Chlortetracycline is a tetracycline antibiotic that also exhibits antioxidative, anti-parasitic, and neuroprotective activities. Chlortetracycline binds the 30S subunit of the bacterial ribosome, inhibiting protein synthesis; it also displays antibacterial and antimalarial properties. Additionally, this compound acts as a radical scavenger. In vivo, chlortetracycline suppresses calpain activity and weakly antagonizes NMDA receptor activity and Ca2+ influx, protecting against cerebral ischemia.