| Abstract: | 本研究目的在探討大蒜精油（garlic oil, GO）及大蒜精油活性成分-二烯丙基硫化物（diallyl sulfide, DAS）、二烯丙基二硫化物（diallyl disulfide, DADS）對大鼠免疫調節作用、肝中磷脂質脂肪酸代謝、肝中解毒酵素系統與抗氧化系統的生理效應。
實驗以四週大離乳雄性ＳＤ大鼠為對象，隨機分為6組，分別為餵飼高油飲食四組，並於實驗期間分別灌食玉米油（CO,2ml/kg, 對照組）、GO（200mg/kg）、DAS（200mg/kg ）或DADS（200mg/kg）；另外二組則為餵飼AIN-76低油飲食，分別灌食CO與GO（200mg/kg）。每週灌食3 次，為期7週，犧牲後解剖取出肝臟、脾臟或採血進行生化分析，也有部分老鼠則在犧牲前進行CKNB或巴豆油（croton oil）處理，誘發接觸性過敏反應（contact hypersensitivity）或刺激性皮膚炎（irritant dermatitis）反應、
結果顯示，在肝中磷脂質脂肪酸組成方面，GO與DADS皆會增加亞麻油酸（18:2,n-6）及減少花生四烯酸（20:4,n-6)(p<0.05），其中又以GO組最為明顯，至於DAS則只增加亞麻油酸，但對花生四烯酸則無影響。進一步分析△6去飽和酉每（△６desaturase）和磷脂質脂解酉每Ａ２，（phospholoipase A2, PLA2）酵素活性及前列線素（prostaglandin E2,PGE2）濃度，發現GO組抑制約45%的△6去飽和酉每活性（P<0.05），但PLA2活性和PGE2濃度則不受GO、DAS或DADS影響。
在脾臟淋巴球增生。CDNB誘發的接觸性過敏反應及巴豆油誘發的刺激性皮膚炎反應方面，結果顯示，相較對照組，GO處理顯著顯著增加脾臟淋巴球增生，並抑制接觸性過敏反應（Ｐ<0.05），但對刺激性皮膚炎反應則沒顯著影響。
在肝中解毒酵素方面，無論是活性分析或是蛋白質表現，DAS處理會增加2B1-POD活性及表現，２E1方面，則僅在蛋白質表現方面受到GO、DAS及DADS的抑制；除此外，GO、DAS與DADS處理也顯著增加了GST活性（P<0.05) ，如以免疫西方墨點法分析，則顯示pGST明顯被誘發，其中又以DADS效果最顯著。
在肝臟氧化及抗氧化作用方面，不同處理對肝中TBARS、維生素Ｅ、還原態麩胱甘月太（GSH ）、氧化態麩胱甘月太（GSSG）及GSH/（GSH +GSSG）皆不影響，但維生素Ｅ及GSH濃度會受飲食處一影響，AIN-76飲食組肝中維生素Ｅ較高油飲食組低；除此外，AIN-76飲食組肝中維生素Ｅ較高油飲食組低；除此外，AIN-76飲食組也有較多GSH濃度及較高GSH /(GSH+GSSG)比值。在抗氧化酵素方面，GO、DAS與DADS均明顯抑制麩胱甘月太過氧化酉每（GSH peroxidase）活性，但均增加麩胱甘月太還原酉每GSH reductase）活性（P<0.05），至於超氧化岐化酉每（superoxide dismutase, SOD）活性，僅見GO灌食在高油飲食組中有活化作用（P<0.05）。在紅血球GSH 濃度方面，高油組DAS與DADS及低油組GO灌食皆可顯著增加GSH濃度（P<0.05），至於高油組中GO灌食皆可顯著增加GSH 濃度（P<0.05），至於，高油組中GO灌食雖也可增加紅血球GSH濃度但未達統計上差異。
由以上結果得知，GO減少肝臟磷脂質脂肪酸組成花生四烯酸量，可能是透過抑制△６desaturase酵素活性所至。除此外，GO可增加脾臟淋巴細胞增生的活性但抑制CDNB 誘發的接觸性過敏反應，因此GO在免疫調節上扮演的角色值得做更進一步探討，並瞭解其活性成分為何。
除此外，GO的生理活性是可能透過改變解毒酵素或抗氧化酵素活性，但GO的這些生理活性並不一定完全與其活性成分DAS或DADS顯現出的效果一致，因此，GO應尚有其他活性成分值得進一步分析。除此外，GO的部分生理效應似乎受到飲食中油脂量的影響。
The purpose of this study was to investigative the physiological roles of garlic oil (GO) and it''s active components-diallyl sulfide (DAS), diallyl disulfide(DADS)on the metabolism of hepatic phospholipid fatty acids; on the immunoresponsiveness: including splenocytes proliferation, CDNB-induced contact hypersensitivity, and croton oil-induced irritant dermatits; on the liver detoxification enzyme system, including P450 content, P450 content, P450 reductase, P450 2B1POD,P450 2E1-NDMA,and glutathione -S-transferase (GST) activities and also to investigate the effect of GO, DAS, and DADS on the antioxidant system, including vitamin E,glutathione (GSH) levels, GSH peroxidase, GSH reductase, and superoxide dismutase (SOD) activities . Meanwhile, the concentration of GSH in RBC was also measured in this study.
In the components of hepatic phospholipid fatty acids, both GO and DADS increased linoleic acid (18:2, n-6) and decreased arachidonic acid (20:4,n-6), but GO showed the stronger effect than DADS. DAS also increased linoleic acid but had no effect on arachidonic acid By examing the activities of hepatic △６desaturase, PLA2 and the concentration of plasma PGE2, results showed that GO significantly inhibits the activity of △6 desaturase (P<0.05), however, the activity of PLA2 and the concentration of PEG2 were not affected by GO, DAS or DADS.
The results of splenocytes proliferation, contact hypersensitivity and irritant dermatitis showed that GO increases the splenocyte proliferation and inhibits the contact hypersensitivity, but shows no effect on the irritant dermatitis.
In detoxification system GO, DAS, and DADS significantly increased the activity of GST. Immuno blotting analysis indicated that pGST expression is apparently induced and DADS shows the strongest effects. In cytochrome P450 system, however, only DAS show the stronger effect than GO and DADS. DAS significantly increased the activity of POD and such a result was supported by the immunoblot assay.
In the hepatic antioxidant system, GO, DAS, and DADS showed no effects on the hepatic TBARS, vitamin E, GSH, and GSSG level, but GO decreased GSH/(GSH+GSSG) than controls (p<0.05) . Of the antioxidant enzyme activities, GO, DAS and DADS significantly inhibited the activity of GSH peroxidase but increased the activity of GSH reductase (P<0.05) , the activity of SOD was only observed to increase in GO-treated group (P<0.05). Although hepatic GSH status was not affect by GO and it''s two active components, the level of GSH in RBC was increased by GO , DAS and DADS, and those obtained in DAS-and DADS-treated groups were significant higher than control.
AS stated above, GO, DAS, and DADS showed physiological activities in rats, but these activities, somehow, are modulated by dietary fat level, such as hepatic vitamin E,GSH, and GSH/(GSH+GSSG)level.
Results suggest that the biological activities of GO may affect the synthesis of arachidonic acid or modulate the activity of cytochrome P450 or antioxidant enzymes, but these biological activities of GO are not as the same with it''s components-DAS and DADS. Hence, the presence of other active components of GO are worth being further evaluated .Besides, the dietary oil level seems to affect the partially biological function of GO. |
