Radical Scavenging Constituents of Cyperus flaccidus

Dalrae Ahn, Hyunjin Lee, Ming Ming Xing, Chao Tao, Eun Byeol Lee, Tae Gwan Lee,Tae Yong Shin, Jae Soon Eun, Hoon Jeon, Jong Pil Lim, and Dae Keun Kim*College of Pharmacy, Woosuk University, Jeonju 565-701, KoreaAbstract −In the course of screening for antioxidant compounds by measuring the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging effect and superoxide quenching activity, methanol extract of Cyperusflaccidus (Cyperaceae) was found to show potent antioxidant activities. Subsequent activity-guided fractionationof the methanolic extract led to the isolation of ten compounds, kaempferol-3,7-O-α-L-dirhamnopyranoside (1),caffeic acid (2), quercetin-3-O-α-L-rhamnopyranosyl(1→6)-β-D-glucopyranoside (3), kaempferol-3-O-α-L-rhamnopyranoside (4), quercetin-3-O-α-L-rhamnopyranoside (5), luteoiln-7-O-β-D-glucopyranoside (6), kaempferol-3-O-α-L-rhamnopyranosyl(1→6)-β-D-glucopyranoside (7), luteoiln (8), quercetin (9) and quercetin-3-O-β-D-glucuronide (10). Their structures were elucidated by spectroscopic studies. Compounds 1- 10 were isolated forthe first time from this plant. Among them, compounds 2, 8 and 9 showed the significant radical scavengingeffects on DPPH, and the potent xanthine-originated superoxide quenching activities. Keywords −Cyperus flaccidus, Cyperaceae, DPPH, Superoxide quenching activity