The monoamine oxidase A, a broad-spectrum inhibitor of fungal ABC and MFS transporter.

Holmes AR, Keniya MV, Ivnitski-Steele I, Monk BC, Lamping E, Sklar LA, Cannon RD. "Antimicrob Agents Chemother. 2011 Dec"

Resistance to the commonly employed azole antifungal fluconazole (FLC) can develop on account of over-expression of ATP-binding cassette (ABC) and major facilitator superfamily (MFS) plasma membrane transporters. An approach to conquering this resistance would be to identify inhibitors of those efflux pumps.

We have created a pump assay appropriate for high-throughput screening (HTS) that uses recombinant Saccharomyces cerevisiae strains hyper-expressing person transporters from the opportunistic fungal pathogen Candida albicans. The recombinant strains possess higher resistance to azoles and also other pump substrates as opposed to parental host strain.

A flow cytometry-based HTS, which measured elevated intracellular retention with the luminescent pump substrate rhodamine 6G (R6G) inside yeast cells, was utilized to screen the Prestwick Chemical Library (PCL) of 1200 marketed medication. 9 compounds were determined as hits as well as the monoamine-oxidase A inhibitor (MAOI) clorgyline was recognized being an inhibitor of two Do. albicans ABC efflux pumps, CaCdr1p and CaCdr2p.

Secondary in vitro assays confirmed inhibition of pump-mediated efflux by clorgyline. Clorgyline also reversed the FLC-resistance of S. cerevisiae strains expressing other person fungal ABC transporters (Candida glabrata Cdr1p or Candida krusei Abc1p) or the Do. albicans major facilitator superfamily (MFS) transporter Mdr1p. Recombinant strains had been also chemosensitized by clorgyline to other azoles (itraconazole and miconazole (MCZ)).

Importantly, clorgyline confirmed synergy with FLC towards FLC-resistant Do. albicans clinical isolates and also a Do. glabrata strain and inhibited R6G efflux from a FLC-resistant Do. albicans clinical isolate. Clorgyline is usually a novel broad-spectrum inhibitor of two courses of fungal efflux pumps that functions synergistically with azoles versus azole-resistant C. albicans and Do. glabrata strains.