Synthesis And Antifungal Activities Of Aminoguanidine Derivatives Of N-arylsulfonyl-3-acylindoles

It is well-known that phytopathogenic fungi are hard to control and easily infect many crops. It is imperative to develop new compounds for effective inhibition of those agricultural diseases. Recently, much attention has been paid to aminoguanidine derivatives due to their diverse biological activities. Baes on the afore-mentioned reports, therefore, in this paper 18 aminoguanidine derivatives (7a-r) were synthesized and bioevaluated in vitro as antifungal agents against seven phytopathogenic fungi.1. 18 aminoguanidine derivatives of N-arylsulfonyl-3-acylindoles (7a–r) were prepared and their structures were confirmed by mp, ESI-MS and 1H NMR. Among these compounds 16 new target compounds were also characterized by ESI-HRMS.2. Their antifungal activities against Fusarium graminearum, Bipolaris sorokiniana, Fusarium oxysporium f. sp. Cucumarinum, Alternaria brassicae, Fusarium oxysporium f. sp. vasinfectum, Pyricularia oryzae and Alternaria alternata were assayed by means of mycelium growth rate at the concentration of 100μg /mL. It was found that 7n and 7o had remarkable antifungal activities against seven phytopathogenic fungi and exhibited more potent antifungal activities than or comparable to hymexazol.3. The structure–activity relationship (SAR) of these compounds was also preliminarily investigated. Generally, introduction of electron-withdrawing group (R~1) on the indolyl ring would lead to less potent compounds than those with electron-donating group; when R~2 was introduced as the electron-withdrawing group, the corresponding compounds exhibited less potent activities than that possessing electron-donating one; the proper length of substituent R~3 of 7a–r were usually very important for their anti-fungal activities. When R~3 was introduced ethyl group, the compounds had superior antifungal activities.In conclusion, we got two lead compounds of aminoguanidine derivatives with potent antifungal activities. And it provides some theoretical and experimental basis to discover bioactive molecules.