Chitin synthase inhibitor 4 is a chitin synthase (CHS) inhibitor with antimicrobial activity.Chitin synthase inhibitor 4 is a CHS-based compound and a candidate fungicide.

Chitin synthase inhibitor 4 (compound 4fh), at a concentration of 50 μM for 3 hours, significantly inhibits chitin synthase and polyoxin D, with respective inhibition rates of 68.08% and 63.84%. Demonstrating effective antifungal properties, it achieves EC50 values of 0.71 and 2.47 μg/mL against V. mali and S. sclerotiorum, respectively. At a higher concentration of 50 μg/mL, it shows remarkable inhibition efficacy against the same fungi, with inhibition rates of 90.3% and 88.7%, respectively. At 1 μg/mL, it notably disrupts hyphal growth, leading to abnormal growth characterized by decreased cell content, cell wall degradation, and plasmolysis.

Chitin synthase inhibitor 4 (compound 4fh) (Oral gavage; Rat with Salmonella typhimurium) has low acute toxicity, with no carcinogenic and mutagenic toxicity risk.[1]
Chitin synthase inhibitor 4 (50 μg/mL) has considerable curative and protective effects against S. sclerotiorum vivo, and no obvious phytotoxicity.[1]