Bioactive compounds and the antioxidant capacities of seed oils from pomegranate (Punica granatum L.) and bitter gourd (Momordica charantia L.)

Abstract Pomegranate and bitter gourd are two of the few edible fruits that contain conjugated α-linolenic acids (CLnAs) in their seeds. The CLnAs have been associated with many effects that are beneficial to health, such as antioxidant and anti-inflammatory properties. Samples of cold-pressed oils from pomegranate and bitter gourd seeds were evaluated for their phytochemical compositions (fatty acids, tocopherols and phytosterols), their qualities and their stability parameters. The in vitro antioxidant capacities of these oils were evaluated by β-carotene bleaching, DPPH• scavenging, oxygen radical absorbance capacity (ORAC) and ABTS• scavenging assays. Several differences in the compositions of the fatty acids, the bioactive compounds and the antioxidant capacities were observed for the two seed oils (pomegranate and bitter gourd) when they were assessed. The highest contents for the phytochemicals (conjugated α-linolenic acids, β-sitosterols, γ-tocopherols) and the in vitro antioxidant capacities were found in the pomegranate seed oil, when using both the DPPH• and ABTS• methods. These results have indicated that seed oils with bioactivity properties can be a challenge for more research, in order to address absorption, health benefits and technological applications.摘要 石榴与苦瓜是少数几种种子中含有共轭α-亚麻酸（conjugated α-linolenic acids，CLnAs）的可食用水果。该类共轭α-亚麻酸已被证实具备多种有益于人体健康的生理活性，包括抗氧化与抗炎特性。本研究以冷榨提取的石榴籽油及苦瓜籽油为样品，对其植物化学组成（脂肪酸、生育酚与植物甾醇）、品质特性及稳定性参数进行了评估。采用β-胡萝卜素漂白法、DPPH•自由基清除法、氧自由基吸收能力（oxygen radical absorbance capacity，ORAC）测定法以及ABTS•自由基清除法，对两种籽油的体外抗氧化能力开展了检测。实验结果显示，两种籽类油在脂肪酸组成、生物活性化合物含量以及体外抗氧化能力方面均存在显著差异。通过DPPH•与ABTS•两种检测方法均可证实，石榴籽油的共轭α-亚麻酸、β-谷甾醇、γ-生育酚等植物化学物质含量，以及体外抗氧化能力均显著高于苦瓜籽油。本研究结果表明，针对具备生物活性的籽类油，在其吸收机制、健康获益及技术应用等方向开展进一步研究仍具有重要意义与探索空间。