Phytochemical and Antioxidant Profile: Cucumber Pulp and Leaves Extracts

Abstract

BACKGROUND: Many vegetables and fruits have been shown to be sources of antioxidant such as lemons, apples, cabbage, mangoes, beets, and guavas   AIM: This research aimed to determine antioxidant activity of Cucumis sativus L. (cucumber) pulp and leaves extracts using DPPH and CUPRAC methods, total phenolic content (TPC), total flavonoid content (TFC), correlation of TPC and TFC on antioxidant activity, correlation between the two methods, identification of marker, and total marker content.   METHODS: Antioxidant activity was examined by determining IC50 and AAI of DPPH and EC50 and AAI of CUPRAC. TFC and TPC was measured using UV-visible spectrophotometer. Correlation of TPC and TFC on antioxidant activity was analysed by Pearson’s method.   RESULTS: AAI of DPPH of cucumber pulp and leaves extracts in the range of 0.22 - 2.18, whereas AAI of CUPRAC 0.07 - 0.95. All extracts showed antioxidant activity. Ethyl acetate cucumber pulp extract had highest antioxidant by DPPH assay, whereas n-hexane cucumber leaves extract had highest antioxidant activity by CUPRAC assay. Ethyl acetate cucumber leaves extract had highest TFC value (21.47 g QE/100 g) and TPC value (2.34 g GAE/100 g). Flavonoids in cucumber pulp extract contributed to antioxidant activity of CUPRAC method and phenolic compounds in cucumber pulp extract gave a contribution to antioxidant activity of DPPH method. Quercetin content as marker in ethanol cucumber pulp extract was 0.00114%. AAI CUPRAC and DPPH of cucumber leaves extract showed positive correlation but not significant.   CONCLUSION: Antioxidant activity between CUPRAC and DPPH methods on cucumber extracts were not linear.