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A series of N -acyl benzothiazoles shows selective and potent cytotoxicity against cancer cell lines expressing cytochrome P450 4F11. A prodrug form is metabolized by cancer cells into an active inhibitor of stearoyl-CoA desaturase (SCD). Substantial variation on the acyl portion of the inhibitors allowed the identification of ( R )- 27 , which balanced potency, solubility, and lipophilicity to allow proof-of-concept studies in mice. The prodrugs were activated inside the tumor, where they can arrest tumor growth. Together, these observations offer promise that a tumor-activated prodrug strategy might exploit the essentiality of SCD for tumor growth, while avoiding toxicity associated with systemic SCD inhibition.

Stearoyl-CoA desaturase (SCD) catalyzes the first step in the conversion of saturated fatty acids to unsaturated fatty acids. Unsaturated fatty acids are required for membrane integrity and for cell proliferation. For these reasons, inhibitors of SCD represent potential treatments for cancer. However, systemically active SCD inhibitors result in skin toxicity, which presents an obstacle to their development. We recently described a series of oxalic acid diamides that are converted into active SCD inhibitors within a subset of cancers by CYP4F11-mediated metabolism. Herein, we describe the optimization of the oxalic acid diamides and related N-acyl ureas and an analysis of the structure-activity relationships related to metabolic activation and SCD inhibition.

The product of cytochrome P450 monooxygenase (P450) ω-hydroxylation of arachidonic acid (AA), 20- hydroxyeicosatetraenoic acid (HETE), is a potent vasoconstrictor. Utilizing microsomes as well as individual CYP4 isoforms we demonstrate here that flavonoids can block 20-HETE formation. Apigenin inhibits CYP4F2 with an IC 50 value of 4.6 μM and 20-HETE formation in human liver and kidney microsomes at 2.4-9.8 μM. Interestingly, the structurally similar naringenin shows no relevant effect on the formation of 20-HETE. Based on these in vitro data, it is impossible to evaluate if a relevant blockade of 20-HETE formation can result in humans from intake of polyphenols with the diet. However, the potency of apigenin is comparable to those of P450 inhibitors such as ketoconazole. Moreover, an IC 50 value in the micromolar range is also described for the inhibition of CYP-mediated drug metabolism leading to food-drug interactions. The modulation of the arachidonic acid cascade by food polyphenols therefore warrants further investigation.