Synthesis and antifungal activity of 2,4-diacetylphloroglucinol analogues

In this letter, we reported synthesis of 2,4-Diacetylphloroglucinol (DAPG) derivatives as a new class of anti fungal agents . A series of DAPG ester analogues with diverse length of acyl substitution on aromatic hydroxyls were synthesized and characterized by 1 H, 13 C NMR and ESI-MS. Their antifungal activities were evaluated in vitro against six important plant fungal pathogens using mycelial growth inhibitory rate assay. A clear structure-activity relationship (SAR) study of the diacylphloroglucinols was investigated. Compounds 2 , 2a - d , 2i , 2j and 2k exhibited broad-spectrum anti fungal activity, in addition, the anti fungal activity was correlated with the lipid-water partition coefficient of the compounds (log P ), these active analogues have log P between − 0.53 and 0.19. Particularly compound 2k (log P 0.19) was found active to Glomerella cingulata with IC 50 value of 1.26  μ g/mL; compound 2 (log P  − 0.51) was identified the most active one against Pyricularia oryzaecar (IC 50 1.52  μ g/mL). The results suggest that compound 2 and 2k might be promising candidates in the development of new pesticides.