| 摘要: | 許多研究顯示類胡蘿蔔素具有改善抗氧化及降低脂質過氧化
的能力，故推測類胡蘿蔔素具有降低與自由基和活性氧有關的心血
管疾病以及癌症，但也有體外實驗發現beta-胡蘿蔔素不具有增加抗氧
化與降低脂質過氧化的效果。目前研究中較少探討類胡蘿蔔素對大
白鼠初代肝細胞中抗氧化狀態及脂質過氧化的影響。故本研究採用
體外實驗方式，先以類胡蘿蔔素處理大白鼠初代肝細胞，期望類胡
蘿蔔素能對肝細胞產生保護的作用，再加入過氧化氫(H2O2)作為氧
化誘導劑，以增加細胞內之氧化壓力，進而探討抗氧化酵素活性以
及脂質過氧化的影響。
結果顯示：第一，肝細胞在正常的情況之下，細胞生存力隨著
培養時間的增加而減弱，即LDH leakage隨著培養時間的增加而增
加。由本實驗結果將後續實驗的觀察時間點定為24小時；第二，
加入0~100 uM 過氧化氫，觀察細胞之脂質過氧化及抗氧化狀態的
變化以決定後續實驗之氧化誘導劑的添加濃度及添加時間。由本實
驗結果決定以10 uM過氧化氫處理10分鐘；第三，在大白鼠初代
肝細胞中添加抗氧化劑（包括：beta-carotene、canthaxanthin、alpha-
carotene、lutein、retinol或alpha-tocopherol）於培養液中培養20小
時，再添加或不添加10 uM過氧化氫培養10分鐘，之後觀察細胞
的脂質過氧化以及抗氧化狀態的改變；發現不同類胡蘿蔔素間抗氧
化狀態有顯著性差異：canthaxanthin、lycopene或lutein較beta-胡蘿
蔔素可增加抗氧化酵素活性（如：SOD、GRd和GST），亦發現
類胡蘿蔔素有減少脂質過氧化的趨勢。同時乳化態的類胡蘿蔔素抗
氧化效果較脂溶性的類胡蘿蔔素效果顯著。
The studies have shown the important roles of carotenoids in
improving antioxidative capacity and decreasing lipid peroxidation,
indicating carotenoids may decrease the incidence of cardiovascular
disease and cancer related to free radicals and reactive oxygen species.
However, it was reported that no effect of beta-carotene on enhancing
antioxidative status and lowering lipid peroxidation in vitro was observed.
The effects of carotenoids on antioxidative status and lipid peroxidation
in rat hepatic explants were less studied. Therefore, it was hypothesized
that carotenoids could protect rat hepatic explants from peroxidation in
vitro. Furthermore, this study investigated the effects of carotenoids on
antioxidant enzyme activities and lipid peroxidation after the addition of
hydrogen peroxide as an oxidative inducer to increase oxidative stress in
the cells.
Firstly, the results showed that lactate dehydrogenase (LDH) leakage
was increased with increased culture time, suggesting cell viability of the
hepatocytes was decreased under the normal condition. The time course
study found that LDH leakage was significantly increased after 24-h beta-
carotene treatment. Secondly, the dose and timing were determined by
the results of lipid peroxidation and antioxidative status after the addition
of 0~100 uM hydrogen peroxide. The dose and time course studies
indicated that the treatment of 10 uM hydrogen peroxide for 10 min could
induce the antioxidative enzyme activities. Thirdly, the effects of beta-
carotene, canthaxanthin, alpha-carotene, lutein, retinol or alpha-tocopherol
on lipid peroxidation and antioxidative status after 20-h incubation with or
without pretreatment of 10 uM hydrogen peroxide for 10 min were
investigated. The data indicated that various antioxidative status was
observed after the addition of different carotenoids. Canthaxathin,
lycopene, or lutein increased the activities of superoxide dismutase,
glutathione reductase, and glutathione S-transferase as compared to bata-
carotene. In addition, carotenoids had a tendency to inhibit lipid
peroxidation. It was also found that beadlet carotenoids, especially
anthaxanthin and lutein, had better antioxidative effectiveness compared
to oil-soluble carotenoids (crystalline form). |
