Characterization of Sinapyl Derivatives in Pineapple (Ananas comosus [L.] Merill) Juice

Three previously unidentified phenolic compounds were found in pineapple ( Ananas comosus [L.] Merill) juice in substantial concentrations and were isolated by semipreparative reverse phase HPLC. The structures were elucidated from UV spectra, acid hydrolysis, and subsequent amino acid analysis, mass spectrometry, and two-dimensional NMR spectroscopy. The compounds are identified as S -sinapyl- l -cysteine, N -l - γ -glutamyl- S -sinapyl- l -cysteine, and S -sinapylglutathione. Keywords: Pineapple juice; Ananas comosus [L.] Merill; phenolics; sinapyl derivatives; glutathione