Porphyran isolated from Pyropia yezoensis inhibits lipopolysaccharide-induced activation of dendritic cells in mice.

We previously demonstrated that porphyran, a sulfated polysaccharide extracted from Pyropia yezoensis, shows protective effects on LPS-induced septic shock in the mouse. However, the immune cell-mediated inhibitory effect of porphyran in LPS-induced activation of immune cells has not been well investigated. In this study, we found that treatment of porphyran suppressed LPS-induced upregulation of costimulatory molecule and C-C chemokine receptor type 7 (CCR7) expression in bone marrow-derived dendritic cells (BMDCs) in vitro and spleen DCs in vivo. Moreover, the LPS-induced expression of IL-6, IL-12, and TNF-α in the culture medium of BMDCs and serum dose-dependently decreased by porphyran treatment, which contributed to the inhibition of the intracellular cytokine production in spleen DCs. In addition, LPS-induced differentiation of helper T1 (Th1) and cytotoxic T1 (Tc1) cells was effectively suppressed by porphyran treatment in mice. The inhibitory effect of porphyran in LPS-induced immune activation was mediated by competitive binding of porphyran with LPS in spleen DCs. Thus, these results suggest that porphyran is a promising potential therapeutic agent in endotoxin-mediated inflammatory disease and septic shock.

Improved method for the determination of 12 non-nutritive sweeteners and monitoring in various foods using liquid chromatography-tandem mass spectrometry.

An improved and highly sensitive method was developed and validated for the determination of 12 (7 permitted and 5 non-permitted in Korea) non-nutritive sweeteners in various foods using liquid chromatography-electrospray ionisation-tandem mass spectrometry. The chromatographic separation was performed on an Xbridge BEH C18 column (3 mm × 100 mm, 2.5 µm) with gradient elution using 10 mM ammonium acetate in water and 10 mM ammonium acetate in methanol. Sample preparation consisted of simple dilution, homogenisation, centrifugation and purification with a C18 cartridge prior to analysis. The relative matrix effect (%ME) was within ±20% for all sweeteners. The method also showed good linearity (R2 > 0.99). The limit of detection and limit of quantification values in sample were in the range of 0.02-2.66 and 0.06-8.05 mg kg-1, respectively. The recoveries at three concentration levels ranged between 80% and 119%, with relative standard deviation values below 10%. In addition, the expanded uncertainties determined for 12 sweeteners in 5 different food matrices were confirmed to be <14%. Finally, the method was successfully applied to the analysis of sweeteners in 681 food samples purchased in Korea, Australia and Turkey. These results demonstrate that the method is suitable for the simultaneous determination of multiple-sweeteners in a variety of foods.

Assessment of the dietary intake of propylene glycol in the Korean population.

An improved method for the analysis of propylene glycol (PG) in foods using a gas chromatography-flame ionisation detector (GC-FID), with confirmation by GC-MS, was validated by measuring several analytical parameters. The PG concentrations in 1073 products available in Korean markets were determined. PG was detected in 74.1% of the samples, in a concentration range from the limit of detection (n.d., 0.39 µg ml(-1)) to 12,819.9 mg kg(-1). The Korea National Health and Nutrition Examination Survey (KNHANES) 2011-2013 reported the mean intake levels of PG from all sources by the general population and consumers were 26.3 mg day(-1) (0.52 mg kg(-1) day(-1)) and 34.3 mg day(-1) (0.67 mg kg(-1) day(-1)), respectively. The 95th percentile intake levels of the general population and consumers were 123.6 mg day(-1) (2.39 mg kg(-1) day(-1)) and 146.3 mg day(-1) (2.86 mg kg(-1) day(-1)), respectively. In all groups of the general population, breads were the main contributors to the total PG intake. These reports provide a current perspective on the daily intake of PG in the Korean population.

Validation and measurement uncertainty evaluation of the GC-MS method for the direct determination of hexamethylenetetramine from foods.

A simple GC-MS method has been developed and validated for the direct determination of hexamethylenetetramine (HMT). The separation of HMT was performed using a MXT-1 column. The calibration curve was linear over the concentration range 0.1-25 µg/mL, with a good correlation coefficient (r =0.9996). The recoveries of HMT from foods spiked at 1, 5, and 10 µg/g ranged from 91.7% to 115.2%. Intra-day (n=5) and inter-day (n=5) precision were less than 7%. The limit of detection and the limit of quantification of the method were 0.05 and 0.15 µg/mL, respectively. The uncertainties associated with food matrix and calibration contributed most to the overall expanded uncertainty. The method validation data indicated that quantitative method could be applied to the direct determination of non-hydrolyzed HMT in foods.

Assessment of caffeine intake in the Korean population.

An improved method for the analysis of caffeine in foods by HPLC was validated by measuring several analytical parameters. The caffeine contents of 1202 products available from Korean markets were analysed. A consumption study was conducted by using data from the Korea National Health and Nutrition Examination Survey (KNHANES), 2010-12, to estimate the caffeine intakes of the Korean population. The mean intakes of caffeine from all sources in the general population and consumers were 67.8 and 102.6 mg day(-1) for all age groups, respectively. The 95th percentile intakes of the general population and consumers were 250.7 and 313.7 mg day(-1), respectively. In those aged 30-49 years, the caffeine intakes of the general population and consumers were highest at 25.5% (101.8 mg kg(-1) day(-1)) and 36.6% (0.9 mg kg(-1) day(-1)), respectively, compared with the maximum recommended daily intake (400 mg day(-1)) for adults. In the general population, the main contributors to the total caffeine intake were carbonated beverage for the younger age groups and coffee for the adults. These data provide a current perspective on caffeine intake in the Korean population.

Pancreatic lipase inhibitory gallotannins from Galla Rhois with inhibitory effects on adipocyte differentiation in 3T3-L1 cells.

Activity-guided isolation of a methanolic extract of Galla Rhois using pancreatic lipase and 3T3-L1 adipocytes led to the isolation of seven phenolic compounds: protoaphin-fb (1), 2-O-digalloyl-1,3,4,6-tetra-O-galloyl-ß-D-glucose (2), 1,2,3,4,6-penta-O-galloyl-ß-D-glucose (3), 1,2,4,6-tetra-O-galloyl-ß-D-glucose (4), 3-hydroxy-5-methoxy-phenol 1-O-ß-D-glucoside (5), methylgallate (6), and gallic acid (7). Their structures were established on the basis of NMR and MS spectroscopic data interpretation. All isolates were evaluated for their inhibitory effects on pancreatic lipase, and compounds 1-5 exhibited potent inhibitory effects on this enzyme, with IC50 values ranging from 30.6 ± 2.4 to 3.5 ± 0.5 mM. In addition, the highly galloylated compound 2 was also found to induce potent inhibition of adipocyte differentiation in 3T3-L1 cells.

Antimicrobial activity of plant extracts against Salmonella Typhimurium, Escherichia coli O157:H7, and Listeria monocytogenes on fresh lettuce.

Plant extracts have been found to be effective in reducing microorganisms. This study evaluated antimicrobial activity of 12 plant extracts against Salmonella Typhimurium, Escherichia coli O157:H7, and Listeria monocytogenes by using a disk diffusion assay, and Syzygium aromaticum (clove) showed the highest inhibitory effect. To investigate the efficacy of clove extract that inactivates pathogens on lettuce, inoculated lettuce with S. Typhimurium, E. coli O157:H7, and L. monocytogenes was treated with diluted clove extracts or distilled water for 0, 1, 3, 5, and 10 min. Clove extract treatment significantly reduced populations of the 3 tested pathogens from the surface of lettuce. Practical Application: This result indicated that clove extract is a useful antimicrobial agent to reduce the microbial level of foodborne pathogens on fresh lettuce. It also might be a natural antimicrobial for reducing or replacing chemical sanitizers in food preservation.