Unusual Immuno-Modulatory Triterpene-Caffeates in the Skins of Russeted Varieties of Apples and Pears

Three triterpene-caffeates have been isolated from skins of a russeted apple cultivar “Merton Russet” and identified by LC–MS and NMR as betulinic acid-3-cis-caffeate, betulinic acid-3-trans-caffeate, and oleanolic acid-3-trans-caffeate. Betulinic acid-3-trans-caffeate and oleanolic acid-3-trans-caffeate were also found in russeted pear skins. These compounds have not been previously reported in apples or pears, or in any other foods. Their...