Phenylethanoid glycosides from Michelia champaca leaves

ABSTRACT Chemical investigation on the leaves of Michelia champaca L. (Magnoliaceae) led to the isolation of five previously undescribed phenylethanoid glycosides (PhGs), 4- O - β - d -glucopyranosyl-acteoside ( 1 ), 4"'- O -(6- O - E -caffeoyl)- β - d -glucopyranosyl-acteoside ( 2 ), 4"'- O -(6- O - E -caffeoyl)- β - d -glucopyranosyl-isoacteoside ( 3 ), 6""- O - E -feruloyl-echinacoside ( 4 ), and 6""- O - p - E -coumaroyl-echinacoside ( 5 ), together with eighteen known PhGs. Their structures were determined by spectroscopic and chemical methods. All the known PhGs except acteoside ( 8 ) were not previously reported in the genus. Twenty-one PhGs exhibited more potent DPPH radical scavenging activity and FRAP than l -ascorbic acid ( l -AA), and twenty-two PhGs showed better ABTS radical cation scavenging activity than l -AA. In addition, twelve PhGs displayed more potent cellular reactive oxygen species (ROS) scavenging activity than curcumin. The results revealed that the leaves of M. champaca are a rich source of phenylethanoid glycosides and antioxidants.