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ABSTRACT: Advanced glycation end products (AGEs) play an important role in the development of chronic diabetic complications. Chlorogenic acid (CGA) is a phenolic compound formed by the esterification of caffeic and quinic acids. In this study, we evaluated the inhibitory effects of CGA against the formation of AGEs and AGEs protein cross-linking in vitro. An in vitro assay for glycation of bovine serum albumin by high glucose showed that CGA inhibited AGEs formation with an IC(50) value of 148.32 μM and was found to be more effective than aminoguanidine, a well-known AGEs inhibitor (IC(50); 807.67 μM). In an indirect AGE-ELISA assay, the CGA exhibited more potent inhibitory activity on the cross-linking of AGEs to collagen than aminoguanidine. In addition, the inhibitory effects of CGA on AGEs formation and on its cross-linking with collagen might be caused by its interactions with reactive decarbonyl compounds, such as methylglyoxal. These results suggest that CGA could be beneficial in the prevention of AGEs progression in patients with diabetes because CGA can attenuate AGEs deposition in glucose.
Archives of Pharmacal Research 03/2011; 34(3):495-500. · 1.59 Impact Factor
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ABSTRACT: Puerarin is a natural product isolated from Puerarin lobata and has various pharmacological effects, including anti-hyperglycemic and anti-allergic properties. In the present study, we investigated the effect of puerarin against advanced glycation end products (AGEs)-induced inflammation in mouse mesangial cells. Puerarin acts by inducing the expression of heme oxygenase-1 (HO-1) in a dose- and time-dependent manner. Puerarin was able to enhance phosphorylation of protein kinase C (PKC) delta, but not PKC alpha/beta II, in a time-dependent manner. Induction of HO-1 expression by puerarin was suppressed by GF109203X, a general inhibitor of PKC, and by rottlerin, a specific inhibitor of PKC delta. However, induction was not suppressed by Gö6976, a selective inhibitor for PKC alpha/beta II. Additionally, the knockdown of endogenous PKC delta by small interfering RNA (siRNA) resulted in the inhibition of HO-1 expression and Akt phosphorylation. Puerarin increased antioxidant response element (ARE)-Luciferase activity in a dose- and time-dependent manner in transfected mouse mesangial cells. Mutation of the ARE sequence abolished puerarin-induced HO-1 expression. Furthermore, puerarin treatments resulted in a marked increase in NF-E2 related factor-2 (Nrf-2) translocation, leading to up-regulation of HO-1 expression. However, transfection of Nrf-2 specific siRNA abolished HO-1 expression. Pretreatment with puerarin inhibited the expressions of COX-2, MMP-2 and MMP-9. But, these effects were reversed by ZnPP, an inhibitor of HO-1. Taken together, our results demonstrate that puerarin-induced expression of HO-1 is mediated by the PKC delta-Nrf-2-HO-1 pathway and inhibits N-carboxymethyllysine (CML)-induced inflammation in mouse mesangial cells.
Toxicology and Applied Pharmacology 04/2010; 244(2):106-13. · 4.45 Impact Factor
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ABSTRACT: An anthraquinone, emodin (1), and five flavonoids, kaempferol-3-O-beta-D-glucoside (2), quercetin (3), quercitrin (4), isoquercitrin (5), and (+)-catechin (6), were isolated from an AcOEt-soluble extract of the fruits of Rumex japonicus. Their structures were determined by spectroscopic data interpretation. All the isolates were evaluated for their potential to inhibit AGEs (advanced glycation end products) formation and AGEs cross-linking, and to break already formed AGEs cross-links.
Chemistry & Biodiversity 01/2009; 5(12):2718-23. · 1.80 Impact Factor
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ABSTRACT: Aldose reductase (AR) and TGF-beta have been implicated in the development of diabetic complications, such as cataracts. In an attempt to obtain potential agents for the prevention of diabetic cataracts from natural products, we purified genistein from the roots of Pueraria lobata and investigated its inhibitory effects upon AR activity and its antioxidant effects on rat lenses. The inhibition of AR activity by genistein increased in a dose-dependent manner and the opacities of lenses were significantly improved when treated with genistein. In addition, we determined the effects of genistein on mechanisms induced by exposure to high glucose in human lens epithelial (HLE-B3) cells. We found that genistein was able to reduce the expression of TGF-beta2, alphaB-crystallin, and fibronectin mRNAs in HLE-B3 cells that were cultured in high glucose conditions. In addition, a reduction in glutathione (GSH) levels and thiobarbituratic acid-reactive substances was observed. These results show that genistein is protective against lens opacity and also inhibits high glucose-mediated toxic effects in HLE-B3 cells. These effects are likely achieved by preventing AR and cellular oxidation; therefore, genistein may be a potential therapeutic agent for preventing and treating complications associated with diabetes mellitus, such as diabetic cataracts.
European Journal of Pharmacology 11/2008; 594(1-3):18-25. · 2.52 Impact Factor
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ABSTRACT: A new coumaroyl triterpene, 3-O-trans-p-coumaroyl actinidic acid (1), as well as five known triterpenes, ursolic acid (2), 23-hydroxyursolic acid (3), corosolic acid (4), asiatic acid (5) and betulinic acid (6) were isolated from an EtOAc-soluble extract of the roots of Actinidia arguta. The structure of compound 1 was elucidated from interpretation of the spectroscopic data, particularly by extensive 1D and 2D NMR studies. All the isolates (1-6) were evaluated in vitro for their inhibitory activities on pancreatic lipase (PL). Of the isolates, the new compound 1 possessed the highest inhibitory activity on PL, with an IC(50) of 14.95 microM, followed by ursolic acid (2, IC(50) = 15.83 microM). The other four triterpenes (3-6) also showed significant PL inhibitory activity, with IC(50) values ranging from 20.42 to 76.45 microM.
Archives of Pharmacal Research 06/2008; 31(5):666-70. · 1.59 Impact Factor
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ABSTRACT: Ellagic acid (1), 3,3'-di-O-methylellagic acid (2), 3,3',4-tri-O-methylellagic acid (3), isovitexin (4), kaempferol 3-O-beta-D-glucuronide methyl ester (5), quercetin 3-O-alpha-L-arabinopyranosyl-(1-->6)-beta-D-galactopyranoside (6), ursolic acid, pomolic acid, tormentic acid, euscaphic acid, euscaphic acid 28-O-beta-D-glucopyranoside, and maslinic acid were isolated from the AcOEt- and BuOH-soluble MeOH extract of Duchesnea chrysantha (whole plant). The isolates were subjected to in vitro bioassays to evaluate their inhibitory activity on rat-lens aldose reductase (RLAR) and formation of advanced glycation end products (AGEs). The ellagic acids and flavonoids, compounds 1-6, exhibited moderate inhibitory effects on RLAR. However, compounds 1 and 4-6 showed excellent inhibitory activities towards the formation of AGEs. This is the first report that 4 and 6 exhibit inhibitory activity towards AR and AGEs formation.
Chemistry & Biodiversity 02/2008; 5(2):352-6. · 1.80 Impact Factor
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ABSTRACT: Two isoflavone C-glucosides, puerarin (1) and PG-3 (2), a but-2-enolide, (+/-)-puerol B (3), two isoflavone O-glucosides, daidzin (4) and genistin (5), and three pterocarpans, (-)-medicarpin (6), (-)-glycinol (7) and (-)-tuberosin (8), were isolated from a MeOH extract of the roots of Pueraria lobata, using an in vitro bioassay based on the inhibition of the formation of advanced glycation end products (AGEs) to monitor chromatographic fractionation. The structures of 1-8 were determined by spectroscopic data interpretation, particularly by 1D- and 2D-NMR studies, and by comparison of these data with values in the literature. All of the isolates (1-8) were evaluated for their inhibitory activity on AGEs formation in vitro. Of these, puerarin (1), PG-3 (2), and (+/-)-puerol B (3) exhibited more potent inhibitory activity than the positive control aminoguanidine.
Archives of Pharmacal Research 11/2006; 29(10):821-5. · 1.59 Impact Factor
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ABSTRACT: A new 2-arylbenzofuran, puerariafuran (1), as well as three known compounds, coumestrol (2), daidzein (3), and genistein (4), were isolated from a MeOH extract of the roots of Pueraria lobata as active constituents, using an in vitro bioassay based on the inhibition of advanced glycation end products (AGEs) to monitor chromatographic fractionation. The structure of 1 was determined by spectroscopic data interpretation, particularly by extensive 1D and 2D NMR studies. All the isolates (1-4) were evaluated for the inhibitory activity on AGEs formation in vitro.
CHEMICAL & PHARMACEUTICAL BULLETIN 10/2006; 54(9):1315-7. · 1.59 Impact Factor
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ABSTRACT: Three naphthopyrone glucosides, cassiaside (1), rubrofusarin-6-O-beta-D-gentiobioside (2), and toralactone-9-O-beta-D-gentiobioside (3), were isolated from the BuOH-soluble extract of the seeds of Cassia tora as active constituents, using an in vitro bioassay based on the inhibition of advanced glycation end products (AGEs) to monitor chromatographic fractionation. The structures of 1-3 were determined by spectroscopic data interpretation, particularly by extensive 1D and 2D NMR studies. All the isolates (1-3) were evaluated for the inhibitory activity on AGEs formation in vitro.
Archives of Pharmacal Research 08/2006; 29(7):587-90. · 1.59 Impact Factor
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ABSTRACT: Fractionation of an EtOAc-soluble extract of the stems of Rumex japonicus led to the isolation of two new 24-norursane type triterpenoids, 2alpha,3alpha,19alpha-trihydroxy-24-norurs-4(23),12-dien-28-oic acid (1) and 4(R),23-epoxy-2alpha,3alpha,19alpha-trihydroxy-24-norurs-12-en-28-oic acid (2), along with the known compounds myrianthic acid (3), tormentic acid, and emodin. The structures of 1 and 2 were elucidated by spectroscopic methods, particularly by extensive 1D and 2D NMR studies.
CHEMICAL & PHARMACEUTICAL BULLETIN 01/2006; 53(12):1594-6. · 1.59 Impact Factor
