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6. Hybrid Chitosan/CaO-Based Nanocomposites Doped with Plant Extracts from Azadirachta indica and Melia azedarach: Evaluation of Antibacterial and Antibiofilm Activities

Author

Paunova-Krasteva, Tsvetelina, primary, Hemdan, Bahaa A., additional, Dimitrova, Petya D., additional, Damyanova, Tsvetozara, additional, El-Feky, Amal M., additional, Elbatanony, Marwa M., additional, Stoitsova, Stoyanka, additional, El-Liethy, Mohamed Azab, additional, El-Taweel, Gamila E., additional, and El Nahrawy, Amany M., additional

Published
2022
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7. Bioactive Azadirachta indica and Melia azedarach leaves extracts with anti-SARS-CoV-2 and antibacterial activities

Author

Hemdan, Bahaa A., Mostafa, Ahmed, Elbatanony, Marwa M., El-Feky, Amal M., Paunova-Krasteva, Tsvetelina, Stoitsova, Stoyanka, El-Liethy, Mohamed Azab, El-Taweel, Gamila E., Abu Mraheil, Mobarak, and Justus Liebig University Giessen

Subjects
ddc:610
Abstract

The leaves of Azadirachta indica L. and Melia azedarach L., belonging to Meliaceae family, have been shown to have medicinal benefits and are extensively employed in traditional folk medicine. Herein, HPLC analysis of the ethyl acetate fraction of the total methanolic extract emphasized the enrichment of both A. indica L., and M. azedarach L. leaves extracts with phenolic and flavonoids composites, respectively. Besides, 4 limonoids and 2 flavonoids were isolated using column chromatography. By assessing the in vitro antiviral activities of both total leaves extracts against Severe Acute Respiratory Syndrome Corona virus 2 (SARS-CoV-2), it was found that A. indica L. and M. azedarach L. have robust anti-SARSCoV- 2 activities at low half-maximal inhibitory concentrations (IC50) of 8.451 and 6.922 μg/ mL, respectively. Due to the high safety of A. indica L. and M. azedarach L. extracts with half-maximal cytotoxic concentrations (CC50) of 446.2 and 351.4 μg/ml, respectively, both displayed extraordinary selectivity indices (SI>50). A. indica L. and M. azedarach L. leaves extracts could induce antibacterial activities against both Gram-negative and positive bacterial strains. The minimal inhibitory concentrations of A. indica L. and M. azedarach L. leaves extracts varied from 25 to 100 mg/mL within 30 min contact time towards the tested bacteria. Our findings confirm the broad-spectrum medicinal value of A. indica L. and M. azedarach L. leaves extracts. Finally, additional in vivo investigations are highly recommended to confirm the anti-COVID-19 and antimicrobial activities of both plant extracts.

Published
2023
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16. Hybrid Chitosan/CaO-Based Nanocomposites Doped with Plant Extracts from Azadirachta indicaand Melia azedarach: Evaluation of Antibacterial and Antibiofilm Activities

Author

Paunova-Krasteva, Tsvetelina, Hemdan, Bahaa A., Dimitrova, Petya D., Damyanova, Tsvetozara, El-Feky, Amal M., Elbatanony, Marwa M., Stoitsova, Stoyanka, El-Liethy, Mohamed Azab, El-Taweel, Gamila E., and El Nahrawy, Amany M.

Abstract

This study examines substances from plant leaves of Azadirachta indicaand Melia azedarachextracted with methanol (80%) and then successively fractionated with increasing gradient polarity solvents. The methanol extract from the two plant leaves was selected to be incorporated with nanocomposites because of their high antimicrobial activities. HPLC analysis was performed for the determination of total phenolics and flavonoids. LC–ESI–MS positive ion acquisition mode revealed the presence of four main chemical classes: limonoids, triterpenes, fatty acids, and phenolics. Sol–gel processes were adapted to prepare CaO/chitosan composite loaded with the methanol extract of the two plant leaves, acting as innovative antibacterial agents. The fabricated nanocomposites were characterized by XRD, TEM, SEM, and FTIR methods. Minimal bactericidal concentrations (MBC) were established by agar plating using bacteria treated with MIC and at least 2 concentrations double higher than the MIC. Biofilm was cultivated in the presence of sub-MICs of the extracts and the nanocomposites, followed by quantification with the crystal violet assay. The examined chitosan–CaO-based hybrid nanocomposites loaded with the methanol fractions from the leaves of A. indicaand M. azedarachhad an excellent performance as biofilm inhibitors. This indicates their good potential for biomedical applications.

Published
2023
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23. Enhanced cellular uptake of platinum by a tetracationic Pt(II) nanocapsule and its implications to cancer treatment

Author

Ahmedova, Anife, primary, Mihaylova, Rositsa, additional, Stoykova, Silviya, additional, Mihaylova, Veronika, additional, Paunova-Krasteva, Tsvetelina, additional, Mihaylov, Lyuben, additional, Stoitsova, Stoyanka, additional, Nihtianova, Diana, additional, Momekov, Georgi, additional, Momekova, Denitsa, additional, and Yoshizawa, Michito, additional

Published
2020
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24. Cell response of Antarctic strain Penicillium griseofulvum against low temperature stress.

Author

KRUMOVA, Ekaterina Ts., KOEVA, Ekaterina K., STOITSOVA, Stoyanka R., PAUNOVA-KRASTEVA, Tsvetelina S., STOYANCHEVA, Galina D., and ANGELOVA, Maria B.

Abstract

During the evolution organisms are subjected to the continuous impact of environmental factors. In recent years an increasing number of studies have focused on the physicochemical limits of life on Earth such as temperature, pressure, drought, salt content, pH, heavy metals, etc. Extreme environmental conditions disrupt the most important interactions that support the function and structure of biomolecules. For this reason, organisms inhabiting extreme habitats have recently become of particularly great interest. Although filamentous fungi are an important part of the polar ecosystem, information about their distribution and diversity, as well as their adaptation mechanisms, is insufficient. In the present study, the fungal strain Penicillium griseofulvum isolated from an Antarctic soil sample was used as a study model. The fungal cellular response against short term exposure to low temperature was observed. Our results clearly showed that short-term low temperature exposure caused oxidative stress in fungal cells and resulted in enhanced level of oxidative damaged proteins, accumulation of reserve carbohydrates and increased activity of the antioxidant enzyme defence. Ultrastructural changes in cell morphology were analysed. Different pattern of cell pathology provoked by the application of two stress temperatures was detected. Overall, this study aimed to observe the survival strategy of filamentous fungi in extremely cold habitats, and to acquire new knowledge about the relationship between low temperature and oxidative stress. [ABSTRACT FROM AUTHOR]

Published
2022

27. Plastic Degradation by Extremophilic Microbial Communities Isolated from Bulgaria and Russia.

Author

Atanasova, Nikolina, Paunova-Krasteva, Tsvetelina, Stoitsova, Stoyanka, Kambourova, Margarita, Shapagin, Alexey, Matveev, Vladimir, Provotorova, Ekaterina, Elcheninov, Alexander, Sokolov, Tatyana, and Bonch-Osmolovskaya, Elizaveta

Subjects
MICROBIAL communities, LOW density polyethylene, HOT springs, POLYVINYL alcohol, PLASTIC analysis (Engineering), THERMOPHILIC microorganisms, SYNTHETIC fibers, PLASTICS
Abstract

This work reports the potential impact of extremophiles in resolving one of the biggest contemporary ecological problem - accumulation of huge amounts of plastic pollutants. Lye (C1) and water mud (C2) from Atanasovsko ezero, Bulgarian salterns were enriched for 2 weeks in a mineral salt medium provided with four synthetic plastics, Polycaprolactone (PCL), Polyvinyl alcohol (PVA), Polystyrene (PS), and Polypropylene (PP). Esterase activity was established for C1 on PVA and for C2 - on PCL and PVA. Scanning electron microscopy analysis of the plastics showed most explicit alterations on PCL surface. While the presence of C1 in the culture medium caused damage of the plastic surface, C2 interacted with it directly by forming a biofilm in surface breaks. Metagenomic analysis of C2, control and C2 with PCL revealed lower phylogenetic diversity in the presence of PCL and sharp rise of Gammaproteobacteria 16S rRNA sequences. The flourishing of the family Halomonadaceae was accompanied by a strong domination of the genus Halomonas, suggesting its active participation in PCL degradation. Thermophilic microorganisms in samples from Kamchatka hot springs were enriched in a medium with high- and low-density polyethylene in anaerobic conditions, at 78oC. Degradation of polyethylene after incubation was monitored by SEM. Results of 16S rRNA genes profiling compared with control variants revealed a domination of bacteria of phylum Dictyoglomi and family Thermoanaerobacteraceae in anaerobic thermophilic Kamchatka enrichments in the presence of polyethylene. These results indicate the possibility of thermophilic anaerobes to degrade the two types of polyethylene. [ABSTRACT FROM AUTHOR]

Published
2021

32. Developing an international Pseudomonas aeruginosa reference panel

Author

DeSoyza, Anthony, Hall, Amanda J, Mahenthiralingam, Eshwar, Drevinek, Pavel, Kaca, Wieslaw, Drulis-Kawa, Zuzanna, Stoitsova, Stoyanka, Coenye, Tom, Zlosnik, James, Burns, Jane, Sa Correia, Isabelle, DeVos, Daniel, Pirnay, Jean-Paul, Kidd, Timothy, Reid, David, Manos, Jim, Klockether, Jens, Wiehlmann, Litz, Tuemmler, Burkhard, McClean, Siobhan, Winstanley, Craig, EU COST, and EU COST Action

Subjects
Medical Sciences, pseudomonas aeruginosa, cystic fibrosis, reference panel
Abstract

Pseudomonas aeruginosa is a major opportunistic pathogen in cystic fibrosis (CF) patients and causes a wide range of infections among other susceptible populations. Its inherent resistance to many antimicrobials also makes it difficult to treat infections with this pathogen. Recent evidence has highlighted the diversity of this species, yet despite this, the majority of studies on virulence and pathogenesis focus on a small number of strains. There is a pressing need for a P. aeruginosa reference panel to harmonize and coordinate the collective efforts of the P. aeruginosa research community. We have collated a panel of 43 P. aeruginosa strains that reflects the organism's diversity. In addition to the commonly studied clones, this panel includes transmissible strains, sequential CF isolates, strains with specific virulence characteristics, and strains that represent serotype, genotype or geographic diversity. This focussed panel of P. aeruginosa isolates will help accelerate and consolidate the discovery of virulence determinants, improve our understanding of the pathogenesis of infections caused by this pathogen, and provide the community with a valuable resource for the testing of novel therapeutic agents.

Published
2013

35. Phenotypic characterization of an international Pseudomonas aeruginosa reference panel: strains of cystic fibrosis (CF) origin show less in vivo virulence than non-CF strains

Author

Cullen, Louise, primary, Weiser, Rebecca, additional, Olszak, Tomasz, additional, Maldonado, Rita F., additional, Moreira, Ana S., additional, Slachmuylders, Lisa, additional, Brackman, Gilles, additional, Paunova-Krasteva, Tsvetelina S., additional, Zarnowiec, Paulina, additional, Czerwonka, Grzegorz, additional, Reilly, James, additional, Drevinek, Pavel, additional, Kaca, Wieslaw, additional, Melter, Oto, additional, De Soyza, Anthony, additional, Perry, Audrey, additional, Winstanley, Craig, additional, Stoitsova, Stoyanka R., additional, Lavigne, Rob, additional, Mahenthiralingam, Eshwar, additional, Sá-Correia, Isabel, additional, Coenye, Tom, additional, Drulis-Kawa, Zuzanna, additional, Augustyniak, Daria, additional, Valvano, Miguel A., additional, and McClean, Siobhán, additional

Published
2015
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50. Cyclic enterobacterial common antigens from Escherichia coli O157 as microbe-associated molecular patterns.

Author

Paunova-Krasteva, Tsvetelina S., Pavlova, Velichka A., De Castro, Cristina, Ivanova, Radka M., Molinaro, Antonio, Nikolova, Elena B., and Stoitsova, Stoyanka R.

Subjects
SUGARCANE products, FOODBORNE diseases, IMMUNE system, ANTIGENS, ESCHERICHIA coli
Abstract

Copyright of Canadian Journal of Microbiology is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2014
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