Antioxidant activity and the estimation of total phenolic content of Citrullus colocynthis stem

To examine the antioxidant and free radical scavenging activity of Citrullus colocynthis stem, five different extracts were investigated. Various in vitro antioxidant assay including DPPH (2,2-diphenylpicrylhydrazyl) radical, superoxide radical, hydroxyl radical scavenging activity along with reducing power and metal chelating activity were done and compared with standard antioxidants such as ascorbic acid, BHT (Butylated hydroxytoluene) and EDTA (Ethylene diamine tetra acetic acid). Total phenolic content was determined as mg/g Gallic acid equivalent and was correlated with antioxidant assays. All the five extracts showed significant antioxidant activity in dose dependent manner. Methanolic extract possesses the highest scavenging ability for all the assays and total phenolic content in it was 40.12 mg/g gallic acid equivalent. In case of methanolic extract significant correlation was observed between total phenolic content and various antioxidant assays suggesting its role as a source of valuable antioxidants against free radicals associated oxidative stress.