Isolation and Identification of Anthocyanins from Nesaea Crassicaulis

Jing Wang

Student thesis: Master thesis

Abstract

Anthocyanins were extracted from leaves of Nesaea Crassicaulis by 2.5% HCOOH in acetone, pre-purified by reverse-phase C18 columns and cation exchange columns, and then fractionized by semi-preparative HPLC (high performance liquid chromatography). The molecular structures were identified using LC-MS (liquid chromatography-mass spectrometry) and 1D and 2D NMR (nuclear magnetic resonance spectroscopy). Seven anthocyanins were identified. Four of them were assigned to be delphinidin-3,5-di-β–D-glucopyranose(M.W.=627), cyanidin-3,5-di-β–D-glucopyranose(M.W.=611), peonidin-3,5-di-β–D-glucopyranose(M.W.=625) and cyanidin-3-β–D-glucopyranose(M.W.=449). Three of them were deduced to be Peonidin-3-β–D-glucopyranose(M.W.=463), Petunidin-3,5-di-β–D-glucopyranose(M.W.=641) and Malvidin-3,5-di-β–D-glucopyranose(M.W.=655). Cyanidin-3,5-di-β–D-glucopyranose was the main anthocyanin, which took up about 50% of the total amount of anthocyanins in Nesaea Crassicaulis. The electrochemical properties of the former five anthocyanins (627, 611, 625, 449 and 463) were analyzed by electrochemical detector (ECD). All of them were oxidized in several steps at different oxidation potentials. (627), (611) and (449) had the same first oxidation potential 450mV (150mV vs ferrocene). (463) and (625) were more resistant to oxidation and had a first oxidation potential at 700mV (400mV vs ferrocene). (463) and (449) which had one glucose less than the others underwent gradual oxidation after the first oxidation potential and had no apparent second oxidation potential.

EducationsChemistry, (Bachelor/Graduate Programme) Graduate
LanguageEnglish
Publication date15 Aug 2008
SupervisorsPoul Erik Hansen

Keywords

  • Anthocyanin
  • Nesaea Crassicaulis