Identification and quantification of low molecular weight phenolic antioxidants in seeds of evening primrose (Oenothera biennis L.).
Crude extracts of evening primrose meal were prepared in 56% (v/v) acetone and separated into six fractions (I-VI) using a Sephadex LH-20 column. Qualitative tests for phenolic and vanillin positive compounds produced positive results for all fractions. Silica gel thin-layer chromatography of fractions III and V allowed the location and isolation of two spots containing moderate to strong antioxidative compounds. High-performance liquid chromatography of the spot isolated from fraction III showed the resolution of two structurally related compounds, whereas that of the spot from fraction V showed the presence of one compound. Nuclear magnetic resonance spectroscopy and electron impact mass spectrometry produced sufficient evidence to identify the isolated compounds as (+)-catechin, (-)-epicatechin, and gallic acid. These compounds accounted for about 10.5 and 1.7% of the dry mass of the crude extracts and meal, respectively.
Wettasinghe
Mahinda
M
Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland, A1B 3X9 Canada.
Shahidi
Fereidoon
F
Amarowicz
Ryszard
R
D000975:Antioxidants / Q000032:analysis* / Q000737:chemistry; D001547:Benzaldehydes / Q000032:analysis / Q000737:chemistry; D002392:Catechin / Q000032:analysis / Q000737:chemistry; D002850:Chromatography, Gel / Q000379:methods; D005707:Gallic Acid / Q000032:analysis / Q000737:chemistry; D008958:Models, Molecular; D008970:Molecular Weight; D010636:Phenols / Q000032:analysis* / Q000737:chemistry; D027824:Rosaceae / Q000737:chemistry*; D012639:Seeds / Q000737:chemistry*
D000975:Antioxidants; D001547:Benzaldehydes; D010636:Phenols; D005707:Gallic Acid; D002392:Catechin; C100058:vanillin