Rückriemen Jana, Klemm Oliver, Henle Thomas
Institute of Food Chemistry, Technische Universität Dresden, D-01062 Dresden, Germany.
Institute of Food Chemistry, Technische Universität Dresden, D-01062 Dresden, Germany.
Food Chem. 2017 Sep 1;230:540-546. doi: 10.1016/j.foodchem.2017.03.075. Epub 2017 Mar 15.
Manuka honey (Leptospermum scoparium) exerts a strong antibacterial effect. Bacterial enzymes are an important target for antibacterial compounds. The enzyme urease produces ammonia and enables bacteria to adapt to an acidic environment. A new enzymatic assay, based on photometric detection of ammonia with ninhydrin, was developed to study urease activity. Methylglyoxal (MGO) and its precursor dihydroxyacetone (DHA), which are naturally present in manuka honey, were identified as jack bean urease inhibitors with IC values of 2.8 and 5.0mM, respectively. Urease inhibition of manuka honey correlates with its MGO and DHA content. Non-manuka honeys, which lack MGO and DHA, showed significantly less urease inhibition. MGO depletion from manuka honey with glyoxalase reduced urease inhibition. Therefore, urease inhibition by manuka honey is mainly due to MGO and DHA. The results obtained with jack bean urease as a model urease, may contribute to the understanding of bacterial inhibition by manuka honey.
麦卢卡蜂蜜（Leptospermum scoparium）具有很强的抗菌作用。细菌酶是抗菌化合物的重要作用靶点。脲酶可产生氨并使细菌能够适应酸性环境。为研究脲酶活性，开发了一种基于茚三酮光度法检测氨的新型酶活性测定方法。麦卢卡蜂蜜中天然存在的甲基乙二醛（MGO）及其前体二羟基丙酮（DHA）被鉴定为刀豆脲酶抑制剂，其IC值分别为2.8和5.0 mM。麦卢卡蜂蜜对脲酶的抑制作用与其MGO和DHA含量相关。缺乏MGO和DHA的非麦卢卡蜂蜜对脲酶的抑制作用明显较弱。用乙二醛酶去除麦卢卡蜂蜜中的MGO会降低对脲酶的抑制作用。因此，麦卢卡蜂蜜对脲酶的抑制作用主要归因于MGO和DHA。以刀豆脲酶作为模型脲酶获得的结果，可能有助于理解麦卢卡蜂蜜对细菌的抑制作用。
