oxidations. We also provided seven CTL-A analogues and elucidated preliminary structure–activityrelationships. The in vivo ALI mouse model further suggested that CTL-A alleviated acutelunginjury with reductions in lung edema and pathological deterioration, which is better than sivelestat, one approved elastase inhibitor. The activity of CTL-A against elastase, along with its cellular safety and well-established