Novel azamacrolides comprising the triazole moiety were synthesized and evaluated for their quorum sensing inhibitor activities on the Agrobacterium tumefaciens. It was found that the inhibition rate of compound Z12-3 at 200 mg/L (0.45 mM) can reach 67%. The potential binding modes between these molecules and the TraR QS receptor was performed by molecular docking. The results showed that the two nitrogen atoms in the triazole ring of Z12-3 formed hydrogen bonds with GLN-2, and the carbonyl group (C=O) in the amide formed hydrogen bonds with water. It was worth noting that the carbonyl group on the macrolides formed hydrogen bonds with the G-106 base in the DNA. These azamacrolides may block quorum sensing expression through key amino acid residues or DNA bases in the TraR QS receptor by hydrogen-bonded.

Bamboo is rich in starch and sugars and can be infected by mold and stain fungi, degrading its performance, shortening its service life, and reducing its utilization value. It is crucial to investigate how to protect bamboo against mold and stain fungi. The zone of inhibition test was used to evaluate the antifungal activity of azoxystrobin, kresoxim-methyl, pyraclostrobin and 3-iodo-2-propynyl-butylcarbamate (IPBC) against stain fungi (Botryodiplodia theobromae, Fusarium moniliforme, and Alternaria alternate) and mold fungi (Aspergillus niger, Penicillium citrinum, and Trichoderma viride) to develop new chemicals to protect bamboo against stain fungi and molds. The inhibitory activity of the composite pyraclostrobin and IPBC with different ratios was evaluated. Water-based formulations of the fungi were used to treat the bamboo, and the mold and stain resistance of the bamboo was investigated at different chemical retention rates. The results showed that the antifungal activity of pyraclostrobin was significantly higher than that of azoxystrobin and kresoxim-methyl. Different degrees of inhibitory activities against the stain and mold fungi were observed, and the inhibitory activity was higher against stain fungi than against molds. The three stain fungi were completely inhibited at a 7:3 ratio of pyraclostrobin to IPBC and 0.1% concentration. As the ratio increased, the inhibitory effect against mixed mold strains improved. The control efficacy of the pyraclostrobin formulations Str-1 and Str-2 at 0.1% concentration was 100% against Alternaria alternate and 70.8% against Fusarium moniliforme. The control efficacy of the composite formulations SI-1 and SI-2 at 0.1% concentration was 100% against all three stain fungi and greater than 91.8% against the mixed mold strains. This study provides new insights into the utilization of pyraclostrobin and its composite formulations as new bamboo antifungal agents.