Antimikrobni učinak karvakrola i eteričnog ulja origana (O. compactum) na bakteriju Staphylococcus aureus

master's thesis

• Title (english): Antimicrobial effect of carvacrol and oregano essential oil (O. compactum) on the bacterium Staphylococcus aureus
• Author: Marko Brajak
• Mentor: Maja Šegvić Klarić (mentor)
• Committee member: Maja Šegvić Klarić (predsjednik povjerenstva)
• Committee member: Ana-Marija Domijan (član povjerenstva)
• Committee member: Darija Stupin Polančec (član povjerenstva)
• Granter: University of Zagreb; Faculty of Pharmacy and Biochemistry; (Department of microbiology); Zagreb
• Defense date and country: 2024-11-14, Croatia
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Pharmacy; Pharmacy

Abstract

Zbog sve većeg razvoja antimikrobne rezistencije (AMR) intenzivno se istražuju različite alternative antibioticima ili
potencijalne kombinacije s prirodnim tvarima koje bi smanjile korištenje antibiotika. Eterična ulja i njihove sastavnice
pokazale su se u brojnim istraživanjima kao potentne aktivne tvari svojim antimikrobnim, ali i antioksidativnim i protuupalnim
djelovanjem. Mupirocin je jedan od najčešće korištenih topikalnih antibiotika pogotovo za infekcije kože uzrokovane S.
aureusom. Razvojem posebnih formulacija antibiotika zajedno s eteričnim uljima ili njihovim sastavnicama mogao bi se postići
sinergistički učinak u vidu korištenja manjih koncentracija antibiotika i pojačanog antimikrobnog djelovanja takvih
formulacija. Dok antibiotici ciljaju specifične bakterijske procese, eterična ulja narušavaju integritet bakterijskih stanica i
utječu na smanjenje produkcije biofilma, čime se pojačava ukupni antimikrobni učinak. Kako bi se uopće započelo s razvojem
takvih formulacija, potrebno je utvrditi učinkovitost djelovanja eteričnog ulja i njegovih sastavnica te kombinacija s
antibiotikom. Stoga je cilj ovoga rada bio utvrditi antimikrobni potencijal eteričnog ulja origana (O. compactum) i njegove
glavne sastavnice karvakrola pojedinačno i u kombinacijama s antibiotikom mupirocinom. U radu su ispitivane MIC
vrijednosti mupirocina (MUP), karvakrola (KAR) i eteričnog ulja origana (ET.U.) pojedinačno i u kombinacijama. MIC
mupirocina za S. aureus sojeve kretao se u rasponu 0,076 – 0,141 μg/mL, dok su MIC-ovi karvakrola i eteričnog ulja origana
bili nekoliko redova veći: karvakrol 525 – 700 μg/mL, eterično ulje origana 625 – 750 μg/mL. U ispitivanju kombinacija MUP
i KAR/ET.U. na soju S. aureus NCTC 12493 dokazan je aditivni učinak dok je na S. aureus ATCC 2592 rezultat bio
indiferentan. Prilikom ispitivanja inhibicije nastanka biofilma u pojedinačnim ispitivanjima dokazana je statistički značajna
razlika u smanjenju produkcije biofilma u odnosu na pozitivnu kontrolu, ali nije zabilježena statistički značajna razlika u
povećanju koncentracija pojedinih aktivnih tvari. Kombinacija MUP + KAR/ET.U. pokazala je statistički značajnu razliku u
smanjenju produkcije biofilma u odnosu na identične koncentracije mupirocina. Najjači učinak imala je kombinacija
koncentracija od 0,0625 μg/mL MUP + 150 μg/mL KAR i identična kombinacija od 0,0625 μg/mL MUP + 150 μg/mL ET.U.
Ovime je dokazano da kombinacija manjih koncentracija mupirocina i eteričnog ulja origana, odnosno njegove glavne
sastavnice karvakrola nije djelovala na značajno smanjenje MIC-a mupirocina, ali može potentno djelovati na smanjenju
produkcije biofilma S. aureus.

Abstract (english)

Due to the increasing development of antimicrobial resistance (AMR), various alternatives to antibiotics or potential
combinations with natural substances that could reduce antibiotic use are being intensively researched. Essential oils and their components have demonstrated potent active properties in numerous studies, exhibiting not only antimicrobial effects but also antioxidant and anti-inflammatory activities. Mupirocin is one of the most commonly used topical antibiotics, especially for skin infections caused by S. aureus. The development of specific antibiotic formulations together with essential oils or their components could achieve a synergistic effect, allowing the use of lower antibiotic concentrations and enhancing the antimicrobial action of such formulations. While antibiotics target specific bacterial processes, essential oils disrupt bacterial cell integrity and reduce biofilm production, thereby enhancing the overall antimicrobial effect. To initiate the development of such formulations, it is necessary to establish the efficacy of essential oil and its components, as well as their combinations with antibiotics. Therefore, the aim of this study was to determine the antimicrobial potential of oregano essential oil (O. compactum) and its main component, carvacrol, both individually and in combination with the antibiotic mupirocin. The study investigated the minimum inhibitory concentration (MIC) values for mupirocin (MUP), carvacrol (CAR), and oregano essential oil (EO) both individually and in combination. The MIC of mupirocin for S. aureus strains ranged from 0.076 to 0.141 μg/mL, whereas the MICs for carvacrol and oregano essential oil were several orders higher: carvacrol 525–700 μg/mL and oregano essential oil at 625–750 μg/mL. In tests of MUP and CAR/EO combinations on the S. aureus NCTC 12493 strain, an additive effect was observed, while the results for S. aureus ATCC 2592 were indifferent. When examining inhibition of biofilm formation in individual tests, a statistically significant reduction in biofilm production was noted compared to the positive control; however, increasing the concentrations of individual active substances did not produce a statistically
significant difference. The combination of MUP + CAR/EO showed a statistically significant reduction in biofilm production
compared to identical mupirocin concentrations. The strongest effect was seen with the combination of 0.0625 μg/mL MUP + 150 μg/mL CAR, and 0.0625 μg/mL MUP + 150 μg/mL EO. This demonstrated that while combining lower concentrations of mupirocin with oregano essential oil or its main component (carvacrol) did not significantly reduce mupirocin’s MIC, it could effectively reduce S. aureus biofilm production.

• Keywords: Staphylococcus aureus; mupirocin; karvakrol; eterično ulje origana; Origanum compactum; antimikrobni učinak; biofilm
• Keywords (english): Staphylococcus aureus; mupirocin; carvacrol; oregano essential oil; Origanum compactum; antimicrobial effect; biofilm
• Language: croatian
• URN:NBN: urn:nbn:hr:163:496162
• Study programme: Title: Pharmacy - integrated undergraduate and graduate - university study; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: sveučilišni magistar farmacije (sveučilišni magistar farmacije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2025-02-05 12:23:16