2.5. Free radical scavenging activity of OP-Gel-Curcumin dressings
The free radical scavenging activity of OP-Gel-Curcumin and OP-Gel-Aloe Curcumin dressings was determined according to the method prescribed by Lo Nostro et al. [21]. Briefly, 20 mg of the dressings with varying curcumin content were incubated with diphenyl picryhydrazyl (DPPH) (10−4 mol/L in ethanol) for 20 min. After incubation, the absorbance of the DPPH solution was measured by using a UV–vis spectrophotometer (Shimadzu UV-2450) at 517 nm against ethanol as blank. DPPH ethanol reagent without sample was used as control and the free radical scavenging activity was calculated as follows: