New Quinazoline Compounds Antibacterial Activity Screening And Mechanism Of A Preliminary Study

The effect of new quinazoline derivatives were tested against pathogenic fungi by using the mycelial growth rate method in the laboratory. Preliminary bioassay tests showed that some compounds possessed good antifungal activities, such as 4-ethylthio-6-fluoroquinazoline(q17), 4-n-Propylthio-6-fluoroquinazoline(q21) and 4-allylthio-6-fluoroquinazoline(q25). Further bioassays disclosed that compounds q17, q21 and q25 showed remarkable inhibitory effect on all kinds of tested plant pathogenic fungi with q17 showing the best results. The EC50 of q17 on G. zeae, F. oxysporum, C. mandshurica, R. solani, T. cucumeris, P. infestans, S. sclerotiorum, B. cinerea, C. gloeosporioides were 12.41 g/mL, 18.19μg/mL, 19.24μg/mL, 24.91μg/mL, 30.75μg/mL, 26.77μg/mL, 11.40μg/mL, 8.31μg/mL, 64.18μg/mL, respectively. Compound q17 had more potent antifungal activities against most of the tested fungi, and showed a broad-spectrum bioactivity.Action mechanisim of compound(q17) against F. oxysporum was studied, and hymexazol serving as the control. After treating F. oxysporum with compound q17 at 100μg/mL, only 6.5% of its spore bourgeoned. The permeability of the cell membrane increased along with the malformation of the hyphal and condensation of its endosome. After treatment with compound q17 at 100μg/mL within 12 h, the mycelial reducing sugar, D-GlcNAc content and chitinase activity declined, and the ability of sugar absorption by the cell from the culture medium was depressed, but the soluble protein content showed no obvious change.