1576
Chem. Pharm. Bull. 64, 1576–1581 (2016)
Vol. 64, No. 11
Regular Article
Discovery of Chromeno[4,3-c]pyrazol-4(2H)-one Containing Carbonyl or
Oxime Derivatives as Potential, Selective Inhibitors PI3Kα
Liang Lu,# Shao Sha,# Kai Wang, Yuan-Heng Zhang, Yan-Dong Liu, Guo-Dong Ju,
Baozhong Wang,* and Hai-Liang Zhu*
State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University; Nanjing 210093, People’s Republic of
China.
Received May 11, 2016; accepted June 15, 2016; advance publication released online September 1, 2016
A series of novel chromeno[4,3-c]pyrazol-4(2H)-one containing carbonyl or oxime derivatives (4a–n,
5a–n) have been synthesized and evaluated their biological activities as phosphatidyl inositol 3-kinase (PI3K)
inhibitors. Out of them, compound 5l showed the most potent antiproliferative activities against HCT-116
with IC50 of 0.10µM in vitro, and exhibited the most potent activity for PI3Kα with the value of 0.012µM.
Docking simulation of 5l into PI3Kα active site were performed to determine the probable binding model,
and it indicated that compound 5l could be optimized as a potential inhibitor of PI3Kα in the further study.
Key words chromeno[4,3-c]pyrazol-4(2H)-one derivative; inhibitor; antiproliferative
Three distinct classes of lipid phosphatidyl inositol 3-kinas- of 2-alkyl-chromeno[4,3-c]pyrazol-4(2H)-one derivatives con-
es (PI3Ks), as a family, play a key role in cellular processes taining benzyl and alkyl chain as potential PI3K inhibitors.26)
by regulating functions such as cell metabolism, prolifera- In our previous studies, we found that there is large space in
tion, differentiation, motility, and intracellular trafficking.1–4) the active pocket if compounds based-on chromeno[4,3-c]-
Class I PI3K, the best studied of the three PI3K classes, are pyrazol-4(2H)-one skeleton as PI3K inhibitors. In continua-
heterodimers consisting of a p110 catalytic subunit and a p85 tion to extend our research on chromeno[4,3-c]pyrazol-4(2H)-
regulatory subunit, comprising four isoforms (α, β, δ, γ). In one derivatives, herein, we introduced acetophenone fragment
recent years, PI3Kα is recognized as one of most potent tar- into the derivatives in order to they can well-bonded with
get in the treatment of cancer.5–8) All of these enzymes are the PI3K protein, and the result of the molecular docking
activated by receptor tyrosine kinases (RTKs) and G-protein showed they have the lower CDOCKER_INTERACTION_
coupled receptors (GPCRs) on the cell surface.9) Subsequent ENERGY (Table 1). It indicated that these compounds may
PI3K phosphorylate the 3′-hydroxyl group of phosphatidyl bond well in the active pocket of PI3K. Therefore, we de-
inositol 4,5-bisphosphate (PIP2) to generate phosphatidyl signed and synthesized a series of 2-(2-oxo-2-phenylethyl)-
inositol 3,4,5-triphosphate (PIP3), which lead to activation of chromeno[4,3-c]pyrazol-4(2H)-one derivatives. In previ-
downstream signaling pathways.10) The cellular levels of PIP3 ous reports of 6-bromoindirubin-3′-oxime (BIO), 3′-oxime
are negatively regulated by phosphatase and tensin homolog substitution played a key role in kinase inhibitory effects.27)
deleted from chromosome 10 (PTEN), which is a phospha- Thus, carbonyl in 2-(2-oxo-2-phenylethyl)chromeno[4,3-c]-
tase that converts PIP3 back to PIP2.11,12) PI3K and PTEN are pyrazol-4(2H)-one derivatives was then replaced by oxime,
contradictory of oncogenic signaling. The importance of the for this modification might enhance solubility, kinase inhibi-
PI3K in cancer is emphasized by the evidence that activat- tion and cell permeability. Target compound synthesized from
ing mutation of PI3Kα is most commonly observed in many 4-hydroxycoumarin. Upon biological evaluation was carried
cancers.13,14) In addition, activated PTEN is commonly lost in out, some of the synthesized compounds were found as poten-
many tumors.12,15) Therefore, small molecule inhibitors against tial PI3Kα inhibitors. The apoptosis study was also carried out
PI3Kα is necessary to cancer treatment, for PI3K pathway by flow cytometry to show that these compounds induced apo-
has a key role in cancer. There are many researches about in- ptosis in a dose-dependent manner. Docking simulations were
hibitor of PI3Kα,16,17) and some inhibitors have entered clinical performed using the X-ray crystallographic structure of PI3Kα
trials.18–21)
(PDB code: 3HHM, retrieved from the RCSB Protein Data
Several natural products as PI3K inhibitors are widely Bank) in complex with the most potent inhibitor to explore the
known, including first-generation PI3K inhibitors such as binding modes of the compound at the active site.
wortmannin (Fig. 1), quercetin and myricetin.22) Second-
Based on the reported pathway for the synthesis of com-
generation PI3K inhibitors are designed small molecules, pound 3, the target compounds (4a–n, 5a–n) were synthesized
including LY294002 (a quercetin analogue) and its analogues, by routes outlined in Chart 1. First of all, 3-formyl-4-chlo-
of which LY294002 was proved to be the most potent PI3K rocoumarin (2) was synthesized from 4-hydroxycoumarin
inhibitor.23,24) Then, GDC0941 as a considerable PI3K in- under Vilsmeier conditions (phosphorus oxychloride/N,N-
hibitors was reported in 2011.25) It was a feasible program dimethylformamide (POCl3/DMF)). Secondly, compound 2
that chromeno[4,3-c]pyrazol-4(2H)-one was designed as the and 80% hydrazine hydrate were dissolved in ethanol, using
core region, and our research team already reported a series triethylamine as catalyst, and reacted to get chromeno[4,3-c]-
pyrazol-4(2H)-one (3). Thirdly, compound 3 and α-bromo-
# These authors contributed equally to this work.
acetophenone were allowed to react in acetone to get the de-
*To whom correspondence should be addressed. e-mail: wbz@nju.edu.cn; zhuhl@nju.edu.cn
© 2016 The Pharmaceutical Society of Japan