CDA-IN-1 (Compound vs#2-1) is an inhibitor of chitin deacetylase (CDA) that exhibits antifungal activity. By inhibiting fungal CDA activity, it activates plant immune responses and leads to the accumulation of reactive oxygen species (ROS), hindering fungal growth. At a concentration of 100 μM, CDA-IN-1 achieves inhibition rates of 86.9% on P. xanthii's PxCDA1 and 74.5% on PxCDA2. CDA-IN-1 is applicable in research on fungal plant diseases, such as cucumber powdery mildew and tomato gray mold.