Antifungus Activity of DIMBOA from Maize Seedlings Compared with Several Phenolic Acids

The main fungal toxic secondary compound of 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA) was extracted from 7-day-old maize seedlings.Its antifungus activity against Rhizoctonia solani was tested in culture dishes and compared with that of other three phenolic compounds in maize including,ferulic acid,p-hydroxycinnamic acid and caffeic acid.The results showed that DIMBOA inhibited the hyphae growth of R.solani by 18.52% at the concentration of 50 μg/mL.The other three phenolic compounds also inhibited the hyphae growth of R.solani by 26.30%,8.50%and 6.30%respectively at the concentration of 250 μg/mL.Furthermore,there were synergistic effects between DIMBOA and p-hydroxycinnamic acid,and among the three phenolic acids on the inhibition of the hyphae growth of R.solani.With the same concentration,the inhibition rate of the mixture with 1:1 ferulic acid and p-hydroxycinnamic acid increased 18.89%when it was compared with that of p-hydroxycinnamic acid alone or increased 13.33%when it was compared with that of ferulic acid alone.With the same concentration,inhibition rate of the mixture with 1:1 p-hydroxycinnamic acid and caffeic acid increased 9.63%or 14.83%when it was compared with that of p-hydroxycinnamic acid alone or caffeic acid alone.The inhibition rate of the 1:1 mixture of ferulic acid and caffeic acid was 11.48%or 22.23%higher than that of ferulic acid or caffeic acid separately.Even more,the inhibition rate of the mixture of any two compounds was higher than the sum of the inhibition rate of the two compounds.The results infered that proper ratio of different secondary compounds in plant was impotant for plant disease resistant.