Eun-Joo Kum

Antifungal Activity of Phenanthrene Derivatives from Aerial Bulbils of Dioscorea batatas Decne

Plants of the genus Dioscorea have long been used as oriental folk medicine, and Dioscorea batatas Decne has been cultivated for healthy food in Korea. Although the bulbils were produced 2,000 ton annually, there are few reports for bioactive compounds in bulbils. In this study, three phenanthrenes and two phenanthraquinones were isolated from the aerial bulbils of D. batatas Decne, and their structures were elucidated. Among them, compound 2 (6-hydroxy-2,7-dimethoxy-1,4-phenanthraquinone) has not been reported previously. Evaluation of antimicrobial activities based on disk-diffusion assay, MIC and MFC showed the compound 12 (6,7-dihydroxy-2,4-dimethoxyphenanthrene) has strong antimicrobial activity with 25 ㎍/㎖ of MIC and MFC against Candida albicans. Our results suggested that compound 12 has a potent antifungal activity, and the antimicrobial activity and its spectrum are modulated by hydroxylation and methoxylation of phenanthrene ring moiety of the compound.

GLR1 Plays an Essential Role in the Homeodynamics of Glutathione and the Regulation of H2S Production during Respiratory Oscillation of Saccharomyces cerevisiae

The role of glutathione (GSH) and its homeodynamics during respiratory oscillation of Saccharomyces cerevisiae were investigated. Pulse injection of thiol redox modifying agents, such as diethylmaleate, N-ethylmaleimide, DL-butione-[S,R]-sulfoxamine, or 5-nitro-2-furaldehyde into the culture perturbed oscillation, although the degree of perturbation varied. Analysis of the expression profiles of GSH1 and GLR1, the activities of glutathione reductase, oscillations in cysteine and GSH concentrations, and the chemostat culture of the GLR1 disruptant indicated that GLR1 plays an essential role in the homeodynamics of GSH and the regulation of H2S production.

Isolation of Acinetobacter calcoaceticus BP-2 Capable of Degradation of Bisphenol A

Bisphenol A (BPA), 2,2-bis(4-hydroxyphenyl)propane, has been widely used as a monomer for production of epoxy resins and polycarbonate plastics, and final products of BPA include adhesives, protective coatings, paints, optical lens, building materials, compact disks and other electrical parts. Since BPA is a toxic chemical to elicit acute cell cytotoxicity and chronic endocrine disrupting activity, the degradation of BPA has been focused during last decades. To overcome the problem of photo-, and chemical-degradation of BPA, in this study, a bacterium that is able to biodegrade BPA, was isolated. The bacterium, isolated from the soil of plastic factory, was identified as Acinetobacter calcoaceticus (strain BP-2) based on physiological and 16S rDNA sequencing analysis. A. calcoaceticus BP-2 was able to grow in the presence of 1140 μg ml -1 BPA. Biodegradation experiments showed that BP-2 mineralized BPA via 4-hydroxybenzoic acid and 4-hydroxyacetophenone, and average degradation rate was 53.3 μg ml -1 day -1 under optimal conditions (pH 7 and 30℃). In high density resting cell (3.5 g-dcw.l -1 ) experiments, the maximal degradation rate was increased to 89.7 μg ml -1 h -1 . Our results suggest that BP-2 has high potential as a catalyst for practical BPA bioremediation.

Spectrophotometric Determination of Bisphenol A by Complexation with Ferricyanide and Ferric chloride solution

Bisphenol A (BPA) has been widely used as a monomer for production of epoxy resins and polycarbonate plastics. The annual production of BPA exceeds 640,000 metric tons in worldwide. BPA, a suspected phenolic endocrine disruptor, is moderately soluble and frequently detected in industrial wastewater. To date, HPLC and GC has been used for BPA analysis. However, HPLC and GC-analysis need high operation cost, experts, and an elaborate pre-treatment of samples, and is difficult to apply on-time and mass analysis. Therefore, simple, mass and rapid detection of BPA in environments is necessary. In the present study, spectrophotometric method of BPA quantification was developed. Based on blue-color product formation with BPA and ferric chloride/ferricyanide under the optimized conditions, the standard curve was acquired (λ???=0.061 BPA [μM]+0.07155, R 2 =0.992). Using an established method, the BPA contents in the soil extract, and different water samples and living products, including disposable syringe, cup and plastic tube, were analyzed. The results suggested that the method is useful for BPA determination from different massive samples. Since the BPA metabolites, nontoxic 4-hydroxyacetophenone or 4-hydroxybenzaldehyde, did not form blue-color product, this method is also useful to screen a microorganism for BPA bioremediation.

Toxicity Evaluation of Endocrine Disrupting Chemicals Using Human HepG2 Cell Line, Lumbricus rubellus and Saccharomyces cerevisiae

Toxicity evaluation systems for various chemicals and their metabolites have been developed during last decades. In this study, the acute toxicity of endocrine disrupting chemicals, such as endosulfan, bisphenol A, vinclozolin, and 3,5-dichloroaniline, was evaluated using HepG2 cell line, Lumbricus rubellus and Saccharomyces cerevisiae, respectively. The extents of toxicity of the chemicals in different bioassay systems varied substantially, such as endosulfan>3,5-dichloroaniline> bisphenol A in HepG2 cell line system, endosulfan>bisphenol A>3,5-dichloro aniline in L. rubellus system, and 3,5-dichloroaniline>endosulfan>bisphenol A in S. cerevisiae system. Meanwhile, no cytotoxicity was observed by treatment of vinclozolin in the evaluation systems. Our results suggest that earthworm and yeast are useful to evaluate acute toxicity of endocrine disrupting chemicals, and direct comparison of toxicity data from different bioassay systems is unattainable. Based on our results, we propose that the bioassay system with earthworm or yeast, a rapid, simple and economic system, could be applied as pre-test for the toxicity evaluation using human cell line or animals.