Sulfur-containing constituents and one 1H-pyrrole-2-carboxylic acid derivative from pineapple [ Ananas comosus (L.) Merr.] fruit

Abstract

Two sulfur-containing compounds, ( S)-2-amino-5-(( R)-1-carboxy-2-(( E)-3-(4-hydroxy-3-methoxyphenyl)allylthio)ethyl-amino)-5-oxopentanoic acid ( 1) and ( S)-2-amino-5-(( R)-1-(carboxymethylamino)-3-(( E)-3-(4-hydroxyphenyl)allylthio)-1-oxopropan-2-ylamino)-5-oxopentanoic acid ( 2), and one 1H-pyrrole-2-carboxylic acid derivative, 6-(3-(1H-pyrrole-2-carbonyloxy)-2-hydroxypropoxy)-3,4,5-trihydroxy-tetrahydro-2H-pyran-2-carboxylic acid ( 3), together with eighteen known phenolic compounds, were isolated from the fruits of pineapple. Their structures were elucidated by a combination of spectroscopic analyses. Some of these compounds showed inhibitory activities against tyrosinase. The half maximal inhibitory concentration values of compounds 1, 4, 5, 6, 7 are lower than 1 mM. These compounds may contribute to the well-known anti-browning effect of pineapple juice and be potential skin whitening agents in cosmetic applications.