Free Radical Scavenging Capacity and Total Phenolic Contents in Peel and Fleshy Crude Extracts of Selected Vegetables

Context: Vegetables are sources of natural antioxidants which have beneficial health-promoting properties. Aims: This research was conducted to evaluate the antioxidant potentials and total phenolic contents in vegetable extracts. Settings and Design: The experiment was divided two groups using six vegetable peels and fleshes, including potato (Solanum tuberosum L.), carrot (Daucus carota L.), bitter gourd (Monordica Charantia L.), pumpkin (Cucurbita moschana Duchesn), Chinese radish (Raphanus sativus L.), and cucumber (Cucumis sativus L.). Materials and Methods: The samples were extracted with 95% ethanol for 24 hrs and then analyzed the antioxidant activities by DPPH and FRAP assay and total phenolic contents was determined by Folin-Ciocalteu assay. Statistical analysis used: All the analysis was done in triplicate, and values are represented as means ± standard deviations. The data were subjected to one-way analysis of variance (ANOVA) and significance differences between mean values were determined by Tukey’s multiple comparison tests (p < 0.05). Pearson correlation coefficient was determined between the antioxidant activities and total phenolic contents using SPSS version 21. Results: The results revealed that antioxidant activities were different statistically significant in each group (p < 0.05). Carrot peel was the most potent in DPPH radical scavenging activity (61.80 ± 6.14%) and reducing power (0.75 ± 0.25 mM Fe²⁺/g extract) and potato flesh could inhibit DPPH radical (35.60 ± 0.63 %) and had the highest FRAP value (0.61 ± 0.78 mM Fe²⁺/g extract). Pumpkin peel and Chinese radish flesh had the most total phenolic contents as 110.45 ± 22.49 and 142.15 ± 3.53 mg GAE/g extract, respectively. Although no correlations was between antioxidant activities and total phenolic contents in extracts but were significant correlations between DPPH and FRAP assay in vegetable peels and fleshes as 0.931 and 0.819, respectively. Conclusion: This study substantiates the potential of vegetable peels to be used as functional foods and natural free radical scavengers.