A High Throughput Screen Identifies Potent and Selective Inhibitors to Human Epithelial 15-Lipoxygenase-2

Lipoxygenase (LOX) enzymes catalyze the hydroperoxidation of arachidonic acid and other polyunsaturated fatty acids to hydroxyeicosatetraenoic acids with varying positional specificity to yield important biological signaling molecules. Human epithelial 15-lipoxygenase-2 (15-LOX-2) is a highly specific LOX isozyme that is expressed in epithelial tissue and whose activity has been correlated with suppression of tumor growth in prostate and other epithelial derived cancers. Despite the potential utility of an inhibitor to probe the specific role of 15-LOX-2 in tumor progression, no such potent/specific 15-LOX-2 inhibitors have been reported to date. This study employs high throughput screening to identify two novel, specific 15-LOX-2 inhibitors. MLS000545091 is a mixed-type inhibitor of 15-LOX-2 with a Ki of 0.9+/-0.4 µM and has a 20-fold selectivity over 5-LOX, 12-LOX, 15-LOX-1, COX-1, and COX-2. MLS000536924 is a competitive inhibitor with a Ki of 2.5+/-0.5 µM and also possesses 20-fold selectivity toward 15-LOX-2 over the other oxygenases, listed above. Finally, neither compound possesses reductive activity towards the active-site ferrous ion

Azole Antifungal Sensitivity of Sterol 14α-Demethylase (CYP51) and CYP5218 from Malassezia globosa

Malassezia species are known to play a role in several human skin diseases including dandruff, seborrheic dermatitis, pityriasis versicolor and malassezia folliculitis and may also exacerbate atopic dermatitis and psoriasis even though they are members of the normal skin microbial flora, being present on the skin of 75 to 98% of healthy individuals. There are presently fourteen recognized species of Malassezia, eight of which are associated with humans. Malassezia are unique amongst fungi in requiring exogenous lipids for growth. We have investigated Malassezia globosa cytochromes P450 CYP51 and CYP5218 as sterol 14α-demethylase (the target of azole antifungals) and a putative fatty acid metabolism protein (and a potential azole drug target), respectively. MIC100 studies showed itraconazole should be considered as an alternative to ketoconazole given the potency and safety profiles and the CYP51 assay system can be used in structure-activity studies in drug development