Chemical Constituents of Carissa opaca Extracts and Their Evaluation as Antioxidants and Preservatives in Edible Oils

Abstract

Carissa opaca (Stapf ex Haines) leaves were extracted using Soxhlet

apparatus with petroleum ether (COE-PE), chloroform (COE-CH), ethyl

acetate (COE-EA), acetone (COE-AC), methanol (COE-ME), n-butanol

(COE-BU) and water (COE-WA). Antioxidant potential of Carissa

opaca extracts (COEs) was evaluated by four methods: ferric thiocyanate,

thiobarbituric acid, scavenging of DPPH^• and total antioxidant capacity

along with determination of total phenolics and antioxidant potential of

COEs in peanut and sunflower oils. Results revealed that COEs had

significant antioxidant potential (inhibition of lipid peroxidation > 50 %)

and DPPH· scavenging potential (scavenging > 80 %). Moreover, total

phenolic content was also higher in the extracts: COE-AC = 940 and

COE-BU = 600 mg of gallic acid equivalents (GAE). Application of

COEs as natural antioxidants in peanut and sunflower oils significantly

reduced lipid peroxidation (inhibition > 60 %). A strong correlation of

total phenols was observed with DPPH^• and total antioxidant capacity

assays (R² = 0.9776 and R² = 0.8104, respectively).