• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2546-2552
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• 2012

A novel biguanide-functionalized $Fe_3O_4/SiO_2$ magnetite nanoparticle with a core-shell structure was developed for utilization as a heterogeneous organosuperbase in chemical transformations. The structural, surface, and magnetic characteristics of the nanosized catalyst were investigated by various techniques such as transmission electron microscopy (TEM), powder X-ray diffraction (XRD), vibrating sample magnetometry (VSM), elemental analyzer (EA), thermogravimetric analysis (TGA), $N_2$ adsorption-desorption (BET and BJH) and FT-IR. The biguanide-functionalized $Fe_3O_4/SiO_2$ nanoparticles showed a superpara-magnetic property with a saturation magnetization value of 46.7 emu/g, indicating great potential for application in magnetically separation technologies. In application point of view, the prepared catalyst was found to act as an efficient recoverable nanocatalyst in nitroaldol and domino Knoevenagel condensation/Michael addition/cyclization reactions in aqueous media under mild condition. Additionally, the catalyst was reused six times without significant degradation in catalytic activity and performance.

• Fashion & Textile Research Journal
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• v.7 no.1
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• pp.81-84
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• 2005

Skin patch test and antibacterial properties of the reaction products between poly(hexamethyl biguanide) hydrochloride and trimethylol melamine on textile fabrics were examined. Antibacterial activities of anti-microbial agent treated samples are very good. The reduction ratios against four kinds of colonies are 99.9 % after repeated laundering ten times. Skin patch test results for anti-microbial agent treated samples are almost-negative by Hi-scope judgement and macroscopical judgement.

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3640-3644
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• 2012

An efficient synthetic method for direct Henry reaction catalyzed by a biguanide; namely metformin, as an organosuper-base, between a variety of aromatic and aliphatic aldehydes and nitromethane under neat conditions has been developed. Convenient procedure for removal of the catalyst, chemoselective acquiring of ${\beta}$-nitroalcohols as predominant products, as far as possible short reaction time with excellent conversions are advantages of the developed protocol.

• The Korean Journal of Vision Science
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• v.20 no.4
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• pp.531-541
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• 2018

Purpose : To evaluate the acute cytotoxic effect of polyhexamethylene biguanide (PHMB), epigallocatechin gallate (EGCG) and PHMB/EGCG mixture on the cultured human corneal epithelial cell (HCEpiC). Methods : HCEpiCs were cultured in the media of HCEpiC containing 0.00001~0.005% PHMB, 0.001~5% EGCG and 0.00005% PHMB/0.05% EGCG mixture respectively for 30, 60, 120 and 240 min. Cultured HCEpiCs were fixed and stained with Draq5 and cell viability and apoptosis were evaluated using confocal microscope and ImageXpress $Ultra^{TM}$. Results : Cultured HCEpiC did not show cytotoxic effect at below 0.00005% PHMB and below 0.05% EGCG concentration. In the media containing 0.00005% PHMB/0.05% EGCG, acute cytototoxic effect was not found, whereas damaged HCEpiCS were increased and survival cells were decreased in the media incubated for 240 min. Conclusion : The mixture of 0.00005% PHMB/0.05% EGCG showed non acute cytotoxic effect on the cultured HCEpiCs, however it is needed to investigate its chronic cytotoxic effect.

• Parasites, Hosts and Diseases
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• v.44 no.4 s.140
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• pp.313-320
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• 2006

In an effort to characterize, on the molecular scale, the Acanthamoeba initially isolated from the cornea of an amoebic keratitis patient associated with overnight-wear orthokeratology lens in Korea, we conducted mitochondrial DNA restriction fragment length polymorphism, 18S rDNA sequencing, and drug sensitivity analyses on the isolate (KA/PE1). The patient was treated with polyhexamethylene biguanide, chlorhexidine and oral itraconazole, which resulted in resolution of the patient's ocular inflammation. The majority of the molecular characteristics of the KA/PE1 were determined to be identical, or quite similar, to those of A. castellanii Ma strain, which had been isolated also from amoebic keratitis. The risk of Acanthamoeba keratitis as a potential complication of overnight orthokeratology is briefly discussed.

• Parasites, Hosts and Diseases
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• v.36 no.1
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• pp.7-14
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• 1998

In order to understand the action mechanism of polyhexamethylene biguanide (PHMB) to the cyst of Accnthcnloebc on the morphological basis, the cysts of four corneal isolates of Acanthanoebc were treated with minimal cysticidal concentration (MCC) of PHMB and their ultrastructural changes were examined by transmission electron microscopy. The most striking change of cysts treated with PHMB compared with normal cysts was the shrinkage of intracystic amoebae, which resulted in the separation of the plasma membrane of intracystic amoeba from endocystic wall. Subplasmalemmal lipid droplets became irregularly shaped . In severely damaged cysts, cytoplasm was aggregated and organelles were severely deformed. Cytoplasmic materials were leaked out through the damaged plasma membrane. Most cysts showed aggregation of nuclear chromatin material. Number of mitochondrial cristae was also reduced. Ecto- and endo-cystic walls were relatively well tolerated. Findings in the present study revealed that PHMB affected mainly on plasma membrane, but lesser on organellar membrane of intracystic amoeba. It seemed likely that PHMB might kill cystic forms of Accnthamoebc by similar mechanism in which this environmental biocide can damage the cell wall of Escherichia coli by binding with acidic phospholipids.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.307.1-307.1
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• 2003

Metfotrmin is a biguanide antihyperglycemic agent often used for the treatment of non-insulin dependent diabetics(NIDDM). Metformin lowers both fasting and postprandial plasma glucose concentrations by improving insulin sensitivity at hepatic and peripheral tissues. The pharmacokinetics and pharmacodynamics of metformin were studied in Korean healthy volunteers at fasting state over 10 hours. (omitted)

• Archives of Pharmacal Research
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• v.13 no.1
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• pp.74-77
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• 1990

N-(2-Amamantyl)-N-(5-arylhydrazono-6-methyl-4-oxopyrimidin-2-yl) guanidines (IIIa, b), 2-(2-admantyl-amino)-4-amino-s-triazine (IVa) and its 6-chloromethyl derivative (IVb) were prepared by cylization of 1-(2-admantyl) biguanide HCl (I) with ethyl 2-arylhydrazono-3-oxobutyrates (II), ethyl formate and ethyl chloroacetate, respectively. Where 1-(2-admantyl)-3-(4, 5-dioxo-2-imidazolidinylidene)guanidine (V) was used as intermediate for the synthesis of amides (VIIa, b), hydrazide (VIII) and azomethine derivatives (IX, b) of alkyl 2-(2-admantyl-amino)-4-amino-2-triazine-6-carboxylates (VI a, b). The antimicrobial testing of the prepared compounds proved that compound 1Xb was the most active. It showed a marked bacteriostatic effect against Staphylococcus aureus and Bacillus subtilis.

• Korean Journal of Clinical Pharmacy
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• v.25 no.3
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• pp.131-137
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• 2015

Background: The protective effect of metformin against breast cancer is inconclusive. Objective: To evaluate the effect of metformin on breast cancer risk and mortality in patients with type 2 diabetes. Method: A comprehensive literature search was performed for pertinent articles published prior to June 30, 2014, using PubMed and EMBASE. Study heterogeneity was estimated with $I^2$ statistic. The data from the included studies were pooled and weighted by random-effects model. The quality of each included study was assessed on the basis of the 9-star Newcastle-Ottawa Scale and publication bias was evaluated by visual inspection of a funnel plot. Results: Ten studies were included in the meta-analysis of the association of metformin and breast cancer risk. By synthesizing the data from the studies, the pooled odds ratio (OR) was 0.72 (95% CI: 0.59, 0.87) (p = 0.0005). Three cohort studies were included for meta-analysis of the association between metformin and breast cancer-related mortality. Metformin was associated with a significant decrease in mortality (Risk ratio: 0.68; 95% CI: 0.51, 0.90, p = 0.007). Conclusion: The present meta-analysis suggests that metformin appears to be associated with a lower risk of breast cancer incidence and mortality in patients with type 2 diabetes.

• Microbiology and Biotechnology Letters
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• v.40 no.3
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• pp.180-185
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• 2012

Type 2 Diabetes Mellitus, a chronic metabolic disorder which results from a high blood glucose level, is one of the most prevalent and costly diseases of our time. Considering increasing rates of obesity and the aging population in Korea, the number of diabetic patients is likely to rise rapidly in the future. There are five conventional diabetic drugs which work through different mechanisms; sulfonylureas, biguanide, meglitinide, alpha-glucosidase inhibitors, and thiazolidinedione. Although they all have antidiabetic effects, some side effects such as hypoglycemia, weight gain and gastrointestinal intolerance are associated with them. Incretin based therapies, utilizing glucagon-like peptide-1 (GLP-1) and dipeptidyl peptidase-4 (DPP-4) inhibitors, which have a lower risk of adverse side effects, have recently been introduced. At present PPAR-targeting drugs are being actively developed. In this research review, particular emphasis has been placed on the current trends and possible biological targets for the new generation of antidiabetic drugs.