Optimization of the synthesis of BET BD2 selective inhibitor XY153.

XY153 is a promising BET BD2 inhibitor with an IC50 value of 0.79 nM against BRD4 BD2. It shows 354-fold selectivity over BRD4-BD1 and 6-fold selectivity over other BET BD2 domains. However, the reported synthesis route of XY153 and its derivatives are extremely poor-yielding. After the synthesis of three key fragments, XY153 can only be obtained with a yield of 1.3 % in the original four-step reaction. In this study, we reported a three-step alternative route in the synthesis process of XY153. The reaction conditions for this route were thoroughly investigated and optimized, resulting in a significantly improved yield of 61.5 %. This efficient synthesis route establishes a robust chemical foundation for the rapid synthesis of XY153 derivatives as BET BD2 inhibitors in the near future.

Construction of Diversified Penta-Spiro-Heterocyclic and Fused-Heterocyclic Frameworks with Potent Antitumor Activity.

Invited for the cover of this issue are Xuewu Liang, Hong Liu and co-workers at the Shanghai Institute of Materia Medica and Shenyang Pharmaceutical University. The image depicts how a rhodium-catalyzed methodology leads to novel penta-spiro/fused-heterocyclic frameworks with potent antitumor activity through C-H activation/[4+1] and [4+2] annulation cascades. Read the full text of the article at 10.1002/chem. 202301553.

Construction of Diversified Penta-Spiro-Heterocyclic and Fused-Heterocyclic Frameworks with Potent Antitumor Activity.

Multiple-spiro/fused-heterocyclic frameworks containing indazolone are structurally unique and represent a class of potentially dominant skeletons. In this work, we successfully fulfilled Rh(III)-catalyst mediated substrate- and pH- controlled strategies to construct four novel types of complicated penta-spiro/fused-heterocyclic frameworks via C-H activation/[4+1] and [4+2] annulation cascades. This method had mild reaction conditions, a broad scope of substrates, moderate to good yields, and valuable applications, which could realize for the first time the generation of the novel di-spiro-heterocyclic and multiple fused-heterocyclic products with unique structures. More importantly, novel spiro[cyclohexane-indazolo[1,2-a]indazole] scaffold constructed by this method exhibited potent antitumor activity against a variety of refractory solid tumors and hematological malignancies in vitro. Overall, our work provided new insights into the construction of complex and diverse multiple spiro/fused-heterocyclic systems and offered novel valuable lead compounds for the discovery of antitumor drugs.

Rational design, synthesis and biological evaluation of benzo[d]isoxazole derivatives as potent BET bivalent inhibitors for potential treatment of prostate cancer.

Multivalency is an attractive strategy for effective binding to target protein. Bromodomain and extra-terminal (BET) family features two tandem bromodomains (BD1, BD2), which are considered to be potential new targets for prostate cancer. Herein, we report the rational design, optimization, and evaluation of a class of novel BET bivalent inhibitors based on our monovalent BET inhibitor 7 (Y06037). The representative bivalent inhibitor 17b effectively inhibited the cell growth of LNCaP, exhibiting 32 folds more potency than monovalent inhibitor 7. Besides, 17b induced 95.1 % PSA regression in LNCaP cell at 2 µM. Docking study was further carried out to reveal the potential binding mode of 17b with two BET bromodomains. Our study demonstrates that 17b (Y13021) is a promising BET bivalent inhibitor for the treatment of prostate cancer.

Discovery and structure-activity relationship studies of novel Bcl-2/Mcl-1 dual inhibitors with indole scaffold.

The Bcl-2 anti-apoptotic proteins were widely overexpressed in diverse tumor cells, especially for Bcl-2 and Mcl-1, which regarding as important targets of apoptosis induction and resistance of chemotherapy. We identified novel Bcl-2/Mcl-1 dual inhibitors with indole scaffold by the optimization of hit 1. Structure modification against several moieties including hydrophobic fragment, side chain and benzoic acid fragment was conducted and the structure-activity relationship was analyzed. The representative compound 12f exhibited sub-micromolar binding affinities to Bcl-2/Mcl-1 without binding affinity to Bcl-XL. Mechanism of action studies suggested that compound 12f dose-dependently triggered apoptosis in HL-60 cells. Compound 12f represents a novel Bcl-2/Mcl-1 dual inhibitor which deserving further study.

Development of a series of novel Mcl-1 inhibitors bearing an indole carboxylic acid moiety.

The B cell lymphoma protein 2 (Bcl-2) family proteins regulate cell apoptosis by participating in the endogenous apoptosis pathway. As an important anti-apoptotic protein, Myeloid cell leukemia 1 (Mcl-1) is overexpressed in a variety of tumor cells, and targeting this protein has been a promising strategy for cancer therapy. Herein, based on the 1H-indole-5-carboxylic acid structure previously discovered, we have developed a series of novel compounds with increased affinities and selectivity toward Mcl-1 through structure-based drug design. Among those compounds, 26 exerted relatively better affinity and selectivity for Mcl-1 with moderate inhibition in HL-60 cells. Mechanism studies showed that compound 26 could induce cancer cells apoptosis in an Mcl-1-dependent manner. It also exhibited good microsomal and plasma stability with acceptable pharmacokinetics profiles. Furthermore, treatment with target compound in a 4T1 xenograft mouse model significantly suppressed the tumor growth. Overall, the small molecule described herein represents a promising Mcl-1 inhibitor for further study.

Synthesis of Paclitaxel Derivatives for Remote Loading into Liposomes and Improved Therapeutic Effect.

A series of novel paclitaxel derivatives modified by boronic acid according to the characteristics of the interaction between RB(OH)2 and different strapping agents of intraliposomal aqueous phase were designed and synthesized, which were then used to develop remote poorly water-soluble drugs loading into liposomes. Meanwhile, we screened nineteen paclitaxel boronic acid derivatives for their cytotoxic activities against three cancer cell lines (A549, HCT-116 and 4T1) and one normal cell line (LO2), and performed liposome formulation screening of active compounds. Among all the compounds, the liposome of 4d, with excellent drug-encapsulated efficiency (>95% for drug-to-lipid ratio of 0.1 w/w), was the most stable. Furthermore, the liposomes of compound 4d (8 mg/kg, 4 times) and higher dose of compound 4d (24 mg/kg, 4 times) showed better therapeutic effect than paclitaxel (8 mg/kg, 4 times) in the 4T1 tumor model in vivo, and the rates of tumor inhibition were 74.3%, 81.9% and 58.5%, respectively. This study provided a reasonable design strategy for the insoluble drugs to improve their drug loading into liposomes and anti-tumor effect in vivo.

Design, synthesis and biological evaluation of dual Bcl-2/Mcl-1 inhibitors bearing 2-(1H-indol-4-yl)benzoic acid scaffold.

The anti-apoptotic protein inhibitors of the B cell lymphoma 2 (Bcl-2) family have been developed as new anticancer therapies. Numerous studies illustrated the great potential in the development of dual Bcl-2/myeloid cell leukemia 1 (Mcl-1) inhibitors. Herein, we reported a series of Bcl-2/Mcl-1 inhibitors that optimized from a hit compound 1 via structure-based rational design. The biological evaluation suggested that most compounds exhibited potent binding affinities at submicromolar to both Bcl-2 and Mcl-1 without any Bcl-xL binding affinities, especially compound 9o, with a Ki value of 0.07 µM to Mcl-1 and 0.66 µM to Bcl-2, that has great potential for developing dual inhibitors targeting Bcl-2 and Mcl-1.

Design, synthesis and biological evaluation of selective histone deacetylase 6 (HDAC6) inhibitors bearing benzoindazole or pyrazoloindazole scaffold as surface recognition motif.

A series of compounds were designed and synthesized based on the compound 11i bearing phenylpyrazole scaffold with histone deacetylase 6 (HDAC6) inhibitory activity. Most of the compounds showed considerable inhibitory activity against HDAC6 and compound A16 with good inhibitory activity was found therein. We further found that A16 had an inhibitory effect on inflammatory mediators (NO, TNF-α, IL-6) involved in inflammatory response and neuroendocrine regulation. In addition, A16 has a certain neuroprotective effect on PC12 cells injured by hydrogen peroxide. Acute toxicity assay showed that the LD50 of A16 was 274.47 mg/kg in mouse model. Furthermore, A16 displayed good stability properties in microsomes and plasma.

Synthesis and antitumor effects of novel 18ß-glycyrrhetinic acid derivatives featuring an exocyclic α,ß-unsaturated carbonyl moiety in ring A.

A series of novel 18ß-glycyrrhetinic acid (GA) derivatives featuring an exocyclic α,ß-unsaturated carbonyl moiety in ring A were synthesized and evaluated for their antitumor activities. Compounds 5c and 5l showed stronger cytotoxicity than other compounds and reported GA analogue CDODA-Me (methyl 2-cyano-3,11-dioxo-18ß-olean-1,12-dien-30-oate). 5c and 5l induced apoptosis in cancer cells accompanying with c-Flip reduction and Noxa induction, associated with decreased HDAC3 expression and increased acetylation of H3. 5l displayed better stability properties than 5c and CDODA-Me in microsomes and plasma, 5l also showed favorable pharmacokinetic profiles and inhibited tumor growth in mice. Compound 5l represents a new type of GA derivatives with improved antitumor activity.

Design, Synthesis and Bioactivity Evaluation of 4,6-Disubstituted Pyrido[3,2-d]pyrimidine Derivatives as Mnk and HDAC Inhibitors.

Both HDACs and Mnks play important role in translating multiple oncogenic signaling pathways during oncogenesis. As HDAC and Mnk are highly expressed in a variety of tumors; thus simultaneous inhibit HDAC and Mnk can increase the inhibition of tumor cell proliferation and provide a new way of inhibiting tumor growth. Based on the previous work and the merge pharmacophore method; we designed and synthesized a series of 4,6-disubstituted pyrido[3,2-d]pyrimidine derivatives as HDAC and Mnk dual inhibitors. Among them; compound A12 displayed good HDAC and Mnk inhibitory activity. In vitro antiproliferative assay; compound A12 exhibited the best antiproliferative activity against human prostate cancer PC-3 cells. Docking study revealed that the pyrido[3,2-d]pyrimidine framework and hydroxamic acid motif of compound A12 were essential for maintaining the activity of HDAC and Mnk. These result indicated that A12 was a potent Mnk /HDAC inhibitor and will be further researched.

Design, synthesis and biological evaluation of benzimidazole derivatives as novel human Pin1 inhibitors.

In this work, a series of novel benzimidazole derivatives were designed and synthesized as Pin1 inhibitors. Protease-coupled assay was used to investigate the Pin1 inhibitory potency of all synthesized compounds. Thirteen of them showed preferable Pin1 inhibitory effects with IC50 values lower than 5 µM, and 12a, 15b, 15d and 16c exhibited the most promising Pin1 inhibitory activity at low micromolar level (0.33-1.00 µM) than the positive control compound Juglone. Flow cytometry results showed that treating PC-3 cells with 16c caused slight cycle arrest in a concentration-dependent manner. The structure-activity relationships of R1, R2, R3 and linker of the benzimidazole derivatives were analyzed in detail, which would help further exploration of new Pin1 inhibitors.

Design, synthesis and biological evaluation of novel indole derivatives as potential HDAC/BRD4 dual inhibitors and anti-leukemia agents.

HDAC inhibitors and BRD4 inhibitors were considered to be potent anti-cancer agents. Recent studies have demonstrated that HDAC and BRD4 participate in the regulation of some signal paths like PI3K-AKT. In this work, a series of indole derivatives that combine the inhibitory activities of BRD4 and HDAC into one molecule were designed and synthesized through the structure-based design method. Most compounds showed potent HDAC inhibitory activity and moderate BRD4 inhibitory activity. In vitro anti-proliferation activities of the synthesized compounds were also evaluated. Among them, 19f was the most potent inhibitor against HDAC3 with IC50 value of 5 nM and BRD4 inhibition rate of 88% at 10 µM. It was confirmed that 19f could up-regulate the expression of Ac-H3 and reduce the expression of c-Myc by western blot analysis. These results indicated that 19f was a potent dual HDAC/BRD4 inhibitor and deserved further investigation.

Discovery of novel (+)-Usnic acid derivatives as potential anti-leukemia agents with pan-Pim kinases inhibitory activity.

Usnic acid (UA) is the main secondary metabolite isolated from lichens, with moderate anticancer activity. A small group of (+)-UA derivatives characterized with flavanone moiety was designed and synthesized, and their anticancer activities were evaluated in leukemia cells. It was demonstrated that (+)-UA derivatives 6a-6g inhibited the proliferation of leukemia cells HL-60 and K562 with low micromolar IC50 values. Mechanisms of action were investigated to find that 6g induced apoptosis in HL-60 and K562 cell lines, and affected the expression of MNK/eIF4E axis-related proteins, such as Mcl-1, p-eIF4E, p-4E-BP1. Finally, kinase inhibition assay suggested 6g was a potential inhibitor of pan-Pim kinases. Meanwhile, the blocking of phosphorylation of BAD and 4E-BP1 by 6g, together with the proposed binding mode of 6g with Pim-1 further confirmed its Pim inhibition effects. Our finding provides the sight towards the potential mechanism of (+)-UA derivatives 6g as anti-leukemia agents.

Structure-Based Design of Novel Benzimidazole Derivatives as Pin1 Inhibitors.

Peptidyl-prolyl cis/trans isomerase Pin1 plays a key role in amplifying and translating multiple oncogenic signaling pathways during oncogenesis. The blockade of Pin1 provided a unique way of disrupting multiple oncogenic pathways and inducing apoptosis. Aiming to develop potent Pin1 inhibitors, a series of benzimidazole derivatives were designed and synthesized. Among the derivatives, compounds 6h and 13g showed the most potent Pin1 inhibitory activity with IC50 values of 0.64 and 0.37 µM, respectively. In vitro antiproliferative assay demonstrated that compounds 6d, 6g, 6h, 6n, 6o and 7c exhibited moderate antiproliferative activity against human prostate cancer PC-3 cells. Taken together, these unique benzimidazole derivatives exhibited great potential to be further explored as potent Pin1 inhibitors with improved potency.

Design, synthesis and biological evaluation of ring A modified 11-keto-boswellic acid derivatives as Pin1 inhibitors with remarkable anti-prostate cancer activity.

Pin1 (Protein interaction with never in mitosis A1) is a validated molecular target for anticancer drug discovery. Herein, we reported the design, synthesis, and structure-activity relationship study of novel ring A modified AKBA (3-acetyl-11-keto-boswellic acid) derivatives as Pin1 inhibitors. Most compounds showed superior Pin1 inhibitory activities to AKBA. One of the most promising compounds, 10a, potently inhibited Pin1 with IC50 value of 0.46 µM, while it displayed excellent anti-proliferative effect against prostate cancer cells PC-3 with GI50 value of 1.82 µM. Structure-activity relationship indicated that reasonable structural modifications in ring A had significant impact on improving activity. Further mechanism research revealed that 10a decreased the level of Cyclin D1 and caused cell cycle arrest at G0/G1 phase in PC-3 cancer cells. Thus, compound 10a may serve as potential anti-prostate cancer agent for further investigation through Pin1 inhibition.

Design, synthesis and biological evaluation of novel hydroxamic acid based histone deacetylase 6 selective inhibitors bearing phenylpyrazol scaffold as surface recognition motif.

In recent years, inhibition of HDAC6 became a promising therapeutic strategy for the treatment of cancer and HDAC6 inhibitors were considered to be potent anti-cancer agents. In this work, celecoxib showed moderate degree of HDAC6 inhibition activity and selectivity in preliminary enzyme inhibition activity assay. A series of hydroxamic acid derivatives bearing phenylpyrazol moiety were designed and synthesized as HDAC6 inhibitors. Most compounds showed potent HDAC6 inhibition activity. 11i was the most selective compound against HDAC6 with IC50 values of 0.020µM and selective factor of 101.1. Structure-activity relationship analysis indicated that locating the linker group at 1' of pyrazol gave the most selectivity. The most compounds 11i (GI50=3.63µM) exhibited 6-fold more potent than vorinostat in HepG2 cells. Considering of the high selectivity against HDAC6 and anti-proliferation activity, such compounds have potential to be developed as anti-cancer agents.

Design and synthesis of novel 6-hydroxy-4-methoxy-3-methylbenzofuran-7-carboxamide derivatives as potent Mnks inhibitors by fragment-based drug design.

A novel series of 6-hydroxy-4-methoxy-3-methylbenzofuran-7-carboxamide derivatives featured with various C-2 substituents were designed and synthesized as Mnks inhibitors through fragment-based drug design. Among them, 5b, 5i, 5o and 8k showed the best Mnk2 inhibitory activity with IC50 values of 1.45, 1.16, 3.55 and 0.27 µM, respectively. And these compounds inhibited the activity of Mnk1 at the same time. Furthermore, compounds 5o and 8k exhibited anti-proliferative effects to human leukemia cancer THP-1 and MOLM-13 cell lines and colon cancer HCT-116 cell line. Moreover, Western blot assay suggested that 8k could decrease the levels of p-eIF4E in a dose-dependent manner in HCT-116 cells. Docking studies demonstrated strong interactions between 8k and Mnk2. Therefore, this unique benzofuran scaffold demonstrated great potential to be further explored as potent Mnks inhibitors with improved potency.

[Design, synthesis and antiproliferative activity in cancer cells of novel dihydropyrazolyl and pyrazolyl artemisinin-phenyl ethers].

To explore potent anticancer agent based on artemisinin scaffold, a series of 10-O-phenyl ethers derivatives containing dihydropyrazolyl or pyrazolyl moiety have been designed and synthesized. Their structures were determined by LC-MS and ¹H-NMR date. Inhibitory effects of the target compounds in human breast cancer MCF-7, MCF/Adr, MDA-MB-231 cells and prostate cell line PC-3 were determined by MTT assay. Those derivatives displayed good antiproliferative activity against the tested cancer cells. Particularly, target compounds exhibited significant cytotoxicity against drug-resistance cells MCF/Adr, which was worthy for further investigation.

Discovery and structure-activity relationship studies of N-substituted indole derivatives as novel Mcl-1 inhibitors.

Myeloid cell leukemia-1 (Mcl-1) is an important antiapoptotic protein functioning through protein-protein interactions. We discovered LSL-A6 (2-((2-carbamoyl-1-(3-(4-methoxyphenoxy)propyl)-1H-indol-6-yl)oxy)acetic acid) with a novel N-substituted indole scaffold to interfere Mcl-1 binding as a novel Mcl-1 inhibitor. Molecular modeling indicated that this compound binds with Mcl-1 by interaction with P2 and R263 hot-spots. Structure modification focused on several moieties including indole core, hydrophobic tail and acidic chain were conducted and structure-activity relationship was analyzed. The most potent compound 24d which exhibited Ki value of 110nM for interfering Mcl-1 binding was obtained after hit-to-lead modification.