Novel purine derivatives as selective CDK2 inhibitors with potential anticancer activities: Design, synthesis and biological evaluation.

Purine analogues were discovered to be inhibitors of CDK2, suggesting a potential therapeutic scaffold. This paper addresses the design, synthesis, and anticancer evaluation of purine analogues as kinase inhibitors. In the early stages of the investigation, the designed compounds demonstrated a promising docking score and greater protein-ligand stability in MD simulation than the standard, indicating a higher affinity against CDK2. Thus, we synthesised new purine analogues under simple and optimised reaction conditions. Among the studies under NCI-60, 5g and 5i were the most effective, with a percentage GI of 98.09 and 90 against OVCAR-4 and SNB-75, respectively, at a dose of 10 µM. Additionally, 5g and 5i demonstrated 7.80-fold and 1.54-fold greater cytotoxicity against PA-1 and MCF-7, with IC50s of 1.08 µM and 3.54 µM, respectively, compared to seliciclib (8.43 µM and 5.46 µM). In addition, 5g and 5i showed selective cytotoxicity against PA-1 and MCF-7 than normal cells, with selectivity indexes of 26.40 and 15.45, respectively, as compared to the standard (SI=3.83 and 5.91). In the kinase selectivity assay, both compounds demonstrated greater affinity against CDK2 than other kinases, with IC50 of 0.21 µM and 0.59 µM, in contrast to the standard (IC50 = 0.63 µM). Furthermore, 5g confirmed kinase inhibition in the western blot by lowering CDK2, cyclin A2, and other downstream substrates. Moreover, it triggered cell death by apoptosis and cell cycle arrest in G2/M. Taken together, 5g merits further investigation in PKPD research to discover a potential therapeutic candidate against cancer.

PI3Kδ and mTOR dual inhibitors: Design, synthesis and anticancer evaluation of 3-substituted aminomethylquinoline analogues.

Phosphatidylinositide-3-kinase (PI3K) and the mammalian target of rapamycin (mTOR) have recently been identified as potential cancer targets. In our work, a new family of quinoline analogues was designed, developed, and evaluated as dual inhibitors of PI3Kδ/mTOR. The preliminary biological activity analysis led to the discovery of the lead compounds 5h and 5e. Compounds 5h and 5e exhibited excellent anti-tumor potency with IC50 of 0.26 µM and 0.34 µM against Ramos cells, respectively. Importantly, based on the enzymatic activity assay results, compounds 5h and 5e were identified as dual inhibitors of PI3Kδ and mTOR, with IC50 values of 0.042 µM and 0.056 µM for PI3Kδ and 0.059 µM and 0.073 µM for mTOR, respectively. Furthermore, these compounds showed superior selectivity for blocking PI3Kδ compared to other PI3K isoforms (α, ß, and γ), supporting the concept of developing inhibitors that specifically target PI3Kδ/mTOR. The most effective compound 5h was chosen for additional biological testing. At a low dose of 0.5 µM, a western blot investigation confirmed the anticancer effects by inhibiting the PAM cascade, which in turn reduced downstream biomarkers pAkt (Ser473), pAkt (Thr308), and pRPS6 (Ser235/236). Furthermore, it increased apoptosis at the early (10.03 times) and late (17.95 times) stages in the Annexin-V assay as compared to the standard. In addition, the expression of p53, caspase-3, caspase-9, and the Bax/BCl-2 ratio were all significantly increased by compound 5h in the ELISA assay. Based on these results, it appears that 5h may activate the intrinsic apoptosis pathway, which in turn triggers cell death. Furthermore, the anticancer effects could be attributed to the inhibition of PI3Kδ/mTOR, as shown by docking interactions. Lastly, it demonstrated improved in vitro metabolic stability and passed the in silico ADMET/drug-likeness test. This profile recommends 5h for future in vivo PK-PD and efficacy investigations in animal cancer models.

A novel class of pyrazole analogues as aurora kinase A inhibitor: design, synthesis, and anticancer evaluation.

Pyrazole, as a small molecule, was discovered for higher cytotoxicity and affinity towards Aurora-A kinase. Based on these facts, a novel pyrazole substituted at the 4th position was designed, synthesized, and evaluated against MCF-7, MDA-MB-23, and Vero (non-cancerous kidney cell) cell lines. Compounds5hand5eexhibited greater cytotoxicity in the series against MCF-7 and MDA-MB-231, with GI50 values of 0.12 µM and 0.63 µM, respectively, as compared to Imatinib (GI50 values of 16.08 µM and 10.36 µM). All of the compounds displayed selective cytotoxicity against cancer cells but not on normal Vero cells, supporting the design strategy to be a selective anticancer agent. Furthermore, compounds 5h and 5e inhibited Aurora-A kinase with IC50 values of 0.78 µM (4.70-fold) and 1.12 µM (2.84-fold), respectively, as compared to alisertib (IC50 = 3.36 µM). In addition, compound 5h significantly arrested the cell cycle at G2/M (34.89 %, 5.56-fold) and the apoptotic phase (25.04 %, 11.81-fold) compared to the control. It also triggered an increase in early (7.43 %) and late (14.89 %) phase apoptosis compared to vehicle (0.235 and 0.36 %, respectively), causing 37.89-fold higher total apoptosis in the annexin-V assay. These data imply that Aurora-A kinase inhibition may be linked to apoptosis induction and cell cycle arrest. Furthermore, their higher docking score in the study confirmed evidence of Aurora-kinase suppression. It was observed that fluorine and imidazole increased the H-bond and lipophilic interactions with the binding residue. Also, the substitution of electron-rich and lipophilic groups increased hydrophobic interactions. Moreover, the three-atom linkage (CH2NHCH2) expanded compound 5h to fill the cavity. Based on current findings, it is concluded that compounds 5h and 5e with strong Aurora-A kinase suppression may be promising anticancer agents.

Determination of doxepin hydrochloride in spiked human plasma and capsule after derivatization with eosin Y using resonance Rayleigh scattering, second-order scattering and frequency doubling scattering methods.

Doxepin hydrochloride (DOX) is a tricyclic antidepressant drug. Three sensitive spectrofluorimetric methods, namely resonance Rayleigh scattering (RRS), frequency doubling scattering (FDS) and second-order scattering (SOS), were developed and validated for their estimation of doxepin in spiked human plasma and formulation using liquid-liquid extraction method through the formation of an ion pair complex with eosin Y at a pH of 4.5. Various factors affecting fluorescence intensity were optimized, and the reaction kinetics was determined using the Arrhenius equation method. Different scattering methods such as RRS, FDS and SOS were developed at maximum scattering wavelengths λex /λem = 567/567 nm for RRS, 720/360 nm for SOS and 260/520 nm for FDS, respectively. The methods exhibited high sensitivities, and the detection limits for DOX were found to be 0.82, 1.20 and 1.03 ng/ml for RRS, FDS and SOS methods, respectively. The FDS method exhibited the highest sensitivity. The methods were validated using the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use guidelines and applied to determine DOX in capsule and spiked human plasma samples.

Discovery of new pyrazole-4-carboxamide analogues as potential anticancer agents targeting dual aurora kinase A and B.

Aurora kinases A and B are critical regulators of cell division and cytokinesis. Abnormal expression of Aurora kinases A and B causes chromosomal instability and disrupts several tumor suppressor and oncoprotein-controlled pathways. As a result, there has been a spike in interest in developing inhibitors against these kinases as anticancer treatments. This paper addresses the discovery, anticancer evaluation and druggability study of new pyrazole-4-carboxamide analogues as kinases inhibitors. Among the compounds, 6k demonstrated the highest cytotoxicity against HeLa and HepG2 cells, with IC50 of 0.43 µM and 0.67 µM, respectively. It selectively inhibited Aurora kinases A and B, with IC50 values of 16.3 nM and 20.2 nM, respectively, in comparison to other kinases. Molecular investigations revealed that 6k induced the inhibition of phosphorylated Thr288 (Aurora kinase A) and phosphorylated Histone H3 (Aurora kinase B), confirming its mechanism of action. Beside, compound 6k arrested the cell cycle at the G2/M phase by modulating cyclinB1 and cdc2 protein levels and increasing the Sub-G1 cell population. It also significantly increased polyploidization (>8 N) and abnormal mitosis, likely due to Aurora kinase inhibition. Furthermore, 6k boosted apoptosis through the intrinsic route, with elevated levels of p53, Bak, Bax, cleaved caspase-3, and cleaved PARP. Moreover, docking and MD simulations validated kinase inhibition-induced anticancer effects. Additionally, 6k satisfied drug-likeness parameters and remained stable in the in vitro metabolism. These findings indicate that 6k warrants further in vivo pharmacokinetic and pharmacodynamics investigations.

A Review of the Therapeutic Importance of Indole Scaffold in Drug Discovery.

Indole is known as a versatile heterocyclic building block for its multiple pharmacological activities and has a high probability of success in the race for drug candidates. Many natural products, alkaloids, and bioactive heterocycles contain indole as the active principle pharmacophore. These encourage the researchers to explore it as a lead in the drug development process. The current manuscript will serve as a torchbearer for understanding the structurally diverse class of indole derivatives with extensive pharmacological activity. The current manuscript describes the intermediates and their functional groups responsible for superior biological activity compared to the standard. The review is written to help researchers to choose leads against their target but also to provide crucial insight into the design of a hybrid pharmacophore-based approach in drug design with enhanced potential. The present reviews on the indole derivatives correlate the structures with biological activities as well as essential pharmacophores, which were highlighted. The discussion was explored under challenging targets like dengue, chikungunya (anti-viral), antihypertensive, diuretic, immunomodulator, CNS stimulant, antihyperlipidemic, antiarrhythmic, anti-Alzheimer's, and neuroprotective, along with anticancer, antitubercular, antimicrobial, anti-HIV, antimalarial, anti-inflammatory, antileishmanial, antianthelmintic, and enzyme inhibitors. So, this review includes a discussion of 19 different pharmacological targets for indole derivatives that could be utilized to derive extensive information needed for ligand-based drug design. The article will guide the researchers in the selection, design of lead and pharmacophore, and ligand-based drug design using indole moiety.

Synthesis, Anticancer Evaluation and Molecular Docking of Hexahydroquinoline Derivatives as Mcl-1 Inhibitors and Apoptosis Inducers.

BACKGROUND: Hexahydroquinoline as a small molecule was reported for good cytotoxicity and affinity towards Mcl-1. Hence, new compounds were explored as Mcl-1 inhibitors to be potent anticancer agents. OBJECTIVE: Compounds were synthesized and screened for cytotoxicity. The active compound was evaluated for cell cycle analysis, Mcl-1 inhibition, caspase-3, and caspase-9 activation. Further compounds were docked with Mcl-1 to confirm the mechanism of cytotoxicity. METHODS: Compounds were confirmed by spectral techniques and screened for cytotoxicity at National Cancer Institute (USA). The active derivatives were screened by SRB and MTT. In addition, the potent compound was studied for apoptosis and cell cycle analysis by PI staining, Mcl-1 inhibition by TR-FRET assay, and activation assay of caspase-3 and caspase-9 with the Elisa technique. RESULTS: Compounds 6a and 6b exhibited the highest growth inhibition of 86.28% and 93.20% against SR and HOP- 62, respectively. Compound 6a showed higher cytotoxicity (IC50 = 0.4 µM) against THP-1 and HL-60. It showed 15- fold higher apoptosis compared to control by arresting cells at the Sub-G1 in the cell cycle. It also showed a potent inhibition with IC50 of 1.5 µM against the anti-apoptotic protein Mcl-1, which may induce apoptosis. Furthermore, apoptosis was evidenced by an increase in cleaved caspase-3 and caspase-9 to 4.20 and 3 folds, respectively higher than control. The docking score of compound 6a was in good agreement with the Mcl-1 inhibition assay. CONCLUSION: Compound 6a inhibited anti-apoptotic protein Mcl-1 and induced activation of pro-apoptotic proteins caspase-3 and caspase-9. These dual results suggested the mechanism of apoptosis and cytotoxicity.

Synthesis, Cytotoxicity Evaluation and Molecular Docking of Fluorine Containing Hexahydroquinoline-3-Carbonitrile Derivatives.

BACKGROUND: Fluorine containing hexahydroquinoline-3-carbonitrile derivatives were found to have potent cytotoxicity. Furthermore, fluorine can modulate pharmacokinetic and pharmacodynamic profile of drugs. Hence, new derivatives containing fluorine were explored as potential cytotoxic agents. OBJECTIVE: Difluoro substituted compounds containing aromatic/heteroaromatic rings were designed, synthesized and screened for in vitro cytotoxicity on cancer cell lines. The active compounds were subjected to docking on Mcl-1 and ADME/T prediction. METHODS: The synthesized compounds were characterized using various spectral techniques like FT-IR, 1H NMR, 13C NMR and Mass spectra. Compounds were screened for cytotoxicity on NCI-60 cell lines at the National Cancer Institute. The active compounds were evaluated additionally by MTT and SRB assay. RESULTS: Compounds (6l and 6o) showed maximum cytotoxicity with (% GI) of 69 and 63.7 at 10 µM drug concentration, respectively. Compound 6i showed potent cytotoxicity with GI50 of 7.2 µM against Ishikawa cell line. Compound 6o was nearly as active as a reference with IC50 of 9.39 µM and 13.54 µM against HT-29 and HCT-116, respectively, and compound 6l also showed equal potency to that of reference with IC50 of 9.66 µM against Caco-2. Compounds 6i, 6o and 6l showed high docking scores, suggesting their cytotoxicity. Furthermore, ADME/T prediction revealed that all the compounds had drug-likeness properties. CONCLUSION: Enhanced lipophilic interaction of compounds due to the presence of fluorine in compounds 6i and 6l was revealed during the docking study. Compound 6i can be explored as a lead molecule against other endometrial cancer in futuristic drug development.