Abstract:
All of the six Zhengguangmycin constituents A
2, A
4, A
5, A
6, B
2, A
5033 and a mixed preparation comprising of components A
2+B
2 blocked the CHO cells at the G
2 phase. This blocking effect was doseg dependent within the range of 20～100 μg/ml. At the same dosage (40μg/ml), the G
2 blocking was compared. A
4 and A
5 showed stronger effect than A
6, A
2, A
2+B
2 and B
2. But A
5033 exhibited no G2 blocking effect. Equivalent effect was observed when the concentration of A5033 was 300μg/ml and that of A5 was 40μg/ml.At comparable toxic dosage (1/20 LD50), all of the seven constituents induced big polyploid cells in mice bearing Ehrlich ascites carcinoma. Since there is a parallel relationship between G2 blocking and antitumor activity, we presume that the mechanism of antitumor activity of Zhengguangmycin is its G2 blocking effect.
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