Ispitivanje interakcija mikotoksina sterigmatocistina ciklodekstrinima i humanim serumskim albuminom spektrofotometrijskim metodama

master's thesis

• Title (english): Study of noncovalent interactions of sterigmatocystin, cyclodextrins and human serum albumin by spectrophotometric methods
• Author: Lucija Šćur
• Mentor: Daniela Jakšić (mentor)
• Committee member: Daniela Jakšić (predsjednik povjerenstva)
• Committee member: Hrvoje Rimac (član povjerenstva)
• Committee member: Ivo Piantanida (član povjerenstva)
• Granter: University of Zagreb; Faculty of Pharmacy and Biochemistry; (Department of microbiology); Zagreb
• Defense date and country: 2021-09-01, Croatia
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Pharmacy; Pharmacy

Abstract

Ciklodekstrini (CXD) ciklički su oligosaharidi koji u vodenim otopinama stvaraju inkluzijske komplekse s malim organskim spojevima. Sugamadeks je modificirani oblik CXD gama (CXD-γ), a u Hrvatskoj je registriran kao lijek Bridion (CXD-Br) koji se koristi kod reverzije intramuskularne blok anestezije. Sterigmatocistin (STC) jedan je od najčešćih mikotoksina u zatvorenim prostorima u kojima ljudi borave i rade. Ovaj toksični, mutageni i genotoksični mikotoksin dokazanoga kancerogenoga učinka u životinjama (grupa IARC 2B), prekursor je i u biosintezi AFB1 koji se povezuje sa hepatocelularnim karcinomom kod ljudi (grupa IARC 1). Poznato je da CXD, stupaju u značajne interakcije sa AFB1 te su CXD te su našli primjenu u kromatografskim metodama dokazivanja ovoga mikotoksina. Obzirom na konformacijsku podudarnost kemijskih struktura STC i anestetika rokuronija, kao i na sličnost u kemijskim strukturama STC i AFB1, može se pretopstaviti interakcija STC sa CXD o čemu su podaci u literaturi limitirani. U ovome radu ispitane su nekovalentne interakcije STC sa CXD beta (CXD-β), CXD-γ i CXD-Br. Kako bi se procijenio afinitet vezanja STC i CXD na temelju spektrofotometrijskih mjerenja (UV/Vis, cirkularni dikroizam- CD i fluorimetrija) izračunate su logK. Kako bi se procijenila mogućnost primjene CXD kao antidota izračunat je i afinitet vezanja za humani serumski albumin (HSA) istim metodama te je proveden kompetitivni fluorimetrijski eksperiment istiskivanja STC vezanog za HSA. Prema dobivenim rezultatima može se zaključiti da CXD-β, CXD-γ i CXD-Br stupaju u snažne nekovalentne interakcije sa STC. Pri tome je najveći afinitet vezanja (logK) izračunat za CXD-Br (6,46) i CXD-γ (6,15), a nešto niži za CXD-β (5,62). Ispitivanjem je također pokazano da se STC veže i za protein HSA no nižim afinitetom u odnosu na CXD uz logK od 4,99 (CD spektroskopija) do 5,24 (fluorimetrija). U kompetitivnom fluorimetrijskom eksperimentu dokazali smo da svi ispitani CXD istiskuju STC iz kompleksa sa HSA. Dobiveni rezultati ukazuju na mogućnost primjene CXD kao antidota kod trovanja mikotoksinom STC.

Abstract (english)

Cyclodextrins (CXD) are cyclic oligosaccharides that create inclusion complexes with small organic compounds in aqueous solutions. Sugammadex is a modified form of CXD gamma (CXD-γ), and in Croatia it is registered as a drug Bridion (CXD-Br) used in intramuscular block anesthesia reversion. Sterigmatocystin (STC) is one of the most common mycotoxins in indoor living and working environments. This toxic, mutagenic, and genotoxic mycotoxin with a demonstrated carcinogenic effect in animals (group IARC 2B), is also a precursor in the biosynthesis of AFB1, which is associated with hepatocellular carcinoma in humans (group IARC 1). It is known that CXD, engage in significant interactions with AFB1 and thus they have found application in chromatographic-based analysis of this mycotoxin. Given the structural resemblance of STC and the anesthetic rocuronium and AFB1, the interaction of STC with CXD can be anticipated and worth investigating since the data in the literature is limited.
In this diploma thesis the non-valent interactions of STC with CXD beta (CXD-β), CXD-γ and CXD-Br were explored. To assess the possibility of using CXD as an antidote for STC poisoning, the binding affinity for human serum albumin (HSA) was assessed by the same methods. In addition, a competitive fluorimetry experiment was conducted to demonstrate displacement of STC from HSA-STC complex by CXDs.
According to the results obtained, it can be concluded that CXD-β, CXD-γ and CXD-Br engage in strong non-covalent interactions with STC. The highest binding affinity (logK) was calculated for CXD-Br (6.46) and CXD-γ (6.15), and slightly lower for CXD-β (5.62). The study also showed that STC binds to the HSA protein but with a lower affinity compared to CXD with a corresponding logK of 4.99 (CD spectroscopy) to 5.24 (fluorimetry). Competitive fluorimetry experiments demonstrated that all CXDs are capable of STC displacing from the complex with HSA. The obtained results support the application of CXDs as antidote treatment in poisoning caused by mycotoxin STC.

• Keywords: sterigmatocistin; ciklodekstrini; humani serumski albumin; cirkularni dikroizam; UV/Vis; fluorimetrija; antidot
• Keywords (english): sterigmatocystin; cyclodextrines; human serum albumin; circular dichroism; UV/Vis; fluorimetry; antidote
• Language: croatian
• URN:NBN: urn:nbn:hr:163:302430
• Study programme: Title: Pharmacy; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: magistar/magistra farmacije (magistar/magistra farmacije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2022-02-08 14:07:41