利用體外小鼠淋巴瘤細胞tk試驗法評估蛋黃油及蛋黃熱加工品之基因毒性

Abstract

蛋黃的脂質組成中包含豐富的磷脂質，並廣泛地被認為具有生理機能。然而，蛋黃中亦含有多量的膽固醇，因此經由特定加工方法所製備的蛋黃油產品可能會產生安全上的風險。本研究利用小鼠淋巴瘤細胞株L5178Y（tk+/-）評估蛋黃油與高溫加熱之蛋黃產品的基因毒性。我們首先以細胞毒性試驗評估後續基因毒性之試驗劑量。試驗將樣品以絕對酒精溶解，添加於含5%馬血清之RPMI1640培養基（內含1 x 10^6 cells），均匀混合處理三小時後，觀察細胞毒性。結果發現，三種試驗樣品中，以經過260℃的自製蛋黃油（PYO）對L5178Y細胞之毒性最大，當樣品濃度為0.8 mg/mL時，細胞的致死率達100%，而濃度為0.625 mg/mL時，其細胞致死率約為30%。以70－90%細胞存活的樣品濃度為最高濃度進行基因毒性試驗。先將L5178Y以不同濃度的樣品處理三小時之後，將收集的細胞分為兩部分，一部份繼續培養十二天，測定其存活率；另一部份以含或不含嘧啶類似物TFT（5-trifluorothymidine）3 μg/mL的培養基培養細胞，計算以樣品處理過後引發的突變率。結果顯示，三種試驗樣品不論是否經S9處理，其結果與控制組相比較，對L5178Y tk^(+/-)細胞株皆沒有顯著之致突變性。The oil components in egg yolk is rich in phospholipids, which were reported to possess various bioactivities. On the other hand, it contains considerable amounts of cholesterol as well, and may transformed into oxidized cholesterol during heat processing. The processed egg yolk oil (PYO) products could therefore be harmful to health. In this study, mouse lymphoma cell L5178Y (tk+/-) assay was employed to exam the genotoxicity of the egg oil samples. Three kinds of egg yolk oil samples, namely, processed yolk oil, commercial yolk oil and solvent-extracted yolk oil were dissolved in absolute ethanol, respectively. In cytotoxicity tests, each sample with various concentrations was added into RPMI1640 medium with 5% horse serum containing 1 × 10^7 L5178Y tk+/- cells to incubate for three hours. Among the three kinds of yolk oil samples, processed yolk oil revealed the highest cytotoxicity. Cell survivals were suppressed to 70% when incubated with 0.625 mg/mL of PYO and to 0% when with 1 mg/mL of that. In genotoxicity tests, a thymidine analogue TFT (5-trifluorothymidine) was applied to detect the mutation by 12-days incubation after the 2 days expression period followed the treatment. As the results, whether the three kinds of egg oil samples were treated with S9 mixture or not, no significant genotoxicity was shown toward the cells.