Design and synthesis of substituted dihydropyrimidinone derivatives as cytotoxic and tubulin polymerization inhibitors

Recognition of arylmethylidene derivatives of imidazothiazolotriazinones as novel tubulin polymerization inhibitors

Two series of arylmethylidene derivatives of imidazothiazolotriazinone differing in the structure of the imidazothiazolotriazine fragment were synthesized and their antiproliferative activity and effect on tubulin polymerization were evaluated. Some of the synthesized derivatives showed a significant antiproliferative effect, among which (Z)-7-(2,4-dichlorobenzylidene)-1,3-diethyl-1,3a,4,9a-tetrahydroimidazo[4,5-e]thiazolo[2,3-c][1,2,4]triazine-2,8(3H,7H)-dione 2n exhibited the highest antiproliferative activity. The GI50 values of the compound against 56 of the 58 cell lines were 19.4-87.8 nM; against the remaining 2 cell lines, they were 0.544-1.29 μM. Moreover, further mechanism analysis demonstrated that 2n caused G2/M arrest, induced cell apoptosis in K562 cells and blocked tubulin polymerization in the same way as colchicine.

Benzimidazole derivatives as tubulin polymerization inhibitors: Design, synthesis and in vitro cytotoxicity studies

A new class of benzimidazole derivatives as tubulin polymerization inhibitors has been designed and synthesized in this study. The in vitro anticancer profile of the developed molecules was reconnoitred on selected human cancer cells. The highest cytotoxicity was illustrated by compounds 7n and 7u with IC50 values ranging from 2.55 to 17.89 µM with specificity toward SK-Mel-28 cells. They displayed 5-fold less cytotoxicity towards normal rat kidney epithelial NRK52E cells, which implies that they are not harmful to normal, healthy cells. The cellular staining procedures like AO/EB, DCFDA, and DAPI were applied to comprehend the inherent mechanism of apoptosis which displayed nuclear and morphological alterations. The Annexin V binding and JC-1 studies were executed to evaluate the extent of apoptosis and the decline in mitochondrial transmembrane potential in SK-Mel-28 cell lines. Compound 7n dose-dependently arrested the G2/M phase of the cell cycle and the target-based outcomes proposed tubulin polymerization inhibition by 7n (IC50 of 5.05±0.13 μM). Computational studies were also conducted on the tubulin protein (PDB ID: 3E22) to investigate the stabilized binding interactions of compounds 7n and 7u with tubulin, respectively.

Development of tubulin polymerization inhibitors as anticancer agents

INTRODUCTION

Microtubules are intracellular, filamentous, polymeric structures that extend throughout the cytoplasm, composed of α-tubulin and β-tubulin subunits. They regulate many cellular functions including cell polarity, cell shape, mitosis, intracellular transport, cell signaling, gene expression, cell integrity, and are associated with tumorigenesis. Inhibition of tubulin polymerization within tumor cells represents a crucial focus in the pursuit of developing anticancer treatments.

AREAS COVERED

This review focuses on the natural product and their synthetic congeners as tubulin inhibitors along with their site of interaction on tubulin. This review also covers the developed novel tubulin inhibitors and important patents focusing on the development of tubulin inhibition for cancer treatment reported from 2018 to 2023. The scientific and patent literature has been searched on PubMed, Espacenet, ScienceDirect, and Patent Guru from 2018-2023.

EXPERT OPINION

Tubulin is one of the promising targets explored extensively for drug discovery. Compounds binding in the colchicine site could be given importance because they can elude resistance mediated by the P-glycoprotein efflux pump and no colchicine site binding inhibitor is approved by FDA so far. The research on the development of antibody drug conjugates (ADCs) for tubluin polymerization inhibition could be significant strategy for cancer treatment.

Avermectin B1a Shows Potential Anti-Proliferative and Anticancer Effects in HCT-116 Cells via Enhancing the Stability of Microtubules

Avermectins are a group of macrocyclic lactones that are commonly used as pesticides to treat pests and parasitic worms. Some members of the avermectin family, such as ivermectin, have been found to exhibit anti-proliferative activity toward cancer cells. This study aimed to investigate the potential anti-cancer activities of avermectin B1a using the HCT-116 colon cancer cell line. The MTT assay was used to calculate the IC50 by incubating cells with increasing doses of avermectin B1a for 24, 48, and 72 h. Flow cytometry was used to evaluate apoptosis following the 24 h incubation of cells. The migration capacity of the HCT-116 cells in the absence or presence of avermectin B1a was also investigated. Finally, tubulin polymerization in the presence of avermectin B1a was evaluated. Avermectin B1a presented anti-proliferative activity with an IC50 value of 30 μM. Avermectin B1a was found to promote tubulin polymerization at 30 μM. In addition, avermectin B1a induced apoptosis in HCT-116 cells and substantially diminished their ability to migrate. Avermectin B1a exhibits significant anti-cancer activity and enhances tubulin polymerization, suggesting that it can be used as a promising microtubule-targeting agent for the development of future anticancer drugs.

Regioselective synthesis and in vitro cytotoxicity evaluation of 3-thiooxindole derivatives: Tubulin polymerization inhibition and apoptosis inducing studies

Herein, regiospecific nucleophilic ring-opening of spiroaziridine oxindoles has been established to afford 3-substituted-thiooxindole derivatives as anticancer agents. Among the new series, compounds 7d and 9c exhibited promising cytotoxic activity toward HCT-116 cells with IC₅₀ values of 6.73 ± 0.36 and 6.64 ± 0.95 µM, respectively. Further, AO/EB, DCFDA, and DAPI staining studies were executed to establish the underlying apoptosis mechanism which displayed significant nuclear and morphological alterations. JC-1 staining and annexin V binding assay inferred the loss of mitochondrial membrane potential in HCT-116 cancer cells. Cell cycle analysis showed the treatment of 9c against HCT-116 cells, arrested the cell cycle in G2-M phase. In addition, tubulin binding assay revealed that compound 9c exhibited tubulin polymerase inhibition with IC₅₀ value of 9.73 ± 0.18 μM. This inhibition of tubulin polymerase was further supported by binding interactions of 9c with tubulin through docking studies on PDB ID: 3E22.

Dihydropyrimidinones as potent anticancer agents: Insight into the structure-activity relationship

Cancer is a serious disease that has been around for a long time but currently has no sustainable solution. Several medications currently available offer an opportunity for the manifestation of cancer treatment; however, the "search for better" has led to the development and study of a variety of new scaffolds. Dihydropyrimidinones (DHPMs) are a privileged scaffold, prominent for their versatile range of biological activities. In recent years, the anticancer potential of these unsaturated pyrimidine ring systems has been traversed, along with their synthesis methods and the interlinked mechanisms leading to the anticancer activity. This review summarizes the structure-activity relationship of DHPMs as potential anticancer agents. This study is a short review of their synthesis, mechanism of action, and structure-activity relationships (SARs) that are answerable for the anticancer activity of DHPMs and have been thoroughly researched and assessed.

Triazolo-linked benzimidazoles as tubulin polymerization inhibitors and DNA intercalators: Design, synthesis, cytotoxicity, and docking studies

A simple "click" protocol was employed in the quest of synthesizing 1,2,3-triazole-linked benzimidazoles as promising anticancer agents on various human cancer cell lines such as A549, HCT116, SK-Mel-28, HT-29, and MCF-7. Compound 12j demonstrated significant cytotoxic potential towards SK-Mel-28 cancer cells (IC₅₀ : 4.17 ± 0.09 µM) and displayed no cytotoxicity (IC₅₀ : > 100 µM) against normal human BEAS-2B cells inferring its safety towards normal healthy cells. Further to comprehend the underlying apoptosis mechanisms, AO/EB, dichlorodihydrofluorescein diacetate (DCFDA), and 4',6-diamidino-2-phenylindole (DAPI) staining were performed, which revealed the nuclear and morphological alterations. Compound 12j displayed impairment in cellular migration and inhibited colony formation. The annexin V binding assay and JC-1 were implemented to evaluate the scope of apoptosis and the loss of the mitochondrial transmembrane potential in SK-Mel-28 cells. Cell-cycle analysis revealed that compound 12j arrested the cells at the G2/M phase in a dose-dependent manner. Target-based assays established the inhibition of tubulin polymerization by 12j at an IC₅₀ value of 5.65  ± 0.05 μM and its effective binding with circulating tumor DNA as a DNA intercalator. The detailed binding interactions of 12j with tubulin and DNA were examined by docking studies on PDB ID: 3E22 and DNA hexamer (PDB ID: 1NAB), respectively.

Design, Synthesis, and Biological Evaluation of Novel Dihydropyrimidinone Derivatives as Potential Anticancer Agents and Tubulin Polymerization Inhibitors

The severity and prevalence of cancer in modern time are a huge global health burden. Continuous efforts are being made toward the development of newer therapeutic candidates to treat and manage this ailment. The dihydropyrimidinone scaffold is one of the key nuclei that have been highly explored and investigated against cancer. It has the potential to combat the consequences of cancer by interacting with several biological targets. Tubulin polymerization inhibition is one such strategy to prevent the progression of cancer. In the presented work, we have synthesized a series of sixteen dihydropyrimidinone derivatives by following a rational drug design. The synthesized compounds have been characterized by ¹H NMR and ¹³C NMR and were further evaluated for cytotoxic activity against breast cancer cell lines (MCF-7 and MDA-MB-231), lung cancer cell lines (A549), and colon cancer cell lines (HCT-116). Compounds 5D and 5P were found most potent and revealed a better cytotoxic activity compared with the standard drug colchicine. Furthermore, the tubulin polymerization inhibition assay revealed that compound 5D showed better inhibition than colchicines, whereas compound 5P revealed an almost equal inhibition to that of colchicine. Furthermore, to investigate the possible mode of action and binding patterns, compounds 5P and 5D were subjected to molecular docking against tubulin (Protein Data Bank ID: ISA0). The results showed that compounds revealed significant interactions and were well occupied inside the cavity of tubulin. The compounds 5D and 5P may serve as new leads in drug development against cancer.

Design, synthesis, and bioevaluation of imidazo [1,2-a] pyrazine derivatives as tubulin polymerization inhibitors with potent anticancer activities

Through structural optimization and ring fusion strategy, we designed a series of novel imidazo[1,2-a]pyrazine derivatives as potential tubulin inhibitors. These compounds displayed potent anti-proliferative activities (micromolar to nanomolar) against a panel of cancer cell lines (including HepG-2, HCT-116, A549 and MDA-MB-231 cells). Among them, compound TB-25 exhibited the strongest inhibitory effects against HCT-116 cells with an IC₅₀ of 23 nM. Mechanism studies revealed that TB-25 could effectively inhibit tubulin polymerization in vitro, and destroy the dynamic equilibrium of microtubules in HCT-116 cells. In addition, TB-25 dose-dependently induced G2/M phase cell cycle arrest and apoptosis in HCT-116 cells. Furthermore, TB-25 suppressed HCT-116 cell migration in a concentration-dependent manner. Finally, molecular docking showed that TB-25 fitted well in the colchicine binding site of tubulin and overlapped nicely with CA-4. Collectively, these results suggest that TB-25 represents a promising tubulin inhibitor deserving further investigation.

Synthesis and evaluation of novel almazole D analogs as anticancer agents

Novel almazole D-amide conjugates, esters, and N-alkylated analogs were synthesized and investigated for their anticancer activity against seven cancer cell lines. Among the series, compounds 5g and 5m showed significant anticancer activities against multiple cell lines with moderate selectivity indices. Compound 5g had IC₅₀ values of 5.86 ± 0.31, 9.94 ± 0.06, 12.74 ± 0.12, and 9.40 ± 0.03 μM against the B16-F10, DU145, HeLa, and LC-540 cell lines, respectively, while compound 5m showed IC₅₀ values of 6.35 ± 0.09, 9.17 ± 0.11, 9.00 ± 0.011, 19.65 ± 0.63, 8.13 ± 0.04, and 11.56 ± 0.01 μM against B16-F10, DU145, HeLa, HepG2, LC-540, and SK-BR-3 cells, respectively. Compared to almazole D, which only showed significant activity against B16-F10 cells (IC₅₀  = 9.05 ± 0.008 μM), the synthesized analogs showed improved anticancer activity against multiple cell lines. The kinase inhibition assay coupled with the docking studies revealed that epidermal growth factor receptor (EGFR) kinase inhibition via interaction with amino acid residue T790 on the EGFR is one of the possible mechanisms by which 5g exerts its anticancer potential. The ADMET prediction and drug-likeness of the analogs project the synthesized analogs as promising agents, which can be further developed for application in cancer therapy.

Novel Dihydropyrimidinone Derivatives as Potential P-Glycoprotein Modulators

P-glycoprotein (Pgp), an ATP binding cassette (ABC) transporter, is an ATP-dependent efflux pump responsible for cancer multidrug resistance. As part of efforts to identify human Pgp (hPgp) inhibitors, we prepared a series of novel triazole-conjugated dihydropyrimidinones using a synthetic approach that is well suited for obtaining compound libraries. Several of these dihydropyrimidinone derivatives modulate human P-glycoprotein (hPgp) activity with low micromolar EC₅₀ values. Molecular docking studies suggest that these compounds bind to the M-site of the transporter.

Discovery of pyrimidine-bridged CA-4 CBSIs for the treatment of cervical cancer in combination with cisplatin with significantly reduced nephrotoxicity

A series of pyrimidine-bridged CA-4 derivatives (9a-u) targeting colchicine site were designed, synthesized and evaluated. Among them, the most potent compound 9j showed favorable anti-proliferative activities against a panel of cervical cancer cells (IC₅₀ = 0.09-0.15 μM) and tubulin polymerization inhibitory activity (IC₅₀ = 4.6 μM). Meanwhile, compound 9j exhibited superior anti-proliferative activity against cisplatin-resistant HeLa/DDP and SiHa/DDP cells than CA-4 and cisplatin. Particularly, the combination of 30 mg/kg 9j with 3 mg/kg cisplatin resulted in a 73% tumor suppression rate in HeLa xenograft model and reduced the renal dysfunction and injuries caused by high doses of cisplatin. Moreover, 9j was highly selective over the normal human proximal tubular cells (HK-2 cells, IC₅₀ = 188 μM). Mechanism studies revealed that 9j could disrupt tubulin polymerization and vasculature, arrest the cell cycle at the G₂/M phase, induce apoptosis, and suppress clonogenesis and migration in HeLa cells. Further druggability characterization in terms of pharmacokinetic profile, acute toxicity, and hERG inhibition confirmed 9j could serve as a promising and safe combination agent for cervical cancer therapy.

Green synthesis, structural analysis and anticancer activity of dihydropyrimidinone derivatives

In this study, for the first time, we have used Citrus macroptera juice to synthesize dihydropyrimidine (DHPM) derivatives via the Biginelli reaction, which showed better yield, shorter reaction time, and did not require an organic solvent for the reaction. A series of DHPM derivatives were synthesized, and characterized, and structural analysis was achieved through SCXRD & Hirshfeld surface analysis. We observed that these synthesized dihydropyrimidine (DHPM) derivatives showed C–H⋯π, C–H⋯O, C–H⋯N, C–H⋯C, lone pair⋯π, π⋯π, etc. interactions. We also performed in silico studies for their inhibitory activities against human kinesin Eg5 enzyme, and the cytotoxic activity of the synthesized compounds was carried out against A549 lung adenocarcinoma cells. In silico analysis demonstrated that compounds with a chloro-group at the 3- or 4-position in the substituted ring of DHPM showed higher binding affinity for the human kinesin Eg5 enzyme (−7.9 kcal mol⁻¹) than the standard drug monastrol (−7.8 kcal mol⁻¹). Furthermore, in vitro cellular studies revealed that compounds with a chloro-group at the 3- or 4-position in the substituted ring of DHPM induced significant cell death in human A549 lung adenocarcinoma cells. This result indicates that a deactivating group (chlorine) at the 3- or 4-position in the substituted ring of DHPM might be a promising anticancer drug candidate for treating different types of cancers, particularly cancer of the lung.

Green synthesis, study and development of new potent dihydropyrimidinone analogues as anti-cancer drugs.

Novel N-bridged pyrazole-1-carbothioamides with potential antiproliferative activity: design, synthesis, in vitro and in silico studies

Thiazole-substituted pyrazole is an important structural feature of many bioactive compounds, including antiviral, antitubercular, analgesic and anticancer agents. Herein we describe an efficient and facile approach for the synthesis of two series of 36 novel N-bridged pyrazole-1-phenylthiazoles. The antiproliferative activity of a set of representative compounds was evaluated in vitro against different human cancer cell lines. Among the identified compounds, compound 18 showed potent anticancer activity against the examined cancer cell lines. The in silico molecular docking study revealed that compound 18 possesses high binding affinity toward both SK1 and CDK2. Overall, these results indicate that compound 18 is a promising lead anticancer compound which may be exploited for development of antiproliferative drugs.

Synthesis and biological evaluation of novel imidazo[1,2-a]pyridine-oxadiazole hybrids as anti-proliferative agents: Study of microtubule polymerization inhibition and DNA binding

Efforts towards the development of potential anticancer agents, a new series of imidazo[1,2-a]pyridine-oxadiazole hybrids were synthesized and evaluated for their in vitro anticancer activity against lung cancer (A549) and prostate cancer (PC-3, DU-145) cell lines. Amongst the compounds tested, 6d showed the highest potency on A549 cells with an IC₅₀ value of 2.8 ± 0.02 μM. Flow cytometric analysis of compound 6d treated A549 cells showed apoptosis induction by annexin-v/PI dual staining assay and the effect of 6d on different phases of cell cycle was also analyzed. Target based studies demonstrated the inhibition of tubulin polymerization by 6d at an IC₅₀ value of 3.45 ± 0.51 μM and its effective binding with CT-DNA. Further, the molecular modelling studies revealed that 6d has a prominent binding affinity towards α/β-tubulin receptor with admirable physico-chemical properties.

β-Carboline-based molecular hybrids as anticancer agents: a brief sketch

Cancer is a huge burden on the healthcare system and is foremost cause of mortality across the globe. Among various therapeutic strategies, chemotherapy plays an enormous role in overcoming the challenges of treating cancer, especially in late stage detection. However, limitations such as extreme side/adverse effects and drug resistance associated with available drugs have impelled the development of novel chemotherapeutic agents. In this regard, we have reviewed the development of β-carboline-based chemotherapeutic agents reported in last five years. The review mainly emphasizes on the molecular hybrids of β-carbolines with various pharmacophores, their synthetic strategies, and in vitro anticancer evaluation. In addition, the mechanisms of action, in silico studies, structural influence on the potency and selectivity among diverse cancer cell lines have been critically presented. The review updates readers on the diverse molecular hybrids prepared and the governing structural features of high potential molecules that can help in the future development of novel cytotoxic agents.

Design, synthesis and biological evaluation of novel imidazole-chalcone derivatives as potential anticancer agents and tubulin polymerization inhibitors

Novel imidazole-chalcone derivatives were designed and synthesized as tubulin polymerization inhibitors and anticancer agents. The antiproliferative activity of the imidazole-chalcone was assessed on some human cancer cell lines including A549 (adenocarcinoma human alveolar basal epithelial cells), MCF-7 (human breast cancer cells), MCF-7/MX (mitoxantrone resistant human breast cancer cells), and HEPG2 (human hepatocellular carcinoma cells). Generally, the imidazole-chalcone derivatives exhibited more cytotoxicity on A549 cancer cells in comparison to the other three cell lines, among them compounds 9j' and 9g showed significant cytotoxicity with IC₅₀ values ranging from 7.05 to 63.43 μM against all the four human cancer cells. The flow cytometry analysis of A549 cancer cells treated with 9g and 9j' displayed that these compounds induced cell cycle arrest at the G2/M phase at low concentrations and increased the number of apoptotic cells (cells in subG1 phase) at higher concentrations. They have also inhibited tubulin polymerization similar to combretastatin A-4 (CA-4). Annexin V binding staining assay in A549 cancer cells revealed that compound 9j' induced apoptosis (early and late). Finally, molecular docking studies of 9j' into the colchicine-binding site of tubulin presented the probable interactions of these compounds with tubulin.

Cinnamide derived pyrimidine-benzimidazole hybrids as tubulin inhibitors: Synthesis, in silico and cell growth inhibition studies

An approach in modern medicinal chemistry to discover novel bioactive compounds is by mimicking diverse complementary pharmacophores. In extension of this strategy, a new class of piperazine-linked cinnamide derivatives of benzimidazole-pyrimidine hybrids have been designed and synthesized. Their in vitro cytotoxicity profiles were explored on selected human cancer cell lines. Specifically, structural comparison of target hybrids with tubulin-DAMA-colchicine and tubulin-nocodazole complexes has exposed a deep position of benzimidazole ring into the αT5 loop. All the synthesized compounds were demonstrated modest to interesting cytotoxicity against different cancer cell lines. The utmost cytotoxicity has shown with an amine linker of benzimidazole-pyrimidine series, with specificity toward A549 (lung cancer) cell line. The most potent compound in this series was 18i, which inhibited cancer cell growth at micromolar concentrations ranging 2.21-7.29 µM. Flow cytometry studies disclosed that 18i inhibited the cells in G2/M phase of cell cycle. The potent antitumor activity of 18i resulted from enhanced microtubule disruption at a similar level as nocodazole on β-tubulin antibody, explored using immunofluorescence staining. The most active compound 18i also inhibited tubulin polymerization with an IC₅₀ of 5.72 ± 0.51 µM. In vitro biological analysis of 18i presented apoptosis induction on A549 cells with triggering of ROS generation and loss of mitochondrial membrane potential, resulting in DNA injury. In addition, 18i displayed impairment in cellular migration and inhibited the colony formation. Notably, the safety profile of most potent compound 18i was revealed by screening against normal human pulmonary epithelial cells (L132: IC₅₀: 69.25 ± 5.95 μM). The detailed binding interactions of 18i with tubulin was investigated by employing molecular docking, superimposition and free energy analyses. Thus remarks made in this study established that pyrimidine-benzimidazole hybrids as a new class of tubulin polymerization inhibitors with significant anticancer activity.

Targeting tubulin polymerization and DNA binding of 4-thiazolidinone–umbelliferone hybrids: synthesis and cytotoxicity evaluation

The discovery of a series of combretastatin A-4 inspired novel molecular hybrids of 4-thiazolidinone–umbelliferone as prominent cytotoxic agents was reported.

Synthesis and biological evaluation of substituted N-(2-(1H-benzo[d]imidazol-2-yl)phenyl)cinnamides as tubulin polymerization inhibitors

A new series of N-(2-(1H-benzo[d]imidazol-2-yl)phenyl) cinnamides was prepared and evaluated for their in vitro cytotoxic activity using various cancer cell lines viz. A549 (human non-small cell lung cancer), MDA-MB-231 (human triple negative breast cancer), B16-F10 (mouse melanoma), BT-474 (human breast cancer), and 4 T1 (mouse triple negative breast cancer). In the series of tested compounds, 12h showed potent cytotoxic activity against non-small cell lung cancer cell line with IC₅₀ value of 0.29 ± 0.02 µM. The cytoxicity of most potent compound 12h was also tested on NRK-52E (normal rat kidney epithelial cell line) and showed less cytotoxicity compared to cancer cells. Tubulin polymerization assay indicated that the compound 12h was able to impede the cell division by inhibiting tubulin polymerization. Moreover, molecular docking study also suggested the binding of 12h at the colchicine-binding site of the tubulin protein. Cell cycle analysis revealed that the compound 12h arrests G2/M phase. In addition, 12h induced apoptosis in A549 cell lines was evaluated by various staining studies like acridine orange, DAPI, analysis of mitochondrial membrane potential, annexin V-FITC, and DCFDA assays.

Design, synthesis, and molecular docking study of new monastrol analogues as kinesin spindle protein inhibitors

Lung, colorectal, and breast cancers are the top three types of cancer by incidence and are responsible for one-third of the cancer incidence and mortality. A series of 18 3,4-dihydropyrimidine analogues bearing a 1,2-methylenedioxybenzene component at position 4 with diverse side chains at positions 5 and 6 was designed and synthesized as inhibitors of the Eg5 kinesin enzyme. Target compounds were screened for their anticancer activity according to the NCI-USA protocol toward a panel of 60 cancer cell lines. Compounds 12a and 12b displayed the best antiproliferation activity against many cell lines. Interestingly, compound 12a displayed lethal effects against non-small-cell lung cancer NCI-H522 cells (-42.26%) and MDA-MB-468 breast cancer cells (-1.10%) at a single-dose assay concentration of 10^-5  M. Compounds 11c, 11d, 11g, 12a-d, 13, 15, and 18a were assayed against the kinesin enzyme, with IC₅₀ values ranging from 1.2 to 18.71 μM, which were more potent compared with monastrol (IC₅₀  = 20 μM). Cell cycle analysis of NCI-H522 cells treated with compound 12a showed cell cycle arrest at the G2/M phase. Furthermore, the expression levels of active caspase-3 and -9 were measured. A molecular docking study was performed for some demonstrative compounds as well as monastrol docked into the allosteric binding site of the kinesin spindle protein.

Exploration of carbamide derived pyrimidine-thioindole conjugates as potential VEGFR-2 inhibitors with anti-angiogenesis effect

The development of new small molecules from known structural motifs through molecular hybridization is one of the trends in drug discovery. In this connection, we have combined the two pharmacophoric units (pyrimidine and thioindole) in a single entity via molecular hybridization strategy along with introduction of urea functionality at C2 position of pyrimidine to increase the efficiency of H-bonding interactions. Among the synthesized conjugates 12a-aa, compound 12k was found to exhibit significant IC₅₀ values 5.85, 7.87, 6.41 and 10.43 μM against MDA-MB-231 (breast), HepG2 (liver), A549 (lung) and PC-3 (prostate) cancer cell lines, respectively. All these compounds were further evaluated for their inhibitory activities against VEGFR-2 protein. The results specified that among the tested compounds, 12d, 12e, 12k, 12l, 12p, 12q, 12t and 12u prominently suppressed VEGFR-2, with IC₅₀ values of 310-920 nM in association to the positive control (210 nM). Angiogenesis inhibition was evident by tube formation assay in HUVECs and cell-invasion by transwell assay. The mechanism of cellular toxicity on MDA-MB-231 was found through depolarisation of mitochondrial membrane potential, increased ROS production and subsequent DNA damage resulting in apoptosis induction. Moreover, clonogenic and wound healing assays designated the inhibition of colony formation and cell migration by 12k in a dose-dependent manner. Molecular docking studies also shown that compound 12k capably intermingled with catalytically active residues GLU-885, ASP-1046 of the VEGFR-2 through hydrogen-bonding interactions.

A Review on Recent Advances in Nitrogen-Containing Molecules and Their Biological Applications

The analogs of nitrogen-based heterocycles occupy an exclusive position as a valuable source of therapeutic agents in medicinal chemistry. More than 75% of drugs approved by the FDA and currently available in the market are nitrogen-containing heterocyclic moieties. In the forthcoming decade, a much greater share of new nitrogen-based pharmaceuticals is anticipated. Many new nitrogen-based heterocycles have been designed. The number of novel N-heterocyclic moieties with significant physiological properties and promising applications in medicinal chemistry is ever-growing. In this review, we consolidate the recent advances on novel nitrogen-containing heterocycles and their distinct biological activities, reported over the past one year (2019 to early 2020). This review highlights the trends in the use of nitrogen-based moieties in drug design and the development of different potent and competent candidates against various diseases.

Synthesis and biological evaluation of novel 5,6,7-trimethoxy flavonoid salicylate derivatives as potential anti-tumor agents

5,6,7-Trimethoxy flavonoid salicylate derivatives were designed by the joining of three important pharmacophores (TMP, flavonoid, and SA) according to the combination principle. A series of novel trimethoxy flavonoid salicylate derivatives were synthesized and their in vitro anti-tumor activities were evaluated. Among these derivatives, compound 7f exhibited excellent antiproliferative activity against HGC-27 cells and MGC-803 cells with IC₅₀ values of 10.26 ± 6.94 μM and 17.17 ± 3.03 μM, respectively. Subsequently, the effects on cell colony formation (clonogenic survival assay), cell migration (wound healing assay), cell cycle distribution (PI staining assay), cell apoptosis (Hoechst 33258 staining assay and annexin V-FITC/PI dual staining assay), lactate level (lactate measurement), microtubules disarrangement (immunofluorescence staining analysis) and docking posture (molecular docking simulation) were determined. Further western blot analysis confirmed that compound 7f could effectively down-regulate the expression of glycolysis-related proteins HIF-1α, PFKM and PKM2 and tumor angiogenesis-related proteins VEGF. Overall, these studies suggested that compound 7f, as the representative compound of those, might be a promising candidate for the treatment of gastric cancer and deserved the further studies.