Abstract

Antioxidant potential and free radical scavenging abilities of curcumin were evaluated using in vitro models such as, reducing potential, 1,1-diphenyl-2-picryl-hydrazil (DPPH), superoxide (O₂^-), hydrogen peroxide (H₂O₂) and nitric oxide (NO) radical scavenging. Curcumin recorded dose-dependent effect and higher reducing potential (OD_max = 0.266). Curcumin could efficiently scavenged DPPH (IC₅₀ = 1.08 ± 0.06 μg/ml), H₂O₂ (IC₅₀ = 10.08 ± 2.01 μg/ml), NO (IC₅₀ = 37.50 ± 1.54 μg/ml), ferric reducing antioxidant power assay (FRAP) (1240 ± 18.54 μM Fe (II)/g) and superoxide anion (IC₅₀ = 29.63 ± 2.07 μg/ml) radicals in a dose-dependent manner. Ex vivo models like erythrocyte lipid peroxidation and erythrocyte haemolysis were also studied. Curcumin could efficiently scavenged the peroxy radicals which can induce haemolysis in erythrocytes (IC₅₀ = 282.7 ± 4.82 μg/ml) and inhibit the erythrocyte membrane lipid peroxidation (IC₅₀ = 12.02 ± 1.03 μg/ml). The presence of antioxidants was confirmed by comparing with natural antioxidant ascorbic acid. The total phenolic content and total antioxidant activity in curcumin were determined as gallic acid and ascorbic acid equivalents, respectively. Results obtained herein can be attributed to the presence of polyphenols (448.4 ± 8.3 mg GAE/g gallic acid equivalent-polyphenols) in curcumin. These observations suggest the antioxidant and free radical scavenging potentials of curcumin.

Key words: Curcumin, free radical scavenging activity, in vitro, ex vivo