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  • 學位論文

中藥活性成分之保護與抗癌作用研究

Studies on the Bioactive Constituent of Chinese Herbs for the Protective and Anticancer effects

指導教授 : 朱嘉一 劉哲育

摘要


近年來已有發現許多天然物中存在許多具生物活性之分子,而且有些甚至具有防癌及抑制癌細胞生長之功效。本研究主要探討小柏鹼 (berberine ; 0.01-1.0 mM) 與黃芩甘 (baicalin ; 2-220 μM)對tert - butyl hydroperoxide (t-BHP) 有機過氧化劑誘發引起初代培養肝細胞毒性之保護作用。於實驗中發現,這兩種生藥活性成分均可以捕捉1,1-diphenyl-2-picrylhydrazyl radical (DPPH) 而顯示其具有抗氧化的效用;更進一步實驗顯示以 t-BHP (1.5mM) 處理初代培養肝細胞 30 分鐘後所被誘發形成的 Malondialdehyde (MDA) 濃度作為脂質過氧化的指標及培養基中Lactate dehydrogenase (LDH), Alanine aminotransferase (ALT) 等酵素釋放量可被小柏鹼與黃芩甘所抑制。接著,進行動物活體實驗。在大白鼠腹腔注射t-BHP (0.1 mmol/kg) 前五天前先處理小柏鹼與黃芩苷( 0.5及 5 mg/kg )生藥活性成分。結果顯示,這兩種生藥活性成分對生化酵素均具有抗氧化的效果。另外,因為許多具有抗氧化的藥物往往也具有抑癌特性。本研究再深入發現小柏鹼 (50 μM) 造成HepG2細胞凋亡 (cell apoptosis) ,但對正常的Chang liver 細胞並無此影響。實驗結果顯示,小柏鹼對於肝癌細胞株 (HepG2) 經過24小時處理造成DNA片段斷裂現象。另外,小柏鹼會誘發一些分解性酵素 (如 caspase-8及caspase-3)的活性。還會引起poly ADP-ribose polymerase (PARP) 裂解及cytochrome c的釋放。肝癌細胞株(HepG2) 經過12及24小時處理也會活化Fas和粒線體膜電位 (∆Ψm) 的下降,綜合以上實驗結果顯示,這兩種生藥活性成分可能經由捕捉自由基的能力來保護由 t-BHP 所引起之氧化壓力 (Oxidative stress) 造成的傷害。小柏鹼抗癌作用可能經由抑制粒線體與核酸內切酵素途徑而進行。

並列摘要


Recent studies have provided strong evidence that many daily-consumed dietary compounds possess cancer-protective properties that might interrupt the carcinogenesis process. Berberine and baicalin were studied for the mechanism of its inhibitory effects on the tert-butyl hydroperoxide (t-BHP)-induced cytotoxicity and lipid peroxidation in primary culture of rat hepatocytes. In this study, berberine and baicalin showed an effective antioxidant property tested by its capacity of quenching 1,1-diphenyl-2-picrylhydrazyl radical (DPPH). Further investigations showed that berberine (0.01-1.0 mM) and baicalin (2-220 μM) decreased the formation of malondialdehyde (MDA), leakage of lactate dehydrogenase (LDH) and alanine aminotransferase (ALT) and repair synthesis of DNA induced by 30-min treatment of t-BHP (1.5 mM) in primary cultured rat hepatocytes. The in vivo study showed that the i.p. pretreatment of berberine and baicalin (0.5 and 5 mg/kg) for 5 days before a single dose of t-BHP (0.1 mmol/kg) significantly lowered the serum levels of hepatic enzyme markers (ALT and AST) and reduced oxidative stress in the liver. Besides, because many antioxidant compounds have the anticancer property. we further demonstrated that berberine (50 μM) exhibited significant cytotoxicity in hepatoma HepG2 cells but is ineffective in Chang liver cells. The results showed that HepG2 cells underwent internucleosomal DNA fragmentation after 24 h treatment with berberine. Moreover, berberine induced the activation of caspase-8 and caspase-3, and caused the cleavage of poly ADP-ribose polymerase (PARP) and the cytochrome c release. The loss of mitochondrial membrane potential (Δψm) at 24 h and activation of Fas at 12 h were also showed in the berberine-treated HepG2 cells. The sum of the results suggested that the protective effect of berberine and baicalin against oxidative stress induced by t-BHP is via its ability of quenching free radicals. These result provided that potential of anti-hepatoma activity of berberine may be mediated through a caspases-mitochondria dependent pathway.

並列關鍵字

Berberine Baicaluin Antioxidant Apotosis Hepatoma

參考文獻


行政院衛生署出版114-116
究(1980)。台灣醫學雜誌 79: 694-699
34.Huang DC, and Strasser A (2000) BH3-only proteins-
9.Bova S, Padrini R, Goldman WF, Berman DM, Cargnelli G
19.Fukutake M, Yokota S, Kawamura H, Iizuka A, Fukuda K,

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