Hyungjae Lee

Fatty Acid Desaturases, Polyunsaturated Fatty Acid Regulation, and Biotechnological Advances.

Polyunsaturated fatty acids (PUFAs) are considered to be critical nutrients to regulate human health and development, and numerous fatty acid desaturases play key roles in synthesizing PUFAs. Given the lack of delta-12 and -15 desaturases and the low levels of conversion to PUFAs, humans must consume some omega-3 and omega-6 fatty acids in their diet. Many studies on fatty acid desaturases as well as PUFAs have shown that fatty acid desaturase genes are closely related to different human physiological conditions. Since the first front-end desaturases from cyanobacteria were cloned, numerous desaturase genes have been identified and animals and plants have been genetically engineered to produce PUFAs such as eicosapentaenoic acid and docosahexaenoic acid. Recently, a biotechnological approach has been used to develop clinical treatments for human physiological conditions, including cancers and neurogenetic disorders. Thus, understanding the functions and regulation of PUFAs associated with human health and development by using biotechnology may facilitate the engineering of more advanced PUFA production and provide new insights into the complexity of fatty acid metabolism.

Anthocyanins in the ripe fruits of Rubus coreanus Miquel and their protective effect on neuronal PC-12 cells

Phenolics of the fresh ripe fruits of Rubus coreanus Miquel were extracted and separated into anthocyanin and the non-anthocyanin fractions, which were used for the evaluation for antioxidant capacity and neuroprotective effects. The anthocyanin fraction accounted for approximately 47-55% of the total antioxidant capacity of the whole extract and had significantly higher free radical-scavenging capacity than the non-anthocyanin fraction. Furthermore, the anthocyanins alleviated intracellular oxidative stress, as assayed by in vitro fluorescent measurements. The anthocyanins showed neuroprotective effects on PC-12 cells in vitro against oxidative stress in a dose-dependent manner. Triple quadrupole LC/MS and Q-TOF LC/MS analyses revealed four major anthocyanins; cyanidin 3-O-sambubioside, cyanidin 3-O-glucoside, cyanidin 3-O-xylosylrutinoside, and cyanidin 3-O-rutinoside in increasing order of amounts. These results demonstrated that anthocyanins are the major components and contributors to the antioxidant capacity of ripe R. coreanus Miquel fruits. Further studies are warranted to determine whether consumption of the fruits reduces oxidative stress in the brain and promotes health.

Physicochemical properties of granular and non-granular cationic starches prepared under ultra high pressure

Granular and non-granular cationic starches were prepared through the reaction of tapioca and corn starches with 2,3-epoxypropyl trimethyl ammonium chloride (ETMAC) using conventional and ultra high pressure (UHP)-assisted reactions. The cationic starches were characterized with respect to morphology, degree of substitution (DS), FT-IR, (13)C NMR, X-ray diffraction pattern, solubility and swelling power, pasting viscosity, and flocculating activity. Non-granular (relative to granular) cationic starches possessed higher DS values. While DS values of non-granular cationic starches were lower for UHP-assisted (relative to conventional) reaction, granular cationic starches did not differ for both reactions. For flocculation activity, granular cationic starches with lower solubility and higher swelling power were higher than non-granular counterparts with reversed patterns in solubility and swelling power, regardless of conventional and UHP-assisted reactions. Overall results suggested that flocculation activity of cationic starches may be directly associated with their swelling powers (relative to DS values).

Effects of ethanol and its metabolite acetaldehyde on responses of the rat bladder

To investigate the pharmacological effects of ethanol and its metabolite acetaldehyde on isolated rat bladder muscle, and thus assess the potential influence of ethanol ingestion on the risk of urinary retention in patients with benign prostatic hyperplasia.

Effects of jam processing on anthocyanins and antioxidant capacities of Rubus coreanus Miquel berry

The effects of jam processing on total phenolics, total flavonoids, total anthocyanins, and antioxidant capacities of fresh Rubus coreanus Miquel (bokbunja) fruits at various pH levels were investigated. Aqueous methanol of 80%(v/v) was found to be the most efficient solvent for extracting phenolics in fruits and jams. More than 90% of total phenolics, antioxidant capacities, and total flavonoids were retained after processing, while approximately 35% of total anthocyanins were lost. Among various pH treatments, jams prepared at pH 2.0–3.0 lost 33–35% of total anthocyanins, while treatments at pH 3.5–4.0 degraded 40–48% of total anthocyanins. Among the various treatments between pH 2.0 and 4.0, jam prepared at pH 3 had the highest sensory scores and overall acceptability. The results suggest that jam making with fruits rich in anthocyanins at lower pH may protect bioactive anthocyanins from thermal processing.

Total phenolic contents and antioxidant activities of Korean domestic honey from different floral sources

Total phenolic contents and antioxidant activities of 7 Korean domestic honey varieties and fractions from different floral sources were determined. Extracts of 7 varieties of honey were fractionated in the sequence of n-hexane, chloroform, ethyl acetate, n-butanol, and water. The ethyl acetate fraction (EAF) of all 7 honey varieties retained the majority of the antioxidant activity and the total phenolic content. The antioxidant activities of the EAF from Korean raisin honey were 52.74 and 24.44 mg of vitamin C equivalents/g of dry fraction based on ABTS and DPPH radicals, respectively. Total EAF phenolic contents of 7 honey varieties ranged from 5.27 to 29.17 mg of gallic acid equivalents/g of dry fraction. High correlation coefficients between total phenolic contents and antioxidant activities indicated that phenolic compounds were the major components responsible for the antioxidant activities of honey.

Advances in Nutritional Research on Regulatory T-Cells

Many clinical and animal studies have shown that certain dietary components exert anti-inflammatory properties that aid in the amelioration of chronic inflammatory diseases. Among the various proposed channels through which dietary components affect immune responses, regulatory T-cells (Tregs) are emerging as key targets for the dietary prevention of chronic inflammatory diseases. In this review, immunoregulation by Tregs is briefly described, followed by a summary of recent advances and possible applications of techniques for the study of Tregs. In addition, this review provides an overview of the current knowledge on Treg regulation by certain dietary components, including vitamins, omega-3 polyunsaturated fatty acids, and polyphenols. The caveats of previous studies are also discussed in order to highlight the distinctions between dietary studies and immunological approaches. Consequently, this review may help to clarify the means by which nutritional components influence Tregs.

Antimicrobial activity of solvent fractions and bacterial isolates of Korean domestic honey from different floral sources

Forty solvent fractions and 387 bacterial isolates of seven varieties of Korean domestic honey and manuka honey from New Zealand were screened for antimicrobial activity. The minimum inhibitory concentrations and minimum bactericidal concentrations of the honey fractions were determined; only Bacillus cereus ATCC 14579, ATCC 11778, and F4552 were inhibited by 11, 1, and 16, respectively, out of the 40 honey fractions. The bacterial isolates showed the highest incidence (30.2%) of antimicrobial activity against Listeria monocytogenes ATCC 15313. The growth of at least one of the five foodborne pathogens tested was inhibited by 109 of the 327 isolates (33.3%) from seven types of Korean domestic honey. The percentage of such isolates of manuka honey was significantly higher (76.7%). Solvent fractionation of honey could contribute to the detection of antimicrobial activity of the nonsugar compounds in honey. Moreover, the bacterial isolates from Korean domestic honey may be good sources for the natural antimicrobials used in the food industry and other related industries.

Optimization of thermal processing conditions for brown rice noodles

Based on the current thermal processing conditions for rice noodles (80–85xa0°C for 20–30xa0min), we used response surface methodology to find brown rice (BR) noodle processing conditions that maximize the noodles antioxidant activity, digestibility, and gelatinization. The experiments were designed according to the central composite design, including two independent variables (temperature and time) and six dependent variables [total phenolic contents (TPC), total flavonoid contents (TFC), 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging activities, digestibility, and gelatinization]. Antioxidant activities decreased but digestibility and gelatinization increased with increasing temperature and time. All dependent variables suggested a quadratic model except TFC, but the probability of TPC was not applicable (0.1505), and DPPH radical scavenging activity showed a relatively low R2 (0.6750). Therefore, we applied the other three dependent variables (ABTS radical scavenging activity, digestibility, and gelatinization) to the 3D response surface and proposed three optimum conditions: (1) for antioxidant activity (70xa0°C, 22.95xa0min), (2) for digestibility and gelatinization (88.18xa0°C, 34.89xa0min), and (3) for all three variables (88.5xa0°C, 40xa0min). In a validation test, all dependent variables showed values within a 5xa0% error range except TFC. These results show the optimum processing conditions for BR noodles to maximize antioxidant activity and provide sustainability in BR noodle processing.

Immune Enhancement Effect of Asterias amurensis Fatty Acids through NF-B and MAPK Pathways on RAW 264.7 Cells

Asterias amurensis is a marine organism that causes damage to the fishing industry worldwide; however, it has been considered a promising source of functional components. The present study aimed to investigate the immune-enhancing effects of fatty acids from three organs of A. amurensis on murine macrophages (RAW 264.7 cells). A. amurensis fatty acids boosted production of immune-associated factors such as nitric oxide (NO) and prostaglandin E2 in RAW 264.7 cells. A. amurensis fatty acids also enhanced the expression of critical immune-associated genes, including iNOS, TNF-α, IL-1β, and IL-6, as well as COX-2. Western blotting showed that A. amurensis fatty acids stimulated the NF-κB and MAPK pathways by phosphorylation of NF-κB p-65, p38, ERK1/2, and JNK. A. amurensis fatty acids from different tissues resulted in different levels of NF-κB and MAPK phosphorylation in RAW 264.7 cells. The results increase our understanding of how A. amurensis fatty acids boost immunity in a physiological system, as a potential functional material.