TNP and its analogs: Modulation of IP6K and CYP3A4 inhibition

Abstract

Inositol hexakisphosphate kinase (IP6K) is an important mammalian enzyme involved in various biological processes such as insulin signalling and blood clotting. Recent analyses on drug metabolism and pharmacokinetic properties on TNP ( N 2 -( m -trifluorobenzyl), N 6 -( p -nitrobenzyl)purine), a pan-IP6K inhibitor, have suggested that it may inhibit cytochrome P450 (CYP450) enzymes and induce unwanted drug-drug interactions in the liver. In this study, we confirmed that TNP inhibits CYP3A4 in type I binding mode more selectively than the other CYP450 isoforms. In an effort to find novel purine-based IP6K inhibitors with minimal CYP3A4 inhibition, we designed and synthesised 15 TNP analogs. Structure-activity relationship and biochemical studies, including ADP-Glo kinase assay and quantification of cell-based IP7 production, showed that compound 9 dramatically reduced CYP3A4 inhibition while retaining IP6K-inhibitory activity. Compound 9 can be a tool molecule for structural optimisation of purine-based IP6K inhibitors.

TNP Analogues Inhibit the Virulence Promoting IP3-4 Kinase Arg1 in the Fungal Pathogen Cryptococcus neoformans

“…In addition, modification at N 9 was included in examples 45 and 46 ( Table 6 ). Note that several of these compounds were previously reported in studies of human IPKs as well as other enzyme targets [ 34 , 35 , 37 , 42 , 43 ].…”

“…TNP is an ATP-competitive inhibitor of all three IP6K isoforms in mammalian cells [ 33 ] and was discovered through a purine-based compound library screen against human IP3K [ 34 ]. However, TNP was later found to be more potent against IP6K, with an IC 50 of 0.47 µM [ 33 ] compared to an IC 50 of 10 µM against IP3K [ 34 ], and demonstrated anti-obesity and anti-diabetic effects in a mouse model of high fat diet-induced obesity [ 28 , 35 ]. Although TNP is a potent inhibitor of human IP6K, it does not inhibit rat IPMK at a concentration of 10 µM [ 36 ] and its inhibitor properties against human IPMK have not been determined.…”

“…As a probe and drug, TNP has low water solubility, which negatively impacts its potency, and has off-target effects [ 28 , 35 ]. Using medicinal chemistry approaches, it was shown that modifications could be introduced to TNP to improve its solubility and selectivity for the different IP6K isoforms, with a preference for IP6K1 [ 37 ], providing proof-of-principle that selectivity of TNP for other IPKs in the same family, including IP 3-4 Ks, can be achieved.…”

“…Using medicinal chemistry approaches, it was shown that modifications could be introduced to TNP to improve its solubility and selectivity for the different IP6K isoforms, with a preference for IP6K1 [ 37 ], providing proof-of-principle that selectivity of TNP for other IPKs in the same family, including IP 3-4 Ks, can be achieved. In a separate study, the modification of TNP was able to reduce off-target effects by reducing inhibition of the cytochrome P450 enzyme CYP3A4 [ 35 ].…”

The Inositol Phosphate System—A Coordinator of Metabolic Adaptability

“…A small-scale study on individuals with insulin resistance found that IP6K1 levels (protein and mRNA) deceased under conditions of high intensity exercise that correlated with improved insulin signaling, supporting an antagonistic role for insulin signaling by IP6K1 in humans [ 54 ]. While work is ongoing to create a specific IP6K1 inhibitor for the treatment of insulin resistance this may prove difficult, as IP6K1 is also important in the regulation of phosphate homeostasis [ 55 , 56 ], which is discussed in more detail in a later section.…”