Winterbourne D J, Weingast-Johnson J
Department of Surgery, St. George's Hospital Medical School, London, U.K.
Biochem J. 1994 Jul 15;301 ( Pt 2)(Pt 2):373-7. doi: 10.1042/bj3010373.
Lipofuscin was produced when HT29, a colon carcinoma cell line, was cultured in millimolar concentrations of xanthine and guanine but not in the presence of other bases. Using a simple assay developed to quantify the fluorescent pigment, it was found that maximum levels of lipofuscin were developed in 3 days. Methylxanthines that are not substrates of xanthine dehydrogenase, such as caffeine and theophylline, did not induce formation of lipofuscin. Xanthine-induced lipofuscin formation could be inhibited by oxypurinol, indicating that the pigment may be formed by free radicals generated by xanthine dehydrogenase. It is suggested that the lipofuscin seen in pseudomelanosis coli may result from the accumulation of purines in the colon.
当结肠癌细胞系HT29在毫摩尔浓度的黄嘌呤和鸟嘌呤中培养时会产生脂褐素，但在其他碱基存在的情况下则不会产生。使用一种开发出来用于定量荧光色素的简单检测方法，发现脂褐素在3天内达到最高水平。非黄嘌呤脱氢酶底物的甲基黄嘌呤，如咖啡因和茶碱，不会诱导脂褐素的形成。黄嘌呤诱导的脂褐素形成可被氧嘌呤醇抑制，这表明该色素可能由黄嘌呤脱氢酶产生的自由基形成。有人提出，结肠假黑变病中所见的脂褐素可能是由于结肠中嘌呤的积累所致。
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