Pei-Teh Chang

Quinazolin-4-one Derivatives as Selective Histone Deacetylase-6 Inhibitors for the Treatment of Alzheimer’s Disease

Novel quinazolin-4-one derivatives containing a hydroxamic acid moiety were designed and synthesized. All compounds were subjected to histone deacetylase (HDAC) enzymatic assays to identify selective HDAC6 inhibitors with nanomolar IC50 values. (E)-3-(2-Ethyl-7-fluoro-4-oxo-3-phenethyl-3,4-dihydroquinazolin-6-yl)-N-hydroxyacrylamide, 4b, is the most potent HDAC6 inhibitor (IC50, 8 nM). In vitro, these compounds induced neurite outgrowth accompanied by growth-associated protein 43 expression, and they enhanced the synaptic activities of PC12 and SH-SY5Y neuronal cells without producing toxic or mitogenic effects. Several of the compounds dramatically increased nonhistone protein acetylation, specifically of α-tubulin. Some of the more potent HDAC6 inhibitors decreased zinc-mediated β-amyloid aggregation in vitro. N-Hydroxy-3-(2-methyl-4-oxo-3-phenethyl-3,4-dihydro-quinazolin-7-yl)-acrylamide, 3f, the most promising drug candidate, selectively inhibits HDAC6 (IC50, 29 nM), practically does not affect human ether-a-go-go-related membrane channel activity (IC50 >10 μM) or cytochrome P450 activity (IC50 >6.5 μM) in vitro, and significantly improves learning-based performances of mice with β-amyloid-induced hippocampal lesions.

Bioisosteric replacement of an acylureido moiety attached to an indolin-2-one scaffold with a malonamido or a 2/4-pyridinoylamido moiety produces a selectively potent Aurora-B inhibitor.

Bioisosteric replacement of acylureido moiety in 6-acylureido-3-pyrrolylmethylidene-2-oxoindoline derivatives resulted in a series of malonamido derivatives with indolin-2-one scaffold (11-14). Further conformational restrictions of the malonamido moiety led to 2-oxo-1,2-dihydropyridine (21-25) or a 4-oxo-1,4-dihydropyridine derivatives (31-36). 4-Oxo-1,4-dihydropyridine derivatives were more potent Aurora B inhibitors than their 2-oxo-1,2-dihydropyridine counterparts and demonstrated cytotoxicities against A549 and HepG2 cells in the submicromolar range. In A549 cells, 31h decreased phosphorylation of histone H3, triggered polyploidy, induced expression of pro-apoptotic Fas and FasL with subsequent activation of caspase 8, resulting into apoptosis. In a Huh7-xenograft mouse model, 31h demonstrated potent in vivo efficacy with a daily dose of 5 mg/kg.

Design, synthesis and biological evaluation of benzo[1.3.2]dithiazolium ylide 1,1-dioxide derivatives as potential dual cyclooxygenase-2/5-lipoxygenase inhibitors.

3-(4-Bromophenyl)-6-nitrobenzo[1.3.2]dithiazolium ylide 1,1-dioxide (5) was discovered as a new prototype for dual inhibitors of cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX). Thus, the structure-activity relationships of benzo[1.3.2]dithiazolium ylide 1,1-dioxide skeleton were carried out. The 6-NO(2) group played an essential role in the inhibitory activity. In addition, moderate-sized lipophilic substituents at the para-position of the 3-aryl moiety were required for dual COX-2/5-LOX inhibitory activity. Among the identified potent dual inhibitors, 3-(4-tbutylphenyl) derivative 30c (IC(50) values of 0.27 μM and 0.30 μM against COX-2 and 5-LOX, respectively) and 3-(4-biphenyl) derivative 30f (IC(50) values of 0.50 μM and 0.15μM against COX-2 and 5-LOX, respectively) were the most potent dual COX-2/5-LOX inhibitors. Intraperitoneal administration of 30c at 100mg/kg demonstrated potent acute anti-inflammatory activity. As a result, benzo[1.3.2]dithiazolium ylide 1,1-dioxide represented a novel scaffold for the exploitation in developing dual COX-2/5-LOX inhibitors.

Discovery of N-arylalkyl-3-hydroxy-4-oxo-3,4-dihydroquinazolin-2-carboxamide derivatives as HCV NS5B polymerase inhibitors.

The metal ion chelating β‐N‐hydroxy‐γ‐ketocarboxamide pharmacophore was integrated into a quinazolinone scaffold, leading to N‐arylalkyl‐3‐hydroxy‐4‐oxo‐3,4‐dihydroquinazolin‐2‐carboxamide derivatives as hepatitis C virus (HCV) NS5B polymerase inhibitors. Lead optimization led to the identification of N‐phenylpropyl carboxamide 9 k (IC50=8.8 μM). Compound 9 k possesses selectivity toward HCV1b replicon Ava.5 cells (EC50=17.5 μM) over parent Huh‐7 cells (CC50=187.5 μM). Compound 9 k effects a mixed mode of NS5B inhibition, with NTP‐competitive displacement properties. The interaction between 9 k and NS5B is stabilized by the presence of magnesium ions. Docking studies showed that the binding orientation of 9 k occupies the central portions of both magnesium‐mediated and NTP‐ribose‐response binding sites within the active site region of NS5B. As a result, 3‐hydroxy‐4‐oxo‐3,4‐dihydroquinazolin‐2‐carboxamide derivatives are disclosed herein as novel, mainly active site inhibitors of HCV NS5B polymerase.