Spectroscopic determination of glucosinolates in plants Sinapis alba and Lepidium draba : diploma thesis

Abstract

U ovom radu UHPLC-DAD-MS/MS analizom odreĎen je glukozinolatni profil različitih biljnih dijelova biljke Lepidium draba i nepoznatog biljnog uzorka te glukozinolatni profil sjemenki biljke Sinapis alba. Glukozinolati su iz uzoraka izolirani u desulfatiranome obliku modificiranom metodom ISO 9167-1. Dobiveni glukozinolatni profil biljke Lepidium draba usporeĎen je s glukozinolatnim profilom nepoznate biljne vrste kako bi se odredile kemotaksonomske značajke nepoznatog biljnog uzorka. U oba uzorka, najveći udio glukozinolata je pronaĎen u listu, a najmanji u stabljici. Pri tome, najzastupljeniji spoj u listu oba uzorka je glukorafanin (41,49 ± 4,05 μmol/g suhog biljnog materijala biljke Lepidium draba te 40,40 ± 3,62 μmol/g suhog biljnog materijala nepoznatog uzorka), a u cvatu pak glukosinalbin (32,03 ± 5,43 μmol/g u biljci Lepidium draba te 34,73 ± 0,76 μmol/g u nepoznatom uzorku). Najzastupljeniji glukozinolati u oba uzorka potječu od metionina. Na temelju znatne sličnosti glukozinolatnih profila uzoraka te UV i MS2 spektara, zaključeno je da nepoznatni uzorak vjerojatno pripada vrsti Lepidium draba. Obzirom da je glukozinolatni profil sjemenki biljke Sinapis alba bio uvelike jednostavniji od gore navedenih uzoraka, taj uzorak je posluţio za potvrdu strukture najzastupljenijeg spoja sjemenki - desulfoglukosinalbina. Struktura je potvrĎena NMR tehnikom te je utvrĎena β konfiguracija anomernog ugljikovog atoma glukozne jedinice glukosinalbina.In this paper, UHPLC-DAD-MS/MS analysis was used for determination of the glucosinolate profile of various plant parts of Lepidium draba and an unknown plant sample, as well as the glucosinolate profile of Sinapis alba seeds. Glucosinolates were isolated from the samples in their desulfated form using a modified ISO 9167-1 method. The obtained glucosinolate profile of Lepidium draba was compared with the glucosinolate profile of the unknown plant species in order to determine chemotaxonomic characteristics of the unknown plant sample. In both samples, the highest glucosinolate content was found in the leaves, while the lowest content was found in the stem. The most abundant compound in the leaves of both samples was glucoraphanin (41.49 ± 4.05 μmol/g dry plant material of Lepidium draba and 40.40 ± 3.62 μmol/g dry plant material of the unknown sample) and glucosinalbin in the inflorescence (32.03 ± 5.43 μmol/g in Lepidium draba and 34.73 ± 0.76 μmol/g in the unknown sample). The most abundant glucosinolates in both samples are derived from methionine. Based on the significant similarity in the glucosinolate profiles and UV and MS2 spectra of the samples, it was concluded that the unknown sample likely belongs to the Lepidium draba species. Since the glucosinolate profile of Sinapis alba seeds was much simpler than that of the above-mentioned samples, this sample was used for confirmation of the structure of the most abundant compound in the seeds - desulfoglucosinalbin. The structure was confirmed using NMR techniques, and the β configuration of the anomeric carbon atom of the glucose unit of glucosinalbin was determined