• Korean Journal of Pharmacognosy
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• v.46 no.3
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• pp.260-267
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• 2015

Advanced glycation end products (AGEs) have been postulated to play a central role in the development of diabetic complications. A variety of different agents that inhibit AGEs have been under investigation. In this study, 111 herbal medicines from China have been investigated with an in vitro evaluation system using AGEs formation inhibitory activity. Of these, 9 herbal medicines (IC₅₀: <5 μg/ml) were found to have significant AGEs formation inhibitory activity. Particularly, herbal medicines Barleria cristata (leaves), Calotropis gigantea (stems), Ardisia virens (leaves), Dalbergia yunnanensis (leaves) Pittosporum runcatum (leaves), Ardisia japonica (leaves), Rhododendron racemosum (twigs), Oxyria sinensiss (aerial parts), Pyrrosia calvata (whole plants), showed more potent inhibitory activity (approximately 15-40 fold) than the positive control aminoguanidine (IC₅₀: 76.47 μg/ml).

• Korean Journal of Pharmacognosy
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• v.46 no.3
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• pp.268-278
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• 2015

In this study, 80 herbal medicines from Vietnam have been investigated with an in vitro evaluation system using advanced glycation end products (AGEs) formation inhibitory activity. Of these, 10 herbal medicines (IC₅₀: <5 μg/ml) were found to have significant AGEs formation inhibitory activity. Particularly, herbal medicines Strobilanthes pateriformis (aerial parts), Rhodamnia dumetorum (twigs), Glochidion rubrum (twigs), Dipterocarpus obtusifolius (twigs), Bombax ceiba (twigs), Amesiodendron chinense (twigs), Bauhinia coccinea (twigs), Lithocarpus laouanensis (twigs), Bauhinia bracteata (twigs) and Connarus paniculatus (twigs), showed more potent inhibitory activity (approximately 16-31 fold) than the positive control aminoguanidine (IC₅₀: 76.47 μg/ml).

• Korean Journal of Pharmacognosy
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• v.40 no.4
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• pp.388-393
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• 2009

Advanced glycation end products (AGEs) have been implicated in the development of diabetic complications. The AGEs inhibitors or cross-link breakers attenuate various functional and structural manifestations of diabetic complications. In this study, 64 herbal medicines from China and Vietnam have been investigated with an in vitro evaluation system using AGEs inhibitory activity. Of these, eight herbal medicines ($IC_{50}$<50 ${\mu}g$/ml) were found to have strong AGEs inhibitory activity compared with aminoguanidine (14 days, $IC_{50}$=75.98 ${\mu}g$/ml; 28 days, $IC_{50}$=88.27 ${\mu}g$/ml). Particularly, four herbal medicines, Buddleja officinalis (whole plant), Syzygium cuminii (leaf), Eugenia caryophyllate (seed), and Paeonia suffruticosa (root) showed more potent inhibitory activity (approximately 5-6 fold) than the positive control aminoguanidine.

• Nutrition Research and Practice
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• v.5 no.2
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• pp.93-100
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• 2011

Inhibition of angiotensin I-converting enzyme (ACE) activity is the most common mechanism underlying the lowering of blood pressure. In the present study, five organic extracts of a marine brown seaweed Ecklonia cava were prepared by using ethanol, ethyl acetate, chloroform, hexane, and diethyl ether as solvents, which were then tested for their potential ACE inhibitory activities. Ethanol extract showed the strongest ACE inhibitory activity with an $IC_{50}$ value of 0.96 mg/ml. Five kinds of phlorotannins, phloroglucinol, triphlorethol-A, eckol, dieckol, and eckstolonol, were isolated from ethanol extract of E. cava, which exhibited potential ACE inhibition. Dieckol was the most potent ACE inhibitor and was found to be a non-competitive inhibitor against ACE according to Lineweaver-Burk plots. Dieckol had an inducible effect on the production of NO in EAhy926 cells without having cytotoxic effect. The results of this study indicate that E. cava could be a potential source of phlorotalnnins with ACE inhibitory activity for utilization in production of functional foods.

• Preventive Nutrition and Food Science
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• v.7 no.4
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• pp.447-450
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• 2002

Previously, a methanol extract from seeds of Paeonia lactiflora was shown to have a potent inhibitory activities against tyrosinase and soybean lipoxygenase (SLO). Seven stilbenes, trans-resveratrol-4-Ο-$\beta$-D-glucoside, trans resveratrol, trans-$\varepsilon$-viniferin, cis-$\varepsilon$-viniferin, gnetin H, suffruticosol A and B were isolated from the seeds as active principles for inhibition of the enzymatic activity. Among them, the resveratrol trimer, gnetin H exhibited the most potent inhibitory activities against tyrosinase and SLO, respectively. Additionally, the resveratrol dimers, trans-$\varepsilon$-viniferin and cis-$\varepsilon$-viniferin exhibited significant inhibitory activity against the two oxidative enzymes. Meanwhile, three other stilbene derivatives, such as trans-resveratrol, suffruticosol A and suffruticosol B had also weak inhibition activity. The least inhibitory activity was observed in transresveratrol-4-Ο-$\beta$-D-glucoside. These results suggest that resveratrol dimers and trimer in the seeds of Paeonia lactiflora are potentially useful therapeutic agents against pathological disorders such as hyperpigmentation and inflammation.

• Natural Product Sciences
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• v.9 no.4
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• pp.299-303
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• 2003

For the screening of inhibitors of sterol biosynthesis from natural products, a simple and rapid assay method was developed using recombinant yeast carrying human lanosterol synthase, main target of this assay method. Sterol biosynthesis inhibition activity was monitored only by the inhibition of growth of the recombinant yeast. By changing the substrate, this assay method can figure out which step is inhibited in the sterol biosynthesis by the test material. With this assay method total 102 plant samples were screened for their inhibitory activity of sterol biosynthesis. Among plant water extracts screened, 11 plant samples showed inhibitory activity on sterol biosynthesis in ergosterol (-) medium. For selection of the specific inhibitory materials, 11 plant samples were reassayed in ergosterol (+) medium. After all 5 plant samples, Abutilon avicennae Gaertn. (stem), Alnus japonica Steud. (stem), Amaranthus mangostanus L. (aerial part), Philadelphus schrenckii Pupr. (leaf) and Pimpinelia brachycarpa Nakai (aerial part), showed specific inhibitory activity.

• Korean Journal of Pharmacognosy
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• v.39 no.3
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• pp.223-227
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• 2008

Advanced glycation end products (AGEs) contribute to the progression of micro and macrovsacular complication of diabetes and therefore present a promising target for therapeutic agents. In this study, 40 Korean herbal medicines have been investigated with an in vitro evaluation system using AGEs inhibitory activity. Of these, 21 herbal medicines $(IC_{50}<50{\mu}g/ml)$ exhibited an inhibitory activity against AGEs formation compared with anminoguanidine $(IC_{50}=72.12{\mu}g/ml)$. Particularly, 7 herbal medicines, Actinidia arguta (root and stem), Crataegus pinnatifida (twig), Camellia japonica (whole), Kalopanax pictus (bark), Lagerstroemia indica (leaf-stem), Reynoutria sachalinensis (root) showed more potent inhibitory activity (approximately 3-10 fold) than the positive control aminoguanidine.

• YAKHAK HOEJI
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• v.40 no.6
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• pp.653-658
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• 1996

As part of our search for less toxic antimicrobial agents from natural resources. rutin was isolated from Sophora japonica and then hydrolyzed to quercetin. Antimicrobial activity of quercetin was tested in vitro against five kinds of gram positive and ten kinds of gram negative bacteria by serial broth dilution method. Among fifteen kinds of bacteria tested, the antimicrobial activity of quercetin was the most potent against Proteus vulgaris showing minimal inhibitory concentration(MIC) of 125 ${\mu}$g/ml. To investigate the effect of antimicrobial combinations of quercetin with four kinds of antibiotics (ampicillin, cefazolin, oxytetracycline and chloramphenicol). the fractional inhibitory concentration index (FICI) was determined by checkerboard assay for each strain. The antimicrobial combinations of quercetin with four kinds of antibiotics resulted in synergism in one instance, additive effect in four instances, but no antagonism was observed.

• Korean Journal of Pharmacognosy
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• v.42 no.1
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• pp.46-53
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• 2011

Advanced glycation end products (AGEs) have been postulated to play a central role in the development of diabetic complications. A variety of different agents that inhibit AGEs have been under investigation. In this study, 66 herbal medicines from China have been investigated with an in vitro evaluation system using AGEs formation inhibitory activity. Of these, 31 herbal medicines ($IC_{50}$ < $50\;{\mu}g/ml$) were found to have significant AGEs formation inhibitory activity. Particularly, 5 herbal medicines, Camptotheca acuminata (branches and leaves), Quercus franchetii (branches), Camellia pitardii (leaves, branches, and fruits), Antidesma bunius (whole plants), and Loranthus parasiticus (whole plants) showed more potent inhibitory activity (approximately 6-20 fold) than the positive control aminoguanidine ($IC_{50}=52.96\;{\mu}g/ml$).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.3-6
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• 2001

In common globular proteins, the native form is in its most stable state. However, the native form of inhibitory serpins (serine protease inhibitors) and some viral membrane fusion proteins is in a metastable state. Metastability in these proteins is critical to their biological functions. Our previous studies revealed that unusual interactions, such as side-chain overpacking, buried polar groups, surface hydrophobic pockets, and internal cavities are the structural basis of the native metastability. To understand the mechanism by which these structural defects regulate protein functions, cavity-filling mutations of a 1-antitrypsin, a prototype serpin, were characterized. Increasing conformational stability is correlated with decreasing inhibitory activity. Moreover, the activity loss appears to correlate with the decrease in the rate of the conformational switch during complex formation with a target protease. We also increased the stability of a 1-antitrypsin greatly via combining various stabilizing single amino acid substitutions that were distributed throughout the molecule. The results showed that a substantial increase of stability, over 13 kcal/mol, affected the inhibitory activity with a correlation of 11% activity loss per kcal/mol. The results strongly suggest that the native metastability of proteins is indeed a structural design that regulates protein functions and that the native strain of a 1-antitrypsin distributed throughout the molecule regulates the inhibitory function in a concerted manner.