• Natural Product Sciences
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• v.16 no.1
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• pp.54-57
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• 2010

Effects of the species Scrophularia takesimensis, S. kakudensis, S. boreali-koreana, and S. buergeriana on rat lens aldose reductase inhibition have been investigated. Among them, the extracts of S. kakudensis and S. boreali-koreana were exhibited good inhibitory potencies compared with those of S. takesimensis and S. buergeriana. The $IC_{50}$ values of the aerial part extracts from S. kakudensis and S. boreali-koreana were demonstrated 0.46 and 0.35 mg/ml, respectively.

• Natural Product Sciences
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• v.17 no.3
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• pp.230-233
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• 2011

To evaluate the potential of naturally occurring aldose reductase (AR) inhibitors from food material, MeOH extract and stepwise polarity fractions from tartary buckwheat and two common Korean buckwheat cultivars, yangjul-maemil and daesan-maemil, were tested on AR inhibition in rat lens in vitro. The EtOAc fraction from tartary buckwheat exhibited good AR inhibitory activity ($IC_{50}$ value, $8.19\;{\mu}g$/ml). A portion of the EtOAc fraction from tartary buckwheat led to the isolation of rutin by MeOH recrystalization. Rutin exhibited good AR inhibitory activity ($IC_{50}$ value, $9.28\;{\mu}M$). These results suggest that tartary buckwheat could be a useful food material in the development of a novel AR inhibitory agent against diabetic complications.

• Korean Journal of Pharmacognosy
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• v.40 no.4
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• pp.394-399
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• 2009

Aldose reductase (AR) is a critical enzyme in the development of the diabetic complications. AR, the first enzyme in the polyol pathway, catalyzes the reduction of the aldehyde form of glucose to sorbitol with concomitant conversion of NADPH to $NADP^+$. None of aldose reductase inhibitor (ARI) has achieved worldwide use because of limited efficacy or undesirable side effects. Therefore, evaluating natural sources for ARI potential may lead to the development of safer and more effective agents against diabetic complications. Forty eight Chinese herbal medicines have been investigated for inhibitory activities on AR. Among them, seven herbal medicines, Buddleja officinalis (whole plant), Lonicera japonica (leaf and flower), Polygonum aviculare (aerial part), Polygonum aviculare (whole plant), Salvia miltiorrhiza (root), Schisandra chinensis (stem), and Zanthoxylum armatum (leaf and stem) exhibited a significant inhibitory activity against AR. Particularly, L. japonica and P. aviculare showed two times more potent inhibitory activity than the positive control, 3,3-tetramethyleneglutaric acid (TMG).

• Korean Journal of Medicinal Crop Science
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• v.20 no.4
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• pp.222-230
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• 2012

We evaluated the inhibitory effects of extracts and components of Geranium thunbergii on aldose reductase (AR) and galactitol formation in rat lenses with high levels of galactose as a part of our ongoing search of natural sources for therapeutic and preventive agents for diabetic complications. The inhibitory effects of water, methanol and ethanol extracts of G. thunbergii on rat lens AR (RLAR) were determined. Comparing inhibitory effects of various solvent extracts, ethanol extract showed RLAR inhibitory activity ($IC_{50}$ values, 5.24 and $6.39{\mu}g/m{\ell}$, respectively). The ethanol extract was fractionated to chloroform, ethyl acetate and water. Of these, the ethyl acetate fraction from ethanol extract of G. thunbergii exhibited RLAR inhibitory activity ($IC_{50}$ value, $2.64{\mu}g/m{\ell}$). In order to identify the bioactive components of ethyl acetate soluble fraction of ethanol extract from G. thunbergii, eight compounds, namely gallic acid (1), protocatechuic acid (2), p-hydroxybenzoic acid (3), brevifolin carboxylic acid (4), geraniin (5), ellagic acid (6), kaempferol-3-O-arabinofuranosyl-7-O-rhamnopyranoside (7), kaempferitrin (8) were isolated. The isolates were subjected to in vitro bioassays to evaluate their inhibitory activity on RLAR and galactitol formation in rat lenses. The ellagic tannins (5, 6) and flavonoid (7) exhibited strong inhibitory effects on RLAR. Also, these three compounds (5, 6 and 7) suppressed galactitol accumulation in rat lens under high galactose conditions, demonstrating the potential to prevent galactitol accumulation exo vivo. These results suggest that the extracts and components of G. thunbergii are a promising agent in the prevention or treatment of diabetic complications.

• KSBB Journal
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• v.23 no.5
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• pp.419-424
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• 2008

In this study, we examined the anti-diabetic activity in vitro by the crude extracts of Tetragonia tetragonioides which has been known to superior plants for the traditional prevention and treatment of stomach-related diseases. $\alpha$-Amylase and $\alpha$-glucosidase, the principal enzymes involved in the metabolism of carbohydrates, and aldose reductase, the key enzyme of the polyol pathway, have been shown to play the important roles in the complications associated with diabetes. A hexane (HX) fraction of T. tetragonioides were shown to inhibit more than 50% of salivary and pancreatin $\alpha$-amylase activity at concentration of 2.882 mg/mL and 2.043 mg/mL, respectively. In addition, the HX and ethylacetate (EA) fraction showed the highest inhibitory activity on yeast $\alpha$-glucosidase at values of $IC_{50}$ of 0.723 mg/mL and 1.356 mg/mL respectively. The HX, dichloromethane (DCM) and EA fraction showed more higher inhibitory activity on yeast $\alpha$-glucosidase than commercial agent such as 1-deoxynorjirimycin and acarbose. Also, the aldose reductase from human muscle cell had been inhibited strongly by the DCM fraction and HX fraction at 51.95% and 47.22% at a concentration of 1 mg/mL, respectively. Our study, for the first time, revealed the anti-diabetic potential of T. tetragonioides and this study could be used to develop medicinal preparations or nutraceutical and functional foods for diabetes and related symptoms.

• Journal of Applied Biological Chemistry
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• v.60 no.1
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• pp.29-33
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• 2017

The methanol extract of Rhododendron mucronulatum for. albiflorum (RMFA) stems inhibited aldose reductase (AR) activity. The RMFA fractions obtained by stepwise extraction with solvents of different polarity were tested for AR inhibition in vitro using the lens of a rat. Among them, the ethyl acetate (EtOAc) fraction inhibited AR more than the other fractions. Quercetin (1) from the EtOAc fraction showed a high AR inhibition with $IC_{50}$ of $2.11{\mu}M$. The stems of RMFA contained the highest amount (5.12 mg/g extract) of quercetin. Our results suggest that RMFA, which contained quercetin, could be a useful material for the development of supplementary functional foods.

• Natural Product Sciences
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• v.17 no.2
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• pp.130-134
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• 2011

The purpose of this study was to evaluate the therapeutic potential of naturally occurring aldose reductase (AR) inhibitors isolated from Korean native plants. The MeOH extract and stepwise polarity fractions of dandelions were tested on rat lens AR inhibition in vitro. Of these, the EtOAc fractions from the leaves of dandelions (Traxacum coreanum, T. officinale, and T. ohwianum) exhibited an AR inhibitory activity ($IC_{50}$ values, 2.37, 1.73 and 2.68 ${\mu}g/ml$, respectively). A chromatography of the EtOAc fraction from the leaves of T. coreanum led to the further isolation of two flavonoids identified as luteolin and luteolin 7-O-glucopyranoside. These compounds exhibited strong AR inhibitory activity, with $IC_{50}$ values of 0.15 and 1.05 ${\mu}M$, respectively. These results suggested that luteolin is a potent AR inhibitor within dandelions and that it could be a useful lead compound in the development of a novel AR inhibitory agent against diabetic complications.

• Archives of Pharmacal Research
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• v.29 no.6
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• pp.479-483
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• 2006

Eight compounds were isolated from the fruiting bodies of Ganoderma applanatum, and were identified as 2-methoxyfatty acids (1), 5-dihydroergosterol (2), ergosterol peroxide (3) $3{\beta},7{\beta},20,23{\zeta}-tetrahydroxy-11,15-dioxolanosta-8-en-26-oic$ acid (4), $7{\beta},20,23{\zeta}-trihydroxy-3,11,15-trioxolanosta-8-en-26-oic$ acid (5), cerevisterol (6), $7{\beta},23{\zeta}-dihydroxy-3,11,15-trioxolanosta-8,20E(22)-dien-26-oic$ acid (7), and $7{\beta}-hydroxy-3,11,15,23-tetraoxolanosta-8,20E(22)-dien-26-oic$ acid methyl ester (8) by spectral analysis. All compounds were isolated for the first time from this fruiting bodies, and their effect on rat lens aldose reductase (RLAR) activity was tested. Among these eight compounds, ergosterol peroxide (3) was found to exhibit potent RLAR inhibition, its $IC_{50}$ value being $15.4\;{\mu}g/mL$.

• Journal of Applied Biological Chemistry
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• v.51 no.1
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• pp.13-16
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• 2008

Five anthraquinones, emodin (1), ${\omega}$-hydroxyemodin (2), chrysophanol-8-O-${\beta}$-D-glucoside (3), emodin-8-O-${\beta}$-D-glucoside (4), and physcion-8-O-${\beta}$-D-glucoside (5), and five flavonoids, kaempferol-3-O-${\beta}$-D-glucoside (6), quercetin (7), quercitrin (8), isoquercitrin (9), and (+)-catechin (10), were isolated from the EtOAc-soluble extract of the fruits of Rumex japonicus. The structures of 1-10 were identified by spectroscopic methods including NMR studies. This is the first report on the isolation of compounds 3-5 from this plant. The isolates were subjected to in vitro bioassays to evaluate their inhibitory activities on the rat lens aldose reductase (RLAR), among which two anthraquinones (1 and 4), and five flavonols (5-9) showed significant activities on RLAR.

• Korean Journal of Medicinal Crop Science
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• v.18 no.5
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• pp.305-310
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• 2010

Taxifolin-3-O-$\beta$-D-xylopyranoside and quercetin-3-O-$\alpha$-L-rhamnopyranoside were isolated from an EtOAc-soluble extract of the leaves of Chamaecyparis obtuse. Quercetin-3-O-$\alpha$-L-rhamnopyranoside was found to possess a potent inhibitory activity of human recombinant aldose reductase in vitro, its $IC_{50}$ value being $11.5\;{\mu}M$. Kinetic analysis showed that quercetin-3-O-$\alpha$-L-rhamnopyranoside exhibited uncompetitive inhibition against DL-glyceraldehyde. Also, quercetin-3-O-$\alpha$-L-rhamnopyranoside suppresses sorbitol accumulation in rat lens under high glucose conditions, demonstrating the potential to prevent sorbitol accumulation in vivo. These results suggest that this compound may be a promising agent in the prevention or treatment of diabetic complications.