Chang-Kee Hyun

Utilization of bovine blood plasma proteins for the production of angiotensin I converting enzyme inhibitory peptides

Hydrolysates of whole bovine plasma and its separated proteins, albumin and globulins, which inhibit the angiotensin I converting enzyme (ACE) were prepared by enzymic hydrolysis with several proteases available for industrial use. Alcalase produced ACE inhibitory peptides from plasma proteins most efficiently and the Alcalase hydrolysate of albumin showed the most high activity (IC50=0.56 mg/ml). Sequential ultrafiltration of the hydrolysate with MW cut-off 10 000, 3000 and 1000 resulted in increased activity of each filtrate up to IC50 of 0.12 mg/ml. Sephadex G-25 gel chromatography of the hydrolysate eluted a peptide fraction below MW 1000 of the most potent activity (IC50=0.09 mg/ml). The hydrolysate was compared with the tryptic hydrolysate of casein considering the practical production of a functional food material in industry. The former was found to be more advantageous to separate the purified peptide fraction by industrial processes.

Cytotoxic effects of the components in heat-treated mistletoe (Viscum album)

Major cytotoxic components were fractionated from Korean mistletoe and the changes of their cytotoxic effects caused by heat treatment were investigated. The high cytotoxicity of isolated lectin I completely disappeared by heating for 30 min. The fractions of viscotoxins and alkaloids maintained their activities even after heating for 60 and 180 min, respectively. The alkaloid fraction was more cytotoxic to tumor MSV cells than to non-tumor A31 cells and the activity pattern was not changed by heat treatment. The possible contributions of alkaloids and viscotoxins to the activities of heat-treated mistletoe extracts such as tea or decoctions are discussed.

Antigenotoxicity of peptides produced from silk fibroin

Abstract This study was conducted to examine in vitro antigenotoxic effects of the peptides derived from the hydrolysates of silk fibroin in mouse embryo 3T3 cells. The hydrolysates were prepared by acid or enzymic hydrolysis of fibroin, and antigenotoxicities were determined by measuring the reduced levels of DNA damage using the Comet assay. The fibroin preparation isolated from cocoons was efficiently digested by hydrolytic reactions with acid or Alcalase, an industrial protease. The acid- and Alcalase hydrolysates showed higher antigenotoxic activities than peptic- and tryptic hydrolysates. Active peptide fractions were separated from acid- and Alcalase hydrolysate by gel filtration chromatography. It was deduced from the chromatograms and amino acid analyses that the size (3–7 amino acids) and the glycine plus alanine content of peptides might be important factors for their activities. In addition, it was found that the antigenotoxic effect of peptides was due both to the protective interactions between cells and peptide molecules and to the direct inactivation of the mutagen, MNNG by peptides. Considering the availability and safety of silk fibroin and the superior antigenotoxic effects of produced peptides, the results of this study showed the possibility of utilizing fibroin as a source for chemopreventive functional peptides.

Utilization of bovine blood plasma obtained from a slaughterhouse for economic production of probiotics

Abstract The growth of a probiotic-strain of Lactobacillus sp. in a bovine blood plasma-based medium and its stability against the freeze-drying process were investigated. Nitrogen sources in a complex (MRS) medium were replaced by the enzymatic hydrolysate of blood plasma using a selected industrial protease. The cell mass produced in the medium under optimum conditions, 5.2 × 10 9 CFU/ml, was significantly high, and about 74% of that in MRS medium. The blood protein hydrolysate in the medium also enhanced the survival rate of the strain against freeze-drying, for which sucrose was selected as the most effective stabilizer.

Lactobacillus plantarum HAC01 regulates gut microbiota and adipose tissue accumulation in a diet-induced obesity murine model

The functional features of Lactobacillus plantarum HAC01 (HAC01), isolated from fermented Korean kimchi, were studied with regard to the fat mass, immunometabolic biomarkers and dysbiosis in a diet-induced obesity (DIO) murine model. L. rhamnosus GG (LGG) served as reference strain and a PBS-treated group as control. The administration of L. plantarum HAC01 resulted in reduction of the mesenteric adipose depot, the conjunctive tissue closely associated with the gastrointestinal tract, where lipid oxidative gene expression was upregulated compared to the control group. Metagenome analysis of intestinal microbiota showed that both strains HAC01 and LGG influenced specific bacterial families such as the Lachnospiraceae and Ruminococcaceae rather than the phyla Firmicutes and Bacteroidetes as a whole. The relative abundance of the Lachnospiraceae (phylum Firmicutes) was significantly higher in both LAB-treated groups than in the control. Comparing the impact of the two Lactobacillus strains on microbial composition in the gut also suggests strain-specific effects. The study emphasises the need for deeper studies into functional specificity of a probiotic organism at the strain level. Alleviation of obesity-associated dysbiosis by modulation of the gut microbiota appears to be associated with “indicator” bacterial taxa such as the family Lachnospiraceae. This may provide further insight into mechanisms basic to the mode of probiotic action against obesity and associated dysbiosis.