Vrednotenje protibakterijske aktivnosti knjižnice spojin na bakterije iz rodu Enterococcus

Habinc, Tjaša (author), Hrast Rambaher, Martina (mentor), Golob, Majda (comentor)

V zadnjih desetletjih je opazen izrazit porast odpornosti bakterij proti obstoječim antibiotikom, kar nakazuje prihod obdobja, v katerem bo možnosti za zdravljenje bakterijskih okužb vse manj. Bakterijske okužbe zdravimo s protibakterijskimi učinkovinami, ki lahko delujejo preko petih osnovnih mehanizmov delovanja, vendar so številne bakterije proti tem mehanizmom že razvile naravno ali pridobljeno odpornost. Pri odkrivanju novih protibakterijskih učinkovin je lahko v pomoč metoda vrednotenja knjižice spojin, pri kateri se testira veliko število spojin z namenom identifikacije tistih, ki izkazujejo protibakterijsko aktivnost. Odkrite učinkovine lahko delujejo baktericidno ali bakteriostatično. Eden ključnih parametrov za vrednotenje protibakterijske aktivnosti je minimalna inhibitorna koncentracija, ki predstavlja najnižjo koncentracijo učinkovine, ki še zavira rast bakterije. V okviru magistrske naloge smo ovrednotili protibakterijsko aktivnost knjižice spojin Fakultete za farmacijo Univerze v Ljubljani proti dvema bakterijskima vrstama iz rodu Enterococcus, in sicer Enterococcus faecalis (EFS) in Enterococcus faecium (EFM). Med 1971 testiranimi spojinami smo z metodo redčenja določili minimalno inhibitorno koncentracijo petnajstim spojinam, ki so pri prvotnem testiranju izkazale protibakterijsko aktivnost. Učinkovito protibakterijsko aktivnost proti bakteriji EFS so izkazale spojine 1, 2, 7, 8, 12, 13, 14 in 15, za katere so bile vrednosti minimalne inhibitorne koncentracije nižje od 128 µg/mL. Proti bakteriji EFM pa je učinkovito protibakterijsko aktivnost izkazalo sedem spojin, in sicer 7, 9, 11, 12, 13, 14 in 15. Najnižjo vrednost minimalne inhibitorne koncentracije je izkazala spojina 7, ki je zavrla rast bakterije EFS pri koncentraciji 2 µg/mL, hkrati je najbolj izrazito protibakterijsko aktivnost izkazala tudi proti bakteriji EFM, katere je rast zavrla že pri koncentraciji 4 µg/mL. Spojine 3, 4, 5, 6 in 10 niso izkazale protibakterijskega učinka proti bakterijama EFM in EFS niti pri najvišji testirani koncentraciji, kar lahko nakazuje na odpornost bakterij, pri čemer je potrebno upoštevati tudi možnost prenizkih koncentracij zaradi dodatnega redčenja osnovnih raztopin. Spojina z znanim mehanizmom delovanja je spojina 12, ki deluje na DNA-girazo. Spojina 7, ki je izkazala učinkovito protibakterijsko aktivnost v kombinaciji z nizko minimalno inhibitorno koncentracijo, predstavlja izhodišče za nadaljnje raziskave in bi se lahko v prihodnosti uporabila pri razvoju novih protibakterijskih učinkovin.

• Language: Slovenian
• Keywords: protibakterijske učinkovine, minimalna inhibitorna koncentracija, protibakterijska aktivnost, rod Enterococcus
• Work type: Master's thesis/paper
• Organization: FFA - Faculty of Pharmacy
• Year: 2025
• PID: 20.500.12556/RUL-173620
• Publication date in RUL: 19.09.2025

Secondary language

• Language: English
• Title: Evaluation of the antibacterial activity of a compound library against bacteria of the Enterococcus genus

Abstract

In the past few decades, there has been a significant increase in the resistance of bacteria to existing antibiotics, which indicates the coming of an era in which there will be fewer and fewer treatment options for bacterial infections. Bacterial infections are treated with antibacterial agents that can work through five basic mechanisms of action, but many bacteria have already developed natural or acquired resistance to these mechanisms. The discovery of new antibacterial agents can be aided by a compound library screening method, in which a large number of compounds are tested to identify those that exhibit antibacterial activity. The active substances can have a bactericidal or bacteriostatic effect. One of the key parameters for evaluating antibacterial activity is the minimum inhibitory concentration (MIC), which is the lowest concentration of the active substance that still inhibits the growth of the bacteria. As part of my master's thesis, I evaluated the antibacterial activity of a book of compounds from the Faculty of Pharmacy at the University of Ljubljana against two bacterial species from the Enterococcus genus, namely Enterococcus faecalis and Enterococcus faecium. Using the dilution method, we determined the MIC of fifteen compounds that showed antibacterial activity in the initial test, among 1971 tested compounds. Effective antibacterial activity against EFS was demonstrated by compounds 1, 2, 7, 8, 12, 13, 14, and 15, which had MIC values lower than 128 µg/mL. Seven compounds, namely 7, 9, 11, 12, 13, 14, and 15 demonstrated effective antibacterial activity against the EFM bacterium. The compound 7 showed the lowest MIC value, inhibiting the growth of EFS bacteria at a concentration of 2 µg/mL, and also showed the most pronounced antibacterial activity against EFM bacteria, which it inhibited at a concentration of 4 µg/mL. Compounds 3, 4, 5, 6 and 10 did not show antibacterial activity against EFM and EFS bacteria even at the highest tested concentration, which may indicate bacterial resistance, taking into account the possibility of too low concentrations due to additional dilution of the basic solutions. The compound with a known mechanism of action is compound 12, which acts on DNA gyrase. Compound 7, which demonstrated effective antibacterial activity in combination with a low minimum inhibitory concentration, is a starting point for further research and could be used in the future in the development of new antibacterial agents.

• Keywords: antibacterial agents, minimum inhibitory concentration, antibacterial activity, genus Enterococcus