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Nguyen H.M.,Korea University | Hwang I.-C.,Central Research Institute | Park J.-W.,Seafood Research and Education Center | Park H.-J.,Korea University | Park H.-J.,Clemson University
Pest Management Science | Year: 2012

Background: In the natural environment, photodegradation is one of the most common degradative processes of pesticides. In order to reduce the photodegradation of pesticides, and so increase their killing activity against target pests, chitosan-coated beeswax solid lipid nanoparticles (CH-BSLNs) were prepared by a combination of hot homogenization and sonication, with deltamethrin as an active ingredient. Results: Under optimal conditions, the highest encapsulation efficiency (95%) and a high payload of deltamethrin (approximately 12.5%) were achieved. In direct photolysis, in the case of CH-BSLNs after UV irradiation for 24 h, 37.3% of deltamethrin remained, as opposed to only 14.6% of the free-form deltamethrin. In addition, in indirect photolysis, in the case of CH-BSLNs after UV irradiation for 2 h in 2% acetone solution, approximately 74.5% of deltamethrin remained, as opposed to only 37.6% of the free-form deltamethrin. Conclusion: CH-BSLNs showed good protection for deltamethrin against photodegradation. This novel nanocarrier may be useful in crop protection as an economical strategy to enhance the effect of pesticides in the field and protect the environment as well. © 2012 Society of Chemical Industry.

Ngo D.-H.,Pukyong National University | Qian Z.-J.,Pukyong National University | Ryu B.,Pukyong National University | Park J.W.,Seafood Research and Education Center | Kim S.-K.,Pukyong National University
Journal of Functional Foods | Year: 2010

In the present study, a peptide possessing antioxidant properties was isolated from Nile tilapia (Oreochromis niloticus) scale gelatin. Gelatin protein was hydrolyzed using alcalase, pronase E, trypsin and pepsin. Antioxidant efficacy of respective hydrolysates were evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, hydroxyl radical and superoxide radical anion scavenging activities. Moreover, protective effect on DNA damage caused by hydroxyl radicals generated was determined. Further, the level of reactive oxygen species (ROS) was determined using a fluorescence probe, 2',7'-dichlorofluorescin diacetate (DCFH-DA), which could be converted to highly fluorescent dichlorofluorescein (DCF) with the presence of intracellular ROS on mouse macrophages, RAW 264.7 cells. Among hydrolysates, alcalase-derived hydrolysate exhibited the highest antioxidant activity compared to other enzymatic hydrolysates. Therefore, it was further analyzed and the sequence of an active peptide present in it was identified as Asp-Pro-Ala-Leu-Ala-Thr-Glu-Pro-Asp-Pro-Met-Pro-Phe (1382.57Da). This peptide showed no cytotoxic effect on mouse macrophages (RAW 264.7) and human lung fibroblasts (MRC-5). In addition, it scavenged hydroxyl, DPPH and superoxide radicals at the IC50 values of 7.56, 8.82 and 17.83μM, respectively. These results suggest that the peptide derived from Nile tilapia (O. niloticus) scale gelatin acts as a candidate against oxidative stress and could be used as a potential functional food ingredient. © 2010 Elsevier Ltd.

Karadeniz F.,Pukyong National University | Kang K.-H.,Pukyong National University | Park J.W.,Seafood Research and Education Center | Park S.-J.,Pukyong National University | Kim S.-K.,Pukyong National University
Bioscience, Biotechnology and Biochemistry | Year: 2014

8,4⌄-dieckol is a natural product which has been isolated from brown alga, Ecklonia cava. This polyphenolic compound is a phlorotannin derivative with a broad range of bioactivities. Its inhibitory activity on human immunodeficiency virus type-1 (HIV-1) was tested and the results indicated that 8,4⌄-dieckol inhibited HIV-1 induced syncytia formation, lytic effects, and viral p24 antigen production at noncytotoxic concentrations. Furthermore, it was found that 8,4⌄-dieckol selectively inhibited the activity of HIV-1 reverse trancriptase (RT) enzyme with 91% inhibition ratio at the concentration of 50 μM. HIV-1 entry was also inhibited by 8,4⌄-dieckol. According to data from this study, 8,4⌄-dieckol is an effective compound against HIV-1 with high potential for further studies. These results suggest that it might be used as a drug candidate for the development of new generation therapeutic agents, although further studies on the mechanism of inhibition should be addressed. © 2014 Japan Society for Bioscience, Biotechnology, and Agrochemistry.

Poowakanjana S.,Seafood Research and Education Center | Park J.W.,Seafood Research and Education Center
Journal of Aquatic Food Product Technology | Year: 2012

The biochemical and gel properties of Pacific sardine and Pacific mackerel were characterized as affected by preparation and cooking methods. Four to eight times more salt soluble proteins were extracted from water-washed paste than fish protein isolate (FPI) paste. Higher total sulfhydryl content was measured in FPI, indicating the exposure of sulfhydryl groups during alkaline extraction. Comparing gel properties based on two cooking methods (slow and fast), the two pelagic fish proteins performed quite differently. Heating rate did not differentiate between surimi and FPI gels from sardine. However, mackerel exhibited higher texture values when using the fast cooking method, indicating the presence of high levels of proteolytic enzymes. Water-washed surimi gels were whiter than FPI for both species. Water retention ability appeared to be higher with mackerel than sardine, regardless of isolation and cooking method. Sodium dodecyl sulfate polyacrylamide gel eletrophoresis (SDS-PAGE) also supported a difference in processing chemistry and thermal behavior between two methods for protein isolation and cooking, respectively. © 2012 Taylor & Francis Group, LLC.

Poowakanjana S.,Seafood Research and Education Center | Mayer S.G.,University of Portland | Park J.W.,Seafood Research and Education Center
Journal of Food Science | Year: 2012

Rheological and Raman spectroscopic properties of surimi from three species [Alaska pollock (AP) (cold water), Pacific whiting (temperate water), and threadfin bream (warm water)] were investigated as affected by various chopping conditions. Comminuting Alaska pollock surimi at 0 °C demonstrated superior gel hardness and cohesiveness when chopping time was extended to 15-18 min; however, long chopping time at higher temperatures resulted in a significantly decreased gel texture particularly at 20 °C. Warm water fish threadfin bream exhibited higher gel texture when chopping was done longer at higher temperature. Rheological properties were significantly affected by both chopping time and temperature. Species effect, based on their thermal stability, was readily apparent. Raman spectroscopy revealed a significant change in disulfide linkage and the reduction of secondary structure upon extended chopping. Dynamic oscillation rheology demonstrated the damage of light meromyoisn and lowering of onset of gelling temperature as the chopping time was extended. © 2012 Institute of Food Technologists ®.

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