics is significant and critical to the correct interpretation of often-observed multiphasic dynamic behaviors, and thus the previously invoked ground-state heterogeneity may not be relevant to the excited-state isomerization reaction.


Assuntos
Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Cianobactérias/metabolismo , Fotorreceptores Microbianos/química , Proteínas de Bactérias/genética , Domínio Catalítico , Cianobactérias/química , Cianobactérias/genética , Isomerismo , Cinética , Fotorreceptores Microbianos/genética , Fotorreceptores Microbianos/metabolismo
9.
Ecotoxicol Environ Saf ; 200: 110730, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32464439

RESUMO

Monitoring of oxidative stress caused by a wide range of reactive oxygen species (ROS) is essential to have an idea about the fitness and growth of photosynthetic organisms. The imaging-based oxidative stress measurement in cyanobacteria using 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) dye has the limitation of small sample size as the only selected number of cells are analyzed to measure the ROS levels. Here, we developed a method for oxidative stress measurement by DCFH-DA and flow cytometer (FCM) using unicellular Synechococcus elongatus PCC 7942 and filamentous Fremyella diplosiphon BK14 cyanobacteria. F. diplosiphon BK14 inherently possess high levels of ROS and showed higher sensitivity to hydrogen peroxide treatment in comparison to S. elongatus PCC 7942. We successfully measured oxidative stress in glutaredoxin lacking strain (Δgrx3) of S. elongatus PCC 7942, and wild-type Synechocystis sp. PCC 6803 using FCM based method. Importantly, ROS were not detected in these two strains of cyanobacteria by fluorescence microscope-based method due to their small spherical morphology. Δgrx3 strain showed high ROS levels in comparison to its wild-type strain. Treatment of abiotic factors such as high PAR in wild-type and Δgrx3 strains of S. elongatus PCC 7942, low PAR or low PAR + UVR in wild-type S. elongatus PCC 7942, and high PAR or high PAR + NaCl in Synechocystis sp. PCC 6803 increased oxidative stress. In summary, the FCM based method can measure ROS levels produced due to physiological conditions associated with genetic changes or abiotic stress in a large population of cells regardless of their morphology. Therefore, the present study shows the usefulness of the method in monitoring the health of organisms in a large scale cultivation system.


Assuntos
Cianobactérias , Citometria de Fluxo/métodos , Estresse Oxidativo , Synechococcus , Cianobactérias/química , Cianobactérias/efeitos dos fármacos , Fluoresceínas , Fluorescência , Corantes Fluorescentes , Peróxido de Hidrogênio/toxicidade , Microscopia de Fluorescência , Mutação , Espécies Reativas de Oxigênio/análise , Synechococcus/química , Synechococcus/efeitos dos fármacos , Synechococcus/genética , Synechocystis
10.
J Agric Food Chem ; 68(22): 6212-6220, 2020 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-32400160

RESUMO

Cyanobacteria and microalgae are characterized by a rich and varied profile of chlorophyll (8-20 mg/g) and carotenoid (>2.2 mg/g) pigments, being noteworthy material for natural pigment production in the food industry. We propose a systematic workflow that uses high-performance liquid chromatography (HPLC) coupled with high-resolution tandem mass spectrometry in a broadband collision-induced dissociation mode (bbCID) acquisition mode to simultaneously obtain MS and MSn spectra. Metabolomic studies showed for the first time the presence of carotenoids with 5,6-epoxy-groups (5,6-epoxy- and 5,8-furanoid ß-cryptoxanthin), carotenoids from the α-branch (5,8-furanoid-2'-3'-didehydro α-cryptoxanthin), and 2'-dehydrodeoxomyxol in cyanobacteria. To support the new findings, an in silico search retrieved the putative sequences of carotenogenic enzymes involved in the corresponding biosynthetic pathways (ZEP, NSY, CrtL-b and CrtR) in the analyzed cyanobacteria species. Consequently, high-throughput metabolomics studies assisted by molecular analysis offer a powerful tool for providing insights into the characterization of bioactive compounds and their metabolism in cyanobacteria and microalgae.


Assuntos
Carotenoides/metabolismo , Cianobactérias/metabolismo , Vias Biossintéticas , Carotenoides/química , Cromatografia Líquida de Alta Pressão , Criptoxantinas/análise , Criptoxantinas/metabolismo , Cianobactérias/química , Metabolômica , Espectrometria de Massas em Tandem
11.
Sci Rep ; 10(1): 8679, 2020 05 26.
Artigo em Inglês | MEDLINE | ID: mdl-32457360

RESUMO

Cyanobacteria are ubiquitous organisms with a relevant contribution to primary production in all range of habitats. Cyanobacteria are well known for their part in worldwide occurrence of aquatic blooms while producing a myriad of natural compounds, some with toxic potential, but others of high economical impact, as geosmin. We performed an environmental survey of cyanobacterial soil colonies to identify interesting metabolic pathways and adaptation strategies used by these microorganisms and isolated, sequenced and assembled the genome of a cyanobacterium that displayed a distinctive earthy/musty smell, typical of geosmin, confirmed by GC-MS analysis of the culture's volatile extract. Morphological studies pointed to a new Oscillatoriales soil ecotype confirmed by phylogenetic analysis, which we named Microcoleus asticus sp. nov. Our studies of geosmin gene presence in Bacteria, revealed a scattered distribution among Cyanobacteria, Actinobacteria, Delta and Gammaproteobacteria, covering different niches. Careful analysis of the bacterial geosmin gene and gene tree suggests an ancient bacterial origin of the gene, that was probably successively lost in different time frames. The high sequence similarities in the cyanobacterial geosmin gene amidst freshwater and soil strains, reinforce the idea of an evolutionary history of geosmin, that is intimately connected to niche adaptation.


Assuntos
Proteínas de Bactérias/metabolismo , Cianobactérias/genética , Naftóis/metabolismo , Actinobacteria/genética , Actinobacteria/metabolismo , Proteínas de Bactérias/classificação , Proteínas de Bactérias/genética , Cianobactérias/química , Cianobactérias/classificação , Gammaproteobacteria/genética , Gammaproteobacteria/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Genoma Bacteriano , Família Multigênica , Naftóis/análise , Naftóis/isolamento & purificação , Filogenia , Extração em Fase Sólida , Terpenos/análise
12.
Molecules ; 25(7)2020 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-32244512

RESUMO

Marine Cyanobacteria (blue-green algae) have been shown to possess an enormous potential to produce structurally diverse natural products that exhibit a broad spectrum of potent biological activities, including cytotoxic, antifungal, antiparasitic, antiviral, and antibacterial activities. Here, we report the isolation and structure determination of palstimolide A, a complex polyhydroxy macrolide with a 40-membered ring that was isolated from a tropical marine cyanobacterium collected at Palmyra Atoll. NMR-guided fractionation in combination with MS2-based molecular networking and isolation via HPLC yielded 0.7 mg of the pure compound. The small quantity isolated along with the presence of significant signal degeneracy in both the 1H and 13C-NMR spectra complicated the structure elucidation of palstimolide A. Various NMR experiments and solvent systems were employed, including the LRHSQMBC experiment that allows the detection of long-range 1H-13C correlation data across 4-, 5-, and even 6-bonds. This expanded NMR data set enabled the elucidation of the palstimolide's planar structure, which is characterized by several 1,5-disposed hydroxy groups as well as a tert-butyl group. The compound showed potent antimalarial activity with an IC50 of 223 nM as well as interesting anti-leishmanial activity with an IC50 of 4.67 µM.


Assuntos
Antimaláricos/química , Antimaláricos/farmacologia , Macrolídeos/química , Macrolídeos/farmacologia , Organismos Aquáticos/química , Cianobactérias/química , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Testes de Sensibilidade Parasitária , Relação Estrutura-Atividade
13.
Mar Drugs ; 18(3)2020 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-32245015

RESUMO

Toxins from marine animals provide molecular tools for the study of many ion channels, including mammalian voltage-gated potassium channels of the Kv1 family. Selectivity profiling and molecular investigation of these toxins have contributed to the development of novel drug leads with therapeutic potential for the treatment of ion channel-related diseases or channelopathies. Here, we review specific peptide and small-molecule marine toxins modulating Kv1 channels and thus cover recent findings of bioactives found in the venoms of marine Gastropod (cone snails), Cnidarian (sea anemones), and small compounds from cyanobacteria. Furthermore, we discuss pivotal advancements at exploiting the interaction of κM-conotoxin RIIIJ and heteromeric Kv1.1/1.2 channels as prevalent neuronal Kv complex. RIIIJ's exquisite Kv1 subtype selectivity underpins a novel and facile functional classification of large-diameter dorsal root ganglion neurons. The vast potential of marine toxins warrants further collaborative efforts and high-throughput approaches aimed at the discovery and profiling of Kv1-targeted bioactives, which will greatly accelerate the development of a thorough molecular toolbox and much-needed therapeutics.


Assuntos
Canalopatias/tratamento farmacológico , Toxinas Marinhas/farmacologia , Bloqueadores dos Canais de Potássio/farmacologia , Superfamília Shaker de Canais de Potássio/antagonistas & inibidores , Animais , Caramujo Conus/química , Cianobactérias/química , Gânglios Espinais/citologia , Gânglios Espinais/efeitos dos fármacos , Humanos , Toxinas Marinhas/uso terapêutico , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Bloqueadores dos Canais de Potássio/uso terapêutico , Anêmonas-do-Mar/química , Superfamília Shaker de Canais de Potássio/metabolismo
14.
J Antibiot (Tokyo) ; 73(8): 585-588, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32286514

RESUMO

Three new carboxylic acid derivatives, pestallic acids F and G (1 and 2), pestalotiopyrone N (3), and a new diphenylketone derivative named neopestalone (5) were obtained from the liquid cultures of marine alga-derived endophytic fungus Pestalotiopsis neglecta SCSIO41403, along with six known compounds (4, 6-10). The structures of those new compounds were elucidated mainly by analysis of their NMR and MS data. The isolated compounds were evaluated for their anti-Dengue virus and COX-2 inhibitory activities, and two diphenylketone derivatives (5 and 6) exhibited obvious COX-2 inhibitory activities, with the IC50 values being 5.8 and 3.4 µM, respectively.


Assuntos
Organismos Aquáticos/química , Cianobactérias/química , Endófitos/química , Cetonas/química , Cetonas/farmacologia , /química , Antivirais/química , Antivirais/farmacologia , Ácidos Carboxílicos/química , Ácidos Carboxílicos/farmacologia , Inibidores de Ciclo-Oxigenase 2/química , Inibidores de Ciclo-Oxigenase 2/farmacologia , Vírus da Dengue/efeitos dos fármacos
15.
J Antibiot (Tokyo) ; 73(8): 526-533, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32235860

RESUMO

Two laxaphycin type-B cyclic dodecapeptides, laxaphycins B5 and B6, were obtained from UIC 10484, a freshwater cf. Phormidium sp. Analysis using the 16S rRNA sequence found UIC 10484 to clade with UIC 10045, a known laxaphycin type-A and -B producer, and MS/MS analysis revealed the presence of two novel laxaphycin type-B compounds. The structures of the metabolites were elucidated using 2D NMR and MS/MS. The absolute configurations of the amino acids were determined by advanced Marfey's analysis. Both metabolites were evaluated against the same three cancer cell lines. The IC50 of both laxaphycins B5 and B6 was near 1 µM against breast cancer MDA-MB-231, melanoma MDA-MB-435, and ovarian cancer OVCAR3 cell lines.


Assuntos
Cianobactérias/química , Peptídeos Cíclicos/química , Aminoácidos/genética , Neoplasias da Mama/tratamento farmacológico , Linhagem Celular Tumoral , Cianobactérias/genética , Feminino , Água Doce , Humanos , Espectroscopia de Ressonância Magnética/métodos , Melanoma/tratamento farmacológico , Neoplasias Ovarianas/tratamento farmacológico , Peptídeos Cíclicos/farmacologia , RNA Ribossômico 16S/genética , Espectrometria de Massas em Tandem/métodos
16.
Mar Drugs ; 18(3)2020 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-32210159

RESUMO

Jahanyne, a lipopeptide with a unique terminal alkynyl and OEP (2-(1-oxo-ethyl)-pyrrolidine) moiety, exhibits anticancer activity. We synthesized jahanyne and analogs modified at the OEP moiety, employing an α-fluoromethyl ketone (FMK) strategy. Preliminary bioassays indicated that compound 1b (FMK-jahanyne) exhibited decreased activities to varying degrees against most of the cancer cells tested, whereas the introduction of a fluorine atom to the α-position of a hydroxyl group (2b) enhanced activities against all lung cancer cells. Moreover, jahanyne and 2b could induce G0/G1 cell cycle arrest in a concentration-dependent manner.


Assuntos
Desenho de Fármacos , Pontos de Checagem da Fase G1 do Ciclo Celular/efeitos dos fármacos , Lipopeptídeos/farmacologia , Neoplasias Pulmonares/tratamento farmacológico , Apoptose/efeitos dos fármacos , Organismos Aquáticos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Cianobactérias/química , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Lipopeptídeos/síntese química , Lipopeptídeos/uso terapêutico , Neoplasias Pulmonares/patologia , Estrutura Molecular , Relação Estrutura-Atividade
17.
Photochem Photobiol Sci ; 19(5): 585-603, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32163064

RESUMO

Photosynthetic organisms are exposed to a fluctuating environment in which light intensity and quality change continuously. Specific illumination of either photosystem (PSI or PSII) creates an energy imbalance, leading to the reduction or oxidation of the intersystem electron transport chain. This redox imbalance could trigger the formation of dangerous reactive oxygen species. Cyanobacteria, like plants and algae, have developed a mechanism to re-balance this preferential excitation of either reaction center, called state transitions. State transitions are triggered by changes in the redox state of the membrane-soluble plastoquinone (PQ) pool. In plants and green algae, these changes in redox potential are sensed by Cytochrome b6f, which interacts with a specific kinase that triggers the movement of the main PSII antenna (the light-harvesting complex II). By contrast, although cyanobacterial state transitions have been studied extensively, there is still no agreement about the molecular mechanism, the PQ redox state sensor and the signaling pathways involved. In this review, we aimed to critically evaluate the results published on cyanobacterial state transitions, and discuss the "new" and "old" models in the subject. The phycobilisome and membrane contributions to this physiological process were addressed and the current hypotheses regarding its signaling transduction pathway were discussed.


Assuntos
Cianobactérias/metabolismo , Complexo de Proteína do Fotossistema I/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Cianobactérias/química , Oxirredução , Complexo de Proteína do Fotossistema I/química , Complexo de Proteína do Fotossistema II/química
18.
J Biol Chem ; 295(19): 6754-6766, 2020 05 08.
Artigo em Inglês | MEDLINE | ID: mdl-32184354

RESUMO

The atypical trichromatic cyanobacterial phytochrome NpTP1 from Nostoc punctiforme ATCC 29133 is a linear tetrapyrrole (bilin)-binding photoreceptor protein that possesses tandem-cysteine residues responsible for shifting its light-sensing maximum to the violet spectral region. Using bioinformatics and phylogenetic analyses, here we established that tandem-cysteine cyanobacterial phytochromes (TCCPs) compose a well-supported monophyletic phytochrome lineage distinct from prototypical red/far-red cyanobacterial phytochromes. To investigate the light-sensing diversity of this family, we compared the spectroscopic properties of NpTP1 (here renamed NpTCCP) with those of three phylogenetically diverged TCCPs identified in the draft genomes of Tolypothrix sp. PCC7910, Scytonema sp. PCC10023, and Gloeocapsa sp. PCC7513. Recombinant photosensory core modules of ToTCCP, ScTCCP, and GlTCCP exhibited violet-blue-absorbing dark-states consistent with dual thioether-linked phycocyanobilin (PCB) chromophores. Photoexcitation generated singly-linked photoproduct mixtures with variable ratios of yellow-orange and red-absorbing species. The photoproduct ratio was strongly influenced by pH and by mutagenesis of TCCP- and phytochrome-specific signature residues. Our experiments support the conclusion that both photoproduct species possess protonated 15E bilin chromophores, but differ in the ionization state of the noncanonical "second" cysteine sulfhydryl group. We found that the ionization state of this and other residues influences subsequent conformational change and downstream signal transmission. We also show that tandem-cysteine phytochromes present in eukaryotes possess similar amino acid substitutions within their chromophore-binding pocket, which tune their spectral properties in an analogous fashion. Taken together, our findings provide a roadmap for tailoring the wavelength specificity of plant phytochromes to optimize plant performance in diverse natural and artificial light environments.


Assuntos
Proteínas de Bactérias/química , Cianobactérias/química , Fotorreceptores Microbianos/química , Fitocromo/química , Substituição de Aminoácidos , Proteínas de Bactérias/genética , Cianobactérias/genética , Mutação de Sentido Incorreto , Fotorreceptores Microbianos/genética , Fitocromo/genética
19.
Toxicol Lett ; 326: 106-113, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32142839

RESUMO

This study aimed to investigate the toxic effects of microcystin-LR (MC-LR), which is released from several bloom-forming cyanobacteria, on the glucose metabolism of pancreatic ß cells in vivo and in vitro. Male mice and the pancreatic MIN6 cells were respectively treated with varying concentrations of MC-LR. After 3- or 6- months of MC-LR exposure, increase in the body weight of mice was found to be inhibited, and the structure of their pancreatic tissues was damaged with impaired glucose tolerance and impaired insulin secretion. Further, these toxic effects became more pronounced with time and with increased dosages. Direct cytotoxic effects of MC-LR were observed in the MIN6 pancreatic ß-cells possibly due to their expression of the MC-LR specific transporter. MC-LR entered the MIN6 cells that significantly reduced the cell viability. Both in vivo and in vitro experiments demonstrated that MC-LR was able to induce apoptosis, possibly associated with mitochondrial damage. Above all, these findings implied that MC-LR may be transported into the pancreatic ß cells and cause subsequent cytotoxicity.


Assuntos
Apoptose/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Cianobactérias/química , Glucose/metabolismo , Células Secretoras de Insulina/efeitos dos fármacos , Microcistinas/toxicidade , Pâncreas/efeitos dos fármacos , Animais , Masculino , Camundongos
20.
Environ Monit Assess ; 192(4): 244, 2020 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-32198545

RESUMO

The information available on microalgae-sourced compounds, especially antibiotics and other bioactive compounds, and their potential commercial applications is still insufficient. In this study, antibacterial activity, metabolites, and molecular characterization of Phormidium autumnale, which was isolated from samples collected from different natural freshwater sources in Ankara, Turkey, were investigated. Sequencing results of 16s rDNA confirmed the molecular identification of P. autumnale by 99%. It was determined that the peak values of some phenolic compounds and cyclic peptides were consistent with the 1653-1389 cm-1 band regions in the FTIR spectra of the species. The antibacterial activities of P. autumnale cyanobacteria (CBA) extracts that were obtained by using different solvents were tested on Escherichia coli, Staphylococcus epidermidis, methicillin-resistant (MR) Staphylococcus aureus, Streptococcus agalactiae, and Enterococcus faecalis by using a disc diffusion method. Also, the minimum inhibition concentration (MIC) and antimicrobial indexes of all extracts were determined. It was found that P. autumnale methanol extracts showed antibacterial activity on all test bacteria, whereas acetone extracts showed effects only on E. coli. For the inhibition of MR S. aureus, the control methanol extract was found to give very similar results to those exhibited by the control antibiotics, and the antimicrobial index results were determined to be 58.7-67.5%. According to the results of the analysis of methanol extract, gentisic acid, vanillic acid, 4-hydroxybenzoic acid, p-coumaric acid, and catechin (especially phenolic compounds) were determined to be the active compounds. It can be concluded that P. autumnale is an alternative to current commercial applications as an antibacterial agent in phytotherapy.


Assuntos
Cianobactérias , Escherichia coli , Compostos Fitoquímicos , Staphylococcus aureus , Antibacterianos/isolamento & purificação , Antibacterianos/farmacologia , Cianobactérias/química , Cianobactérias/genética , Escherichia coli/efeitos dos fármacos , Água Doce , Testes de Sensibilidade Microbiana , Compostos Fitoquímicos/isolamento & purificação , Compostos Fitoquímicos/farmacologia , Fitoterapia , Staphylococcus aureus/efeitos dos fármacos , Turquia
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