Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan.
Cytotechnology. 2006 Nov;52(3):189-98. doi: 10.1007/s10616-007-9057-4. Epub 2007 Feb 24.
The MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) assay is widely accepted as a simple and reproducible method for determining cell proliferation or cytotoxicity in vitro. In this study, we show that the flavonoids quercetin, rutin and luteolin but not apigenin can reduce MTT in the absence of live cells in the following order: quercetin >> rutin > luteolin > apigenin. Moreover, this reduction can be influenced by medium type and serum. The final concentrations of the flavonoids used were 200, 100, 50, 25 and 12.5 mug/mL. MTT reduction in Dulbecco's Modified Eagle's Medium (DMEM) is statistically higher than those in RPMI 1640 and F12 media, which are generally similar. Particularly for luteolin, MTT reduction is considerably higher with serum than without serum. In the case of quercetin at 50 mug/mL, a serum concentration of even only 0.01% is sufficient to significantly enhance MTT reduction versus that at 0% (P < 0.05). Serum at concentrations ranging from 0% to 5% also dose-dependently affects the pattern of formazan crystal formation. In the presence of 0.156-5% serum, the formazan crystals gradually change from being small, numerous and scattered to being large, few and clumpy. The authors hypothesize that flavonoid structure, nutrient concentration in the culture medium as well as serum components directly affect MTT reduction by flavonoids in the absence of cells.
MTT（3-(4,5-二甲基噻唑基-2)-2,5-二苯基四氮唑溴盐）测定法被广泛认为是一种用于测定体外细胞增殖或细胞毒性的简单且可重复的方法。在本研究中，我们表明，在没有活细胞的情况下，以下黄酮类化合物（槲皮素、芦丁和木樨草素）而非芹菜素可以降低 MTT，其顺序为：槲皮素>芦丁>木樨草素>芹菜素。此外，这种还原作用可以受到培养基类型和血清的影响。所用黄酮类化合物的最终浓度为 200、100、50、25 和 12.5μg/ml。在 DMEM（杜尔贝科改良伊格尔培养基）中 MTT 的减少在统计学上高于 RPMI 1640 和 F12 培养基，这两种培养基通常相似。特别是对于木樨草素，与无血清相比，含血清时 MTT 的减少要高得多。对于 50μg/ml 的槲皮素，即使血清浓度仅为 0.01%，也足以显著增强 MTT 还原作用，与 0%相比（P<0.05）。0%至 5%的血清浓度也会对甲瓒晶体形成的模式产生剂量依赖性影响。在存在 0.156-5%的血清时，甲瓒晶体逐渐从小而多且分散变为大而少且聚集。作者假设黄酮类化合物的结构、培养基中的营养浓度以及血清成分直接影响无细胞状态下黄酮类化合物对 MTT 的还原作用。
