食品添加物Morpholine(脂肪酸塩)の突然変異原性に関する研究

抄録

Morpholine is a food additive which is widely used as a surface active agent to protect citrus fruit against deterioration. The toxicity of morpholine is relatively low compared with other food additives. But this is one of the secondary amines which may possibly form N-nitrosomorpholine, known as a carcinogen, in the presence of nitrite in vitro and in vitro.
Thus, in order to investigate the residual levels of morpholine in commercial citrus fruits, we attempted to use gas-liquid chromatography (GC) and further studied the removal efficiency of morpholine from the rind by washing and boiling.
We also investigated distribution and elimination of morpholine orally administrated to rats. The effect of several foods against nitrosation of morpholine by in vitro GC method and the preincubation method using Salmonella typhimurium TA 100 in the presence of S-9 Mix was measured.
The results of the investigation were as follows:
1) Morpholine from citrus fruits was extracted by steam distillation and purified by amberlite IR-120 B column chromatography and determined by use of FID-GC with columns packed with 10% Thermon 1000+3% KOH on Shimalite F.
2) Identification of peak on GC was carried out with GC-MS spectrum and mass chromatography.
3) Residual levels of morpholine in 28 commercial citrus fruits and marmalade varied from ND to 71.1ppm.
4) Removal efficiency of morpholine from the rind of fruits by washing with kitchen detergent or boiling for 20-40 mins varied from 24.3 to 87.0%. Removed morpholine was recovered quantitatively from washed or boiled solutions.
5) Morpholine and morpholine oleate orally administrated to rats was largely excreted unchanged in the urine over a period of 2-6 days. The faecal excretion of morpholine oleate appeared to be a little more than that of morpholine.
6) Morpholine and sodium nitrite reacted easily at pH 3.0 and formed nitrosomorpholine quantitatively over a period of 24 hours.
7) It was found that vitamine C, glucose, mannitol, cabbage juice, orange juice, shiitake extract and saliva inhibited the nitrosation of morpholine in vitro. But catechin, epicatechin and tea extract enhanced the same reaction.
8) Further studies were carried out to test the changes of the numbers of His⁺ revertant colonies by the preincubation method.
9) Nitrosomorpholine induced large numbers of His⁺ revertant colonies with S-9 Mix in Salmonella typhimurium TA 100.
10) His⁺ revertant colonies were decreased by the addition of vitamine C, glucose, mannitol, cabbage juice, orange juice, shiitake extract and saliva to the reaction solution of morpholine and sodium nitrite. But in the case of catechin and tea extract, His⁺ revertant colonies were increased.