Discovery of a Novel Dual Fungal CYP51/Human 5-Lipoxygenase Inhibitor: Implications for Anti-Fungal Therapy

Eric K Hoobler,Josie E Parker,S L Kelly,Steven C Perry,David J Maloney,Anton Simeonov,Christopher J Smyrniotis,Diane E Kelly,Andrew G S Warrilow,Theodore R Holman,Ajit Jadhav,Ganesha Rai,Daotai Nie

doi:10.1371/journal.pone.0065928

Abstract

We report the discovery of a novel dual inhibitor targeting fungal sterol 14α-demethylase (CYP51 or Erg11) and human 5-lipoxygenase (5-LOX) with improved potency against 5-LOX due to its reduction of the iron center by its phenylenediamine core. A series of potent 5-LOX inhibitors containing a phenylenediamine core, were synthesized that exhibit nanomolar potency and >30-fold selectivity against the LOX paralogs, platelet-type 12-human lipoxygenase, reticulocyte 15-human lipoxygenase type-1, and epithelial 15-human lipoxygenase type-2, and >100-fold selectivity against ovine cyclooxygenase-1 and human cyclooxygnease-2. The phenylenediamine core was then translated into the structure of ketoconazole, a highly effective anti-fungal medication for seborrheic dermatitis, to generate a novel compound, ketaminazole. Ketaminazole was found to be a potent dual inhibitor against human 5-LOX (IC50 = 700 nM) and CYP51 (IC50 = 43 nM) in vitro. It was tested in whole blood and found to down-regulate LTB4 synthesis, displaying 45% inhibition at 10 µM. In addition, ketaminazole selectively inhibited yeast CYP51 relative to human CYP51 by 17-fold, which is greater selectivity than that of ketoconazole and could confer a therapeutic advantage. This novel dual anti-fungal/anti-inflammatory inhibitor could potentially have therapeutic uses against fungal infections that have an anti-inflammatory component.

Highlights

Human 5-lipoxygenase (5-LOX) has long been considered a possible therapeutic target for inflammatory diseases
In the process of screening the 15-LOX-1 ‘‘hits’’, we serendipitously discovered a novel 5-LOX inhibitor with a phenylenediamine core moiety, compound 1
In order to evaluate the concept of an improved antiinflammatory effect combined with antifungal potency, we examined the selectivity of ketoconazole and ketaminazole (16) against the human and C. albicans CYP51 proteins, Homo sapiens CYP51 (HsCYP51) and CaCYP51 respectively

Summary

Introduction

Human 5-lipoxygenase (5-LOX) has long been considered a possible therapeutic target for inflammatory diseases. Ketoconazole is a widely used anti-fungal agent that is currently utilized as an active ingredient in anti-dandruff shampoo [9,10] and previously for a wide range of fungal infections. It has been proposed that part of its effectiveness is due to its anti-inflammation activity, since it weakly inhibits 5-LOX [12]. The anti-inflammatory activity of ketoconazole has been seen for itraconazole, a similar anti-fungal therapeutic [13], which suggests a common theme for effective dandruff agents, dual anti-fungal/anti-inflammatory targeting. The potency for ketoconazole and itraconazole against 5-LOX is poor, with IC50 values greater than 50 mM for both molecules, which indicates a potential for improvement in their anti-inflammatory activity [12,13]

Methods

Results

Conclusion