Isolation and Identification of Major Antioxidativeand Anti-Fatty Liver Phytocompounds from LeafExtract of Rhododendron oldhamii Maxim.

• Main Authors: Ya-Ling Liu, 劉雅玲
• Other Authors: 吳志鴻
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/58714096045617805547

碩士 === 國立中興大學 === 森林學系所 === 103 === Rhododendron is not only one of the most famous ornamental plants in the world, but also it is a traditionally medicinal plant. However, the potential bioactivities of Rhododendron oldhamii Maxim. have not yet been studied completely to date. In this study, the methanolic crude extract of R. oldhamii were fractionated and divided into n-hexane, EtOAc, BuOH, and water soluble fractions by liquid–liquid partition. In addition, a number of in vitro assays including DPPH radical scavenging assay, superoxide radical scavenging assay, reducing power assay, and total phenolic contents were carried out to evaluate the antioxidant activities of n-hexane, EtOAc, BuOH, and water soluble fractions. Among them, the EtOAc fraction exhibited the best antioxidant activity. Base on bioactivity-guided isolation principle, the EtOAc fraction was further monitored by an on-line HPLC-DPPH method for a rapid screening of antioxidative phytochemicals. Six specific phytochemicals were isolated and identified as (2R,3R)-epicatechin (1), (2R,3R)-taxifolin (2), (2R,3R)-astilbin (3), hyperoside (4), guaijaverin (5), and quercitrin (6). Of these, compound 3 was found to be the major bioactive compound, and it’s contents were determined to be 130.8 mg per gram of EtOAc fraction. Furthermore, compounds 4 and 6 exhibited the best DPPH radical scavenging activity and superoxide radical scavenging activity, respectively. On the other hand, compounds 4 and 6 also exhibited activity on inhibiting HepG2 cell line lipogenesis. In C57BL/6 mice animal model, feeding of EtOAc fraction from the mathanolic crude extract of R. oldhamii has an effective anti-fatty liver capability, which also lowered cholesterol and fat synthesis related iii mRNA SREBP-1 expression, and increased metabolism related mRNA CPT-1α, PPAR-α and PPAR-γ expression.