scholarly journals Inhibitory Effect of Mentha Longifolia L. Essential Oil against Listeria Monocytogenes Using Transmission Electron Microscopy

2016 ◽  
Vol 2 (1) ◽  
pp. 014-017 ◽  
Author(s):  
R Mahmoudi ◽  
F Katiraee ◽  
H Tajik ◽  
A Abbas ◽  
Farshid .
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Listeria Monocytogenes ◽  
Essential Oil ◽  
Inhibitory Effect ◽  
Transmission Electron ◽  
Mentha Longifolia

Effects of Cymbopogon nardus (L.) W. Watson essential oil on the growth and morphogenesis of Aspergillus niger

2001 ◽  
Vol 47 (1) ◽  
pp. 9-17 ◽  
Author(s):  
Virginia G de Billerbeck ◽  
Christine G Roques ◽  
Jean-Marie Bessière ◽  
Jean-Louis Fonvieille ◽  
Robert Dargent
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Aspergillus Niger ◽  
Essential Oil ◽  
Normal Growth ◽  
Inhibitory Effect ◽  
Mycelium Growth ◽  
Cymbopogon Nardus ◽  
Transmission Electron ◽  
Hyphal Diameter

The growth inhibitory effect of Cymbopogon nardus (L.) W. Watson var. nardus essential oil on Aspergillus niger (Van Tieghem) mycelium was determined on agar medium. The mycelium growth was completely inhibited at 800 mg/L. This concentration was found to be lethal under the test conditions. Essential oil at 400 mg/L caused growth inhibition of 80% after 4 days of incubation, and a delay in conidiation of 4 days compared with the control. Microscopic observations were carried out to determine the ultrastructural modifications of A. niger hyphae after treatment with C. nardus essential oil. The main change observed by transmission electron microscopy concerned the hyphal diameter and the hyphal wall, which appeared markedly thinner. These modifications in cytological structure might be caused by the interference of the essential oil with the enzymes responsible for wall synthesis which disturb normal growth. Moreover, the essential oil caused plasma membrane disruption and mitochondrial structure disorganization. The findings thus indicate the possibility of exploiting Cymbopogon nardus essential oil as an effective inhibitor of biodegrading and storage-contaminating fungi.Key words: essential oil, antifungal agent, hyphal ultrastructure, cell wall, scanning electron microscopy, transmission electron microscopy.

Application of the polycaprolactone polymer for the encapsulation of geraniol: evaluation of the efficiency and stability

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Thaís Karoline Carniel ◽  
Pâmela Fagundes ◽  
Ana Carolina Vivan ◽  
Luciano Luiz Silva ◽  
Micheli Zanetti ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Essential Oil ◽  
Natural Compound ◽  
Thermal Protection ◽  
Miniemulsion Polymerization ◽  
Food Preservation ◽  
Transmission Electron ◽  
Mean Size ◽  
Antibacterial And Antifungal

Abstract Geraniol has been an attractive compound for food preservation due to its antibacterial and antifungal actions. The main objective of this study was to produce and characterize polycaprolactone (PCL) capsules for the protection of the encapsulated geraniol essential oil. The encapsulation was carried out using a miniemulsion polymerization technique with an efficiency of (95.44 ± 0.60%). The capsules were obtained with a mean size of 148 nm and with a polydispersity index of 0.12. Transmission electron microscopy results confirmed the formation of spherical capsules of PCL coating the geraniol. From the analysis of thermogravimetry, it was possible to prove the thermal protection of geraniol by PCL coating since the release of the encapsulated geraniol occurred with temperatures 100 °C higher than the volatilization temperature of the natural compound. An important observation was that the microcapsules of PCL-geraniol immersed in aqueous suspensions at 4 °C showed good stability over 60 days.

scholarly journals Endlicheria bracteolata (Meisn.) Essential Oil as a Weapon Against Leishmania amazonensis: In Vitro Assay

Molecules ◽  
2019 ◽  
Vol 24 (14) ◽  
pp. 2525 ◽  
Author(s):  
Mariana Margatto Rottini ◽  
Ana Claudia Fernandes Amaral ◽  
José Luiz Pinto Ferreira ◽  
Edinilze Souza Coelho Oliveira ◽  
Jefferson Rocha de Andrade Silva ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Flow Cytometry ◽  
Essential Oil ◽  
Cutaneous Leishmaniasis ◽  
Leishmania Amazonensis ◽  
Vitro Assay ◽  
Transmission Electron ◽  
Biological Potential ◽  
Intracellular Amastigote

The difficulties encountered and the numerous side effects present in the treatment of cutaneous leishmaniasis have encouraged the research for new compounds that can complement or replace existing treatment. The growing scientific interest in the study of plants, which are already used in folk remedies, has led our group to test Endlicheria bracteolata essential oil against Leishmania amazonensis. Several species of the Lauraceae family, or their compounds, have relevant antiprotozoal activities Therefore, the biological potential on L. amazonensis forms from the essential oil of Endlicheria bracteolata leaves was verified for the first time in that work. The antileishmanial activity was evaluated against promastigotes and intracellular amastigotes, and cytotoxicity were performed with J774.G8, which were incubated with different concentrations of E. bracteolata essential oil. Transmission electron microscopy and flow cytometry were performed with E. bracteolata essential oil IC50. Promastigote forms showed E. bracteolata essential oil IC50 of 7.945 ± 1.285 µg/mL (24 h) and 6.186 ± 1.226 µg/mL (48 h), while for intracellular amastigote forms it was 3.546 ± 1.184 µg/mL (24 h). The CC50 was 15.14 ± 0.090 µg/mL showing that E. bracteolata essential oil is less toxic to macrophages than to parasites. Transmission electron microscopy showed that E. bracteolata essential oil treatment is capable of inducing mitochondrial damage to promastigote and intracellular amastigote forms, while flow cytometry showed ΔѰm disruption in treated parasites. These results could bring about new possibilities to develop products based on E. bracteolata essential oil to treat cutaneous leishmaniasis, especially for people who cannot receive the conventional therapy.

Lysozyme and Lipase Alter Unfrozen and Frozen/Thawed Cells of Listeria monocytogenes

1992 ◽  
Vol 55 (10) ◽  
pp. 777-781 ◽  
Author(s):  
SOUZAN E. EL-KEST ◽  
ELMER H. MARTH
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Listeria Monocytogenes ◽  
Frozen Storage ◽  
Lytic Action ◽  
Transmission Electron ◽  
Cellular Lysis

Unfrozen and frozen/thawed cells of Listeria monocytogenes strains Scott A, V7, and California were treated with lipase and/or lysozyme. Cells of strain Scott A were more susceptible to the lytic action of lysozyme than were cells of strains V7 and California. Treatment of unfrozen cells with lipase before exposure to lysozyme enhanced cellular lysis. This also was true for cells held frozen for up to 6 weeks before they were thawed and treated with enzymes. Some variation existed among strains of L. monocytogenes in their susceptibility to effects of lysozyme. Frozen storage of cells of all three strains increased their susceptibility to lysis by lipase, and this was related inversely with the percentage of cells that survived freezing and frozen storage. Transmission electron microscopy showed some enzyme-treated cells formed protoplasts.

scholarly journals Clusterin in Alzheimer’s Disease: An Amyloidogenic Inhibitor of Amyloid Formation

2021 ◽  
Author(s):  
Panagiotis M. Spatharas ◽  
Georgia I. Nasi ◽  
Paraskevi L. Tsiolaki ◽  
Marilena K. Theodoropoulou ◽  
Nikos C. Papandreou ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fluorescence Emission ◽  
Inhibitory Effect ◽  
Fibril Formation ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Ft Ir ◽  
Dynamics Simulations ◽  
Peptide Analogues

Abstract Background: Clusterin is a heterodimeric glycoprotein (α- and β-chain), which has been described as an extracellular molecular chaperone. In humans, clusterin is an amyloid associated protein, co-localizing with fibrillar deposits in Alzheimer’s disease. To clarify its implication in the disease, we provide evidence that clusterin has intrinsic amyloidogenic properties, which are intertwined with its inhibitory effect on amyloid-β fibril formation.Methods: Aggregation-prone regions of human clusterin were predicted by AMYLPRED. Synthetic peptide-analogues of each region underwent in vitro aggregation assays, namely, examination with transmission electron microscopy, X-Ray diffraction from oriented fibers, ATR FT-IR spectroscopy, and Congo Red birefringence assays. The same peptide-analogues were co-incubated with amyloid-β and their potential as inhibitors was tested with thioflavin T fluorescence emission measurements and transmission electron microscopy. Molecular dynamics simulations were performed to gain insight into the interaction between amyloid-β and the peptide-analogues.Results: Clusterin peptide-analogues form amyloid-like fibrils, as revealed by transmission electron microscopy. They can form fibers that give cross-β X-ray diffraction patterns and ATR FT-IR spectroscopy confirms the dominance of β-strand secondary structure. They also exhibit apple-green birefringence, when stained with Congo Red and examined between crossed polars of a polarizing light microscope. Furthermore, when amyloid-β is co-incubated with clusterin’s peptide analogues, it shows decreased thioflavin T fluorescence emission over time, while the formation of amyloid-β amyloid fibrils is diminished, as confirmed by transmission electron microscopy. The inhibitory effect of clusterin-peptide analogues on amyloid-β fibril formation was ascertained though molecular dynamics simulations. Conclusions: Clusterin has multiple aggregation-prone regions in its α-chain and these regions have a functional role in the inhibition of amyloid-β fibril formation.

Transmission Electron Microscopy of Unfrozen and Frozen/Thawed Cells of Listeria monocytogenes Treated With Lipase and Lysozyme

1992 ◽  
Vol 55 (9) ◽  
pp. 687-696 ◽  
Author(s):  
SOUZAN E. EL-KEST ◽  
ELMER H. MARTH
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Listeria Monocytogenes ◽  
Storage Time ◽  
Frozen Storage ◽  
Activity Type ◽  
Protoplast Formation ◽  
Transmission Electron ◽  
Three Stages

Unfrozen cells of Listeria monocytogenes typically contained no preplasma space exterior to the plasma membrane (PM) when viewed by transmission electron microscopy. Cells of L. monocytogenes strains Scott A, V7, and California (CA), after freezing and frozen storage, exhibited one or more of the following when viewed with transmission electron microscopy: (a) retraction of cytoplasm and infolding of the PM to form mesosomes, (b) extra-and intracellular rupture of the cell wall (CW), (c) formation of intracellular “bubbles,” and (d) damage to the CW and PM that could have resulted from autolysin activity. Type and degree of effect depended on frozen storage time and strain of L. monocytogenes. Lysozyme treatment of unfrozen or frozen/stored (19 d)/thawed cells of strains Scott A, V7, and CA resulted in protoplast formation and damage to the CW. Three stages of protoplast formation were observed when cells of strain CA were frozen, stored 2 weeks, thawed, and treated with lysozyme. More damage to the CW and PM occurred when frozen storage time was extended for up to 6 weeks before treatment with lysozyme. Lipase and lysozyme treatment of unfrozen or frozen/stored (19 d)/thawed cells of strain Scott A resulted in protoplast formation with some damage to the PM and irregularity in shape of cells. Damage to the PM increased with increasing frozen storage time for up to 6 weeks. Some cells of strain CA resisted freezing, frozen storage for 6 weeks, thawing, and treatment with lipase and lysozyme.

Transmission Electron Microscopy Study of Listeria monocytogenes Treated with Nisin in Combination with either Grape Seed or Green Tea Extract

2008 ◽  
Vol 71 (10) ◽  
pp. 2105-2109 ◽  
Author(s):  
T. SIVAROOBAN ◽  
N. S. HETTIARACHCHY ◽  
M. G. JOHNSON
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Listeria Monocytogenes ◽  
Green Tea ◽  
Morphological Changes ◽  
Grape Seed ◽  
Green Tea Extract ◽  
Transmission Electron ◽  
Phenolic Constituents ◽  
Tea Extract

The objective of this study was to use transmission electron microscopy to investigate the morphological changes that occurred in Listeria monocytogenes cells treated with grape seed extract (GSE), green tea extract (GTE), nisin, and combinations of nisin with either GSE or GTE. The test solutions were prepared with (i) 1% GSE, 1% GTE, 6,400 IU of nisin, and the combination of these dilutions with nisin or with (ii) the pure major phenolic constituents of GSE (0.02% epicatechin plus 0.02% catechin) or GTE (0.02% epicatechin plus 0.02% caffeic acid) and their combinations with 6,400 IU of nisin in tryptic soy broth with 0.6% yeast extract (TSBYE). Test solutions were inoculated with L. monocytogenes at approximately 106 CFU/ml and incubated for 3 or 24 h at 37°C. After 3 h of incubation, cells were harvested and evaluated under a transmission electron microscope (JEOL-100 CX) operating at 80 kV (50,000×). Microscopic examination revealed an altered cell membrane and condensed cytoplasm when L. monocytogenes cells were exposed to a combination of nisin with either GSE or GTE or to pure compounds of the major phenolic constituents in combination. After 24 h of incubation at 37°C, the combinations of nisin with GSE and nisin with GTE reduced the L. monocytogenes population to undetectable levels and 3.7 log CFU/ml, respectively. These observations indicate that the combination of nisin with either GSE or GTE had a synergistic effect, and the combinations of nisin with the major phenolic constituents were most likely associated with the L. monocytogenes cell damage during inactivation in TSBYE at 37°C.

scholarly journals Effects of the essential oil of Lippia gracilis Schauer on caulinary shoots of heliconia cultivated in vitro

2012 ◽  
Vol 14 (1) ◽  
pp. 26-33 ◽  
Author(s):  
C.C. Albuquerque ◽  
T.R. Camara ◽  
A.E.G. Sant'ana ◽  
C. Ulisses ◽  
L. Willadino ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Essential Oil ◽  
Control Treatment ◽  
Ms Medium ◽  
Main Constituent ◽  
Cell Organelles ◽  
Transmission Electron ◽  
Main Components

The effects of thymol and carvacrol and the essential oil of Lippia gracilis on caulinary shoots of heliconia were evaluated. After disinfection, the shoots were inoculated into MS medium and subjected to the treatments with 420 µL L-1 of essential oil (EO) of L. gracilis; 420 µL L-1 of thymol; 420 µL L-1 of carvacrol; 210 µL L-1 of thymol and 210 µL L-1 of carvacrol. The control treatment consisted of the MS medium without any phytoregulators. The main components of EO from L. gracilis are carvacrol, ρ-cimene, and thymol. Seven days after the initiation of the experiments, 36.3% of the control treatment shoots were necrotized, but 90% of the caulinary shoots exposed to EO, thymol, or carvacrol appeared necrotized. Transmission electron microscopy of the shoots revealed that the treatment with EO, thymol, or carvacrol caused the destruction of the plasma cell membranes, and the cell organelles and the nucleus were hardly evident. The EO and its main constituent were toxic to caulinary shoots of heliconia.

scholarly journals Preparation, Characterization, and Cytotoxicity of Various Chitosan Nanoparticles

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Qian Yao ◽  
Wei Liu ◽  
Xiao-Jun Gou ◽  
Xiao-Qiang Guo ◽  
Jun Yan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Biological Activity ◽  
Hepg2 Cells ◽  
Drug Loading ◽  
Chitosan Nanoparticles ◽  
Inhibitory Effect ◽  
Hepatic Carcinoma ◽  
Transmission Electron ◽  
Diverse Biological Activity

Chitosan nanoparticles (CS-NPs) without drug loading have diverse biological activity. In this study, we prepared CS-NPs, CS-NPs solidified by different amount of glutaraldehyde, and CS-NPs modified with either biotin (B-CS-NPs) or biotin and avidin (A-B-CS-NPs) and examined their cytotoxicity on HepG2 cells. The morphology and size were measured by transmission electron microscopy and photon correction spectroscopy, respectively. The extent of solidification was validated by the approach of sonication. Biotin connect density on the surface of B-CS-NPs and A-B-CS-NPs was determined by biotin assay kit. The results showed that most of the NPs were round and their mean sizes were all below 300 nm. Biotin connect density of B-CS-NPs and A-B-CS-NPs was 2.18 ± 0.36 and 1.26 ± 0.11 mol biotin/mol CS, respectively. At relatively low concentration, CS-NPs with higher extent of solidification exhibited more vigorous inhibitory effect against HepG2 cells than those without solidification. When NPs were incubated with cancer cells for 48 h, compared with CS-NPs, the anticancer activity of B-CS-NPs and A-B-CS-NPs was enhanced significantly(P<0.05). In addition, A-B-CS-NPs showed superior cytotoxicity over B-CS-NPs. This study demonstrates that modification with biotin and avidin may be an efficient way in improving antitumor activity of CS-NPs against hepatic carcinoma.

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