Synthesis and cytotoxicity of novel 6,8,9-trisubstituted purine analogs against liver cancer cells

A series of novel 6-(substituted phenyl piperazine)-8-(4-substituted phenyl)-9-cyclopentyl purines, 10-51, were synthesized by a four-step synthesis, achieving an overall yield of about 43 %. The reaction conditions were effectively optimized, and the final products were obtained with high purity and yield in all synthesis steps. The synthesized nucleobases were evaluated for their in vitro cytotoxic activities on selected human cancer cell lines (HUH7 (liver), HCT116 (colon), and MCF7 (breast)) using the Sulforhodamine B (SRB) assay. Among these analogs, compounds bearing 4-trifluoromethyl phenyl (19, 20 and 21), 4-methoxy phenyl (27) and 4-fluoro phenyl (34) substitutions at C-8 of purine were the most potent, and they were also analyzed in drug-resistance and drug-sensitive hepatocellular cancer cell (HCC) panels. Compound 19 displayed remarkable anticancer activities (IC50 = 2.9-9.3 μM) against Huh7, FOCUS, SNU475, SNU182, HepG2, and Hep3B cells compared to the positive control, Fludarabine. Additionally, the pharmacological properties and toxicity profiles of the molecules were investigated computationally by the Swiss-ADME and Pro-Tox II online tools, respectively. Results showed that our compounds have favorable physicochemical characteristics for oral bioavailability and do not reveal any toxicity endpoints such as carcinogenicity, immunotoxicity, mutagenicity, or cytotoxicity.

Newly synthesized 6-substituted piperazine/phenyl-9-cyclopentyl containing purine nucleobase analogs act as potent anticancer agents and induce apoptosis via inhibiting Src in hepatocellular carcinoma cells

Newly synthesized 6-substituted piperazine/phenyl-9-cyclopentyl-containing purine nucleobase analogs were tested for their in vitro anticancer activity against human cancer cells. Compounds 15, 17-24, 49, and 56 with IC50 values less than 10 μM were selected for further examination on an enlarged panel of liver cancer cell lines. Experiments revealed that compound 19 utilizes its high cytotoxic potential (IC50 < 5 μM) to induce apoptosis in vitro. Compound 19 displayed a KINOMEscan selectivity score S35 of 0.02 and S10 of 0.01 and demonstrated a significant selectivity against anaplastic lymphoma kinase (ALK) and Bruton's tyrosine kinase (BTK) over other kinases. Compounds 19, 21, 22, 23, and 56 complexed with ALK, BTK, and (discoidin domain-containing receptor 2) DDR2 were analyzed structurally for binding site interactions and binding affinities via molecular docking and molecular dynamics simulations. Compounds 19 and 56 displayed similar interactions with the activation loop of the kinases, while only compound 19 reached toward the multiple subsites of the active site. Cell cycle and signaling pathway analyses exhibited that compound 19 decreases phosho-Src, phospho-Rb, cyclin E, and cdk2 levels in liver cancer cells, eventually inducing apoptosis.

A Novel 6,8,9-Trisubstituted Purine Analogue Drives Breast Cancer Luminal A Subtype MCF-7 to Apoptosis and Senescence through Hsp70 Inhibition

BACKGROUND

Cancer cells restrain apoptotic and senescence pathways through intracellular heat shock protein 70 (Hsp 70). These cells aid stimulus-independent growth, and their higher metabolism rate requires Hsps. Hsps compensate abnormally increased substrate protein folding rate of cancer cells.

OBJECTIVE

Misfolding of substrate proteins especially signaling substrate proteins, may not function properly. Therefore, Hsp70 folds these substrate proteins into their native-fully functional states, and this mode of action helps cancer cell survival.

METHODS

Targeting Hsps is promising cancer therapy, and in this study, 6,8,9-trisubstituted purine derivatives were designed and synthesized to inhibit Hsp70 and drive cancer cells to apoptosis. Further, oncogenic stimuli through inhibitors can induce an irreversible senescent state and senescence is a barrier to transformation.

RESULTS

Hsp70 helps cancer cells to bypass the cellular senescence program, however, binding of N6-(4- isopropylaniline) analogue (7) depletes Hsp70 function as evidenced by aggregation assay and Hsp70 depletion induces senescence pathway.

CONCLUSION

The purine-based inhibitor-compound 7 effectively inhibits MCF-7 cell line. Moreover, the therapeutic potential with regard to the senescence-associated secretory phenotype has complementary action. Dual action of the inhibitor not only drives the cells to apoptosis but also force the cells to be in the senescence state and provides promising results specially for luminal A type breast cancer therapy.

Entrectinib: A new Selective Tyrosine Kinase Inhibitor Approved for the Treatment of Pediatric and Adult Patients with NTRK Fusion-positive, Recurrent or Advanced Solid Tumors

BACKGROUND

Entrectinib is a highly potent ATP-competitive and selective inhibitor of tyrosine kinases - Trk A B C, ALK, and ROS1. It was developed by Roche and initially approved in Japan in 2019 for the treatment of pediatric and adult patients with NTRK fusion-positive, recurrent, or advanced solid tumors. In August 2019, entrectinib received accelerated approval by the U.S FDA for this indication. It is also the first FDA-approved drug designed to target both NTRK and ROS1.

OBJECTIVE

We aim to summarize recent studies related to the synthesis, mechanism of action, and clinical trials of the newly approved selective tyrosine kinase inhibitor entrectinib.

METHOD

We conduct a literature review of the research studies on the new highly-potent small-molecule entrectinib.

CONCLUSION

Entrectinib, based on three clinical studies (ALKA, STARTRK-1, and STARTRK-2), was well tolerated, with a manageable safety profile. It induced clinically meaningful responses in recurrent or advanced solid tumors associated with NTRK fusion-positive or ROS1+ NSCLC. It demonstrated substantial efficacy in patients with CNS metastases.

Highly efficient chemical phosphorylation of 6-(4-phenylpiperazine-1-yl)-9-(β-D-ribofuranosyl)-9H-purine

Antimetabolites, which are metabolic antagonists used in the treatment of cancer and viral diseases by replacing metabolites, inhibit the action of metabolic enzymes and disrupt the pathways of synthesis of structural units necessary for the formation of nucleic acids. Purine antagonists, that are subunits of antimetabolites, reduce the production of purine bases, and hence, cause the nucleotide production to stop and bring about the death of cancer cells. Fludarabine (2-fluoro-ara-AMP), which is used in chemotherapy, is an antimetabolite of the purine class containing mono phosphate in its structure. In this study, a protocol was presented to effectively and efficiently synthesis of 6-(4-phenylpiperazine-1-yl)-9-(β-D-ribofuranosyl)-9H-purine-5'- O-phosphate compound in six steps and 25% overall yield starting with commercially available 6-chloropurine.

Design, Synthesis and In Vitro Cytotoxic Activity of New 6,9-Disubstituted Purine Analogues

A series of new 6,9-disubstituted purine analogs with 4-substituted piperazine at C-6 and 4-substituted benzyl at N-9 were designed and synthesized in four steps. All synthesized compounds (7-26) were screened initially for their in vitro anticancer activity on Huh7 liver, HCT116 colon and MCF7 breast carcinoma cell lines. Cytotoxic bioactivity studies revealed that all compounds screened, with compound 19 being the exception, were found to have promising cytotoxic activities at IC50 range of 0.05-21.8 ∆M against cancer cells Huh7, HCT116 and MCF7. Among the prepared purine analogs, two of them (12 and 22) exhibited excellent cytotoxic activities, with IC50 0.08-0.13 ∆M, on Huh7 cells comparable to camptothecin (CPT) and better than cladribine, fludarabine and 5-FU. Afterwards, the evaluation of cytotoxicity of the most potent purine analogs was screened against further hepatocellular cancer (HCC) cell lines. The 6-(4-(4-trifluoromethylphenyl)piperazine (12) and 6-(4-(3,4-dichlorophenyl)piperazine analogs (25) displayed a significant IC50 values (IC50 < 0.1-0.13 ∆M) comparable to CPT and better cytotoxic bioactivity when compared with 5-FU, cladribine and fludarabine on HCC cells (Huh7 and HepG2).

Synthesis of novel 6-substituted amino-9-(β-d-ribofuranosyl)purine analogs and their bioactivities on human epithelial cancer cells

New nucleoside derivatives with nitrogen substitution at the C-6 position were prepared and screened initially for their in vitro anticancer bioactivity against human epithelial cancer cells (liver Huh7, colon HCT116, breast MCF7) by the NCI-sulforhodamine B assay. N⁶-(4-trifluoromethylphenyl)piperazine analog (27) exhibited promising cytotoxic activity. The compound 27 was more cytotoxic (IC₅₀ = 1-4 μM) than 5-FU, fludarabine on Huh7, HCT116 and MCF7 cell lines. The most potent nucleosides (11, 13, 16, 18, 19, 21, 27, 28) were further screened for their cytotoxicity in hepatocellular cancer cell lines. The compound 27 demonstrated the highest cytotoxic activity against Huh7, Mahlavu and FOCUS cells (IC₅₀ = 1, 3 and 1 μM respectively). Physicochemical properties, drug-likeness, and drug score profiles of the molecules showed that they are estimated to be orally bioavailable. The results pointed that the novel derivatives would be potential drug candidates.

Synthesis of Some Substituted 6-Phenyl Purine Analogues and Their Biological Evaluation as Cytotoxic Agents

A series of 6-(4-substituted phenyl)-9-(tetrahydropyran-2-yl)purines 3-9, 6-(4-substituted phenyl)purines 10-16, 9-((4-substituted phenyl)sulfonyl)-6-(4-substituted phenyl)purines 17-32 were prepared and screened initially for their in vitro anticancer activity against selected human cancer cells (liver Huh7, colon HCT116, breast MCF7). 6-(4-Phenoxyphenyl) purine analogues 9, 16, 30-32, had potent cytotoxic activities. The most active purine derivatives 5-9, 14, 16, 18, 28-32 were further screened for their cytotoxic activity in hepatocellular cancer cells. 6-(4-Phenoxyphenyl)-9-(tetrahydropyran-2-yl)-9H-purine (9) had better cytotoxic activity (IC50 5.4 μM) than the well-known nucleobase analogue 5-FU and known nucleoside drug fludarabine on Huh7 cells. The structure-activity relationship studies reported that the substitution at C-6 positions in purine nucleus with the 4-phenoxyphenyl group is responsible for the anti-cancer activity.

Synthesis of novel 6-(4-substituted piperazine-1-yl)-9-(β-D-ribofuranosyl)purine derivatives, which lead to senescence-induced cell death in liver cancer cells

Novel purine ribonucleoside analogues (9-13) containing a 4-substituted piperazine in the substituent at N(6) were synthesized and evaluated for their cytotoxicity on Huh7, HepG2, FOCUS, Mahlavu liver, MCF7 breast, and HCT116 colon carcinoma cell lines. The purine nucleoside analogues were analyzed initially by an anticancer drug-screening method based on a sulforhodamine B assay. Two nucleoside derivatives with promising cytotoxic activities (11 and 12) were further analyzed on the hepatoma cells. The N(6)-(4-Trifluoromethylphenyl)piperazine analogue 11 displayed the best antitumor activity, with IC(50) values between 5.2 and 9.2 μM. Similar to previously described nucleoside analogues, compound 11 also interferes with cellular ATP reserves, possibly through influencing cellular kinase activities. Furthermore, the novel nucleoside analogue 11 was shown to induce senescence-associated cell death, as demonstrated by the SAβ-gal assay. The senescence-dependent cytotoxic effect of 11 was also confirmed through phosphorylation of the Rb protein by p15(INK4b) overexpression in the presence of this compound.

Abstract A171: Cytotoxicity of novel substituted purine derivatives against liver cancer cells

Cytotoxic purine and purine nucleoside analogs (PNA) are widely used in cancer treatment (1). In this study, three newly synthesized substituted purine derivatives, AUM18, AUM23 and AUM32* were evaluated for their cytotoxicities by Sulforhodamine B (SRB) assay initially on Hct116 (colon), T47D (breast), and Huh7 (liver) human carcinoma cell lines (2). The IC50 values for the cell lines analyzed were ∼2.0µM for AUM18, ∼0.5µM for AUM23 and ∼5nM for AUM32. The growth inhibitory effects that we observed with these PNAs were comparable to those of the known anticancer agents Camptothecin (IC50 ∼ 10 nM) and 5-Fluorouracil (IC50 ∼10µM). Subsequently, the cytotoxicity of each molecule was tested on the HCC cell line panel composed of Huh7, HepG2, Hep3B, Mahlavu, PLC, SkHep1, Focus, SNU-182 and SNU-475 cells. The IC50 values were again in micromolar varying between 0.1 to 10 µM range. However, we did not observe significant cytotoxic effect on SNU-182 cells with AUM18 PNA and on SNU-475 with AUM32. The differential inhibition that we observe, can be considered as an indication of the specificity of these inhibitors against their target. They might interfere with the activity of certain kinases rather than acting as a multi-kinase inhibitor. Furthermore, we evaluated the protein kinase activity inhibition potential of these novel purine analogs. Therefore, the kinase assay based on the detection of the amount of ATP in the reaction mixture through bioluminescence was performed with Huh7 and Mahlavu cells. Cells incubated with these novel kinase inhibitor candidates and Staurosporine (STS), a multi-kinase inhibitor used as positive control (4). The relative light units that we observed with novel PNAs were comparable to that of STS. Based on our observations, the newly synthesized PNAs, AUM18, AUM23 and AUM32 can be identified as protein kinase inhibitor candidates which must be further analyzed at the molecular level.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A171.

Synthesis of new 3-(substituted phenacyl)-5-[3'-(4H-4-oxo-1-benzopyran-2-yl)-benzylidene]-2,4-thiazolidinediones and their antimicrobial activity

Synthesis of 3-(3-nitrophenacyl)thiazolidine-2,4-dione 2g and 3-(substituted phenacyl)-5-[3'-(4H-4-oxo-1-benzopyran-2-yl)-benzylidene]-2,4-thiazolidinediones 4a-g are reported in this paper. These compounds 4a-g were prepared from 3'-flavone carboxaldehyde and 3-substituted phenacyl-2,4-thiazolidinediones using Knoevenagel reaction. The structures of all compounds were confirmed by IR, 1H-NMR, mass spectral data, and elemental analyses. The molecules 4a-g were evaluated for in-vitro antimicrobial activity against Staphylococcus aureus, Candida albicans, Candida krusei, Candida glabrata, and Candida parapsilosis. Compounds 4c and 4f showed better inhibitory activity when compared to fluconazole against Candida krusei and Candida glabrata.

5'-nor carbocyclic ribavirin

An efficient synthesis of 5'-nor carbocyclic ribavirin (4) is described in 13 steps from conveniently available (+)-(IR,4S)-4-hydroxy-2-cyclopenten-1-yl acetate (6). Compound 4 was evaluated against the following viruses: herpes simplex type 1 and 2, vaccinia, cowpox, smallpox, Ebola, hepatitis B, hepatitis C, adenovirus type 1, influenza A (H1N1 and H3N2), influenza B, parainfluenza type 3, Pichinde, Punta Toro A, respiratory syncytial, rhinovirus type 2, Venezuelan equine encephalitis, yellow fever, and West Nile. No activity was found nor was there any cytotoxicity to the viral host cells.

Evaluation of the Antioxidant Effects of Some Flavonyithiazolidinediones by Determining Their Effects on Lipid Peroxidation, Superoxide Anion Formation, and 2,2-Diphenyl-1-picrylhydrazyl Stable Free Radical

The in vitro antioxidant effects of some flavonylthiazolidinediones (Ia-d, IIa-d) on rat liver microsomal NADPH-dependent lipid peroxidation (LP) levels were determined by measuring the formation of 2-thiobarbituric acid reactive substance. The free radical-scavenging properties of the compounds were examined in vitro by determining the capacity to scavenge superoxide anion formation and of the interaction with the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH). The compounds had no inhibitory effects on LP. However, they had variable inhibitory influence on superoxide anion production and DPPH radical in a concentration-dependent manner. The most active compound, 3-(2,5-dimethoxyphenacyl)-5-[2-phenyl-4H-4-oxo-1-benzopyran-6-yl)methylenyl]-thiazolidine-2,4-dione, Id showed 98% inhibition of superoxide anion production and 95% inhibition of DPPH stable free radical at 10(-3) M.

9-deaza-5'-noraristeromycin

9-deaza-5'-noraristeromycin (2) has been prepared in 10 steps from the readily available (+)-(1R,4S)-4-t-butyldimethylsilyloxycyclopent-2-en-1-yl acetate. Compound 2 was evaluated against a large number of viruses. No activity was found nor did 2 display cyctotoxicity towards the viral host cells.