白花檵木與郁李萃取物之生理活性研究

Study of bioactivities for the extracts of Loropetalum chinense and Prunus glandulosa

高巧玟(Chiu-Wen Kao)

指導教授 ： 林銘澤

大同大學/工程學院/生物工程學系所/碩士(2010年)

摘要

以95%酒精粗萃取白花檵木 (Loropetalum chinense) 與郁李(Prunus glandulosa) 之枝與葉並以水與正己烷、乙酸乙酯及正丁醇連續萃取分層，將萃取物分別命名為酒精粗萃物 (E)、正己烷分劃物 (EH)、乙酸乙酯分劃物 (EE)、正丁醇分劃物 (EB) 與水層分劃物 (EW)，之後測試各萃取物的抗氧化能力與其對細胞之生理活性。
比較DPPH清除自由基能力、ABTS總抗氧化力與還原能力，發現白花檵木較郁李有良好的抗氧化能力，其中以檵枝EE抗氧化能力最優異，分別為trolox的1.4、1.4與1.5倍；沒食子酸為白花檵木主要成分之一，其清除DPPH自由基能力更為trolox的2倍以上。另分析總酚、原花青素與總黃酮量則發現不論白花檵木或郁李都不到catechin的0.4倍。
將分層萃取物分別以MTT、neutral red、SRB法分析HepG2細胞活性，結果顯示經0 ~ 25ppm 萃取物對細胞沒有明顯毒性。另以tert-butyl hydroperoxide (t-BOOH) 傷害HepG2細胞之前或後，分層萃取物處理24小時，發現多數萃取物皆能降低t-BOOH對HepG2細胞的傷害，50 ppm檵葉EE與EB有最好的預防效果，相對細胞活性分別為未傷害處理的控制組之209%與210%，不過其主要成分之一的沒食子酸並沒有保護細胞的能力，其相對活性低於控制組。
最後分析HepG2細胞受t-BOOH傷害後，細胞內活性氧 (ROS) 含量，並觀察細胞凋亡之現象，結果發現檵葉萃取物能有效降低受t-BOOH傷害之HepG2細胞中ROS含量，並能減少細胞凋亡的百分比。
結果顯示檵葉有優異的抗氧化能力，並且能降低HepG2細胞受到t-BOOH之氧化傷害，但保護細胞免於氧化傷害能力，並非來自沒食子酸而是其它物質。

關鍵字

白花檵木 ； 郁李 ； 抗氧化 ； HepG2 ； 萃取

並列摘要

The crude extracts of the branch and leaf of Loropetalum chinense (L. chinense) and Prunus glandulosa (P. glandulosa ) were obtained using 95% ethanol. The 95%-ethanolic extracts were subsequently extracted layer by layer with n-hexane, ethyl acetate and butyl alcohol. The extracts were named alcoholic crude extract (E), hexane-fractionated extract (EH), ethyl acetate-fractionated extract (EE), butanol-fractionated extract (EB) and water-layer extract (EW), respectively. Then, the antioxidant abilities and cellular physiological activities of the crudes were examined.
Based on DPPH free radical scavenging, total ABTS antioxidative and ferric reducing capacities, extracts from L. chinense exhibited better antioxidative abilities than ones from P. glandulosa. The antioxidative abilities of EE from L. chinense branch were 1.4, 1.4 and 1.5 times higher than that of trolox, respectively. The DPPH free radical scavenging capacity of gallic acid, one of the major components in L. chinense extracts, was more than 2 times for that of trolox. Moreover, analysis of the total polyphenol contents, oligomeric proanthocyanidins contents, and total flavonoids contents of extracts and fractionations from L. chinense and P. glandulosa were less than 40% catechin-equivalent.
The cytotoxic activities of the extracts to HepG2 cell were analyzed by MTT, neutral red and SRB assays, and the results showed that crude extracts from 0 to 25 ppm exhibited no significant cytotoxicity. In addition, the extracts were added to HepG2 cells before and after tert-butyl hydroperoxide (t-BOOH) was added, respectively, for 24 hours. The results indicated most of extracts were able to reduce the t-BOOH induced damage on HepG2 cells, and EE and EB of L. chinense leaf showed best preventive effects, exhibiting relative cellular activities at 209% and 210% of untreated control cells, respectively. However, gallic acid did not show any cell protection ability, and its relative cellular activity was lower than that of the control group.
The cellular ROS production and cell apoptosis induced by t-BOOH was also investigated. The result showed that the L. chinense leaf could effectively decrease ROS production and reduce the percentage of apoptotic HepG2 cells induced by t-BOOH.
The extracts of L. chinense leaf displayed superior antioxidative capacity as well as the ability to decrease the oxidative damage induced by t-BOOH, and it is some other substances other than gallic acid for preventing cells from oxidative cytotoxicity.

並列關鍵字

Loropetalum chinense ； Prunus glandulosa ； antioxidant ； HepG2 ； extract

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