Ok-Hee Lee

Evaluation of Proanthocyanidin Contents in Total Polyphenolic Compounds of Pine (Pinus densiflora) Needle Extracts and Their Antioxidative Activities

Flavonoids in pine needles are known to be effective scavengers of free radical. Especially, proanthocyanidin, a kind of flavonoids possesses cardiovascular protection and antioxidative activities. Here, we evaluated proanthocyanidin contents in total polyphenolic compounds of pine needle extracts prepared by using hot water, ethanol, hexane or sub-supercritical . Analyses of total polyphenolic compounds and proanthocyanidin in each extracts indicated that hot water extract contained the highest concentrations, but sub-supercritical extract contained the lowest concentrations. On the other hand, evaluation of proanthocyanidin contents in total polyphenolic compounds in each extracts showed that sub-supercritical extract possessed the highest content, but hot water extract possessed the lowest content. These results indicate that extracts containing high concentrations of both total polyphenolic compounds and proanthocyanidin could be obtained by using hot water or ethanol extractions. Furthermore, extract containing high content of proanthocyanidin out of total polyphenolic compounds could be achieved by using sub-supercritical extraction. Measurement of antioxidative activities of extracts showed that hot water extract possessed the highest activity. In this study, we prepared extracts from pine needles by four different methods and evaluated the antioxidative compounds in extracts that could be used for effective components of functional food products.

Isolation and characterization of a marine bacterium Thalassomonas sp. SL-5 producing β-agarase

A novel agar-degrading bacterium SL-5 was isolated from seashore of Homigot at Kyung-Buk province, and cultured in marine broth 2216 media. The bacterium SL-5 was identified as Thalassomonas genus by 16S rDNA sequencing with 96% identity. Growth rate was faster at than at and agarase was produced as growth-related. The optimum pH of the enzyme activity was 7.0 and the optimum temperature for the reaction was . Although the enzyme had no thermostability, the enzyme activity was remained over 80% at . The enzyme hydrolyzed neoagarohexaose to yield neoagarobiose as the main product, indicating that the enzyme is . Thus, the enzyme would be useful for the industrial production of neoagarobiose.

Isolation and Characterization of a Marine Derived Bacterium Glaciecola sp. SL-12 Producing β-agarase

A novel agar-degrading bacterium SL-12 was isolated from seashore of Kijang at Busan, Korea, and cultured in marine broth 2216 media. Isolated bacterium SL-12 was identified as Glaciecola genus by 16S rDNA sequencing with 98% identity. The optimum pH of the enzyme activity was 7.0 and the optimum temperature for the reaction was 30℃. The enzyme hydrolyzed neoagarohexaose to yield neoagarobiose as the main product, indicating that the enzyme is β-agarase. Thus, isolated bacterium and the enzyme would be useful for the industrial production of neoagarobiose.

Secretory Overexpression of β-Agarase in Bacillus subtilis and Antibacterial Activity of Enzymatic Products

The gene for of an Agarivorans sp. JA-1 was expressed in Bacillus subtilis DB104, 168 and ISW1214 strains for mass-production. Among 3 host strains, B. subtilis ISW1214 secreted the highest amount of recombinant with a specific activity of 201 U/mg and 360 mg of protein into culture broth. This was approximately 130-fold higher than the production in E. coli as an expression host. Recombinant enzyme produced neoagarooligosaccharides such as neoagarohexaose, neoagarotetraose, and neoagarobiose from agar. Produced neoagarooligosaccharides showed antibacterial activities against gram-negative E. coli and gram-positive B. subtilis at a concentration of 1.5%. These data suggest that neoagarooligosaccharides could be an useful preservative for food industry.

Deodorization of Purified Fish Oil from Squids by Organic Acids

To produce high quality fish oil products, additional deodorization experiments on purified fish oil from squid using columns filled with citric acid or gluconic acid were performed. A deodorization effect on the fish oil was observed on both the citric acid and gluconic acid columns. These effects were more efficient on the columns packed with 3 g of organic acid than those with 1 g or 2 g of organic acid. In addition, a better effect was observed in the column packed with gluconic acid than that with citric acid. Peroxide value (POV) and acid value (AV) of the sample treated with citric acid was the as same as the non-treated sample. However, POV and AV of the sample treated with gluconic acid were about 10% higher than the non-treated sample. Contents of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) of the samples treated with citric acid or gluconic acid columns were about 0.5% higher than the non-treated sample. In conclusion, deodorization of squid fish oil by organic acid could be an efficient method to produce high quality fish oil products.

Establishment of the Extraction Process by Evaluation of Proanthocyanidin Contents and Antioxidative Activities of Pine (Pinus densiflora) Needle Extracts.

We evaluated proanthocyanidin contents out of total polyphenolic compounds in two pine needle extracts prepared by combined extraction methods and compared their antioxidative activities. Amounts of total polyphenolic compounds of sub-supercritical hotwater precipitate (SSHP) and sub-supercritical hotwater supermatant (SSHS) were 225.4 and 116.6 mg/g, respectively. Amounts of proanthocyanidin of SSHP and SSHS were 9.9 and 3.6 mg/g, respectively. Thus, the ratio of proanthocyanidin contents over total polyphenolic compounds of SSHP and SSHS were 4.3 and 3.9%, respectively. Antioxidative activities () of SSHP and SSHS measured by DPPH radical scavenging were 41.5 and , respectively. These results indicates that two combined extracts, SSHP and SSHS showed higher antioxidative activities than extract prepared by hot water or sub-supercritical. In conclusion, extraction procedures for SSHP and SSHS could be useful methods for preparing the effective components of functional food products.

Establishment of an Antibacterial Yeast That Producing Bacteriocin Subpeptin JM4-A or Subpeptin JM4-B

In order to obtain yeast cells producing a bacteriocin, Subpeptin JM4-A or Subpeptin JM4-B, the 48 bp oligonucleotides corresponding to Subpeptin JM4-A and Subpeptin JM4-B genes including codon for start and stop were chemically synthesized and cloned into pAUR123, an yeast expression vector. Transformed yeast cells exhibited growth inhibition of Bacillus subtilis, Escherichia coli and Pseudonomas aeruginosa. This result indicates that yeast cells producing Subpeptin JM4-A or Subpeptin JM4-B possess bacteriocidal properties against both Gram positive B. subtilis and Gram negative E. coli and P. aeruginosa cells. The recombinant yeast strains constructed in this study can be applied in the food preservative or. animal foodfeed.