Liquid chromatography-mass spectrometry-based metabolomic analysis of livers from aged rats.

We used UPLC-Q-TOF MS to analyze hepatic metabolites of rats aged 6, 12, 18, and 24 months; the MS data were processed by partial least-squares discriminant analysis (PLS-DA) to investigate the discrimination among sample groups. Rats were significantly separated with increasing age, except those aged between 6 and 12 months. We identified only 25 of 120 metabolites contributing to the separation: lipid metabolites (glycerol-3-phosphate, linolenic acid, lysophosphatidylcholines [lysoPCs]), energy metabolism intermediates (betaine, carnitine, acylcarnitines, creatine, pantothenic acid), nucleic acid metabolites (inosine, xanthosine, uracil, hypoxanthine, xanthine), and tyrosine. Aging accumulated energy metabolism intermediates, hypoxanthine, xanthine, and 2 major lysoPCs (C18:0 and C22:6). The NAD level and NAD/NADH ratio decreased with age. It was indicated that aging might decrease energy production through ß-oxidation because of a decrease in NAD despite the accumulation of lipid energy metabolism intermediates. In addition to energy dysregulation, hypoxanthine and xanthine, which are elevated with age, might accumulate reactive oxygen species in the liver. These results strongly support two aging theories: those of energy dysregulation and free radicals. Additionally, we propose a metabolic pathway related to aging based on these hepatic metabolites. These metabolites and the proposed aging pathway could be used to understand aging and related diseases better, and increase the predictability of aging risk.

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 ß-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.

Optimization of the refining process and oxidative stability of chufa (Cyperus esculentus L.) oil for edible purposes.

Process conditions of alkali refining, bleaching, and deodorization of crude chufa oil extracted from chufa (Cyperus esculentus L.) tubers grown in Korea were optimized to obtain an edible grade vegetable oil. The overall scope of refining conditions was similar to other vegetable oils. The degumming process, however, could be omitted since phospholipids were removed during alkalirefining and bleaching processes. RBD (alkali-refined, bleached, and deodorized) chufa oil fully satisfied Korean quality standards for edible vegetable oil. Chufa oil contained a high level of oleic acid, along with palmitic acid and linoleic acid. Physicochemical properties of chufa oil were similar to olive oil. The order of oxidative stability of chufa oil was crude>deodorized>degummed>refined>bleached oil. RBD chufa oil was virtually colorless and bland tasting, and was considered suitable for edible purposes.

Effects of lipophilic continuous phases and heating methods on thermal degradation and isomerization of ß-carotene.

Rates of thermal degradation and isomerization of all-trans-ß-carotenes in air and in triacylglycerols were determined. Degradation of carotenes in triacylglycerols was faster than that in air. The 13-cis-ß-carotene level in triacylglycerols was higher than in air. Oxidized materials of triacylglycerols probably facilitated isomerization of carotenes and, thus, degradation. Amounts of all-trans-ß-carotenes and all-trans-α-carotenes in pumpkin decreased with an increase in heating time. The proportion of 13-cis-ß-carotene increased after heat treatment started, probably due to thermal isomerization of all-trans-ß-carotenes to cis-isomers, and to decreases in amounts of all-trans-ß-carotenes and all-trans-α-carotenes in pumpkin. Effects of heating methods on proportions of isomers; however, were not different.

Quantitative determination of conjugated linoleic acids in hydrogenated vegetable oils using refractive index.

Conjugated linoleic acid contents in hydrogenated vegetable oils were differentially determined using refractive indices when the iodine value could not be used. The refractive indices of soybean oil, cottonseed oil, and corn oil varied linearly with changes of linoleic acid contents of individual oils with determination coefficients of 0.91, 0.98, and 0.98, respectively. The refractive index can be used as a simple and fast method for control of the hydrogenation process of vegetable oils to obtain a desired conjugated linoleic acid content without fatty acid compositional analysis.

Variations in U.S. Consumers' Acceptability of Korean Rice Cake, Seolgitteok, with respect to Sensory Attributes and Nonsensory Factors.

Because the Korean rice cake, Seolgitteok, is mainly prepared with rice flour containing no gluten-protein associated with celiac disease, it can be considered for inclusion in a gluten-free diet. However, Western consumers may be unlikely to enjoy the plain flavor and chewy texture of Seolgitteok. This study aimed to determine both sensory and nonsensory factors that might affect U.S. consumers' acceptability of Seolgitteok. A total of 119 U.S. consumers rated 5 Seolgitteok samples, differentiated by descriptive sensory analysis, with respect to hedonic impression and just-about-right aspects of sensory attributes. Nonsensory factors such as demographic profile, innovativeness, social representation, sensation-seeking, and personality traits were also assessed. Addition levels of brown rice flour (0% to 100%) and sugar (5% to 20%) not only enriched flavor, but also lessened chewiness of Seolgitteok, thereby increasing an overall hedonic impression. Moreover, consumer acceptability of Seolgitteok varied with respect to nonsensory factors. Seolgitteok was more appreciated by males, sensation seekers, and individuals constrained by social desirability than by other groups. In conclusion, these findings demonstrate that U.S. consumers' acceptability of Seolgitteok varies not only by sensory attributes such as rice flavor, sweetness, and chewiness, but also by nonsensory factors such as gender, sensation-seeking characteristics, and personality traits.

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.

Chemical properties and oxidative stability of perilla oils obtained from roasted perilla seeds as affected by extraction methods.

The chemical properties and oxidative stability of perilla oils obtained from roasted perilla seeds as affected by extraction methods (supercritical carbon dioxide [SC-CO(2)], mechanical press, and solvent extraction) were studied. The SC-CO(2) extraction at 420 bar and 50 °C and hexane extraction showed significantly higher oil yield than mechanical press extraction (P < 0.05). The fatty acid compositions in the oils were virtually identical regardless of the extraction methods. The contents of tocopherol, sterol, policosanol, and phosphorus in the perilla oils greatly varied with the extraction methods. The SC-CO(2) -extracted perilla oils contained significantly higher contents of tocopherols, sterols, and policosanols than the mechanical press-extracted and hexane-extracted oils (P < 0.05). The SC-CO(2) -extracted oil showed the greatly lower oxidative stability than press-extracted and hexane-extracted oils during the storage in the oven under dark at 60 °C. However, the photooxidative stabilities of the oils were not considerably different with extraction methods.

A gas chromatography-tandem quadrupole mass spectrometric analysis of policosanols in commercial vegetable oils.

UNLABELLED: Reportedly policosanols (PCs) have various beneficial functionalities on health. A gas chromatography-tandem mass spectrometry (GC-MS/MS) with a low limit of detection (LOD), and high specificity, recovery, and precision was successfully established for the PC analysis in vegetable oils. The LODs for the PCs were in the range of 0.002 to 0.016 µg/mL. The relative standard deviation (RSD) for the repeated analysis of PCs was less than 3.356%. The mean recoveries for spiked heptacosanol and octacosanol in vegetable oil were 102.3% and 106.3%, respectively. The total PC contents in the vegetable oils varied from 3.01 to 427.83 mg/kg oil. Perilla seed, grape seed, and rice bran oils were found to be highly rich sources of PCs, containing 427.83, 245.15, and 171.17 mg PCs/kg oil, respectively. Corn, sesame, and soybean oils contained only a negligible quantity of PCs. The PC composition in vegetable oils was greatly source dependent. In perilla seed oil, octacosanol was the single most predominant component, representing 55.93% of the total PC. In grape seed oil, however, hexacosanol is the most abundant PC, followed by octacosanol, tetracosanol, and triacontanol in a decreasing order. The major PCs in rice bran oil were triacontanol, octacosanol, hexacosanol, and tetracosanol, which constituted over 87.3% of the total PC. This represents the 1st report on the composition and contents of PC in most vegetable oils analyzed here. PRACTICAL APPLICATION: The information might be used for the development of vegetable oil products with beneficial functionality.

Effects of roasting conditions on the physicochemical properties and volatile distribution in perilla oils (Perilla frutescens var. japonica).

UNLABELLED: Perilla seeds have more than 60% of α-linolenic acid, one of omega-3 essential fatty acids. Headspace volatiles and physicochemical properties including color, fluorescence intensity, and the oxidation products in perilla oil (PO) from perilla seeds roasted at different conditions were analyzed. Roasting temperature was 150, 170, 190, and 210°C, and roasting time was 15 and 30 min at each roasting temperature. PO from higher roasting temperature and longer roasting time had lower L* values, higher a*, b*, and chroma values, more brown pigments and fluorescence intensity, and more conjugated dienoic acids. Pyrazines were major volatiles in PO, and furans, sulfur-containing compounds, and hydrocarbons were also detected by a solid phase microextraction gas chromatography/mass spectrometry. In PO, 2,5-Dimethylpyrazine and 2-furancarboxaldehyde were 2 major volatiles. The principal component analysis of volatiles showed the 1st principal component (PC1) and the 2nd principal component (PC2) express 56.64% and 22.72% of the volatile variability in PO, respectively, which can differentiate PO prepared from roasting conditions clearly. Some physicochemical properties especially brown pigment and volatiles were positively correlated with each other in PO. PRACTICAL APPLICATION: Perilla oil (PO) from perilla seeds possesses more than 60% of α-linolenic acid, one of omega-3 fatty acids. Roasting process has been used to extract oil from perilla seeds. Understanding physicochemical properties of PO from diverse roasting conditions are important steps to produce PO in food industry. Roasting process induces darkening of color, increase of fluorescence intensity, and brown pigments in PO. Pyrazines and furans are major headspace volatiles in PO roasted above 170°C. The results of this study can help to produce PO in industrial scales with desired headspace volatiles, colors, and oxidative state.

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.

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.

AMP-activated protein kinase: a potential target for the diseases prevention by natural occurring polyphenols.

A reduced life span is an outcome associated with many prevalent diseases, including diabetes, obesity, and high blood pressure. In seeking to prevent these diseases, many researchers have looked into potential therapeutic benefits of naturally occurring compounds. AMP-activated protein kinase (AMPK) is a major metabolic-sensing protein implicated in the prevention of metabolic disorders, or in minimizing the effects thereof, via the regulation of both upstream and downstream target molecules. In the field of food and nutrition, the current focus lies in the finding of components that activate AMPK. AMPK is a serine/threonine protein kinase and is activated by several natural compounds, including resveratrol, epigallocatechin gallate, berberine, and quercetin. AMPK activation can induce ATP (adenosine triphosphate) generation through pathways such as glycolysis and beta-oxidation. By contrast, ATP-consuming pathways, including fatty acid and cholesterol syntheses, and gluconeogenesis, are suppressed by AMPK activation. In this review, we will discuss how the activation of AMPK by naturally occurring compounds could help to prevent the development of numerous diseases; the potential mechanism underlying these effects will also be addressed.

Purification, refolding, and characterization of recombinant Pseudomonas fluorescens lipase.

Thermostable Pseudomonas fluorescens SIK W1 lipase (PFL), which is responsible for the spoilage of milk, was overexpressed as inclusion bodies in Escherichia coli. Renaturation of solubilized PFL was achieved by using size-exclusion protein refolding chromatography. The renatured enzyme was purified homogeneously using a combination of gel filtration and ion-exchange FPLC. Its specific activity was found to be enhanced in the presence of Ca2+. Secondary structural changes induced by Ca2+ were monitored by circular dichroism, which demonstrated that the activity increase of PFL in the presence of Ca2+ is strongly correlated with significant increases in alpha-helix and beta-sheet content. In the presence of Ca2+, the PFL structure was found resistant to denaturation by guanidine hydrochloride and to enzyme activity loss due to cosolvents like DMSO and trifluoroethanol, suggesting that Ca2+ plays an important role in inducing conformational changes and consequently in maintaining enzyme structural stability.