文摘
Six triterpenes, including three caffeoyl triterpenes, were purified and isolated from pear fruit (Pyrus pyrifolia Nakai cv. Chuwhangbae) peel extracts using various column chromatography techniques with a guided 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging assay. The isolated compounds were identified as betulinic aldehyde (1), lupeol (2), betulinic acid (3), 3-O-cis-caffeoylbetulinic acid (4), 3-O-trans-caffeoylbetulinic acid (5), and 3-O-trans-caffeoyloleanolic acid (6) on the basis of nuclear magnetic resonance spectroscopy and electrospray ionization mass spectrometry. Four compounds (1, 4鈥?b>6) were identified from Asian pear fruit for the first time. In addition, compounds 4鈥?b>6, containing a caffeic acid moiety, showed higher DPPH radical-scavenging and suppression effects against copper ion-induced oxidation of rat blood plasma than other compounds without a caffeic acid moiety.
Keywords:
Pyrus pyrifolia Nakai; pear fruit peel; caffeoyl triterpenes; 1,1-diphenyl-2-picrylhydrazyl; cholesteryl ester hydroperoxide