• Natural Product Sciences
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• v.19 no.4
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• pp.275-280
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• 2013

Aldose reductase (AR) has been shown to play an important role in the development of diabetic complications. To search for AR inhibitors from Chinese plants, the ethanol extracts of Chinese plants was tested against an inhibition of rat lens AR in vitro. Among Chinese plants tested, Cissus assamica var. pilosissima and Syzygium oblatum showed highest inhibition of AR ($IC_{50}$ values, 0.71 and 0.79 ${\mu}g/ml$, respectively). Cissus assamica var. pilosissima and Syzygium oblatum showed more potent inhibitory activity against AR than the positive control, TMG. Consequently, C. assamica var. pilosissima and S. oblatum have a possibility of new natural resources for the development of AR inhibitor for the prevention of diabetic complications.

• 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.

• Journal of Applied Biological Chemistry
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• v.49 no.1
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• pp.24-27
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• 2006

Four ursane-type triterpenoids, 2${\alpha}$,3${\alpha}$,19${\alpha}$-trihydroxy-24-norurs-4(23),12-dien-28-oic acid (1), 4(R),23-epoxy-2${\alpha}$,3${\alpha}$,19${\alpha}$-trihydroxy-24-norurs-12-en-28-oic acid (2), myrianthic acid (3), and tormentic acid (4), and a phenolic compound, ethyl gallate (5), from an EtOAc-soluble extract of the stems of Rumex japonicus, were subjected to in vitro bioassays to evaluate advanced glycation end products (AGEs) and rat lens aldose reductase (RLAR) inhibitory activity. Compounds 1 and 5 exhibited a significant inhibitory activity on AGEs formation with $IC_{50}$ value of 87 ${\mu}M$ and on RLAR with $IC_{50}$ value of 14.3 ${\mu}M$, respectively. Ethyl gallate (5) was isolated for the first time from this plant.

• Natural Product Sciences
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• v.13 no.2
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• pp.160-163
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• 2007

Four glycosides, rosamultin (1), tetracentronside B (2), 4-O-methylellagic acid 3-O-${\alpha}$-$_L$-rhamnopyranoside (3), and vanillic acid 4-O-${\beta}$-$_L$-glucopyranoside (4), isolated from the roots extract of Potentilla discolor, were subjected to in vitro bioassays to evaluate the inhibitory activity on advanced glycation end products (AGEs) formation and rat lens aldose reductase (RLAR). Compound 3 exhibited a significant inhibitory activity against both AGEs formation and RLAR with IC$_{50}$ values of 79.5 and 8.03 ${\mu}$M, respectively. All the compounds (1-4) were isolated for the first time from this plant.

• 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.

• 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.25 no.1
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• pp.41-46
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• 1994

The ether, ethylacetate and n-butanol soluble fractions from the roots of Scutellaria baicalensis showed a significant inhibition of lens aldose reductase (AR) activity in vitro. During systematic fractionation of the active fractions, 7 flavonoids were isolated and compared their inhibitory activities against rat AR using DL-glyceraldehyde as a substrate, among which baicalin (VII) was found to exhibit the most potent inhibitory activity. Baicalin (VII) and wogonin-7-O-glucuronide (VI), with repeated treatments (30 mg/kg/day, i.p.) throughout the experimental periods caused a significant suppression of cataract formation induced by galactose (40 g/kg/day) as well as the decrease of galactitol accumulation in the rat lens. The flavonoids also exhibited a significant inhibition of sorbitol accumulation in the lenses of diabetic rats induced by streptozotocin (STZ).

• 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.

• Korean Journal of Agricultural Science
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• v.39 no.1
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• pp.69-73
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• 2012

The purpose of this study was to evaluate the potential of naturally occurring aldose reductase (AR) inhibitors from white-color natural products (Aruncus dioicus var. kamtschaticus, Chionanthus retusa, Cosmos bipinnatus, Hibiscus syriacus, Hydrangea paniculata, Magnolia denudata, Prunus padus, Robinia pseudo-accacia, Rhododendron mucronulatum for. albiflorum, Spiraea blumei, and Spiraea prunifolia var. simpliciflora). The MeOH extract of white-color natural products were tested on rat lens AR inhibition in vitro. Among them, the MeOH extract of R. mucronulatum for. albiflorum showed highest inhibition on AR ($IC_{50}$ value, 1.07 ${\mu}g/ml$). These results suggested that R. mucronulatum for. albiflorum, a white-color natural product, could be a useful resource in the development of a novel AR inhibitory agent against diabetic complications.

• Archives of Pharmacal Research
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• v.18 no.2
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• pp.65-68
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• 1995

The methanol extract from the whole parts of the flowers of Chrysanthemum boreals was found to exhibit a significant inhibition of a rat lens aldose reductase (RLAR) activity in vitro. Bioassay guided systematic fractionation of the methanol extract led to the isolation of four flavonoids which were identified as acacetin (1), apigenin (II), luteolin (III) and linarin (IV). Compounds I-III were demonstrated to exhibit a significant inhibition of RLAR. Luteolin (II) was found to be the most potent AR inhibitor with $IC_{50}$ value of $5{\times}10^{-7}M$.