Novel antioxidant compounds from tart cherries (Prunus cerasus)

As indicated by an Fe(II)-induced liposome peroxidation bioassay, the EtOAc extract of tart cherries (Prunus cerasus) was found to have strong antioxi dant activity. Purification of this extract afforded chlorogenic acid methy l ester (1) and three novel compounds, 2-hydroxy-3-(o-hydroxyphenyl) propan oic acid (2); 1-(3',4'-dihydroxycinnamoyl)-cyclopenta- 2,5 -diol (3), and 1 -(3',4'-dihydroxycinnamoyl)-cyclopenta-2,3-diol (4), as determined by their spectral data. At a 20-mu M concentration, the antioxidant activities of c ompounds 3 and 4 were comparable to the antioxidant activities of caffeic a cid, whereas compound 1 showed activity similar to chlorogenic acid. Also, these compounds showed antioxidant activities similar to the commercial ant ioxidants tert-butylhydroquinone and butylated hydroxytoluene. However, com pound 2 was not active when tested at a 100-mu M concentration.