Termodinamika kompleksiranja steroida s ciklodekstrinima i kukurbit[7]urilom

master's thesis

• Title (english): Thermodynamics of steroid complexation reactions with cyclodextrins and cucurbit[7]uril
• Author: Karla Kukina Gradečak
• Mentor: Josip Požar (mentor)
• Committee member: Josip Požar (predsjednik povjerenstva)
• Committee member: Nikola Cindro (član povjerenstva)
• Committee member: Vladimir Stilinović (član povjerenstva)
• Committee member: Mirta Rubčić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Chemistry); Zagreb
• Defense date and country: 2024-09-11, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry

Abstract

U ovom je radu istražena termodinamika inkluzije androsterona, androstandiona i testosterona te triju žučnih soli – natrijeva litokolata, deoksikolata i kolata u β- i γ‑ciklodekstrin te kukurbit[7]uril u vodi. U svim istraženim sustavima nastali su stabilni kompleksi (log K° > 3,5) što je kod heptamernih receptora posljedica isključivo negativne ΔrH°, a γ-ciklodekstrina i pozitivne ΔrS°. Trans‑izomeri steroida s β‑ciklodekstrinom tvore komplekse stehiometrije 1 : 1 i 1 : 2 (steroid : β-ciklodekstrin), dok je u slučaju žučnih soli opažen nastanak isključivo kompleksa stehiometrije 1 : 1. Afinitet γ‑ciklodekstrina prema žučnim solima veći je nego afinitet β-ciklodekstrina, a vidljivo je i da se stabilnost nastalih kompleksa smanjuje s povećanjem broja hidroksilnih skupina u strukturi žučnih soli. Unatoč izrazito negativnim vrijednostima ΔrCp°, standardne reakcijske Gibbsove energije za kompleksiranje androsterona i natrijeva kolata s γ-ciklodekstrinom se ne mijenjaju značajno s temperaturom (temperaturna entalpijsko‑entropijska kompenzacija).

Abstract (english)

The thermodynamics of inclusion of androsterone, androstanedione and testosterone, as well as three bile salts – sodium lithocholate, deoxycholate, and cholate in β-, γ-cyclodextrin and cucurbit[7]uril was investigated in water. In all cases stable complexes were formed (log K° > 3,5). The reactions were enthalpy driven in case of heptameric receptors while the inclusion within γ-cyclodextrin was both enthalpically and entropically favourable. The trans‑isomers form 1 : 1 and 1 : 2 (steroid :
β-cyclodextrin) stoichiometric complexes, whereas bile salts form only 1 : 1 complexes. The affinity of γ‑cyclodextrin towards bile salts is higher compared to β-cyclodextrin and the stability of complexes with both cyclodextrins decrease with increasing number of hydroxyl groups in the bile salt structure. Despite considerably negative ΔrCp° values, the ΔrG° for the reaction of androsterone and sodium cholate with γ‑cyclodextrin does not change apreciably with the temperature (temperature enthalpy‑entropy compensation).

• Keywords: iklodekstrini; kukurbit[7]uril; steroid; termodinamika kompleksiranja
• Keywords (english): complexation thermodynamics; cucurbit[7]uril; cyclodextrins; steroids
• Language: croatian
• URN:NBN: urn:nbn:hr:217:755804
• Project: Number: IP-2019-04-9560; Title: Koordinacijske reakcije makrocikličkih liganada u otopini; Title: Coordination Reactions of Macrocyclic Ligands in Solution; Acronym: MacroSol; Leader: Vladislav Tomišić; Jurisdiction: Croatia; Funder: Hrvatska zaklada za znanost; Funding stream: Research Projects
• Study programme: Title: Graduate university studies in chemistry; specializations in: Graduate university studies in chemistry; Course: Graduate university studies in chemistry; Study programme type: university; Study level: graduate; Academic / professional title: sveučilišni/a magistar/magistra kemije (sveučilišni/a magistar/magistra kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Embargoed access; Embargo expiration date: 2025-09-11
• Created on: 2024-10-04 09:26:13