Dinuclear orthometallated gold(I)-gold(III) anticancer complexes with potent in vivo activity through an ROS-dependent mechanism.

Increasingly explored over the last decade, gold complexes have shown great promise in the field of cancer therapeutics. A major obstacle to their clinical progression has been their lack of in vivo stability, particularly for gold(III) complexes, which often undergo a facile reduction in the presence of biomolecules such as glutathione. Herein, we report a new class of promising anticancer gold(I)-gold(III) complexes with the general formula [XAuI(μ-2-C6F4PPh2)(κ2-2-C6F4PPh2)AuIIIX] [X = Cl (1), Br (2), NO3 (3)] which feature two gold atoms in different oxidation states (I and III) in a single molecule. Interestingly, gold(I)-gold(III) complexes (1-3) are stable against glutathione reduction under physiological-like conditions. In addition, complexes 1-3 exhibit significant cytotoxicity (276-fold greater than cisplatin) toward the tested cancer cells compared to the noncancerous cells. Moreover, the gold(I)-gold(III) complexes do not interact with DNA-like cisplatin but target cellular thioredoxin reductase, an enzyme linked to the development of cisplatin drug resistance. Complexes 1-3 also showed potential to inhibit cancer and endothelial cell migration, as well as tube formation during angiogenesis. In vivo studies in a murine HeLa xenograft model further showed the gold compounds may inhibit tumor growth on par clinically used cisplatin, supporting the significant potential this new compound class has for further development as cancer therapeutic.