Izolacija ad-humulona in določitev vrednosti pKa

diplomsko delo univerzitetnega študijskega programa I. stopnje

Lara Jan Klinc (Author), Urban Bren (Mentor), Sara Štumpf (Co-mentor)

Abstract

Hmelj oz. Humulus lupulus je zelnata trajnica iz družine konopljevk, ki se že stoletja uporablja predvsem v pivovarstvu. Kljub dolgi tradiciji njegove uporabe v prehramben namene pa v zadnjem času pridobiva vse večjo pozornost na področju naravoslovnih ved, predvsem zaradi svoje bogate in kompleksne kemijske sestave. Hmeljevi storžki vsebujejo vrsto bioaktivnih snovi, med katerimi poleg eteričnih olj in polifenolov izstopajo predvsem smole, vključno z ad-humulonom. Zaradi prisotnosti številnih šibkih kislin je določevanje vrednosti pKa posameznih spojin ključnega pomena za razumevanje njihovih spektroskopskih lastnosti, topnosti v različnih medijih in tudi kemijske reaktivnosti. Poleg tega je konstanta, ki opisuje stopnjo protoniranosti glede na pH vrednost, ključna za uspešno uporabo metod računske kemije. V diplomskem delu smo izolirali ad-humulon in mu določili pKa vrednosti. Sprva smo iz posušenih hmeljevih storžkov pripravili hmeljev ekstrakt. Nato smo z uporabo preparativnega HPLC s hitro in preparativno metodo iz ekstrakta izolirali želeno α-kislino. Čistost eluentov smo na vsaki stopnji spremljali z analitskim HPLC. Iz začetnega ekstrakta smo dobili 96 mg ad-humulona. Istovetnost spojine smo določili tako z uporabo analitskega HPLC kot tudi z NMR. Kromatografska čistost izolirane spojine je 84 %. Ad-humulonu smo z UV-Vis spektroskopsko metodo pomerili spektre pri različnih vrednostih pH. Rezultat pKa vrednosti smo dobili z modelnim prileganjem eksperimentalnih in izračunanih vrednosti. Določili smo dve pKa vrednosti. Za prvo deprotonacijo smo dobili vrednost pKa₁ 4,11. Pri drugi deprotonaciji pa je pKa₂ znašala 11,94.

Keywords

hmelj;α-kisline;ad-humulon;kromatografija;pKa vrednost;UV/Vis spektrometrija;diplomske naloge;

Data

Language:	Slovenian
Year of publishing:	2025
Typology:	2.11 - Undergraduate Thesis
Organization:	UM FKKT - Faculty of Chemistry and Chemical Engineering
Publisher:	[L. Jan Klinc]
UDC:	66.061.3:663.791(043.2)
COBISS:	248273667
Views:	0
Downloads:	4
Average score:	0 (0 votes)
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Other data

Secondary language:	English
Secondary title:	Isolation of the ad-humulone and determination of the pKa value
Secondary abstract:	Hop (Humulus lupulus), a perennial herbaceous plant of the Cannabaceae family, has been traditionally employed for centuries, primarily in brewing. In recent years, however, it has attracted a growing attention within the natural sciences owing to its rich and complex chemical composition. Hop cones contain a wide range of bioactive substances, among which, in addition to essential oils and polyphenols, resins—particularly ad-humulone—are of notable significance. Due to the presence of numerous weak acids, determination of the pKa values of individual compounds is of fundamental importance for understanding their spectroscopic properties, solubility in different media, and chemical reactivity. Moreover, the protonation constant as a function of pH is essential for the reliable application of computational chemistry methods. In the present thesis, ad-humulone was isolated and its pKa values determined. Initially, a hop extract was prepared from dried hop cones. The target α-acid was subsequently isolated from the extract using preparative HPLC with a rapid preparative method. At each step, the purity of the eluents was monitored by analytical HPLC. From the initial extract, 96 mg of ad-humulone was obtained. The identity of the compound was confirmed by analytical HPLC and NMR spectroscopy. The chromatographic purity of the isolated compound was 84%. UV/Vis spectroscopy was employed to record spectra of ad-humulone at various pH values, and the pKa values were established through model fitting of the experimental data with calculated values. Two pKa values were determined: for the first deprotonation, pKa₁ = 4.11; for the second deprotonation, pKa₂ = 11.94.
Secondary keywords:	hop;α-acids;ad-humulone;chromatography;pKa value;UV/Vis spectoscopy;
Type (COBISS):	Bachelor thesis/paper
Thesis comment:	Univ. v Mariboru, Fak. za kemijo in kemijsko tehnologijo
Pages:	1 spletni vir (1 datoteka PDF (XII, 45 str.))
ID:	27169853