Bisphenol A (BPA) and its source in foods in Japanese markets.

The determination of bisphenol A (BPA) and/or bisphenol A diglycidyl ether (BADGE) in foods sold in Japanese markets and in water leached from six epoxy resin cans with similar diameters was carried out using high-performance liquid chromatography (HPLC) with electrochemical detection (LC/ECD), LC-mass spectrometric detection (LC/MS) and LC-tandem mass spectrometric detection (LC/MS/MS). BPA concentrations were 0-842 ng g(-1) for 48 canned foods, 0-14 ng g(-1) for 23 foods in plastic containers, and 0-1 ng g(-1) for 16 foods in paper containers. No BADGE was detected in three canned foods. There was no difference in leaching concentrations of BPA into glycine buffers at pHs 8 and 11, and water. The amounts of BPA leached into water from six epoxy resin cans held at 121 degrees C for 20 min were almost the same as the cans' contents and were much higher than the amounts leached from cans held at or below 80 degrees C for 60 min. The amount leached depended on the type of can, but not on the amount of BADGE leached from the cans. Considerably more BPA than BADGE leached to water from six cans. Two cans whose contents had high concentrations of BPA showed no BADGE leaching even at 121 degrees C, suggesting the different kinds of epoxy resin can linings from others. The results imply that the main source of human exposure to BPA is food from cans with linings that contain high percentages of BPA as an additive or an unforeseen contaminant.

Decomposition of bisphenol-A (BPA) by radical oxygen.

A change in bisphenol-A (BPA) concentration leached from polycarbonate (PC) tube to the phosphatidyl ethanolamine (PhE)-containing water was compared to water only. Time-dependent increase in BPA concentration was observed in both samples at 37 degrees C. The leaching velocity of BPA to water was three times faster than that to PhE-containing water and BPA concentration in water reached to 55.8 ng/ml 5 weeks later. When BPA was determined immediately after BPA addition of various concentration of PhE up to 2.5mg/ml to water, the BPA recoveries were over 93%. But, when incubated at 37 degrees C for a special time, BPA concentration in PhE-containing water in glass tube decreased time-dependently. In the presence of H2O2, time and Fe3+ dose-dependent decrease in the BPA concentration particularly, a drastic decrease above 0.44 mM Fe3+ was observed. These results suggest that BPA would be decomposed by radical oxygen including lipoperoxides. An addition of serum prevented BPA decrease from radical oxygen to a great extent but could not recover the BPA decrease. Thiobarbituric acid (TBA) value, a good parameter of lipid oxidation, decreased gradually in the mixture of H9O2 and Fe3+ in the presence of BPA, implying an inhibition of lipid oxidation due to BPA oxidation by radical oxygen.

Determination of bisphenol A in blood using high-performance liquid chromatography-electrochemical detection with solid-phase extraction.

A method for the determination of bisphenol A (BPA) in blood was investigated using high-performance liquid chromatography-electrochemical detection (HPLC-ED) with solid-phase extraction. When BPA at the concentrations of 25-100 ng/ml were added to whole blood, BPA recoveries were 26-48%. When BPA was added to water, plasma or hemolyzed red blood cells (H-RBC), BPA recoveries in water and plasma were almost similar (94%). However, the recovery in H-RBC was very low (36-46%). When BPA and plasma were added to H-RBC, the recovery was 70-85%. In authentic bovine metHb solution, BPA decreased depending on the metHb concentration, however, BPA recovery in the solution added with more than 17% plasma was higher than that in metHb only. These suggest that metHb influences the BPA recovery in whole blood. However, an accurate determination of BPA using HPLC was easily made possible by separating RBC from plasma.

Sensitive method for the determination of bisphenol-A in serum using two systems of high-performance liquid chromatography.

The aim of this study was to establish an easy and accurate method for the determination of bisphenol-A (BPA) in the body liquid such as serum and urine. Two high-performance liquid chromatography (HPLC) systems, HPLC with electrochemical detector (ED), and HPLC with mass spectrometry (MS) using electrospray ionization (ESI) interface were used for the assay in the serum samples prepared with solid-phase extraction method. Water or EtOH at a concentration below 50% was suitable for the extraction of BPA from serum. The limit of detection of BPA was 0.2 ng ml(-1) for the HPLC-ED method and 0.1 ng ml(-1) for HPLC-MS. There was a good correlation between the data obtained by the two HPLC systems. BPA concentrations in healthy human serum were low (0-1.6 ng ml(-1)). From various commercial fetal bovine serum and sheep plasma, however, significant amounts of BPA were detected. Since no BPA was detected from sheep plasma immediately after collection, the high amounts of BPA were considered to be caused by the handling of blood during the preparation of the products after blood collection. In vitro study showed that the amount of BPA leached from polycarbonate tube into sheep plasma were 40 times larger than those into water and the leached amount of BPA depended on the temperature (37 degrees C>20 degrees C>5 degrees C).

Identification of eicosanoids in the red algae, Gracilaria asiatica, using high-performance liquid chromatography and electrospray ionization mass spectrometry.

Identification of eicosanoids which are metabolites of arachidonic acid in red algae Gracilaria asiatica, one of the popular seaweeds in Japan, was carried out using high-performance liquid chromatography (HPLC) interfaced with electrospray ionization mass spectrometry. Prostaglandin (PG) E2, 15-keto-PGE2, and 8-hydroxyeicosatetraenoic acid (HETE) were detected as major eicosanoids and PGA2, leukotriene B4 as minor ones in G. asiatica. 8- and 12-HETE had the same retention time in HPLC analysis, but using this analytical method, we were able to identify them.

Phospholipid metabolism in European house dust mite (Acari: Pyroglyphidae).

Phospholipid metabolism was studied in European house dust mite, Dermatophagoides pteronyssinus (Trouessart). Analysis of phospholipid metabolites in mite extracts suggested the presence of PLaseA1, PLaseA2, and PLaseC, which have important physiological roles in phospholipid metabolism. The optimum pH of PLaseA1 and PLaseA2 was 8 and 9, and the optimum temperature of PLaseA1 was 45 degrees C; the activity of PLaseA2 was not affected by temperature. The activity of PLaseA1 at pH 8 and 37 degrees C was 5 times higher than that of PLaseA2 in D. pteronyssinus. The optimum temperatures of diacylglycerol production were 25 and 45 degrees C.

Is phospholipase in vinegared oysters a casual agent for human poisoning?

In this survey, lipid metabolism and activities of the lipolytic enzymes diglyceride lipase (DLase) and phospholipase A (PLase A) in the oyster digestive glands (ODGs), with 4% added acetic acid (the same acid concentration as vinegar) and incubated at 37 degrees C for 3 h, were investigated. Significant decreases in triglyceride, phosphatidycholine, and phosphatidylethanolamine and increases in monoglyceride, lysophosphatidylcholine, and lysophosphatidylethanolamine were observed in the acetic acid-treated ODGs. Changes in ODGs treated with PBS were smaller than in the acetic acid-treated ones but larger than in the nontreated ones. Both PLase A1, and PLase A2 in ODGs were activated by addition of acetic acid and incubated at 37 degrees C for 3 h. PLase A1 activities were higher than those of PLase A2, in all experimental ODGs. Addition of formic acid also induced activation of PLase A at pH 2. On the other hand, DLase in ODGs decreased remarkably with acetic acid treatment. These data showed that the increase in lipid metabolites such as free fatty acids and lysophospholipids in the acetic acid-treated ODGs might be due to catabolism of PLase A, which was activated by the acid treatment at 37 degrees C.

Free fatty acids inducing mouse lethal toxicity in lipid extracts of Engraulis japonica, the Japanese anchovy.

Mouse lethal toxicity was detected in the ether extract of Engraulis japonica (anchovy). The mouse toxicity of extracts was more potent from viscera than from other organs. Okadaic acid (C44H68O13) and dinophysistoxin (C45H70O13), lipophilic toxins derived from phytoplankton, which are usually considered to be the diarrhetic shellfish toxins, were not detected in the ether extract of ancovy. There occurred, however, two prominent peaks in high-performance liquid chromatography, which were identified as free eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The mouse toxicity observed correlated with the intensity of these two peaks. Toxicity was reduced considerably by pretreatment with Na2CO3. By quantitating EPA toxicity, it was concluded that the toxicity was not due to EPA only but also to DHA. The results indicate that substances in Japanese anchovy associated with mouse lethal toxicity include free polyunsaturated fatty acids, mainly EPA and DHA.

Studies on the mechanism of antiaggregatory effect of Moutan Cortex.

The effects of Moutan Cortex and one of its major components, paeonol, on platelet aggregation and arachidonic acid (AA) metabolism in human platelets were studied. One week oral administration of water extract of Moutan Cortex [Moutan Cortex (w), 3 g/day] significantly reduced platelet aggregation and thromboxane B2 (TXB2) formation induced by collagen, epinephrine and ADP. Paeonol dose-dependently inhibited ADP and collagen induced platelet aggregation in vitro. Moutan Cortex (w) and paeonol dose-dependently inhibited the conversion of exogenous [14C]AA to [14C]heptadecatetraenoic acid [( 14C]HHT) and [14C]TXB2 by washed human platelets, while both of them increased its conversion to [14C]12-hydroxy eicosatetraenoic acid [( 14C]12-HETE). High dose of Moutan Cortex (w) inhibited the release of [14C]AA from prelabeled platelets in vitro, while paeonol did not. These results suggest that a reduction in platelet aggregation by the oral administration of Moutan Cortex might be ascribed to a decrease in thromboxane synthesis and that paeonol might play an important role in the antiaggregatory effect of Moutan Cortex because of its potent inhibitory effect on platelet aggregation and thromboxane formation.

The effects of the oral administration of fish oil concentrate on the release and the metabolism of [14C]arachidonic acid and [14C]eicosapentaenoic acid by human platelets.

It has been suggested by several investigators that eicosapentaenoic acid (C20:5 omega 3, EPA) might have anti-thrombotic effects. In this experiment, the effect of the oral administration of EPA rich fish oil concentrate on platelet aggregation and the release and the metabolism of [1-14C]arachidonic acid and [(U)-14C]eicosapentaenoic acid by human platelets was studied. Eight healthy male subjects ingested 18 capsules of fish oil concentrate (EPA 1.4 g) per day for 4 weeks. Plasma and platelet concentrations of EPA markedly increased, while those of arachidonic acid (C20:4 omega 6, AA) and docosahexaenoic acid (C22:6 omega 3, DHA) did not change. Platelet aggregation induced by collagen and ADP was reduced. Collagen induced [14C]thromboxane B2 (TXB2) formation from [14C]AA prelabeled platelets decreased. There was no detectable formation of [14C]TXB3 from [14C]EPA prelabeled platelets, and the conversion of exogenous [14C]EPA to [14C]TXB3 was lower than that of [14C]AA to [14C]TXB2. The release of [14C]AA from [14C]AA prelabeled platelets by collagen was significantly decreased. These observations raise the possibility that the release of arachidonic acid from platelet lipids might be affected by the alteration of EPA content in platelets.

Effects of orally administered ethyl ester of eicosapentaenoic acid (EPA; C20:5, omega-3) on PGI2-like substance production by rat aorta.

A highly purified ethyl ester of EPA (EPAEE) (74%) was manufactured from sardine oil. Sixty mg/kg/day of EPAEE was given orally to male Wistar rats for 8 weeks. No side effect or toxicity from the administration of EPAEE was observed. Plasma EPA concentration and the ratio of EPA to arachidonic acid were significantly increased, compared with control Wistar rats. An enhancement of PGI2-like substance production by aortas obtained from rats fed EPAEE was noted. Conversion of EPA to delta 17-6-keto-PGF1 alpha, a stable metabolite of PGI3, could not be detected by an incubation study of 14C-EPA and aortas either from rats fed EPAEE or from control rats. Therefore, PGI2-like substance produced by rat aorta is most likely to be PGI2 itself and not PGI3.