Amino acid-oriented poly-substituted heterocyclic tetramic acid derivatives as potential antifungal agents

In order to find new potential pesticide molecules with antifungal activities, we have designed and synthesized a series of amino acid-oriented poly-substituted tetramic acid derivatives, and evaluated their potential antifungal activities against six kinds of plant pathogenic fungus commonly found in agriculture systematically, including Phomopsis adianticola, Fusarium graminearum, Alternaria tenuis Nees, Magnaporthe oryzae, Gloeosporium theae-sinensis, Sclerotinia sclerotiorum. According to the preliminary bioassay studies, all tested molecules, especially compounds I-2, I-5, I-12, I-15, exhibited significant and broad-spectrum anti-fungal effect in vitro compared to the intermediates M-1, M-2, M-3 and hymexazol. What's more, the inhibition rate of compounds I-5, I-6, I-15 against Phomopsis adianticola reached 74.42%, 60.33%, 65.21%, as well as compounds I-3, I-5, I-15 against Sclerotinia sclerotiorum were 65.65%, 74.92%, 61.36%. Further investigation results indicated that compounds I-2, I-5, I-15 presented obviously inhibitory activities against Phomopsis adianticola compared with hymexazol, which might be considered as the basic active framework for further potential fungicides discovery.