Hae-Ik Rhee

Screening of hexavalent chromium biosorbent from marine algae

Abstract A highly chromate-selective biosorbent with high adsorption capacity was found by examining the chromate adsorption capacities of 48 species of red, brown, or green marine algae sampled from the east coast of Korea. As a result of screening, a red marine alga showed excellent adsorption characteristics. It was identified as Pachymeniopsis sp. The timing of the sampling of Pachymeniopsis sp. did not affect the adsorption capacity of the alga but the optimum period for mass collection was April–May. The alga also showed high selectivity for chromate and its adsorption capacity for other heavy metal ions such as cadmium and manganese was relatively low. An investigation of the adsorption isotherm of Pachymeniopsis sp. as a dried powder for chromate adsorption at 25 °C showed Langmuir-type dependence. The maximum chromate adsorption capacity of the selected alga was about 225 mg/g. The desorption of adsorbed chromate from Pachymeniopsis sp. was done by treating samples with 1 N NaOH. It was confirmed that ion exchange type adsorption was observed with anion exchangers but not with cation exchangers. Therefore it is believed that the chromate adsorption is based on the anionic exchange of Pachymeniopsis sp.

Purification and characterization of cholesterol oxidase from Pseudomonas sp. and taxonomic study of the strain

SummaryA cholesterol-oxidase-producing microorganism, strain COX629, isolated from soil was identified as Pseudomonas sp. The cholesterol oxidase produced by Pseudomonas sp. strain COX629 was purified 2400-fold to homogeneity in an overall yield of 60% from culture broth. The enzyme was a monomer with a molecular weight of 56 000, as estimated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and Sephadex G-150 gel column chromatography. The enzyme showed optimum activity at pH 7.0 and was stable over a rather wide pH range of 4.0 to 11.0. The enzyme showed a high substrate specificity for 3β-hydroxysteroids and the Km value for the oxidation of cholesterol by this enzyme was about 0.2 mM. A characteristic of the enzyme is marked stability at high temperature.

Isolation of Peptide Ligands that Inhibit Glutamate Racemase Activity from a Random Phage Display Library

Several new antibacterial agents are currently being developed in response to the emergence of bacterial resistance to existing antibiotic substances. The new agents include compounds that interfere with bacterial membrane function. The peptidoglycan component of the bacterial cell wall is synthesized by glutamate racemase, and this enzyme is responsible for the biosynthesis of d-glutamate, which is an essential component of cell wall peptidoglycan. In this study, we screened a phage display library expressing random dodecapeptides on the surface of bacteriophage against an Escherichia coli glutamate racemase, and isolated specific peptide sequences that bind to the enzyme. Twenty-seven positive phage clones were analyzed, and seven different peptide sequences were obtained. Among them, the peptide sequence His-Pro-Trp-His-Lys-Lys-His-Pro-Asp-Arg-Lys-Thr was found most frequently, suggesting that this peptide might have the highest affinity to glutamate racemase. The positive phage clones and HPWHKKHPDRKT synthetic peptide were able to inhibit glutamate racemase activity in vitro , implying that our peptide inhibitors may be utilized for the molecular design of new potential antibacterial agents targeting cell wall synthesis.

Oleic acid: an efficient inhibitor of glucosyltransferase.

Among the extracts from 420 kinds of herbs, Prunus salicina, showing the highest glucosyltransferase inhibition activity, was purified and designated GTI‐0163. Structural determination of GTI‐0163 revealed it to be an oleic acid‐based unsaturated fatty acid. GTI‐0163 was an uncompetitive inhibitor of GTase. Among the unsaturated fatty acids, oleic acid showed a significantly higher GTase inhibitory activity than the saturated fatty acids or the ester form of oleic acid. These results strongly suggested that both the number of double bonds and the existence of free carboxyl groups of fatty acids play an important role in GTase inhibitory activity.

Antioxidative effect of purple corn extracts during storage of mayonnaise.

Anthocyanin is a powerful natural antioxidant. Purple corn husk is rich in anthocyanin. In this paper the antioxidative effect of anthocyanin-rich purple corn husk extract (PCHE) in mayonnaise during storage was studied. The antioxidative effect of the mayonnaise containing PCHE was evaluated by measuring peroxide values, p-anisidine values, total oxidation values, acid values, and iodine values at time intervals for 10 weeks. The antioxidative effect of the mayonnaise containing PCHE was higher than that of mayonnaise with chemical antioxidants BHT and EDTA as positive control. The mayonnaise containing 0.4 g/kg PCHE showed the strongest antioxidative performance during storage. This study suggests that PCHE could be used as natural antioxidant in high fat food and as a substitute to chemical antioxidant with its purplish colour marking its difference from ordinary mayonnaise. Such colour difference will tell consumers that their food contains natural antioxidants.

Coptis chinensis Franch. extract up-regulate type I helper T-cell cytokine through MAPK activation in MOLT-4 T cell.

ETHNOPHARMACOLOGICAL RELEVANCE The dried rhizome of Coptis chinensis Franch. (Huanglian) has been widely used in Asian traditional medicine. It was already known that Coptis chinensis Franch. rhizome has various pharmacological properties including its anti-oxidant, anti-cancer, and anti-inflammatory activity. AIM OF THE STUDY To evaluate the immune-enhancement effect of the Coptis chinensis Franch. rhizome extract on helper T cells and its signaling mechanism. MATERIALS AND METHODS MOLT-4 human T cell line was used to investigate the effect of the Coptis chinensis Franch. rhizome extract. Cell viability was measured by the MTT assay and cytokine expression level was analyzed by ELISA and qRTPCR. MAPKs signal molecules activation level was detected by immunoblotting. RESULTS The expression of IFN-γ, a cytokine of type I helper T (Th1) cell, increased; however, IL-4 was not affected by the Coptis chinensis Franch. rhizome extract. Other Th1 cytokines, such as IL-1β, IL-2, and IL-6, also increased. These data suggest that the Coptis chinensis Franch. rhizome extract activates MOLT-4 cell to Th1 cell, not type II helper T cell. Furthermore, the Coptis chinensis Franch. rhizome extract activates the Mitogen-activated protein kinase (MAPKs) signaling pathways. CONCLUSION The results obtained from this study suggest that the Coptis chinensis Franch. rhizome extract should be used as an immune enhancer in anti-inflammatory medicine, adjuvant materials, and as a supplement to treat weakened immune system.

Free radical scavenging and hepatoprotective actions of Quercus aliena acorn extract against CCl4-induced liver

In the present study, we investigated the protective effect of Quercus aliena acorn extracts against CCl4-induced hepatotoxicity in rats, and the mechanism underlying the protective effects. Aqueous extracts of Quercus aliena acorn had higher superoxide radical scavenging activity than other types of extracts. The Quercus aliena acorn extracts displayed dose-dependent superoxide radical scavenging activity (IC50 = 4.92 μg/ml), as assayed by the electron spin resonance (ESR) spin-trapping technique. Pretreatment with Quercus aliena acorn extracts reduced the increase in serum aspartate aminotransferase (AST) and serum alanine aminotransferase (ALT) levels. The hepatoprotective action was confirmed by histological observation. The aqueous extracts reversed CCl4-induced liver injury and had an antioxidant action in assays of FeCl2- ascorbic acid induced lipid peroxidation in rats. Expression of cytochrome P450 2E1 (CYP2E1) mRNA, as measured by RT-PCR, was significantly decreased in the livers of Quercus aliena acorn-pretreated rats compared with the livers of the control group. These results suggest that the hepatoprotective effects of Quercus aliena acorn extract are related to its antioxidative activity and effect on the expression of CYP2E1.

ONE-STEP PURIFICATION OF CHOLESTEROL OXIDASE FROM CULTURE BROTH OF A PSEUDOMONAS SP. USING A NOVEL AFFINITY CHROMATOGRAPHY METHOD

Cholesterol oxidase from the culture broth of a Pseudomonas sp. was purified with a yield of more than 70% by a one-step procedure using a column of cholesterylglycine-carboxymethylcellulose; active enzyme was eluted by Triton X-100. The purified enzyme was homogeneous by SDS-PAGE.

Influence of extract of Rosa Rugosa roots on lipid levels in serum and liver of rats

The effects of the methanol extract of Rosa rugosa roots on serum and liver lipids were studied in rats. The rats were fed the purified diets with or without the methanol extract at the 1% level for 4 weeks. The concentrations of serum and liver total cholesterol were not significantly affected by the feeding of extract. Feeding of the extract, on the other hand, reduced the liver triacylglycerol content without influencing the serum triacylglycerol level. The effects of the extract on lipids profiles were diminished markedly by dietary cholesterol. The results suggest an existence of component in the extract which may ameliorate the accumulation of triacylglycerol in rat liver.

Molecular cloning and expression of a cDNA encoding cytosolic ascorbate peroxidase fromPimpinella brachycarpa

Summary Ascorbate peroxidases (APX) detoxify hydrogen peroxide within the cytosol and chloroplasts of plant cells. In this report, the characterisation of a 997 bp cDNA clone encoding a cytosolic ascorbate peroxidase from Pimpinella brachycarpa , termed Pbapx , is described. Pbapx contains an open reading frame of 753 bp with strong homology to Fragaria ananassa, Capsicum annuum , and Nicotiana tabacum APX. Expression of Pbapx in E. coli cells was significantly increased upon IPTG induction. Furthermore, the Pbapx transcript was expressed in a variety of tissues by RT-PCR, showing that mRNA was detected at higher levels in embryogenic calli and roots, but lower in petioles and leaves. Based on these results, we suggest that this gene may regulate transcription for the development of embryogenic callus in Pimpinella brachycarpa