Scalcon Valeria, Citta Anna, Folda Alessandra, Bindoli Alberto, Salmain Michèle, Ciofini Ilaria, Blanchard Sébastien, de Jésús Cázares-Marinero José, Wang Yong, Pigeon Pascal, Jaouen Gérard, Vessières Anne, Rigobello Maria Pia
Dipartimento di Scienze Biomediche, Università di Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy.
Istituto di Neuroscienze (CNR) Sezione di Padova, c/o Dipartimento di Scienze Biomediche, Via Ugo Bassi, 58/b, 35131 Padova, Italy.
J Inorg Biochem. 2016 Dec;165:146-151. doi: 10.1016/j.jinorgbio.2016.08.005. Epub 2016 Aug 5.
This paper reports the inhibitory effect on the cytosolic thioredoxin reductase (TrxR1) in vitro by the ansa-ferrocifen derivative (ansa-FcdiOH, 1). We found that 1 decreased only slightly enzyme activity (IC=8μM), while 1*, the species generated by enzymatic oxidation by the HRP (horseradish peroxidase)/HO mixture, strongly inhibited TrxR1 (IC=0.15μM). At the same concentrations, neither 1 nor 1* had effect on glutathione reductase (GR). The most potent TrxR1 inhibitor did not appear to be the corresponding quinone methide as it was the case for ferrocifens of the acyclic series, or the stabilized carbocation as in the osmocifen series, but rather the quinone methide radical. This hypothesis was confirmed by ab-initio calculations of the species generated by oxidation of 1 and by EPR spectroscopy. BIAM (biotin-conjugated iodoacetamide) assay showed that 1* targeted both cysteine and selenocysteine of the C-terminal redox center of TrxR1.
本文报道了蒽环二茂铁衍生物（蒽环-FcdiOH，1）在体外对胞质硫氧还蛋白还原酶（TrxR1）的抑制作用。我们发现1只是轻微降低酶活性（IC = 8μM），而由辣根过氧化物酶（HRP）/H₂O₂混合物进行酶促氧化生成的物质1则强烈抑制TrxR1（IC = 0.15μM）。在相同浓度下，1和1对谷胱甘肽还原酶（GR）均无影响。最有效的TrxR1抑制剂似乎既不是相应的醌甲基化物（如非环状系列的二茂铁那样），也不是像奥莫西芬系列中的稳定碳正离子，而是醌甲基化物自由基。通过对1氧化生成的物质进行从头算计算以及电子顺磁共振光谱证实了这一假设。生物素缀合碘乙酰胺（BIAM）测定表明，1*靶向TrxR1 C末端氧化还原中心的半胱氨酸和硒代半胱氨酸。
