Influence of selenium on glucosinolate profile in broccoli sprouts : master thesis

Glukozinolati su produkti sekundarnog metabolizma identificirani u preko 16 različitih biljnih porodica od kojih je najznačajnija porodica Brassicaceae koja uključuje često korišteno povrće u ljudskoj prehrani. U biljkama se nalaze u odvojenim odjeljcima od enzima mirozinaze koja cijepa ove inače kemijski stabilne spojeve na razgradne produkte poput tiocijanata, izotiocijanata, nitrila i indola. Zbog zabilježenog biološkog djelovanja produkata razgradnje, predmet su mnogih istraživanja u posljednje vrijeme. Brassica oleracea var. italica, poznatija kao brokula, jedno je od najpopularnijih vrsta povrća. Hidroponski uzgojeno povrće u fazi klica za svakodnevnu konzumaciju sve je više u upotrebi. Predmet istraživanja ovoga radavsu klice brokule uzgajane u čistoj vodi te različitim koncentracijama selenija: 1 ppm, 2,5 ppm, 5 ppm, 7,5 ppm i 10 ppm s ciljem praćenja utjecaja na profil glukozinolata. Glukozinolati su izolirani, prevedeni u desulfo-oblik te analizirani UHPLC-DAD-MS/MS tehnikom. Analizom je utvrđena prisutnost 12 različitih glukozinolata: progoitrin, glukonapoleiferin, glukoalisin, glukonapin, glukokohlearin, 4-hidroksiglukobrasicin, glukobrasikanapin, glukobrasicin, glukoberteroin, glukonasturcin, 4-metoksiglukobrasicin i neoglukobrasicin. Uočena je dominantna količina glukonapina i glukobrasikanapina s maksimumima od 67,31 µmol/g i 36,14 µmol/g pri 5 ppm selenija. Glukoberteroin je uočen samo u tragovima. Povišene koncentracije selenija negativno su utjecale na rast brokule te su također utjecale na profil glukozinolata u različitim uzorcima. Dva uzorka klica brokule uzgajanih u koncentaciji selenija od 5 ppm i 7,5 ppm podvrgnuta su reakciji s enzimom mirozinazom da bi se dobili razgradni produkti glukozinolata koji su identificirani GC-MS-om. Identificirana su dva nitrila: benzenpropanonitril i 4,5-epitiopentanonitril. Drugi cilj eksperimenta je bio ispitati hoće li brokula kroz sedam dana apsorbirati dio selenija zbog kemijske sličnosti i obilja u kojem je rasla te ga ugraditi u strukturu svojih glukozinolata. Niti jedan selenoglukozinolat ili selenometionin-izvedeni glukozinolat nije detektiran niti su detektirani njihovi produkti razgradnje.Glucosinolates are products of secondary metabolism identified in over 16 different plant families, the most significant of which is the Brassicaceae family, which includes vegetables often used in human nutrition. In plants, glucosinolates are found in special compartments separated from the myrosinase enzyme, which cleaves these otherwise chemically stable compounds into degradation products such as thiocyanate, isothiocyanate, nitrile and indole. Due to the recorded biological activity of degradation products, they have been the subject of many recent researhces. Brassica oleracea var. italica, better known as broccoli, is one of the most popular types of vegetables. Hydroponically grown vegetables sprouts for everyday consumption are being increasingly used. In this work, broccoli sprouts were grown in clean water with different concentrations of selenium: 1 ppm, 2.5 ppm, 5 ppm, 7.5 ppm and 10 ppm to monitor its influence on the glucosinolate profile. Glucosinolates were isolated, converted into desulfo-form and analyzed by UHPLC-DAD-MS/MS technique. The analysis determined the presence of 12 different glucosinolates: progoitrin, gluconapoleiferin, glucoalisin, gluconapin, glucocochlearin, 4-hydroxyglucobrassicin, glucobrassicannapin, glucobrassicin, glucoberteroin, gluconasturtin, 4-methoxyglucobrassicin and neoglucobrassicin. A dominant amount of gluconapin and glucobrassicanapin was observed with maxima of 67.31µmol/g and 36.14 µmol/g, respectively, at a selenium concentration of 5ppm. Glucoberteroin was observed only in traces. Elevated concentrations of selenium had a negative effect on the growth of broccoli and also affected the profile of glucosinolates in different samples. Two samples of broccoli sprouts grown in selenium concentrations of 5 ppm and 7.5 ppm were subjected to reaction with the myrosinase enzyme to obtain glucosinolate degradation products that were identified by GC-MS. Two nitriles were identified: benzenepropanonitrile and cyano-3,4-epithiobutane. The second goal of the experiment was to examine whether the broccoli will absorb part of the selenium in seven days due to the chemical similarity and abundance in which it grew and incorporate it into the structure of its glucosinolates. No selenoglucosinolate or selenomethionine-derived glucosinolates were detected, nor their degradation products