Abstract：
Acyloxydiene-Fe(CO)3 complexes can act as enzyme-triggered CO-releasing molecules (ET-CORMs). Their biological activity strongly depends on the mother compound from which they are derived, i.e. cyclohexenone or cyclohexanedione, and on the position of the ester functionality they harbour. The present study addresses if the latter characteristic affects CO release, if cytotoxicity of ET-CORMs is mediated through iron release or inhibition of cell respiration and to what extent cyclohexenone and cyclohexanedione derived ET-CORMs differ in their ability to counteract TNF-α mediated inflammation. Irrespective of the formulation (DMSO or cyclodextrin), toxicity in HUVEC was significantly higher for ET-CORMs bearing the ester functionality at the outer (rac-4), as compared to the inner (rac-1) position of the cyclohexenone moiety. This was paralleled by an increased CO release from the former ET-CORM. Toxicity was not mediated via iron as EC50 values for rac-4 were significantly lower than for FeCl2 or FeCl3 and were not influenced by iron chelation. ATP depletion preceded toxicity suggesting impaired cell respiration as putative cause for cell death. In long-term HUVEC cultures inhibition of VCAM-1 expression by rac-1 waned in time, while for the cyclohexanedione derived rac-8 inhibition seems to increase. NFκB was inhibited by both rac-1 and rac-8 independent of IκBα degradation. Both ET-CORMs activated Nrf-2 and consequently induced the expression of HO-1. This study further provides a rational framework for designing acyloxydiene-Fe(CO)3 complexes as ET-CORMs with differential CO release and biological activities. We also provide a better understanding of how these complexes affect cell-biology in mechanistic terms.
摘要：
酰氧基二烯-Fe（CO）3复合物可以充当酶触发的CO释放分子（ET-CORM）。它们的生物活性在很大程度上取决于它们衍生的母体化合物，即环己烯酮或环己二酮，以及它们所拥有的酯功能的位置。本研究探讨了如果后一种特征影响CO释放，如果ET-CORM的细胞毒性是通过铁释放或细胞呼吸抑制介导的，以及环己烯酮和环己二酮衍生的ET-CORM在抵抗TNF-α介导的炎症的能力方面存在差异。不考虑配方（DMSO或环糊精），在HUVEC中的毒性对于在外部（rac-4）具有酯官能团的ET-CORM明显更高，与环己烯酮部分的内部(rac-1)位置相比。这与前ET-CORM的CO释放增加平行。毒性不是通过铁介导的，因为rac-4的EC50值显着低于FeCl2或FeCl3，并且不受铁螯合的影响。ATP消耗先于毒性，表明细胞呼吸受损是细胞死亡的推定原因。在长期HUVEC培养物中，rac-1对VCAM-1表达的抑制作用随时间减弱，而对于环己二酮衍生的rac-8抑制似乎增加。NFκB被rac-1和rac-8抑制，而与IκBα降解无关。两种ET-CORM均激活Nrf-2并因此诱导HO-1的表达。本研究进一步为设计具有不同CO释放和生物活性的酰氧基二烯-Fe（CO）3配合物作为ET-CORM提供了合理的框架。我们还提供了对这些复合物如何在机械方面影响细胞生物学的更好理解。
