All the measurements were conducted in triplicate; and radical scavenging activity is calculated as: inhibition efficiency (%) ¼ [(A0 Ax)/A0] 100%. Here A0 is the absorbance of DPPH in ethanol, and Ax is the absorbance of the ethanol solution containing poly(pyrogallic acid) and DPPH. The antioxidant capacity is expressed as IC50, and it is defined as the polymer concentration (in mg/L) at which the absorbance of DPPH free radical is inhibited by 50%