柚皮萃取物對巨噬細胞之抗氧化及抗發炎能力評估

Evaluation of Antioxidant and Anti-inflammatory Properties of Pomelo Peel Extracts on Macrophages

本研究探討台灣特有柑橘屬水果-文旦柚的抗氧化與抗發炎特性，分離文旦柚內外果皮並以冷凍乾燥及熱風乾燥兩種方法進行前處理，續以熱萃取、超音波萃取及高壓萃取得柚皮萃取液，並以LPS誘導小鼠巨噬細胞RAW264.7進行發炎評估。分析結果發現，柚皮萃取液中富含總酚及類黃酮，分別最高可得68.97 mg GAE /g solid extract及57.70mg QE/g solid extract。在高效液相層析中得知，主要類黃酮為黃烷酮類之柚苦苷（Naringin），以凍乾後高壓400 MPa所萃取之中果皮Naringin含量最高達91.36 mg/g solid extract。進一步探討柚皮萃取物對其抗氧化及抗發炎能力評估。在發炎介質方面，凍乾後經高壓400MPa處理所萃之中果皮一氧化氮（Nirtric oxide, NO）生成為3.17μM，此處理能降低巨噬細胞生成；高壓200 MPa降低活性氧分子（Reactive oxygen species, ROS）生成效果可達66.5%。在抗氧化的部分，GSH/GSSG ratio受到發炎反應影響下柚皮萃取物仍可維持較LPS處理更高穀胱甘肽（Glutathione, GSH）含量，並降低GSSG生成。綜合結果，柚皮萃取物可提高抗氧化能力與達到減緩LPS所造成小鼠巨噬細胞的發炎反應。柑橘皮廢棄物是未來開發機能保健產品很好來源，並可增加柑橘產業鏈的價值與利用性。 Citrus fruits are an important cash crop throughout the world. Large amounts of peel wastes are produced from the fresh consumption and processing of these fruits. By using different processing methods, valuable bioactive compounds present in fruit peels can be extracted, which not only provide new value for these by-products, but also enhance industrial business opportunities. In this study, a specialty citrus fruit in Taiwan 'Citrus grandis cv. Wentan' was investigated for its antioxidant and anti-inflammatory properties. The insides and peels of the Wendan pomelos were separated and pre-treated using two methods: freeze drying and hot air drying. The pomelo peel extracts were then obtained using hot water extraction, ultrasound-assisted extraction, and high-pressure extraction. The inflammatory responses were evaluated by stimulating inflammation in mouse macrophages with lipopolysaccharide (LPS).The results showed that the pomelo peel extracts were rich in total phenols and flavonoids, and the highest obtained quantities were 68.97 mg GAE．g^(-1) solid extract and 57.70 mg QE．g^(-1) solid extract, respectively. High-performance liquid chromatography (HPLC) results showed that naringin flavanone was the main flavonoid. The highest naringin content in mesocarps extracted extraction via high-pressure extraction at 400 MPa after freeze-drying was found to be 91.36 mg．g^(-1) solid extract. The antioxidant and anti-inflammatory capacities of pomelo peel extracts were further evaluated. In terms of inflammatory mediation, the extracts of mesocarps processed using high-pressure extraction at 400 MPa after freeze-drying reduced the production of nitric oxide (NO) from macrophages to 3.17 μM, and it was found that the effectiveness of extracts obtained via high-pressure extraction at 200 MPa in reducing the generation of reactive oxygen species (ROS) can reach 66.5%. As for the antioxidant effects of the pomelo extracts, despite the influence of the inflammatory response on the GSH/GSSG ratio, the pomelo peel extracts still maintained a higher glutathione (GSH) content compared to cells treated only using LPS, and also reduced the production of oxidized glutathione (GSSG). In conclusion, pomelo peel extracts can enhance cellular antioxidant capacity, and decelerate the inflammatory responses of LPS-stimulated mouse macrophages. Thus, citrus peel waste is an excellent source from which functional health products may be developed in the future; moreover, this will increase the value and utilization of the citrus fruit production chain.