PPO-IN-10 (Compound 4) is a 2-phenylpyridine derivative of pyrrolidone. PPO-IN-10 inhibits protoporphyrinogen IX oxidase ( PPO ). PPO-IN-10 leads to the formation of photosensitive protoporphyrin IX and the death of weed leaves. PPO-IN-10 can be used in the research of developing new PPO herbicides.