Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 6 de 6
Mais filtros

Base de dados
Intervalo de ano de publicação
Int J Nanomedicine ; 14: 4667-4679, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31308652


Purpose: The pathogenicity in Candida spp was attributed by several virulence factors such as production of tissue damaging extracellular enzymes, germ tube formation, hyphal morphogenesis and establishment of drug resistant biofilm. The objective of present study was to investigate the effects of silver nanoparticles (AgNPs) on growth, cell morphology and key virulence attributes of Candida species. Methods: AgNPs were synthesized by the using seed extract of Syzygium cumini (Sc), and were characterized by UV-Vis spectrophotometer, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and transmission electron microscopy (TEM). ScAgNPs were used to evaluate their antifungal and antibacterial activity as well as their potent inhibitory effects on germ tube and biofilm formation and extracellular enzymes viz. phospholipases, proteinases, lipases and hemolysin secreted by Candida spp. Results: The MICs values of ScAgNPs were ranged from 0.125-0.250 mg/ml, whereas the MBCs and MFCs were 0.250 and 0.500 mg/ml, respectively. ScAgNPs significantly inhibit the production of phospholipases by 82.2, 75.7, 78.7, 62.5, and 65.8%; proteinases by 82.0, 72.0, 77.5, 67.0, and 83.7%; lipase by 69.4, 58.8, 60.0, 42.9, and 65.0%; and hemolysin by 62.8, 69.7, 67.2, 73.1, and 70.2% in C. albicans, C. tropicalis, C. dubliniensis, C. parapsilosis and C. krusei, respectively, at 500 µg/ml. ScAgNPs inhibit germ tube formation in C. albicans up to 97.1% at 0.25 mg/ml. LIVE/DEAD staining results showed that ScAgNPs almost completely inhibit biofilm formation in C. albicans. TEM analysis shows that ScAgNPs not only anchored onto the cell surface but also penetrated and accumulated in the cytoplasm that causes severe damage to the cell wall and cytoplasmic membrane. Conclusion: To summarize, the biosynthesized ScAgNPs strongly suppressed the multiplication, germ tube and biofilm formation and most importantly secretion of hydrolytic enzymes (viz. phospholipases, proteinases, lipases and hemolysin) by Candia spp. The present research work open several avenues of further study, such as to explore the molecular mechanism of inhibition of germ tubes and biofilm formation and suppression of production of various hydrolytic enzymes by Candida spp.

Antifúngicos/farmacologia , Candida/crescimento & desenvolvimento , Candida/patogenicidade , Nanopartículas Metálicas/química , Prata/farmacologia , Antifúngicos/química , Biofilmes/efeitos dos fármacos , Candida/citologia , Candida/efeitos dos fármacos , Parede Celular/efeitos dos fármacos , Proteínas Hemolisinas/metabolismo , Humanos , Hidrólise , Nanopartículas Metálicas/ultraestrutura , Testes de Sensibilidade Microbiana , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Syzygium/química , Virulência/efeitos dos fármacos , Fatores de Virulência
Nanomaterials (Basel) ; 8(8)2018 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-30071582


The objective of the present study was one step extracellular biosynthesis of silver nanoparticles (AgNPs) using supernatant of Candida glabrata isolated from oropharyngeal mucosa of human immunodeficiency virus (HIV) patients and evaluation of their antibacterial and antifungal potential against human pathogenic bacteria and fungi. The mycosynthesized AgNPs were characterized by color visualization, ultraviolet-visible (UV) spectroscopy, fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). The FTIR spectra revealed the binding and stabilization of nanoparticles with protein. The TEM analysis showed that nanoparticles were well dispersed and predominantly spherical in shape within the size range of 2⁻15 nm. The antibacterial and antifungal potential of AgNPs were characterized by determining minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC)/ minimum fungicidal concentration (MFC), and well diffusion methods. The MBC and MFC were found in the range of 62.5⁻250 µg/mL and 125⁻500 µg/mL, which revealed that bacterial strains were more susceptible to AgNPs than fungal strains. These differences in bactericidal and fungicidal concentrations of the AgNPs were due to the differences in the cell structure and organization of bacteria and yeast cells. The interaction of AgNPs with C. albicans analyzed by TEM showed the penetration of nanoparticles inside the Candida cells, which led the formation of "pits" and "pores" that result from the rupturing of the cell wall and membrane. Further, TEM analysis showed that Candida cells treated with AgNPs were highly deformed and the cells had shrunken to a greater extent because of their interaction with the fungal cell wall and membrane, which disrupted the structure of the cell membrane and inhibited the normal budding process due to the destruction and loss of membrane integrity and formation of pores that may led to the cell death.

Mikrochim Acta ; 185(6): 290, 2018 05 10.
Artigo em Inglês | MEDLINE | ID: mdl-29748777


A column sorbent for arsenic was obtained through immobilization of highly branched polyethylenimine (PEI) on graphene oxide (GO). The composite material enables speciation of arsenic by tuning the pH of the sample solution which governs the surface charge of the sorbent, depending on whether amino groups (-NH2) are present (at high pH) or ammonium groups (-NH3+; at low pH). The composite can be applied to improved speciation of arsenic (compared to unmodified GO). There is no need for oxidation or reduction of arsenic. A column procedure was applied for the sequestered extraction and speciation of As(III) and As(V) from environmental water samples before their determination by hydride generation-microwave induced plasma-atomic emission spectrometry. The method has a preconcentration factor of 440 for As(III) and of 400 for As(V). The limits of detection (at 3 S/N) are extremely low, being 1.8 ± 0.2 ngL-1 for As(III) and 1.3 ± 0.08 ngL-1 for As(V). This is much lower than the arsenic guideline value of 10 µgL-1 as given by the WHO. Graphical abstract Graphene oxide interconnected with polyethyleneimine has been employed for the speciation and determination of arsenic. Quantitation by atomic emission spectroscopy reveals a high preconcentration factor (440 and 400) and low LODs of 1.8 ± 0.2 and 1.3 ± 0.08 ngL-1for As(III) and As(V), respectively.

Artif Cells Nanomed Biotechnol ; 46(sup1): 912-925, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29446992


The pathogenicity of Candida species in human is dependent on a variety of virulence factor such as adhesion factors, germ tube and hyphal formation, secretion of hydrolytic phospholipases and proteinases and drug resistance biofilm. ZnO NPs have been synthesized by using leaf extract of Crinum latifolium and were characterized by UV-Vis spectrophotometer, FTIR, SEM, EDX and TEM. In this study for the first time, potent inhibitory effects of ZnO NPs on principal virulence factors of Candida albicans and non-albicans such as germ tube formation, secretion of hydrolytic phospholipases and proteinases and biofilm formation has been investigated. ZnO NPs remarkably reduced the germ tube formation of C. albicans at 1 (86.4%), 0.5 (75.0%), 0.25 (61.4%), 0.125 (34.1%) and 0.062 mg/ml (11.4%). ZnO NPs significantly lowered the phospholipase and proteinase secretion by 58.8 and 95.2% at 0.25 mg/ml, respectively. CSLM results showed that ZnO NPs suppressed biofilm formation up to 85% at 0.25 mg/ml. SEM and TEM micrograph showed that ZnO NPs penetrated inside the cell and causes extensive damaged in cell wall and cell membrane. Inhibition of Candida growth and various virulent factors by ZnO NPs provides an insight towards their therapeutic application for the treatment of Candida-associated infections.

Materiais Biomiméticos/química , Materiais Biomiméticos/farmacologia , Candida/efeitos dos fármacos , Nanopartículas/química , Óxido de Zinco/química , Óxido de Zinco/farmacologia , Antifúngicos/química , Antifúngicos/farmacologia , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Candida/citologia , Candida/crescimento & desenvolvimento , Candida/fisiologia , Espaço Extracelular/efeitos dos fármacos , Espaço Extracelular/enzimologia , Hidrólise , Testes de Sensibilidade Microbiana , Virulência/efeitos dos fármacos
In Silico Pharmacol ; 5: 12, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29098138


Pseudomonas aeruginosa an opportunistic pathogen regulates its virulence through Quorum sensing (QS) mechanism comprising of Las and Rhl system. Targeting of QS mechanism could be an ideal strategy to combat infection caused by P. aeruginosa. Silver nanoparticles (AgNPs) have been broadly applied as antimicrobial agents against a number of pathogenic bacterial and fungal strains, but have not been reported as an anti-QS agent. Therefore, the aim of present work was to show the computational analysis for the interaction of AgNPs with the QS system using an In silico approach. In silico studies showed that AgNPs got 'locked' deeply into the active site of respective proteins with their surrounding residues. The molecular docking analysis clearly demonstrated that AgNPs got bound to the catalytic cleft of LasI synthase (Asp73-Ag = 3.1 Å), RhlI synthase (His52-Ag = 2.8 Å), transcriptional receptor protein LasR (Leu159-Ag = 2.3 Å) and RhlR (Trp10-Ag = 3.1 Å and Glu34-Ag = 3.2 Å). The inhibition of LasI/RhlI synthase by AgNPs blocked the biosynthesis of AHLs, thus no AHL produced, no QS occurred. Further, interference with transcriptional regulatory proteins led to the inactivation of LasR/RhlR system that finally blocked the expression of QS-controlled virulence genes. Our findings clearly demonstrate the anti-QS property of AgNPs in P. aeruginosa which could be an alternative approach to the use of traditional antibiotics for the treatment of P. aeruginosa infection.

J Basic Microbiol ; 57(3): 193-203, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27874198


Green synthesized nanoparticles have gained great attention due to their non-toxic and non-hazardous nature. In the present study, bark extract of the medicinal plant in Ayurveda Crataeva nurvala (Buch-Ham) (CN) was chosen for the biosynthesis of silver nanoparticles (AgNPs). These NPs were characterized by Ultra violet visible spectroscopy, Fourier Transform Infra Red, Atomic Force Microscopy, and Transmission Electron Microscopy (TEM). The average particle size of green synthesized CN-AgNPs was 15.2 ± 1.01 nm. Gas chromatography- mass spectrometry analysis of methanolic bark extract involved in the formation of CN-AgNPs revealed lupeol as a major active component. In this study, CN-AgNPs (15 µg ml-1 ) efficiently suppressed the production of quorum sensing mediated virulence factors viz. pyocyanin, protease, hemolysin, and biofilm formation in Pseudomonas aeruginosa. The pyocyanin production was strongly inhibited (74.64%) followed by proteolysis (47.3%) and hemolysin production (47.7%). However, the biofilm forming ability was maximally reduced up to 79.70%. Moreover, the Confocal Laser Scanning Microscopic Analysis showed that CN-AgNPs inhibit colonization of P. aeruginosa on to the surface. Furthermore, TEM analysis revealed internalization of CN-AgNPs inside the bacterial cell. It is concluded that green synthesized AgNPs have great potential to inhibit virulence factors and biofilm forming ability of drug-resistant clinical isolates of P. aeruginosa.

Biofilmes/efeitos dos fármacos , Capparaceae/química , Nanopartículas Metálicas/química , Extratos Vegetais/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , Fatores de Virulência/antagonistas & inibidores , Antibacterianos/farmacologia , Biofilmes/crescimento & desenvolvimento , Farmacorresistência Bacteriana Múltipla , Proteínas Hemolisinas/antagonistas & inibidores , Proteínas Hemolisinas/biossíntese , Proteínas Hemolisinas/efeitos dos fármacos , Nanopartículas Metálicas/ultraestrutura , Microscopia Confocal , Microscopia Eletrônica de Transmissão , Triterpenos Pentacíclicos/farmacologia , Plantas Medicinais/química , Proteólise/efeitos dos fármacos , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa/fisiologia , Pseudomonas aeruginosa/ultraestrutura , Piocianina/biossíntese , Percepção de Quorum/efeitos dos fármacos , Prata