Identification of Molecular Targets of Novel Metallocene-containing Fluconazole

Fluconazole (FCZ), which belongs to a class of drug called azole antifungals, is used to treat a variety of fungal infections, especially Candida species and Cryptococcus neoformans. Due to its improved safety and predictable absorption compared to other azole drugs, it has been widely used in patients with weak immune system. However, the overuse of FCZ and explosion of immunocompromised patients resulted in a huge amount of failure treatments. In a previous study, we have successfully synthesized four ferrocenyl FCZ (1a - 4a), which were found to be more effective than FCZ against various fungi, as well as FCZ-resistance strains in vitro test. Encouraged by these results, in this work, we synthesized six novel ferrocene/ruthenocene-containing FCZ (5a - 10a) and two organic analogues (phenyl/adamantyl - 11a - 12a) with the aim to improve their antifungal activity and investigate the effect of the metallocene moiety. These compounds were highly effective in vivo against pathogenic fungal infections and potent against parasitic worms such as Brugia, which causes lymphatic filariasis and Trichuris, one of the soil-transmitted helminths that infects millions of people globally. Analogs of FCZ that showed elevated activity against fungi and parasitic nematodes (8a, 10a, 11a, and 12a) were selected to investigate their mechanism of action using a chemogenomic assay. Most interestingly, the genome wide screen revealed that the main targets of the new analogs are different from the main target of FCZ, which is the lanosterol 14a-demethylase encoded by the gene ERG11.