A STUDY OF THE EFFECT OF ZHENGGUANGMYCIN ON THE CELL CYCLE OF CHO CELL LINE AND TUMORS WITH FLOW CYTOMETRY (FCM)

All of the six Zhengguangmycin constituents A₂, A₄, A₅, A₆, B₂, A₅₀₃₃ and a mixed preparation comprising of components A₂+B₂ blocked the CHO cells at the G₂ phase. This blocking effect was doseg dependent within the range of 20～100 μg/ml. At the same dosage (40μg/ml), the G₂ blocking was compared. A₄ and A₅ showed stronger effect than A₆, A₂, A₂+B₂ and B₂. 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.}