TY  - CONF
AU  - Kuzmanović Nedeljković, Snežana
AU  - Ćujić Nikolić, Nada
AU  - Bigović, Dubravka
AU  - Petrović, Predrag
AU  - Pljevljakušić, Dejan
AU  - Šavikin, Katarina
AU  - Filipić, Brankica
PY  - 2022
UR  - https://farfar.pharmacy.bg.ac.rs/handle/123456789/5120
AB  - Among plant natural products, Oregano and Thyme essential oils (EOs) are well-known for 
their antimicrobial and antioxidant activity. The biological activities of EOs may be reduced 
due to oxidation and volatilization. Stability and preservation of EOs can be assured with the 
microencapsulation method based on complex coacervation technology. Cyclodextrins are 
suitable as carriers for volatile substances insoluble in water, and hydroxypropyl-β cyclodextrin (HPCD) leads the group considering the aqueous solubility and safe toxicity 
profile. The aim of this study was to find conditions for preparing Oregano and Thyme EOs 
microencapsulates with the best technological properties.Oregano and Thyme EOs were 
encapsulated by the freeze drying (lyophilization) method. Nine different combinations were 
prepared, where HPCD content (10, 15 and 20%) and EO:HPCD mass ratio (1:1, 1:5 and 
1:10) were varied. After stirring (200 rpm) for 24 h at a room temperature, suspensions were 
filtered through 0.45 mm PTFE filters. Samples were evaporated under vacuum and frozen (-
80 °C for 1 h), then main drying was carried out (-60 °C, pressure of 0.011 mbar for 40 h), 
and final drying (-65 °C, pressure of 0.054 mbar for 1 h). To ensure the particle purity, 
lyophilizates were washed with acetonitrile and dried at 25 °C. The content of each EO was 
determined spectrophotometrically, encapsulation efficiency (EE%) and yield were 
calculated. Duncan’s post hoc test was used to evaluate the differences between samples. 
The best conditions for both EOs were obtained with 15% HPCD and EO:HPCD mass ratio 
of 1:10. Yields of EOs for chosen Oregano and Thyme EOs complexes were 86.81 ± 2.20% 
and 89.83 ± 2.80%, respectively, with the following EE% of 49.08 ± 1.80% and 49.29 ± 
0.18%. Microencapsulation is a promising method for improving the EOs stability profile, 
and these results could be very useful in the pharmaceutical and food industry for the 
implementation of new products.
PB  - Belgrade : Institute of Technical Sciences of SASA
C3  - Twentieth Young Researchers Conference – Materials Science and Engineering, November 30 - December 2, 2022, Belgrade, Serbia - Programme and the Book of Abstracts
T1  - Microencapsulation of Oregano and Thyme essential oils with hydroxypropyl-β cyclodextrin
SP  - 14
EP  - 14
UR  - https://hdl.handle.net/21.15107/rcub_farfar_5120
ER  - 

@conference{
author = "Kuzmanović Nedeljković, Snežana and Ćujić Nikolić, Nada and Bigović, Dubravka and Petrović, Predrag and Pljevljakušić, Dejan and Šavikin, Katarina and Filipić, Brankica",
year = "2022",
abstract = "Among plant natural products, Oregano and Thyme essential oils (EOs) are well-known for 
their antimicrobial and antioxidant activity. The biological activities of EOs may be reduced 
due to oxidation and volatilization. Stability and preservation of EOs can be assured with the 
microencapsulation method based on complex coacervation technology. Cyclodextrins are 
suitable as carriers for volatile substances insoluble in water, and hydroxypropyl-β cyclodextrin (HPCD) leads the group considering the aqueous solubility and safe toxicity 
profile. The aim of this study was to find conditions for preparing Oregano and Thyme EOs 
microencapsulates with the best technological properties.Oregano and Thyme EOs were 
encapsulated by the freeze drying (lyophilization) method. Nine different combinations were 
prepared, where HPCD content (10, 15 and 20%) and EO:HPCD mass ratio (1:1, 1:5 and 
1:10) were varied. After stirring (200 rpm) for 24 h at a room temperature, suspensions were 
filtered through 0.45 mm PTFE filters. Samples were evaporated under vacuum and frozen (-
80 °C for 1 h), then main drying was carried out (-60 °C, pressure of 0.011 mbar for 40 h), 
and final drying (-65 °C, pressure of 0.054 mbar for 1 h). To ensure the particle purity, 
lyophilizates were washed with acetonitrile and dried at 25 °C. The content of each EO was 
determined spectrophotometrically, encapsulation efficiency (EE%) and yield were 
calculated. Duncan’s post hoc test was used to evaluate the differences between samples. 
The best conditions for both EOs were obtained with 15% HPCD and EO:HPCD mass ratio 
of 1:10. Yields of EOs for chosen Oregano and Thyme EOs complexes were 86.81 ± 2.20% 
and 89.83 ± 2.80%, respectively, with the following EE% of 49.08 ± 1.80% and 49.29 ± 
0.18%. Microencapsulation is a promising method for improving the EOs stability profile, 
and these results could be very useful in the pharmaceutical and food industry for the 
implementation of new products.",
publisher = "Belgrade : Institute of Technical Sciences of SASA",
journal = "Twentieth Young Researchers Conference – Materials Science and Engineering, November 30 - December 2, 2022, Belgrade, Serbia - Programme and the Book of Abstracts",
title = "Microencapsulation of Oregano and Thyme essential oils with hydroxypropyl-β cyclodextrin",
pages = "14-14",
url = "https://hdl.handle.net/21.15107/rcub_farfar_5120"
}

Kuzmanović Nedeljković, S., Ćujić Nikolić, N., Bigović, D., Petrović, P., Pljevljakušić, D., Šavikin, K.,& Filipić, B.. (2022). Microencapsulation of Oregano and Thyme essential oils with hydroxypropyl-β cyclodextrin. in Twentieth Young Researchers Conference – Materials Science and Engineering, November 30 - December 2, 2022, Belgrade, Serbia - Programme and the Book of Abstracts
Belgrade : Institute of Technical Sciences of SASA., 14-14.
https://hdl.handle.net/21.15107/rcub_farfar_5120

Kuzmanović Nedeljković S, Ćujić Nikolić N, Bigović D, Petrović P, Pljevljakušić D, Šavikin K, Filipić B. Microencapsulation of Oregano and Thyme essential oils with hydroxypropyl-β cyclodextrin. in Twentieth Young Researchers Conference – Materials Science and Engineering, November 30 - December 2, 2022, Belgrade, Serbia - Programme and the Book of Abstracts. 2022;:14-14.
https://hdl.handle.net/21.15107/rcub_farfar_5120 .

Kuzmanović Nedeljković, Snežana, Ćujić Nikolić, Nada, Bigović, Dubravka, Petrović, Predrag, Pljevljakušić, Dejan, Šavikin, Katarina, Filipić, Brankica, "Microencapsulation of Oregano and Thyme essential oils with hydroxypropyl-β cyclodextrin" in Twentieth Young Researchers Conference – Materials Science and Engineering, November 30 - December 2, 2022, Belgrade, Serbia - Programme and the Book of Abstracts (2022):14-14,
https://hdl.handle.net/21.15107/rcub_farfar_5120 .

TY  - CONF
AU  - Kuzmanović Nedeljković, Snežana
AU  - Stević, Tatjana
AU  - Bigović, Dubravka
AU  - Šavikin, Katarina
AU  - Filipić, Brankica
PY  - 2022
UR  - https://farfar.pharmacy.bg.ac.rs/handle/123456789/5119
AB  - BACKGROUND
COVID-19 pandemic brought a burden to the health care system including a higher rate of patients admitted to the intensive care unit (ICU). Mechanical ventilation, needed in COVID-19 patients admitted to ICU, increases the risk of developing multidrug-resistant (MDR) Acinetobacter baumannii superinfection, which may cause major problems in antibiotic treatment.
OBJECTIVES
The aim of this research was to examine the susceptibility of A. baumannii isolates recovered from COVID-19 patients 
to antibiotics usually used as treatment options, and to Oregano essential oil (EO) as naturally derived compound.
METHODS 
The 54 A. baumannii isolates were recovered from COVID-19 patients admitted to ICU, during period from December 
2020 to February 2021. Biofilm formation ability, as the factor that contributes to bacterial resistance, was examined. Minimum inhibitory concentrations (MICs) were determined for meropenem, imipenem, colistin, gentamicin, tobramycin and levofloxacin. In addition, all 54 isolates of A. baumanii were tested for susceptibility to Oregano EO.
RESULTS 
Results obtained in this study revealed a significant MDR profile of tested A. baumannii isolates. Even 74% (40/54) were strong biofilm producers. A. baumannii isolates were resistant to all tested antibiotics, except to colistin, leaving colistin as the only treatment option. On the other hand, MIC results obtained for Oregano EO were extremely promising: 0.279 mg/mL for all tested isolates. The obtained results emphasize a potentially new treatment approach to infections caused by MDR A. baumannii, using natural products such as EOs.
PB  - Federation of European Microbiological Societies
PB  - Serbian Society for Microbiology
C3  - FEMS Conference on Microbiology in association with Serbian Society of Microbiology, 30 June - 2 July 2022, Serbia - electronic abstract book
T1  - Oregano essential oil sensitivity of multiresistant Acinetobacter baumannii strains isolated from COVID-19 patients
SP  - 272
EP  - 272
UR  - https://hdl.handle.net/21.15107/rcub_farfar_5119
ER  - 

@conference{
author = "Kuzmanović Nedeljković, Snežana and Stević, Tatjana and Bigović, Dubravka and Šavikin, Katarina and Filipić, Brankica",
year = "2022",
abstract = "BACKGROUND
COVID-19 pandemic brought a burden to the health care system including a higher rate of patients admitted to the intensive care unit (ICU). Mechanical ventilation, needed in COVID-19 patients admitted to ICU, increases the risk of developing multidrug-resistant (MDR) Acinetobacter baumannii superinfection, which may cause major problems in antibiotic treatment.
OBJECTIVES
The aim of this research was to examine the susceptibility of A. baumannii isolates recovered from COVID-19 patients 
to antibiotics usually used as treatment options, and to Oregano essential oil (EO) as naturally derived compound.
METHODS 
The 54 A. baumannii isolates were recovered from COVID-19 patients admitted to ICU, during period from December 
2020 to February 2021. Biofilm formation ability, as the factor that contributes to bacterial resistance, was examined. Minimum inhibitory concentrations (MICs) were determined for meropenem, imipenem, colistin, gentamicin, tobramycin and levofloxacin. In addition, all 54 isolates of A. baumanii were tested for susceptibility to Oregano EO.
RESULTS 
Results obtained in this study revealed a significant MDR profile of tested A. baumannii isolates. Even 74% (40/54) were strong biofilm producers. A. baumannii isolates were resistant to all tested antibiotics, except to colistin, leaving colistin as the only treatment option. On the other hand, MIC results obtained for Oregano EO were extremely promising: 0.279 mg/mL for all tested isolates. The obtained results emphasize a potentially new treatment approach to infections caused by MDR A. baumannii, using natural products such as EOs.",
publisher = "Federation of European Microbiological Societies, Serbian Society for Microbiology",
journal = "FEMS Conference on Microbiology in association with Serbian Society of Microbiology, 30 June - 2 July 2022, Serbia - electronic abstract book",
title = "Oregano essential oil sensitivity of multiresistant Acinetobacter baumannii strains isolated from COVID-19 patients",
pages = "272-272",
url = "https://hdl.handle.net/21.15107/rcub_farfar_5119"
}

Kuzmanović Nedeljković, S., Stević, T., Bigović, D., Šavikin, K.,& Filipić, B.. (2022). Oregano essential oil sensitivity of multiresistant Acinetobacter baumannii strains isolated from COVID-19 patients. in FEMS Conference on Microbiology in association with Serbian Society of Microbiology, 30 June - 2 July 2022, Serbia - electronic abstract book
Federation of European Microbiological Societies., 272-272.
https://hdl.handle.net/21.15107/rcub_farfar_5119

Kuzmanović Nedeljković S, Stević T, Bigović D, Šavikin K, Filipić B. Oregano essential oil sensitivity of multiresistant Acinetobacter baumannii strains isolated from COVID-19 patients. in FEMS Conference on Microbiology in association with Serbian Society of Microbiology, 30 June - 2 July 2022, Serbia - electronic abstract book. 2022;:272-272.
https://hdl.handle.net/21.15107/rcub_farfar_5119 .

Kuzmanović Nedeljković, Snežana, Stević, Tatjana, Bigović, Dubravka, Šavikin, Katarina, Filipić, Brankica, "Oregano essential oil sensitivity of multiresistant Acinetobacter baumannii strains isolated from COVID-19 patients" in FEMS Conference on Microbiology in association with Serbian Society of Microbiology, 30 June - 2 July 2022, Serbia - electronic abstract book (2022):272-272,
https://hdl.handle.net/21.15107/rcub_farfar_5119 .