title: Inhibition of advanced glycation endproducts formation by Korean thistle, Cirsium maackii.
abstract: OBJECTIVE
  To evaluate inhibitory potential of seven Korean thistles against the advanced glycation endproducts (AGE) formation as well as to identify responsible compounds from the most active species.
  
  
  METHODS
  We used an in vitro AGE inhibition assay to evaluate the anti-diabetic complication potential of the methanol extracts of the selected Korean thistles.
  
  
  RESULTS
  Among the seven Korean thistles, the leaves of Cirsium maackii (C. maackii) exhibited the most significant inhibitory activity against AGE formation. By means of bioassay-directed fractionation, a lignan, chlorogenic acid and 14 flavonoids were isolated from the active ethyl acetate soluble fraction of a methanol extract from C. maackii leaves. Luteolin and its 5-O-glucoside have been previously isolated; however, a lignan and 13 known compounds were isolated for the first time from C. maackii leaves in this study. Most of the isolated compounds exhibited inhibitory activities against potential AGE formation. Among them, cernuoside was shown to be the most potent AGE inhibitor with an IC50 value of 21.21 μ mol/L. Most importantly, two major flavonoids, luteolin and its 5-O-glucoside, also significantly inhibited AGE formation, with IC50 values of 36.33 and 37.47 μ mol/L, respectively. Structure activity relationship revealed that the presence of free 3' and 4' dihydroxyl group in flavonoids skeleton played an important role in AGE inhibition.
  
  
  CONCLUSIONS
  These results indicate that C. maackii and C. maackii-derived flavonoids might be explored further to develop therapeutic agents for the prevention of diabetic complications due to their significant inhibitory activity against AGE formation.
authors.affiliation: Department of Food Science and Human Nutrition, Chonbuk National University, Jeonju 561-756, Republic of Korea.
authors.forename: Hyun Ah
authors.initials: HA
authors.lastname: Jung
authors.affiliation: Department of Food and Life Science, Pukyong National University, Busan 608-737, Republic of Korea.
authors.forename: Jin Ju
authors.initials: JJ
authors.lastname: Park
authors.affiliation: College of Pharmacy, Catholic University of Daegu, Gyeongbuk 712-702, Republic of Korea.
authors.forename: Byung Sun
authors.initials: BS
authors.lastname: Min
authors.affiliation: Department of Food and Life Science, Pukyong National University, Busan 608-737, Republic of Korea.
authors.forename: Hee Jin
authors.initials: HJ
authors.lastname: Jung
authors.affiliation: Department of Food and Life Science, Pukyong National University, Busan 608-737, Republic of Korea.
authors.forename: Md Nurul
authors.initials: MN
authors.lastname: Islam
authors.affiliation: Department of Food and Life Science, Pukyong National University, Busan 608-737, Republic of Korea. Electronic address: choijs@pknu.ac.kr.
authors.forename: Jae Sue
authors.initials: JS
authors.lastname: Choi
keywords: Advanced glycation endproducts; Cirsium maackii; Diabetic complications; Flavonoids; Thistle