Synthesis And Biological Activity Of 1,4-pentadien-3-one Derivatives Containing Benzothiazole

As an important curcumin analogue,penta-1,4-dien-3-ones are similar to curcumin,possessingantimicrobial,antiviral,anticancer,antirheumatoid,anti-inflammatory and anti-oxidation properties,low toxic effects on plants and human health.Further,it is more stable than curcumin and widely used in pesticide field over the years.Benzothiazole,a fused heterocycle,is widely used in plant diseases due to its antibacterial,antiviral,insecticidal and herbicidal properties.Based on these researches and the principle of active splicing,we attempted to introduce benzothiazole scaffold into the penta-1,4-diene-3-ones skeleton,designed and synthesized 35 novel penta-1,4-diene-3-ones derivatives,all their structures were confirmed via ¹H NMR,¹³C NMR and HRMS.The turbidimetric method was used to assess the antibacterial activity of title compounds,while using Xanthomonas oryzae pv.Oryzae（Xoo）,Xanthomonas axonopodis pv.Citri（Xac）and Ralstonia solanacearum（Rs）as test strains.Preliminary bioassays results indicated that partial title compounds showed fairly good antibacterial activity against Xoo and Xac,compared to the positive controls Bismerthiazol and Thiodiazole-copper,at the concentration of 100μg/mL.The determination results of median effect concentration(EC₅₀)indicated that,for Xoo,compounds A₂,A₁₂,A₁₉,B₈ and B₉ presented EC₅₀0 values of 20.0,11.9,22.8,65.3and 38.9μg/mL,which was preferable than that of Bismerthiazol（73.5μg/mL）,meanwhile,for Xac,compounds A₂,A₄,A₅,A₆,A₁₆,A₁₈,A₂₃,B₇,B₈,B₉ and B₁₂showed EC₅₀0 values of 42.1,47.9,50.8,33.6,35.7,55.2,28.5,49.9,42.6,31.5 and29.8μg/mL,which surpassed that of Bismerthiazol（55.4μg/mL）.Using mycelium growth rate method to evaluate for their antifungal activity,while using Capsicum fusarium wilt,Rhizoctonia solani sorghum,Colletotrichum capsici,Alternaria alternata,Rhizoctonia solani and Curvularia lunata as test objects.The preliminary bioassays results indicated that all target compounds possessed certain antifungal activity at 50μg/mL.Using half-leaf blight spot method to evaluate for the antiviral activity of partial target compounds,against Tobacco mosaic virus（TMV）,and Nicotiana glutinosa L at the same growth stage as test subject.The preliminary bioassays results exhibited that compounds B₁₀0 and B₁₁1 expressed excellent antiviral activity against TMV at 500μg/mL,with curative inhibiting rates of 66.2 and 69.9%,which were superior to that of positive control Ningnanmycin（58.6%）.