p-Hydroxybenzoic acid esters (parabens) inhibited the uptakes of not only proline but also glucose and acetate into cells of Escherichia coli JE1011 in the presence of chloramphenicol. The inhibition was enhanced at higher temperatures, and by longer alkyl side chains of parabens. Parabens injured artificial phospholipid membrane vesicles (liposomes) formed from phosphatidylcholine, cholesterol and stearylamine (molar ratio, 7:1:2), as revealed by the leakage of glucose from the liposomes, and the liposomes were disintegrated by butylparaben at high concentration. The 31P nuclear magnetic resonance (31P NMR) spectra of phosphatidylcholine showed a sharp peak corresponding to orthophosphoric acid in the presence of butylparaben. It was recognized from the change of the 31P NMR spectral pattern that butylparaben made the phase transition temperature of phosphatidylethanolamine 15° lower. The molar ratios of parabens to phospholipids in the three experiments, the uptake experiment using Escherichia coli cells, the leakage experiment using liposomes and the 31P NMR experiment, were roughly estimated at 0.08-0.5:1, 0.5-1.5:1 and 0.12-0.28:1, respectively. These results indicated that parabens disordered the membrane lipid, and nonspecifically inhibited the functions, such as uptake of substances, of the cell membrane. The membranes began to disintegrate at higher concentrations of parabens.
The reduction of post-harvest applied pesticides in potatoes during storage or processing was investigated. After application of DDVP, chloropropham, chlorpyrifos and pyrethrin, potatoes were stored for 13 weeks or processed to prepare French fries without peeling, and the levels of pesticides were determined after each step. DDVP, chloropropham, chlorpyrifos and pyrethrins from potatoes were detected at the levels of 0.03%, 37%, 46%, and 2-35%, respectively, after 13 weeks' storage at room temperature; and at 0.1%, 1.3%, 7.7% and 5.9-10.1% after processing to prepare French fries. However, more than 99% of pesticides was removed by peeling.
A high performance liquid chromatographic method for the simultaneous determination of malachite green (MG) and methylene blue (MB) in cultured fishes has been developed. The muscles of rainbow trout and amago were homogenized with McIlvaine buffer solution (0.3M citrate, 0.6M sodium phosphate dibasic, pH 3.0), and the drugs were extracted from the homogenate with acetonitrile. The acetonitrile layer was washed with n-hexane and dissolved in sodium chloride solution. This mixture was partitioned with dichloromethane. The dichloromethane layer was evaporated under reduced pressure. The residue was dissolved in methanol and analyzed by HPLC. The chromatography was performed on a TSKgel ODS-80TM column (4.6mm i. d., 150mm) with a mobile phase consisting of 0.1M citrate buffer (pH 3.0) and acetonitrile (1:1). Mean recoveries of MG and MB from fishes at the level of 0.1-0.5μg/g were 68.7±1.8-74.0±2.0 and 44.7±4.0-69.7±5.6%, respectively. The detection limits of MG and MB were 0.005 and 0.003μg/g, respectively. A photodiode array detector can be used for identification of residual MG in fish.
Paper products are treated with various compounds such as acid, alkali and others during the production processes. For estimation of the safety of products which are used in contact with foods, we examined six anions, Cl-, NO2-, PO43-, Br-, NO3- and SO42-, and three cations, Na+, K+ and NH4+, in aqueous extracts of the products. The extracts were prepared by immersing 2g of paper products in 100ml of water for 30min at 60°C. Cl- and SO42- were detected in the ranges from 0.5 to 27.6ppm in all 135 samples (average 7.85ppm), and from 0.7 to 47.4ppm in 132 samples (average 9.33ppm), respectively. NO2-, PO43-, Br- and NO3- were detected in trace amounts in some samples. The amounts of Na+ and K+ were nearly equimolar to those of the anions. NH4+ was detected in similar amounts to the former two cations in a half of the analyzed samples. Small amounts of these inorganic ions were detected from most napkins, paper towels, kitchen papers and filter papers. Relatively large amounts of ions were detected from paper board products such as lunch boxes or cake boxes, corrugated fiberboard products and newspapers. Aqueous extracts from most paper cups and glassine papers were acidic, and those from most paper boards and corrugated fiberboards were alkaline.
The pufferfish Fugu vermicularis radiatus (Nashifugu) inhabiting the Yellow Sea, samples of which have recently caused food poisoning incidents in Japan, was examined for toxicity. Specimens were collected from several locations in the Yellow Sea and assayed for anatomical distribution of toxicity by the mouse bioassay method. Specimens collected from Norin-gyoku Sections 138 and 139 showed toxicity scores of 11±1 (mean±S. E.) MU/g muscle and 24±9MU/g testis, and those from Section 283 afforded higher scores of 71±18 and 127±72MU/g, respectively. These scores clearly exceeded the quarantine limit of tetrodotoxin toxicity in Japan (10MU/g edible part), suggesting that such fish had been responsible for the above incidents.
A simultaneous analytical method for residual synthetic antibacterials in fish and meat has been developed. Synthetic antibacterials were extracted with acetonitrile, followed by partition with hexane. Extracts were analyzed by the screening method using HPLC with stepwise gradient elution. Detected synthetic antibacterials were quantitatively analyzed by HPLC under optimum conditions, and UV spectra were taken for further qualitative analysis. The lower limit of determination was 10-50ppb for each synthetic antibacterial. The results of a collaborative study with 10 laboratories indicated that the proposed method gives accurate and reproducible data.
Amaranth (FD & C Red No. 2), ponceau 3R and ponceau R, which have a common constituent, R salt in their structures, stimulate in vitro RNA synthesis by causing the dissociation of chromatin in isolated rat-liver nuclei. The effects of R-amino salt, R salt and amaranth on RNA synthesis and configuration, and the affinity of these chemicals for histone classes in rat-liver chromatin were investigated. Amaranth stimulated RNA synthesis in isolated rat-liver nuclei and dissociated the chromatin. These results were supported by the high affinity of amaranth for histones. R-amino salt weakly stimulated RNA synthesis and its affinity for histones was also weak in comparison with the effects of amaranth. R salt had no effect on the template activity or configuration in the chromatin.
Methods for determining low concentrations of lead and cadmium leached into 4% acetic acid from ceramicware were studied. The limit of leachable lead proposed for ceramic pitchers by the Food and Drug Administration, U. S. A., 0.1ppm in the extraction solution, could be determined by flame-atomic absorption spectrometry at 217.0nm. Using a 10-fold-concentrated extraction solution, we recovered 95.7±6.7% of added lead with a 7.0% coefficient of variation. Release of lead from four pitchers purchased at a department store in Tokyo was between 0.008 and 0.01ppm when the migration test was carried out with 4% acetic acid at 19±3°C for 24hr. Lead was also determined by a flameless method, as these concentrations were lower than the detection limit of the flame method even when the extraction solution was concentrated 10-fold. Cadmium, the release of which is also regulated by the Food Sanitation Law, was not detectable, i. e., if present, its content was less than 0.0005ppm in the extraction solution. Some other dishes which release lead and cadmium were used in place of the pitchers to determine the migration behavior of these metals from other ceramicware. The relation of the release of these metals to extraction time was biexponential when 4% acetic acid or grapefruit juice was used as an extraction solvent, when 4% acetic acid was used for seven days or was changed every 24hr, and when the dishes were kept at 5°C or at room temperature (24±4°C). Some other metals in the extraction solution were determined by ICP-atomic emission spectrometry.
Six female students were orally given 175 and 350ml of a soft drink containing 190mg/L of sodium benzoate (BA-Na) and three male volunteers were also orally given BA-Na solution at a dosage of 20mg/kg body weight. Urinary hippuric acid (HA) and creatinine excreted by the subjects given either the soft drink or the BA-Na solution were determined simultaneously by high performance liquid chromatography (HPLC) from the end of the administration until 4 or 5hr later, at appropriate intervals. In the case of soft drink administration, the concentration of HA attained a maximum in urine taken from 0 to 30min and recovered to the predose level after 3hr. The molar ratios of HA excreted in the 0-3hr urine samples to the administered dose were estimated to be 66-86%, by subtracting the amount of HA excreted in the predose period on the day of the administration. In the case of BA-Na solution administration, the concentration of HA attained a maximum in the 0-1hr urine samples and did not recover to the predose level within 5hr. The molar ratio of HA excreted in the 0-5hr urine samples to the administered dose was estimated to be about 89%, by subtracting the amount of HA excreted in the predose period on the day of the administration. Based upon these findings, it is suggested that the amount of absorbed BA-Na in human subjects can be estimated by determining the amount of HA excreted in the urine.