Rational Design and Screening Study of Novel Lead Compound Based on Acetohydroxyacid Synthase Structure

Design, synthesis and biological evaluation of novel N-nitrophenyl derivatives based on the structure of acetohydroxyacid synthase

Acetohydroxyacid synthase (AHAS, EC: 2.2.1.6) is a target for the development of novel herbicides. Two series of N-nitrophenyl derivatives, type-A and type-B, were designed and synthesized based on the active site of the AHAS structure. All the structures of newly prepared compounds were thorough characterized by IR, and ¹H NMR spectrums. The IC₅₀ values of all synthesized target compounds against AHAS enzyme and EC₅₀ values for herbicidal activity against Brassica campestris L., Amaranthus mangostanus L. and Sorghum sudanense were determined. The bioactive assay results showed that the type-B compounds exhibited highly improved inhibitory activity against the AHAS enzyme and the tested plants comparing to type-A compounds. The IC₅₀ values of most type-B compounds against the AHAS enzyme were between 25-177μM. The EC₅₀ values of several type-B compounds against Sorghum sudanense reached 5.0mg/L. The differences in the biological activity between type-A and type-B compounds were attributed to two structural features - the orthogonal bend at the N-nitro amides group and the common plane structure of another phenyl with chain bridge. With the structure of the target compounds and the IC₅₀ values for AHAS enzyme, a statistically significant CoMFA model with high predict abilities (q²=0.606, r²=0.982, N=4, SEE=0.058, F=280.255) was obtained, and its reliability was verified. The model will provide a theoretical basis for the further structural optimization.

Computational design of novel inhibitors to overcome weed resistance associated with acetohydroxyacid synthase (AHAS) P197L mutant

BACKGOUND

Acetohydroxyacid synthase (AHAS; EC 2.2.1.6) is the first common enzyme in the biosynthetic pathway leading to the branched-chain amino acids in plants and a wide range of microorganisms. With the long-term and wide application of AHAS inhibitors, weed resistance is becoming a global problem, which leads to an urgent demand for novel inhibitors to antagonize both wild-type and resistant AHAS.

RESULTS

Pyrimidinyl salicylic acid derivatives, as one of the main classes of commercial AHAS herbicides, show potential anti-resistant bioactivity to wild-type and P197L mutant. In current work, a series of novel 2-benzoyloxy-6-pyrimidinyl salicylic acid derivatives were designed through fragment-based drug discovery. Fortunately, the newly synthesized compounds showed good inhibitory activity against both wild-type and P197L mutant. Some compounds not only had a lower resistance factor value but also showed excellent inhibitory activity against wild-type AHAS and P197L mutant. Furthermore, greenhouse experiments showed compound 11m displayed almost 100% inhibition against both wild-type and high-resistant Descurainia sophia at a dosage of 150 g a.i. ha^-1 .

CONCLUSION

The present work indicated that the 2-benzoyloxy-6-pyrimidinyl salicylic acid motif was well worth further optimization. Also, compound 11m could be used as a potential anti-resistant AHAS herbicide, which requires further research. © 2016 Society of Chemical Industry.

Design Synthesis and Biological Evaluation of NovelN-Nitro Acid Amide Derivatives as Lead Compounds of Herbicide

A series ofN-nitro acid amide derivatives compounds were synthesized based on the active site of target acetohydroxyacid synthase (AHAS, EC: 2.2.1.6) enzyme. All the structures of newly prepared compounds were thoroughly characterized by satisfied IR and1H NMR spectra. The IC50values against AHAS enzyme and EC50values for herbicidal activity againstAmaranthus mangostanus L.andSorghum sudanenseof all synthesized target compounds were determined. The compoundsII-10,II-21, andII-22with IC50values of 7.09 mg/L, 9.07 mg/L, and 9.11 mg/L and the compoundsII-8andII-22with EC50values of 9.87 mg/L and 19.88 mg/L against root ofAmaranthus mangostanus L.andSorghum sudanensewere illustrated, respectively. Meanwhile, the possible reasons for the lower activity of compounds were analyzed by molecular docking prediction.

Novel lead compound optimization and synthesized based on the target structure of Xanthomonas oryzae pv. oryzae GlmU

Bacterial leaf blight, caused by Xanthomonas oryzae pv. oryzae, is one of the most destructive diseases of rice worldwide. N-acetylglucosamine-1-phosphate uridyltransferase (GlmU) was an attractive target for the development of antimicrobial agents. To develop novel, more potent and even more selective inhibitors of the uridyltransferase activity of Xanthomonas oryzae pv. oryzae GlmU (Xo-GlmU), three types of novel target compounds were optimized and synthesized based on the Xo-GlmU structure in this study. The biological testing results showed that all of the target compounds displayed the higher inhibition than the lead compound with the IC50 values in the 10.82-23.31 µM range, and the inhibition rates were increased by 30%-67%. The binding mode and the possible inhibitory mechanism of the target compounds in the active site were also analyzed by the molecular docking based on the uridyltransferase active site of Xo-GlmU.