Naslov
The analysis of borecole glucosinolates and their breakdown products by HPLC with UV Diode Array and FL detection

Autori
Radojčić, Ivana ; Kovačević-Ganić, Karin ; Delonga, Karmela ; Vorkapić-Furač, Jasna

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Book of Abstract-Eighth International Symposium on Hyphenated Techniques in Chromatography and Hyphenated Chromatographic Analyzers (HTC-8) / Roxal Flemish Chemical Society - Brisel : Roxal Flemish Chemical Society, 2004

Skup
Eighth International Symposium on Hyphenated Techniques in Chromatographyand Hyphenated Chromatographic Analyzers (HTC-8)

Mjesto i datum
Brugge, Belgija, 04.06.2004

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
borecole; glucosinolates; indole breakdown products; HPLC

Sažetak
Borecole (Brassica oleracea var acephala L.) belongs to cruciferous vegetables and is commonly consumed in Dalmatia, the southern region of Croatia. The popularity of this vegetable is due to its flavor, while at the present time, borecole is primarily appreciated by man because of knowledge that it contains some beneficial compounds, especially glucosinolates (GSL), degradation products of which have shown to protect against the development of some kinds of tumors and cancer. The active GSL breakdown products may be the results of various degradation processes: enzymatic, chemical, and thermal (1). The aim of this work was to analyze the composition of borecole glucosinolates and their breakdown products obtained by borecole processing in the conditions similar to those present during digestion, what means the acidic conditions of stomach and neutral conditions in small intestine in the presence of hydrolytic enzyme myrosinase. The analyses were performed by combination of UV Diode Array and fluorescent (FL) detection linked to a RP-LC separation system. Three samples of fresh borecole (I, II and III) were purchased from local market to estimate the composition of GSL by RP-LC of desulphoglucosinolates (DSGSL) (2, 3). One sample (I) was cooked for 20 minutes and treated with acid (0.05 M HCl) and hydrolyzed with exogenous myrosinase (pH 7.0), respectively. The hydrolysis products were analysed by RP-LC (4). All the indole compounds were identified by UV- and FL-detection, while three major degradation compounds of glucobrassicin (GBS) were identified by usage of external standard as indole-3-carbinol (I3C), indole-3-actonitrile (I3CN), and 3, 3´-diindolylmethane (DIM). On the chromatograms of DSGSL of all the borecole samples the most evident peaks are those of desulphated indole glucosinolates GBS, 4-hydroxy-GBS, 4-methoxy-GBS and neoGBS, with predominant content of GBS. In two samples (II and III) the traces of aliphatic glucosinolates sinigrin (SIN), glucoiberin (GBI), and glucoraphanin (GRA) were identified, too. The identification of the peaks was done according to the elution order from the column (ISO method) and UV-spectra (Table 1). By cooking borecole looses about 30 % - 32 % of total GSL, while among the remaining GSL predominates GBS (71.58 % of total), the most widespread indole glucosinolate in Brassica oleracea vegetables type, which is involved, via its breakdown products, in inhibition of chemically induced carcinogenesis (5). Chromatograms of the indole breakdown products of cooked borecole GSL, formed during acidic and enzymatic hydrolysis, are presented in Figure 1. It was possible to distinguish between aromatic and aliphatic structures by fluorescence detection besides UV-detection, because only indole compounds possess native fluorescence. Several small and two dominant peaks (Rt = 30.10 and 38.26 min), both representing indole structure, are evident in chromatogram of borecole breakdown products in acidic medium. The peaks were identified as I3CN and DIM accompanied by unidentified indole compound of smaller polarity. The major indole compound was I3CN. Enzymatic breakdown of GBS under myrosinase action gave rise to compounds identified as I3C, I3CN, and DIM, the predominant one being I3CN. By usage of RP-LC linked to UV Diode Array and fluorescence detection it was possible to separate and identify borecole glucosinolates having various structures (aliphatic with sulphur in side chain, alkenyl, and heteroaromatic - indoles) and their breakdown products with different spectroscopic properties.

Izvorni jezik
Engleski

Znanstvena područja
Biotehnologija

POVEZANOST RADA