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

Abstract

Glukozinolati (β-tioglukozidni-N-hidroksisulfati) su velika grupa sekundarnih metabolita koji daju karakterističan gorki i oštri okus kupusnjačama te su njihovi razgradni produkti biološki aktivni spojevi. Razgradnja može biti termička, enzimska ili kemijska pri čemu nastaju brojni razgradni produkti kao što su tiocijanati i izotiocijanati. Klice rikule su nutritivno bogate, a prednost im je vrlo laki uzgoj. Klijanjem se nutrijenti u sjemenci razgrađuju na sastavne dijelove, razvija se klorofil i povećava se količina proteina, minerala i elemenata u tragovima. Dodatna prednost je da su bogate vitaminima, čiji se sadržaj povećava klijanjem, esencijalnim masnim kiselinama i vlaknima te imaju pozitivan učinak na organizam. Biljke nemaju potrebu za selenom i uglavnom ne podnose koncentracije veće od 10-100 μg/g suhe mase u tkivima, no vrste koje pripadaju obitelji Brassicaceae mogu akumulirati selen u tkivima i tolerirati koncentracije do 1000 μg/g suhe mase. Na taj način, biljke proizvode razne seleno metabolite koji mogu imati ulogu kao sredstva za sprječavanje raka. Istraživanja su pokazala da se u bočni lanac glukozinolata umjesto sumpora može ugraditi atom selena. U ovom diplomskom radu uzgojene su klice rikule te zalijevane otopinama selena različitih koncentracija (1; 2,5; 5; 7,5; 10 ppm). Razvoj biljaka praćen je tijekom 7 dana i jedino pri najvišoj koncentraciji selena nije došlo do razvoja biljke. Nakon sabiranja glukozinolati su izolirani ekstrakcijom 70%-tnim metanolom te analizirani UHPLC-DAD-MS/MS, a njihovi hlapljivi razgradni produkti su izolirani ekstrakcijom diklormetanom i identificirani GC-MS tehnikom. Identificirana su 4 glukozinolata: glukorafanin, glukoerucin, dimer glukosativina i 4-metoksiglukobrasicin, dok je GC-MS tehnikom identificiran erucin kao razgradni produkt glukoerucina.Glucosinolates (β-thioglucoside-N-hydroxysulfates) are a large group of secondary metabolites that give a characteristic bitter and pungent taste to cabbages and their degradation products are biologically active compounds. Degradation can be thermal, enzymatic, or chemical and it forms several degradation products such as thiocyanates and isothiocyanates. Rocket sprouts are nutritionally rich, and their advantage is very easy cultivation. By germination, the nutrients in the seed are broken down into their main components, chlorophyll develops and the amount of proteins, minerals and trace elements increases. An additional advantage is that they are rich in vitamins whose content increases with germination, essential fatty acids and fiber and have a positive effect on the body. Plants do not need selenium and generally do not tolerate concentrations higher than 10-100 μg/g dry weight in tissues, but species belonging to the Brassicaceae family can accumulate selenium in tissues and tolerate concentrations up to 1000 μg/g dry weight. In this way, plants produce various selenium metabolites that can play a role as a means of preventing cancer. Studies have shown that a selenium atom can be incorporated into the side chain of glucosinolates instead of sulfur. In this diploma thesis, rocket sprouts were grown and watered with selenium solutions of different concentrations (1; 2.5; 5; 7.5; 10 ppm). The development of the plants was monitored for 7 days, and only at the highest concentration of selenium the plant did not develop. After collection, glucosinolates were isolated by extraction with 70% methanol and analyzed by UHPLC-DAD-MS / MS, and their volatile degradation products were isolated by extraction with dichloromethane and identified by GC-MS technique. 4 glucosinolates were identified: glucoraphanin, glucoerucine, glucosatin dimer and 4-methoxyglucobrasicin, while GC-MS technique identified erucin which originate from degradation of glucoerucin