A model system which simulated the conditions of the human stomach was used in the experiments. Precursors NaNO2 and MNG formed MNNG and resulted in the positive mutagenic response to Salmonella typhimurium TA 100. When the concentration of the precursors was 50 mM NaNO2 and 100 mM MNG, the induced average number of revertant per plate was 4327 showed an approximate twenty fold spontaneous revertants. With diluting of the precursors, the mutagenic response was lower, showing a dose-response relationship between the mutagenic activity and the precursors concentration. It was found that, when precursor concentration was lower than 22.2 mM NaNO2 and 44.4 mM MNG, the formation of MNNG was blocked completely by the Chinese Kiwi fruit juice and mutation was inhibited. In the same concentration without the Chinese Kiwi fruit juice, the induced revertant was an approximate 13 fold of the spontaneous revertant. The Chinese Kiwi fruit could not block the formation of the MNNG when the precursors concentration was higher than 33.3 mM NaNO2, but it inhibited the mutagenic activity partly. Compared with the Chinese Kiwi fruit juice, the effect of the ascorbic acid solution in the same concentration was much less.It was demonstrated with TLC that MNNG was formed in the model system.

In order to observe the effect of Actinidia chinensis Planch fruit juice on blocking the formation of N-nitrosamide in vivo, 99 pregnant Wistar rats were divided into five groups. The rats of each group were orally given ni-trosamide precursor ethylurea (0.25, 0.50, 1.00, 2.00 4.00 mmol/kg) and NaNO2 (0.125, 0.25, 0.50, 1.00, 2.00 mmol/kg) respectively once a day for three days, on the 7th, 8th and 9th day of pregnancy. Half of the rats in. each group were administrated two precursors and a 4% starch solution, while the other half were administrated two precursors and the tested fruit juice.In the groups without the juice, NEU was formed in vivo, which led to a high mortality of embryos. The embryolethality was 5.21%, 43.66%, 71.7%, 85.8% and 100% respectively, and 4 pregnant rats died in the highest dosage group. However, the rats who received both the two precursors and the tested fruit juice, the living embryos and embryolethality were similar to the control groups except the highest dosage group. The none treatment group and groups only given one of the precursors were done as control groups. The results suggested that the concentrated juice could block the formation of NEU in vivo and prevent the embryotoxicity of NEU.

This paper deals with the inhibitory effects of Actinidia chinensis Planch (AC) on the formation of N-nitrosoproline (NPRO). In self-control studies, 15 male rats and 10 healthy men were the subjects. It was found that AC juice inhibited formation of NPRO in vivo in rats (inhibitory rate, 59.6%), and the effect was better than the same amount of a vitamin C (VC) solution (41.8%); and 150g AC fruit containing 75mg VC could completely inhibit the NPRO formation in vivo in men ingesting 300mg NaNO3 and 500mg L-proline, but 75mg VC only partially inhibited.

This paper deals with the inhibitory effect of Actinidia chinensis Planch (AC) juice on the formation of N-nitrosoproline (NPRO) in pregnant rats and women. In 21 Wistar pregnant rats and 27 pregnant women studies, it was found that NPRO formed in vivo might be transferred into the fetus, and AC juice might block it by inhibiting the NPRO formation in vivo. This was the first time to report that N-nitrosamino acid could be transferred into the fetus

The inhibitory effect of Actinidia chinensis Planch(ACP) juice on the endogenous formation of N-nitroso compounds (NOC) in the subjects from a high-risk area for gastric cancer were observed. Total concentration of volatile N-nitrosamines(VNA)in fasting gastric juice and 24-h urinary excretion of N-nitrosoproline (NPRO) were used as indices of endogenous exposure. After iagestion of 30 ml ACP juice the average total VNA concentration was significantly decreased from 2.08?1.06?g/L to 0.42?0.43?g/L (p

0.05) from those during the test period (18.8?1.22 mg and 0.75?0.07 mg).The mean level of reduced ascorbic acid in blood plasma during the control and test period were 0.83?0.04 mg/100 ml and 0.81?0.02 mg/100ml respectively. The results also showed that the 75 mg intake of ascorbic acid per day could satisfy the normal male college students requirement. This study agreed with the previous works on the subject.

The present investigation was undertaken to evaluate the role of the Chinese fruit juice in blocking nitrosamine formation in vitro.A model system simulated the conditions (pH 3.3, 37℃) known, to exist in the stomach, was used in the experiments. Different amount of nitrite and aminopyrine was incubated with Chinese fruit juice or vitamin C solution or buffer solution for 1 hr. 0.1 ml samples were taken and then subjected to the Ames mutagenicity test. The tester strain TA100 of Salmonella typhi-murium was employed for the detection of mutagenicity due to the N-nitro-samine formed from sodium nitrite and aminopyrine. Test samples and bacteria with or without S-9 mixed with molten top agar and poured onto the minimal agar plates. After incubation, the sample, that gave at least a 2-fold increase in induced revertants, compared to spontaneous revertants, was considered to have mutagenic activity.It showed that the concentration of the precursors was at or above 5 mg/ ml with S-9 and without juice. the samples exhibited mutagenic activity. It suggested that the nitrosamine was formed in this system. While the incorporation of Chinese fruit juice was found to inhibit the formation of nitrosamine at 5mg/ml and 8mg/ml. The cultures did not show mutagenic activity. The induced revertant colonies per plate was 252 ? 4.2. The Chin esefruit juice is more effective than that of vitamin C, the induced revertant colonies per plate was 445 ? 81.2, which shows mutagenic. The difference between the cultures of Chinese fruit juice and vitamin C is significant (P