Novel quinolone derivatives are disclosed. Also disclosed are synthesis and use thereof for treating neurodegenerative diseases. In an aspect, the invention relates to a composition comprising a therapeutically effective amount of the compound as aforementioned, or a pharmaceutically acceptable salt, a solvate or hydrate, a prodrug, or a metabolite thereof and a pharmaceutically acceptable diluent or carrier. Further in another aspect, the invention relates to a composition comprising a compound as aforementioned, or a pharmaceutically acceptable salt, a solvate or hydrate, a prodrug, or a metabolite thereof, and a pharmaceutically acceptable diluent or carrier tor use in treating a neurodegenerative disease. Yet in another aspect, the invention relates to a use of a compound as aforementioned in the manufacture of a medicament for treating a neurodegenerative disease. In one embodiment, the medicament is for treating.Alzheimer's disease.