Methyl coelenterazine (Coelenterazine, 2-methyl analog) has been reported to be a superior antioxidant for cells against reactive oxygen species (ROS) such as singlet oxygen and superoxide anion. The coelenterazine derivative is membrane-permeant, nontoxic and highly reactive toward ROS. As oxidative stress is believed to be a mediator of apoptosis, methyl coelenterazine should be another important tool for studies of apoptosis.Coelenterazine products have been used to detect superoxide and peroxynitrite via chemiluminescence.