Antioxidant activity and total phenolic content of sesame (Sesamum indicum L.) seed oil

Abstract

Minor components, especially antioxidative constituents, play an imperative role in the nutritional and health impact of edible oils. This study was carried out to determine the antioxidant activity and total phenolic content of Sesame (Sesamum indicum L.) seed oil, which currently remains as an underutilized oil in Sri Lanka. The phenolic fraction of the oil was extracted into methanol by passing the oil through a glass column containing silica (60 Å). The Total Phenolic Content (TPC) was determined using Folin-Ciocalteu's colorimetric method and expressed as mg of gallic acid equivalents (GAE) per gram of extract. The antioxidant potential of the oil extracts was assessed using DPPH and ABTS radical scavenging assays and β-carotene/linoleate model system. α-Tocopherol was used as the reference antioxidant. Sesame seed oil extracts possessed a higher TPC (26.00 ± 0.14 mg GAE/g of extract) compared to the reference antioxidant, α-tocopherol (18.00 ± 0.12 mg GAE/g). The DPPH radical scavenging activity of the oil extract and α-tocopherol was 0.026 mg/mL and 0.031 mg/mL, respectively. The ABTS radical scavenging activity of the oil extract and α-tocopherol were 58.0 % and 46.0 %, respectively, at 2.0 % (w/v) concentration. Sesame seed oil extract exhibited a significantly higher percentage (p<0.05) of inhibition of linoleic acid induced oxidation of β-carotene (53.6 %) compared to α-tocopherol (45.0 %) at 2.0 % (w/v) concentration. Results revealed that the sesame seed oil possessed a strong antioxidant activity compared to α-tocopherol, therefore, can be categorized as an edible oil with a high potential of antioxidant activity.