Characterization of a natural antioxidant from shrimp shell waste

The chemical structure of an antioxidant purified from shrimp shell was analyzed. Positive reactions with both Folin-Ciocalteu's phenol reagent and ferric chloride-potassium ferricyanide reagent indicated the antioxidant was a phenolic compound. The presence of a primary amino group was indicated by reaction with ninhydrin. The base peak of the CI mass spectrum, at 165, and the presence of a peak in the EI spectrum at 164 suggested a MW of 164 for the compound. A base peak of 94 in the EI spectrum suggested the presence of a phenolic ring. The proton NMR spectrum was consistent with an ortho-disubstituted benzene. FT-IR indicated hydrogen bonded O-H (3400 cm(-1)) and N-H (3000 cm(-1)) stretching bands, and conjugated C=C stretching or N-H bending (1650 cm(-1)). UV absorption maxima were at 268 and 323 nm with epsilon(max) of 10 492 and 1246, respectively. The antioxidant was proposed to be 1,2-diamino-1-(o-hydroxyphenyl)propene.