[Inhibitory effect of refined Amorphophallus konjac on MNNG-induced lung cancers in mice].

550 seven-wk-old LACA mice were used in 3 batches for studying the inhibitory effect of refined Amorphophallus konjac (Konjaku powder) on MNNG-induced lung cancers. The mice (within each batch) were randomly allocated into four groups, namely, positive control (MNNG), Amorphophallus konjac (A. K.), complex (MNNG+A. K.), and blank control (C) groups. In MNNG group, MNNG (250 micrograms) was injected intravenously once every five days for seven times in each mouse, the total dosage of MNNG being 1.75 mg. In A. K. group, according to w/w, 8% A. K. was well mixed into 92% common diet for long-term breeding. In the complex group, MNNG was given as that in MNNG group and the mice were kept as those in A. K. group. The mice in MNNG group and in C group were all maintained on common diet. The results showed different degrees of inhibitory and preventive effect of refined A. K. on MNNG-induced lung cancers. Refined A. K. not only exerted effect on the number of induced cancer and precancerous lesions, causing a drop in cancer rate from 70.87% to 19.38% and the mean number of cancer and precancerous lesions in each animal, but also altered the constituent ratio of the kinds of tumors, showing a decrease in malignancy (adenoma with malignant change), absence of adenocarcinoma, and relative increase in benign adenoma. The results of experiments in 3 batches also exhibited good reproducibility as well as absence of adverse reaction to Konjaku powder.