Extraction efficiency of hydrophilic and lipophilic antioxidants from lyophilized foods using pressurized liquid extraction and manual extraction.

The efficient extraction of antioxidants from food samples is necessary in order to accurately measure their antioxidant capacities. α-Tocopherol and gallic acid were spiked into samples of 5 lyophilized and pulverized vegetables and fruits (onion, cabbage, Satsuma mandarin orange, pumpkin, and spinach). The lipophilic and hydrophilic antioxidants in the samples were sequentially extracted with a mixed solvent of n-hexane and dichloromethane, and then with acetic acid-acidified aqueous methanol. Duplicate samples were extracted: one set was extracted using an automated pressurized liquid extraction apparatus, and the other set was extracted manually. Spiked α-tocopherol and gallic acid were recovered almost quantitatively in the extracted lipophilic and hydrophilic fractions, respectively, especially when pressurized liquid extraction was used. The expected increase in lipophilic oxygen radical absorbance capacity (L-ORAC) due to spiking with α-tocopherol, and the expected increase in 2,2-diphenyl-1-picrylhydrazyl radical scavenging activities and total polyphenol content due to spiking with gallic acid, were all recovered in high yield. Relatively low recoveries, as reflected in the hydrophilic ORAC (H-ORAC) value, were obtained following spiking with gallic acid, suggesting an interaction between gallic acid and endogenous antioxidants. The H-ORAC values of gallic acid-spiked samples were almost the same as those of postadded (spiked) samples. These results clearly indicate that lipophilic and hydrophilic antioxidants are effectively extracted from lyophilized food, especially when pressurized liquid extraction is used.

Comparison of scavenging capacities of vegetables by ORAC and EPR.

Reactive oxygen species (ROS) are considered to be causative agents of many health problems. In spite of this, the radical-specific scavenging capacities of food samples have not been well studied. In the present work, we have developed an electron paramagnetic resonance (EPR) spin trapping method for analysis of the scavenging capacities of food samples for multiple ROS, utilising the same photolysis procedure for generating each type of radical. The optimal conditions for effective evaluation of hydroxyl, superoxide, and alkoxyl radical scavenging capacity were determined. Quantification of radical adducts was found to be highly reproducible, with variations of less than 4%. The optimised EPR spin trapping method was used to analyse the scavenging capacities of 54 different vegetable extracts for multiple radicals, and the results were compared with oxygen radical absorption capacity values. Good correlations between the two methods were observed for superoxide and alkoxyl radicals, but not for hydroxyl.

Evaluation of a method to quantify quercetin aglycone in onion (Allium cepa) by single- and multi-laboratory validation studies.

Official Methods of Analysis of AOAC International (OMA) 2006.07 was originally designed for quantifying flavonol aglycones in ginkgo dietary supplements. To determine whether the method is applicable to the quantification of flavonol aglycones in lyophilized onion samples, single- and multi-laboratory validation studies were performed. Triplicated measurements on 3 different days revealed that the mean quercetin content was 3.48 g/kg dry weight, and the relative repeatability standard deviation (RSD(r)) and the relative intermediate standard deviation (RSD(int)) were 0.8 and 1.8%, respectively. The recovery of quercetin-3-O-glucoside spiked at 3 different amounts (1.56, 3.12, and 6.24 g/kg dry weight of onion) ranged from 98.42 to 100.31%, and the RSD(r) and RSD(int) ranged from 2.2 to 5.9%, and from 3.4 to 5.2%, respectively. A multi-laboratory validation study showed that the mean quercetin contents were 2.80 and 6.61 g/kg dry weight, and that satisfactory inter-laboratory precision (RSD(r) and RSD(R) ranged from 0.41 to 0.92%, and from 6.73 to 7.62%, respectively); all HorRat values were less than 2. These results indicate that OMA 2006.07 is applicable to the determination of the quercetin content of lyophilized onion samples.

An in vitro effect of coffee on the antigen-specific immune responses of naïve splenocytes.

Coffee is a globally consumed beverage with potential health benefits. However, there are few reports about the effects of coffee on immunological functions. We previously reported that in an allergic mouse model, coffee intake prevented allergy development through augmentation of interleukin (IL)-12p40. In order to investigate the anti-allergic activity of coffee, we examined the effect of coffee on antigen (Ag)-specific responses of immune cells in vitro. Coffee treatment suppressed proliferation and IL-2 secretion of mouse splenocytes in the same way as splenocytes from mice administered coffee orally. However, IL-12p40 secretion decreased significantly as a result of in vitro coffee treatment, which was contrary to the results obtained from experiments of mice administered coffee orally. Therefore, modification associated with oral administration might influence the anti-allergic activity of coffee.

Continuous orally administered coffee enhanced the antigen-specific Th1 response and reduced allergic development in a TCR-transgenic mice model.

Coffee is a globally consumed beverage. Although recent studies have suggested that coffee reduced the risk of lifestyle-related diseases, there are few studies regarding allergic response. This study investigates the effects of orally administered coffee (91 ml/kg/d) on allergic responses using a T cell receptor (TCR)-transgenic DO11.10 mouse allergic model. Splenocytes from coffee-administered naïve mice increased antigen (Ag)-specific interleukin (IL)-12p40 secretion. When Ag sensitization and coffee administration were concurrently performed, the splenocytes from coffee-administered mice showed a decrease of IL-2 and an increase of IL-12p40 secretion. The Ag-specific cutaneous response and serum IgE level were reduced in coffee-administered mice, although, after establishing the allergy, coffee administration did not suppress the allergic reaction. These results suggest that coffee could induce a Th1-type response of the immune system and prevent an allergy developing. Further studies on the optimum dose, cultivar differences, and roasted degree need to be undertaken.

Production of IgE antibody to Japanese cedar pollen allergen Cry j1 by short term culture of human peripheral blood lymphocytes.

Peripheral blood lymphocytes (PBL) from a patient allergic to Japanese cedar pollens, were stimulated with IL-4, IL-13, CD40-Ligand and/or hydrocortisone in the presence of Epstein-Barr virus in 96-well round bottomed culture plates, and the secretion of IgE-class antibody against a Japanese cedar pollen allergen Cry j1 in the supernatants were examined. PBL cultured with IL-4, and IL-4 + CD40-Ligand showed the highest IgE secretion and the cultures were maintained for 30 days. However, we failed to expand the culture with high IgE secretion. It was suggested that patient's PBL stimulated with IL-4 were useful for short term IgE production to Cry j1.

Inhibitory effects of several flavonoids on E-selectin expression on human umbilical vein endothelial cells stimulated by tumor necrosis factor-alpha.

The present study investigates the suppressive effect of flavonoids on TNF-alpha-stimulated E-selectin expression on HUVECs by carrying out a comparative examination of the 37 flavonoids. Several flavonoids: fisetin, luteolin and apigenin (subclass of flavone), kaempferol and quercetin (flavonols), eriodictyol (flavanones), genistein (isoflavones) and butein (chalcone) exhibit the inhibitory effects. Considerations to the structure of flavonoids, the C2-C3 double bond of C-ring and 4-oxo functional group are essential for their inhibition activities. These results help to explain the pharmacological efficacy of flavonoids as anti-inflammatory compounds.

Inhibitory effect of some flavonoids on tumor necrosis factor-alpha production in lipopolysaccharide-stimulated mouse macrophage cell line J774.1.

Certain naturally occurring flavonoids affect immunoregulatory activities in vitro and in vivo against cytokine production. Since tumor necrosis factor (TNF)-alpha is one of the major inflammatory cytokines, the effects of various dietary flavonoids on TNF-alpha production in lipopolysaccharide (LPS)-stimulated J774.1 cells were evaluated in vitro. Flavones, flavonols, and chalcone are the most potent inhibitors of production of TNF-alpha. Flavanone, naringenin, anthocyanidin, pelargodinin, and cyanidin exhibit moderate inhibitory activity. In contrast, genistein isoflavone displays weak inhibition, while eriodictyol flavanone is inactive. It is clear that the double bond between carbons 2 and 3 and the ketone group at position 4 of flavonoids are necessary for potent inhibitory effect. The difference in inhibitory action appears to depend on the categorized subclass of flavonoids.