García-Peláez B, Ferrer-Lorente R, Gómez-Ollés S, Fernández-López J A, Remesar X, Alemany M
Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, Barcelona, Spain.
J Dairy Sci. 2004 Aug;87(8):2331-6. doi: 10.3168/jds.S0022-0302(04)73354-8.
Estrone is a powerful growth-inducing hormone that is present in milk, mainly in the form of fatty acid esters, at concentrations that promote growth in experimental animals. We present here a method useful for the measurement of this natural hormone in foods and applied it to several common dairy products. Samples were frozen, finely powdered, and lyophilized then extracted with trichloromethane/methanol; the dry extract was saponified with potassium hydroxide. The free estrone evolved was extracted with ethyl acetate and was used for the estimation of total estrone content through radioimmunoassay. Application of the method to dairy products showed high relative levels of total estrone (essentially acyl-estrone) in milk, in the range of 1 microM, which were halved in skimmed milk. Free estrone levels were much lower, in the nanomolar range. A large proportion of estrone esters was present in all other dairy products, fairly correlated with their fat content. The amount of estrone carried by milk is well within the range, where its intake may exert a physiological response in the sucklings for which it is provided. These growth-inducing and energy expenditure-lowering effects may affect humans ingesting significant amounts of dairy products.
雌酮是一种强大的促生长激素，它以脂肪酸酯的形式存在于牛奶中，其浓度足以促进实验动物生长。我们在此介绍一种可用于测定食品中这种天然激素的方法，并将其应用于几种常见的乳制品。将样品冷冻、磨成细粉并冻干，然后用三氯甲烷/甲醇萃取；干燥提取物用氢氧化钾皂化。释放出的游离雌酮用乙酸乙酯萃取，并通过放射免疫测定法用于估算总雌酮含量。该方法应用于乳制品时表明，牛奶中总雌酮（主要是酰基雌酮）的相对含量较高，在1微摩尔范围内，而脱脂牛奶中的含量减半。游离雌酮水平要低得多，在纳摩尔范围内。所有其他乳制品中都含有很大比例的雌酮酯，且与它们的脂肪含量有相当的相关性。牛奶中所含雌酮的量完全在这样一个范围内，即其摄入量可能会对食用牛奶的幼崽产生生理反应。这些促生长和降低能量消耗的作用可能会影响大量食用乳制品的人类。
