ACE enzyme (100 [micro]l of 30 mU enzyme), 200 [micro]l of cryptide solutions, and substrate (2 ml of 0.5 mM FAPGG substrate) were mixed, and the absorbance at 340 nm was continuously monitored with a double-beam spectrophotometer in kinetic mode option.
The absorbance was measured at 517 nm using a double-beam spectrophotometer. Lower absorbance of the reaction mixture indicated higher free radical-scavenging activity.
The solution was incubated for 10 min, and the absorbance was measured at 700 nm using a double-beam spectrophotometer. Higher absorbance of the reaction mixture indicated higher reducing power.