Introduction. Rhein (4, 5-dihydroxyanthraquinone-2-carboxylic acid) has various properties, including anti-inflammatory, antioxidant and anticancer activities. However, the mechanism underlying the role of rhein in antimicrobial activity remains largely unknown.Aim. This study aims to identify potential natural compounds of rhein that are capable of inhibiting Cutibacterium acnes and elucidate the effects of rhein on NADH dehydrogenase-2 activity in C. acnes.Methodology. The anti-C. acnes activity of compounds was analysed using minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), the paper disc diffusion test and the checkerboard dilution test. To check whether rhein was inhibitory, putative type II NADH dehydrogenase (NDH-2) of C. acnes was analysed, cloned and expressed in Escherichia coli, and then NDH-2 purification was assessed with Ni-NTA before rhein inhibition of NADH dehydrogenase-2 activity was checked with ferricyanide [K3Fe(CN)6] as a substrate.Results. The results showed that the MIC of rhein against C. acnes was 6.25 µg ml-1, while the MBC was 12.5 µg ml-1, and there was a 38 mm inhibition zone in the paper disc diffusion test. Rhein showed an additive two- to fourfold reduction of the MIC value with four antibiotics on the checkerboard dilution test. The purified NADH dehydrogenase gene product showed a size of approximately 51 kDa and had a V max of 23 µmol and a K m of 280 µm. The inhibitory effect of rhein against NADH dehydrogenase-2 activity was non-competitive with ferricyanide [K3Fe(CN)6] with a K i value of 3.5-4.5 µm.Conclusion. This study provided evidence of the inhibitory effects of rhein on the growth of C. acnes by blocking of NADH dehydrogenase-2 activity. This mechanism of inhibitory activity in the reduction of ROS formation and ATP productivity should be further tested in C. acnes and the question of whether rhein inhibits the natural growth of C. acnes should be investigated.

中文翻译：

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大黄酸通过阻断NADH dehydrogenase-2活性来抑制痤疮丙酸杆菌的生长。

介绍。大黄酸（4，5-二羟基蒽醌-2-羧酸）具有多种特性，包括抗炎，抗氧化和抗癌活性。然而，大黄酸在抗菌活性中发挥作用的基本机制仍然未知。这项研究旨在确定潜在的大黄酸天然化合物，该化合物能够抑制痤疮痤疮杆菌并阐明大黄酸对痤疮丙酸杆菌中NADH脱氢酶2活性的影响。反C。使用最小抑菌浓度（MIC），最小杀菌浓度（MBC），纸片扩散测试和棋盘稀释测试分析化合物的痤疮活性。为了检查大黄酸是否具有抑制作用，分析，克隆并在大肠埃希氏菌中表达了假定的II型NADH脱氢酶（NDH-2），然后用Ni-NTA评估NDH-2的纯化，然后以铁氰化物[K3Fe（CN）6]为底物检查大黄酸对NADH脱氢酶-2活性的大黄酸抑制。结果表明，大黄酸对痤疮丙酸杆菌的MIC为6.25 µg ml-1，而MBC为12.5 µg ml-1，在纸盘扩散测试中有38 mm的抑制区。大黄酸在棋盘稀释测试中显示出MIC值与四种抗生素的MIC值相差两到四倍。纯化的NADH脱氢酶基因产物的大小约为51kDa，Vmax为23μmol，Km为280μm。大黄酸对NADH脱氢酶-2活性的抑制作用与铁氰化物[K3Fe（CN）6]的K i值为3.5-4.5 µm无竞争性。结论。这项研究提供了大黄酸对C的生长的抑制作用的证据。通过阻断NADH脱氢酶2活性来抑制痤疮。这种抑制活性降低ROS形成和ATP生产力的机制应该在痤疮丙酸杆菌中进一步测试，并且应该研究大黄酸是否抑制痤疮丙酸杆菌自然生长的问题。