Unique heterocyclic phenolic compounds from shrimp (Pandalus borealis) and beyond.

Shrimps are the most consumed species among crustaceans and are well appreciated for their flavor and high nutritional value. This work investigated the antioxidative compounds of Northern shrimp (Pandalus borealis) and its processing discards (shells and heads) using various solvents and chromatographic techniques as well as mass spectrometry. Ethanol served as the best extraction medium, and the extracts obtained demonstrated strong antioxidant activity in a β-carotene-linoleate emulsion system. The antioxidative compounds of the extract were isolated using a silica gel column chromatography, followed by thin layer chromatography. This led to the identification of two highly polar and two low polarity compounds. These compounds, for the first time, were isolated and purified by using reversed-phase HPLC. Their structures were tentatively elucidated using electrospray mass spectrometry. These unique compounds were heterocyclic phenolic compounds and identified as 7-(3-butenyl)-2-hydroxy-6-(1,2,5,6-tetrahydropyridin-2-yl) quinoline and 7-(3-butenyl)-2-hydroxy-6-(1,2,5,6-tertahydropyridin-2-yl)-7,8-dihydroquinoline and their isomers. The proposed novel compounds in shrimp provide a reason for their oxidative stability and potential benefits, as well as possibly serving as substrates for the discoloration of shrimp. [ABSTRACT FROM AUTHOR]