Suk Hoo Yoon

Metabolomic Analysis of Livers and Serum from High-Fat Diet Induced Obese Mice

Liver and serum metabolites of obese and lean mice fed on high fat or normal diets were analyzed using ultraperformance liquid chromatography-quadrupole-time-of-flight mass spectrometry, gas chromatography-mass spectrometry, and partial least-squares-discriminant analysis (PLS-DA). Obese and lean groups were clearly discriminated from each other on PLS-DA score plot and major metabolites contributing to the discrimination were assigned as lipid metabolites (fatty acids, phosphatidylcholines (PCs), and lysophosphatidylcholines (lysoPCs)), lipid metabolism intermediates (betaine, carnitine, and acylcarnitines), amino acids, acidic compounds, monosaccharides, and serotonin. A high-fat diet increased lipid metabolites but decreased lipid metabolism intermediates and the NAD/NADH ratio, indicating that abnormal lipid and energy metabolism induced by a high-fat diet resulted in fat accumulation via decreased β-oxidation. In addition, this study revealed that the levels of many metabolites, including serotonin, betaine, pipecolic acid, and uric acid, were positively or negatively related to obesity-associated diseases. On the basis of these metabolites, we proposed a metabolic pathway related to high-fat diet-induced obesity. These metabolites can be used to better understand obesity and related diseases induced by a hyperlipidic diet. Furthermore, the level changes of these metabolites can be used to assess the risk of obesity and the therapeutic effect of obesity management.

Oxidative stability of high-fatty acid rice bran oil at different stages of refining

The contents of natural antioxidants and the oxidative stability of rice bran oils at different refining steps were determined. Tocopherols and oryzanols were constant in crude and degummed oils but decreased in alkali-refined, bleached and deodorized oils. The process of degumming, alkali-refining, bleaching and deodorization removed 34% of the tocopherols and 51% of the oryzanols. During storage of deodorized oil for 7 wk, 34% of the tocopherols and 19% of the oryzanols were lost. The maximum weight gain, peroxide value and anisidine value were obtained from alkali-refined oil during storage. The order of oxidation stability was crude ≥ degummed > bleached = deodorized > alkali-refined oil.

Synthesis of medium-chain glycerides by lipase in organic solvent

Using commercial lipases from various microbial origins, medium-chain glycerides, such as mono-, di-, and tricaprin, were synthesized in isooctane from glycerol and capric acid. The enzyme reaction was performed with 0.35 M capric acid, 0.025 M glycerol, and 0.46 g silica gel to remove water in 5 mL of isooctane with 30 mg lyophilized lipase. Of the 21 kinds of lipases, 11 showed good synthetic activities. Lipases fromPseudomonas aeruginosa (Lipase PS),Rhizomucor miehei lipase andChromobacterium viscosum lipase (Lipase CV) showed high activities for the production of tricaprin, while lipase OF-360 (fromCandida rugosa) and lipase D (Rhizopus delemar) were good for dicaprin production. Lipases CC and MY fromC. rugosa (C. cylindracea) and lipase D (Rhizopus delemar) were good for dicaprin production. Lipases CC and MY fromC. rugosa (C. cylindracea) also showed high activities for dicaprin and tricaprin. Some lipases, especially lipase PS, had high thermal stability over 60°C. The optimal lyophilization pH to dehydrate the lipase coincides with the optimal buffer solution pH for hydrolysis.

Effect of extraction solvents on oxidative stability of crude soybean oil

Oxidative stabilities of crude soybean oils obtained by different extraction solvents such as hexane, water and Folchs solvent (mixture of two volumes of chloroform and one volume of methanol) were determined by gas chromatographic analyses of headspace and peroxide value of oil samples. For the determination of oxidative stability of oil samples, total volatile compounds formation, molecular oxygen disappearance in the headspace and peroxide value of oil samples were measured. Iodine value (133–136), saponification value (195–198), unsaponifiable matters (0.3–0.4%), iron (0.6 ppm), sterols content (2,400–2,590 ppm), tocopherols content (1,250–1,520 ppm) and fatty acid composition of crude oils obtained by different solvent extraction were not significantly different. Acid value of Folch-extracted oil was the highest as 1.3, whereas those of hexane-and aqueous-extracted oils were 0.5 and 0.4, respectively. Crude soybean oil extracted by Folchs method was found to contain the most phosphorus, while hexane- and aqueous-extracted oils contained similar amounts of phosphorous. Crude soybean oil obtained by Folch extraction was most stable in oil oxidation, and oxidative stabilities of oils obtained by hexane and aqueous extraction, which were significantly much less stable than Folch-extracted oil, were not significantly different during ten weeks storage.

Optimization of the refining process of camellia seed oil for edible purposes

Processing conditions during degumming, alkaline refining, bleaching, and deodorization of crude camellia seed oil were optimized to obtain high-quality edible camellia oil. Physicochemical properties of camellia oil were monitored during refining steps. RBD (refined, bleached, and deodorized) camellia oil obtained using optimized refining conditions fully satisfied Korean quality standards for edible oil. The iodine value of camellia oil was 84.2 mg I2/100 g of oil. Camellia oil contained an exceptionally high level of oleic acid (83.1%), along with minor quantities of other fatty acids (8.9% palmitic acid, 4.8% linoleic acid). The total saponin content in crude oil was 437 ppm, as determined by gravimetric analysis. Most (99.8%) of the saponin in crude oil was removed during the refining process. The physicochemical properties of camellia oil were similar to olive oil. RBD camellia oil is virtually colorless and bland tasting and is suitable for edible purposes.

Stability of meoru (Vitis coignetiea) anthocyanins under photochemically produced singlet oxygen by riboflavin.

This study investigated the stability of meoru (wild vine grape) anthocyanins in the aqueous solution under singlet oxygen. Freeze-dried meoru (1 kg) contained 179.98 mg anthocyanins including delphinidin-3-glucoside, malvidin-3,5-diglucoside, cyanidin-3,5-diglucoside, malvidin-3-glucoside, and cyanidin-3-glucoside. Malvidin-3,5-diglucoside and cyanidin-3-glucoside were the meoru anthocyanins at the highest and the lowest concentration, respectively. Little decrease in total anthocyanins in the aqueous solution was observed in the dark with or without riboflavin, or with light without riboflavin. Singlet oxygen degraded the meoru anthocyanins in the aqueous solution, which suggested chemical quenching of singlet oxygen by the anthocyanins. Degradation of the meoru anthocyanins was structure-dependent; diglucoside anthocyanins were more stable than monoglucoside. And malvidin glucoside was more stable than delphinidin or cyanidin glucoside, which suggested the number of hydroxy groups in the structure was partly related with the anthocyanin stability under singlet oxygen. This is the first report on anthocyanins stability affected by its structure under singlet oxygen.

Stereospecific Positional Distribution of Fatty Acids of Camellia (Camellia japonica L.) Seed Oil

The stereospecific positional distribution of fatty acids of camellia seed oil (also called camellia oil) was determined. The camellia oil was mainly composed of neutral lipids (88.2%), and the oleic acid (86.3%) was found to be a major fatty acid of neutral lipids. In the glycolipids and phospholipids, the oleic acid was also found to be a major fatty acid at 62.5% and 54.2%, respectively. The oleic acid was distributed abundantly in all sn-1, 2, and 3 positions. It was found that the oleic acid was present more at sn-2 (93.6%) and 3 positions (94.7%), than at sn-1 position (66.0%). Practical Application:  The information of stereospecific positional distribution of fatty acids in the camellia oil can be used for the development of the structured lipids for food, pharmaceutical, and medical purposes.

Selective removal of free fatty acids in oils using a microorganism

A microorganism assimilating long chain fatty acids without secreting extracellular lipases was screened from soil and was identified as aPseudomonas. Growth factors, nitrogen sources and trace elements required for growth of the microorganism namedPseudomonas strain BG1 were determined. Optimum pH and growth temperature were 6 and 30°C, respectively. BG1 was found to utilize lauric, myristic, palmitic, stearic and oleic acids as carbon sources. BG1 was shown to utilize 0.1% oleic acid almost completely in an emulsion medium within 48 hr. When BG1 was grown in a mixture of triolein and oleic acid, it selectively removed the free fatty acid without loss of triolein and did not produce mono- and diglycerides.

Selectively hydrogenated soybean oil exerts strong anti-prostate cancer activities.

Prostate cancer is the second leading cause of male deaths due to cancer in the United States. Hydrogenated vegetable oils have been suspected of inducing adverse health effects, including atherosclerosis and cancer. Here we report that a selectively hydrogenated soybean oil (SHSO) containing a high quantity of conjugated linoleic acids showed remarkably strong anticarcinogenic activity against prostate cancer in the rat model (Copenhagen rats with MAT-LyLu syngeneic rat prostate cancer cells) study in vivo and human prostate carcinoma cell lines studies in vitro, as compared with native soybean oil. A 5% dietary supplementation with SHSO inhibited the growth of prostate cancer by 80% in vivo. The TUNEL method and immunohistochemical staining assays of bax, bcl-2, and survivin clearly showed that SHSO induced prostate cancer cell apoptosis in the tested rats. DNA fragmentation analysis in vitro further confirmed the apoptotic activity of SHSO on the MAT-LyLu prostate cancer cells. The SHSO also showed strong cytotoxicity on human prostate cancer cells (DU145 and PC3). This represents the first report demonstrating the significant anticancer activities of hydrogenated vegetable oils at low levels of dietary supplementation.

Effects of organic solvents on transesterification of phospholipids using phospholipase A2 and lipase

The transesterification abilities of phospholipase A2 and Mucor javanicus lipase in various organic solvents were studied. Phosphatidylcholine and caprylic acid (molar ratio, 1:6) were transesterified by incubation at 40°C in three organic solvents using phospholipase A2 and M. javanicus lipase. The fatty acid composition of the reaction product was measured using gas chromatography. Caprylic acid was incorporated into the sn-1 and -2 positions at a rate of 87.7% using phospholipase A2 in hexane, and 36.7% using M. javanicus lipase in diethyl ether. Higher acyl migration into sn-2 was observed in diethyl ether than in hexane during transesterification using M. javanicus lipase, however, there was no substantial difference in the caprylic acid content at the sn-2 position. Acyl migration during transesterification in methanol was lower than in other organic solvents. Non-polar hexane and diethyl ether were more effective for transesterification than methanol.