No abstract

Hit, Lead & Candidate Discovery To discover succinate dehydrogenase inhibitors with a novel structure, we introduced cinnamic acid structure to optimize the lead structure 1 and synthesized four series of cinnamon–pyrazole carboxamide derivatives. The bioassay data showed that compounds (E)‐N‐(1‐[4‐chlorophenyl]‐4‐cyano‐1H‐pyrazol‐5‐yl)‐3‐(2‐fluorophenyl) acrylamide (5III‐d) and (E)‐3‐(2‐chlorophenyl)‐N‐(1‐[4‐chlorophenyl]‐4‐cyano‐1H‐pyrazol‐5‐yl) acrylamide (5III‐f) showed the significant antifungal activity against three fungi. In addition, 5III‐d and 5III‐f exhibited the excellent inhibitory effect against succinate dehydrogenase (SDH) enzymes with IC50 values ranging from 19.4 to 28.7 μM. The study demonstrates that the chlorine substituent group is present on both the phenyl and pyrazole rings that have a very good effect on the antifungal effect, and the compounds 5III‐d and 5III‐f can act as potential SDH inhibitors (SDHI) and throw a sprat for a new generation of SDHI.

A series of novel Mannich base derivatives of flavone containing benzylamine moiety was synthesized using the Mannich reaction. The results of antifungal activity are not ideal, but its antifungal effect has a certain increase compared to flavonoids. After that, four bacteria were used to test antibacterial experiments of these compounds; compound 5g (MIC = 0.5, 0.125 mg/L) showed significant inhibitory activity against Staphylococcus aureus and Salmonella gallinarum compared with novobiocin (MIC = 2, 0.25 mg/L). Compound 5s exhibited broad spectrum antibacterial activity (MIC = 1, 0.5, 2, 0.05 mg/L) against four bacteria. The selected compounds 5g and 5s exhibit potent inhibition against Topo II and Topo IV with IC values (0.25-16 mg/L). Molecular docking model showed that the compounds 5g and 5s can bind well to the target by interacting with amino acid residues. It will provide some valuable information for the commercial antibacterial agents.

Acetohydroxy acid synthase (AHAS; EC 2.2.1.6, also referred to as acetolactate synthase, ALS) has been considered as an attractive target for the design of herbicides. In this work, an optimized pyrazole sulfonamide base scaffold was designed and introduced to derive novel potential AHAS inhibitors by introducing a pyrazole ring in flucarbazone. The results of in vivo herbicidal activity evaluation indicates compound 3b has the most potent activity with rape root length inhibition values of 81% at 100 mg/L, and exhibited the best inhibitory ability against Arabidopsis thaliana AHAS. With molecular docking, compound 3b insert into Arabidopsis thaliana AHAS stably by an H-bond with Arg377 and cation-π interactions with Arg377, Trp574, Tyr579. This study suggests that compound 3b may serve as a potential AHAS inhibitor which can be used as a novel herbicides and provides valuable clues for the further design and optimization of AHAS inhibitors.