Identification of Anthocyanins in Lobelia Cardinalis

Dolly Kazoka & Damaris Daniela Georgescu

Studenteropgave: Semesterprojekt

Abstrakt

Abstract The main anthocyanin in Lobelia Cardinalis was extracted by acetone and purified by semi-preparative high performance liquid chromatography (HPLC), the molecular structure was determined by liquid chromatography-mass spectrum LC-MS2 and the structure was eventually identified using 1H nuclear magnetic resonance (NMR). The tentative structure of the main anthocyanin in Lobelia Cardinalis was first proposed by Mozetic B, Nielsen S.L, Lund T, Nielsen H.D, Trebse P; Identification of anthocyanin pigments in amphibious plants by LC-ESI-MSn (Unpublished.) to be cyanidin 3-p-coumaryl-hexose-rhamnosyl-5-hexoside. In this project 1 H NMR was used to possibly confirm the structure. The hexose were identified as glucose and therefore giving the possible full structure to be cyanidin 3-O-[6-O-(4-O-E-p-coumaryl-α-L-rhamnopyranosyl)-β-glucopyranoside]-5-β-D-glucopyranoside. The cyanidin, coumaryl and the anomeric protons were clearly identified. However not all protons on the sugars could be identified and other NMR techniques should be employed. The anomeric protons at 5.50 ppm, 5.19 ppm and 4.70 ppm showed the presence of three sugars and the presence of a signal at 1.005 ppm confirmed the presence of a methyl group on the rhamnose. The LC-MS showed a [M+H] peak at m/z 903.9 and this corresponds to a formula of C42H46O22 and the MS/MS fragmentation showed the presence of cyanidin at m/z 287.2, cyanidin and glucose at m/z 448.8.

UddannelserKemi, (Bachelor/kandidatuddannelse) Bachelor el. kandidat
SprogEngelsk
Udgivelsesdato22 jun. 2007
VejlederePoul Erik Hansen & Torben Lund

Emneord

  • anthocyanin,NMR,HPLC;LC/MS/MS;Lobelia Cardinalis,cyanidin 3-O[6-O-(4-O-E-p-coumaroyl-alpha-L-rhamnopyransyl)-beta-glucopyranoside]-5-beta-D-glucopyranoside