Tubulin Polymerization Research Articles

The Unicellular, Parasitic Fungi, Sanchytriomycota, Possess a DNA Sequence Possibly Encoding a Long Tubulin Polymerization Promoting Protein (TPPP) but Not a Fungal-Type One.

The unicellular, parasitic fungi of the phylum Sanchytriomycota (sanchytrids) were discovered a few years ago. These unusual chytrid-like fungi parasitize algae. The zoospores of the species of the phylum contain an extremely long kinetosome composed of microtubular singlets or doublets and a non-motile pseudocilium (i.e., a reduced posterior flagellum). Fungi provide an ideal opportunity to test and confirm the correlation between the occurrence of flagellar proteins (the ciliome) and that of the eukaryotic cilium/flagellum since the flagellum occurs in the early-branching phyla and not in terrestrial fungi. Tubulin polymerization promoting protein (TPPP)-like proteins, which contain a p25alpha domain, were also suggested to belong to the ciliome and are present in flagellated fungi. Although sanchytrids have lost many of the flagellar proteins, here it is shown that they possess a DNA sequence possibly encoding long (animal-type) TPPP, but not the fungal-type one characteristic of chytrid fungi. Phylogenetic analysis of p25alpha domains placed sanchytrids into a sister position to Blastocladiomycota, similarly to species phylogeny, with maximal support.

Discovery and optimization of 2,3-diaryl-1,3-thiazolidin-4-one-based derivatives as potent and selective cytotoxic agents with anti-inflammatory activity

Several studies have indicated the potential therapeutic outcomes of combining selective COX-2 inhibitors with tubulin-targeting anticancer agents. In the current study, a novel series of thiazolidin-4-one-based derivatives (7a–q) was designed by merging the pharmacophoric features of some COXs inhibitors and tubulin polymerization inhibitors. Compounds 7a–q were synthesized and evaluated for their cytotoxic activity against MCF7, HT29, and A2780 cancer cell lines (IC50 = 0.02–17.02 μM). The cytotoxicity of 7a–q was also assessed against normal MRC5 cells (IC50 = 0.47–13.46 μM). Compounds 7c, 7i, and 7j, the most active in the MTT assay, significantly reduced the number of HT29 colonies compared to the control. Compounds 7c, 7i, and 7j also induced significant decreases in the tumor volumes and masses in Ehrlich solid carcinoma-bearing mice compared to the control. The three compounds also exhibited significant anti-HT29 migration activity in the wound-healing assay. They have also induced cell cycle arrest in HT29 cells at the S and G2/M phases. In addition, they induced significant increases in both early and late apoptotic events in HT29 cells compared to the control, where 7j showed the highest effect. On the other hand, compound 7j (1 μM) displayed weak inhibitory activity against tubulin polymerization compared to colchicine (3 μM). On the other hand, compounds 7a–q inhibited the activity of COX-2 (IC50 = 0.42–29.11 μM) compared to celecoxib (IC50 = 0.86 μM). In addition, 7c, 7i, and 7j showed moderate inhibition of inflammation in rats compared to indomethacin, with better GIT safety profiles. Molecular docking analysis revealed that 7c, 7i, and 7j have higher binding free energies towards COX-2 than COX-1. These above results suggested that 7j could serve as a potential anticancer drug candidate.

Effect of Colchicine Binding Site Inhibitors on the Tubulin Intersubunit Interaction.

Microtubules are dynamic, non-covalent polymers consisting of α- and β-tubulin subunits that are involved in a wide range of intracellular processes. The polymerization and dynamics of microtubules are regulated by many factors, including small molecules that interact with different sites on the tubulin dimer. Colchicine binding site inhibitors (CBSIs) destabilize microtubules and inhibit tubulin polymerization, leading to cell cycle arrest. Because of their therapeutic potential, the molecular mechanism of CBSI function is an area of active research. Nevertheless, important details of this mechanism have yet to be resolved. In this study, we use atomistic molecular dynamics simulations to show that the binding of CBSIs to the tubulin heterodimer leads to the weakening of tubulin intersubunit interaction. Using atomistic molecular dynamics simulations and binding free energy calculations, we show that CBSIs act as protein-protein interaction inhibitors and destabilize interlinkage between α and β subunits, which is crucial for longitudinal contacts in the microtubule lattice. Our results offer new insight into the mechanisms of microtubule polymerization inhibition by colchicine and its analogs.

Discovery of chiral 1,4-diarylazetidin-2-one-based hydroxamic acid derivatives as novel tubulin polymerization inhibitors with histone deacetylase inhibitory activity

Tubulin and histone deacetylase have been clinically proven as promising targets for cancer therapy. Herein, we describe the design and synthesis of chiral 1,4-diarylazetidin-2-one-based hydroxamic acids as novel tubulin/HDAC dual inhibitors. Among them, compound 12a was validated to effectively disrupt tubulin polymerization, and exhibited potent HDAC1/8 inhibitory activities. Meanwhile, 12a showed good antiproliferative activities against four tumor cell lines. Further studies showed 12a works through blocking cellular cycle, inducing apoptosis and inhibiting colony formation. In addition, 12a has suitable physicochemical properties and high liver microsomal metabolic stability. Importantly, compound 12a was found to exhibit significant antitumor efficacy in vivo, thus warranting it as a promising tubulin/HDAC dual inhibitor for further development.

In vivo impact of tubulin polymerization promoting protein (Tppp) knockout to the airway inflammatory response

Microtubule dysfunction has been implicated as a mediator of inflammation in multiple diseases such as disorders of the cardiovascular and neurologic systems. Tubulin polymerization promoting protein (Tppp) facilitates microtubule elongation and regulates tubulin acetylation through inhibition of cytosolic deacetylase enzymes. Pathologic alterations in microtubule structure and dynamics have been described in cystic fibrosis (CF) and associated with inflammation, however the causality and mechanism remain unclear. Likewise, Tppp has been identified as a potential modifier of CF airway disease severity. Here we directly assess the impact of microtubule dysfunction on infection and inflammation by interrogating wild type and a Tppp knockout mouse model (Tppp − / −). Mice are challenged with a clinical isolate of Pseudomonas aeruginosa-laden agarose beads and assessed for bacterial clearance and inflammatory markers. Tppp − / − mouse model demonstrate impaired bacterial clearance and an elevated inflammatory response compared to control mice. These data are consistent with the hypothesis microtubule dysregulation is sufficient to lead to CF-like airway responses in mice.

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.

Semicarbazides carrying indole core: Synthesis, cytotoxicity evaluation against human breast cancer cell lines, and molecular modeling studies.

In this paper, we report the synthesis and cytotoxicity evaluation of novel indole-carrying semicarbazide derivatives (IS1-IS15). The target molecules were obtained by the reaction of aryl/alkyl isocyanates with 1H-indole-2-carbohydrazide that was in-house synthesized from 1H-indole-2-carboxylic acid. Following structural characterization by 1H NMR, 13C NMR, and HRMS, IS1-IS15 were investigated for their cytotoxic activity against human breast cancer cell lines, MCF-7 and MDA-MB-231. According to the data obtained from the MTT assay, phenyl ring with a lipophilic group at its para-position and alkyl moiety were preferential substituents on the indole-semicarbazide scaffold for antiproliferative activity. The effect of IS12 (N-(4-chloro-3-(trifluoromethyl)phenyl)-2-(1H-indole-2-carbonyl)hydrazine-1-carboxamide), the compound that demonstrated remarkable antiproliferative activity on both cell lines, was also evaluated on the apoptotic pathway. Moreover, the calculation of critical descriptors constituting drug-likeness confirmed the position of the selected compounds in the anticancer drug development process. Finally, molecular docking studies suggested the inhibition of tubulin polymerization as the potential activity mechanism of this class of molecules.

Synthesis and anti-tumor activity of piperonal substituted chalcone

Objectives: Chalcones have been identified as potential antitumor agents with a novel target, the tubulin. The aim of the study was to synthesize a piperonal substituted chalcone and evaluate its in vivo antitumor activity. Materials and Methods: Piperonal substituted chalcone was synthesized using Claisen-Schmidt condensation and characterized using various spectroscopic techniques. The lethal dose (LD50) of the synthesized compound was estimated using OECD-425 guidelines in rats. Antitumor activity of the synthesized compound was evaluated on 1-methyl nitrosourea (MNU)-induced mammary tumor in female Wistar rats. Histological evaluation was used to confirm tumor induction and assess treatment with the synthesized compound. The possible mechanism of action of the synthesized compound was elucidated in silico using molecular docking. Results: The compound was synthesized and named C2. C2 was found to be relatively safe with LD50 >2000 mg/kg orally. Moreover, C2 exhibited remarkable antitumor activity, at all the tested doses in a dose dependent manner. Histological evaluation of the MNU-induced mammary tumor rats treated with C2 displayed fewer signs of hyperplasia and small numbers of connective tissue with larger lobules when compared with the untreated group. In silico tubulin-binding interactions revealed that the kinetics of C2 binding to tubulin was like that of colchicine. Comparison of crystal structures of tubulin-C2 and tubulin-colchicine complexes showed that the binding mode of C2 to tubulin was like that of colchicine to tubulin and produced the same conformational changes on the tubulin structure as colchicine. Conclusion: The synthesized chalcone demonstrated remarkable antitumor activities in MNU-induced mammary tumors in rats possibly through inhibition of tubulin polymerization.

Discovery of novel arylamide derivatives containing piperazine moiety as inhibitors of tubulin polymerisation with potent liver cancer inhibitory activity

In this work, a series of novel arylamide derivatives containing piperazine moiety were designed and synthesised as tubulin polymerisation inhibitors. Among 25 target compounds, compound 16f (MY-1121) exhibited low nanomolar IC50 values ranging from 0.089 to 0.238 μM against nine human cancer cells. Its inhibitory effects on liver cancer cells were particularly evident with IC50 values of 89.42 and 91.62 nM for SMMC-7721 and HuH-7 cells, respectively. Further mechanism studies demonstrated that compound 16f (MY-1121) could bind to the colchicine binding site of β-tubulin and directly act on β-tubulin, thus inhibiting tubulin polymerisation. Additionally, compound 16f (MY-1121) could inhibit colony forming ability, cause morphological changes, block cell cycle arrest at the G2 phase, induce cell apoptosis, and regulate the expression of cell cycle and cell apoptosis related proteins in liver cancer cells. Overall, the promising bioactivities of compound 16f (MY-1121) make the novel arylamide derivatives have the value for further development as tubulin polymerisation inhibitors with potent anticancer activities.

Modulation of taxane binding to tubulin curved and straight conformations by systematic 3′N modification provides for improved microtubule binding, persistent cytotoxicity and in vivo potency

The taxane class of microtubule stabilizers are some of the most effective and widely used chemotherapeutics. The anticancer activity of taxanes arises from their ability to induce tubulin assembly by selectively recognizing the curved (c-) conformation in unassembled tubulin as compared to the straight (s-) conformation in assembled tubulin. We first designed and synthesized a series of 3′N-modified taxanes bearing covalent groups. Instead of discovering covalent taxanes, we found a series of non-covalent taxanes 2, in which the 3′N side chain was found to be essential for cytotoxicity due to its role in locking tubulin in the s-conformation. A representative compound bearing an acrylamide moiety (2h) exhibited increased binding affinity to the unassembled tubulin c-conformation and less cytotoxicity than paclitaxel. Further exploration of chemical space around 2h afforded a new series 3, in which derivatives such as 3l bind more tightly to both the s- and c-conformations of tubulin compared to paclitaxel, leading to more efficient promotion of tubulin polymerization and a greater persistence of in vitro efficacy against breast cancer cells after drug washout. Although 3l also had improved in vivo potency as compared to paclitaxel, it was also associated with increased systemic toxicity that required localized, intratumoral injection to observe potent and prolonged antitumor efficacy.

Synthesis and anthelmintic activity of novel thiosemicarbazide and 1,2,4-triazole derivatives: In vitro, in vivo, and in silico study

IntroductionIntestinal parasitic infections are neglected diseases and, due to the increasing resistance of parasites to available drugs, they pose an increasing therapeutic challenge. Therefore, there is a great need for finding new compounds with antiparasitic activity. Objectives: In this work, new thiosemicarbazide and 1,2,4-triazole derivatives were synthesized and tested for their anthelmintic activity. MethodsThe synthesis was carried out by classical methods of organic chemistry. Anthelmintic activity tests were carried out in vitro (Rhabditis sp., Haemonchus contortus, Strongylidae sp.) in vivo (Heligmosomoides polygyrus/bakeri), and in silico analysis was performed. ResultsQuinoline-6-carboxylic acid derivative compounds were designed and synthesized. The highest activity in the screening tests in the Rhabditis model was demonstrated by compound II-1 with a methoxyphenyl substituent LC50 = 0.3 mg/mL. In the next stage of the research, compound II-1 was analyzed in the H. contortus model. The results showed that compound II-1 was active and had ovicidal (percentage of dead eggs > 45 %) and larvicidal (percentage of dead larvae > 75 %) properties. Studies in the Strongylidae sp. model confirmed the ovicidal activity of compound II-1 (percentage of dead eggs ≥ 55 %). In vivo studies conducted in the H. polygyrus/bakeri nematode model showed that the number of nematodes decreased by an average of 30 % under the influence of compound II-1. In silico studies have shown two possible modes of action of compound II-1, i.e. inhibition of tubulin polymerization and SDH. The test compound did not show any systemic toxic effects. Its influence on drug metabolism related to the activity of cytochrome CYP450 enzymes was also investigated. ConclusionThe results obtained in the in vitro, in vivo, and in silico studies indicate that the test compound can be described as a HIT, which in the future may be used in the treatment of parasitic diseases in humans and animals.

Antiproliferative and Tubulin-Destabilising Effects of 3-(Prop-1-en-2-yl)azetidin-2-Ones and Related Compounds in MCF-7 and MDA-MB-231 Breast Cancer Cells.

A series of novel 3-(prop-1-en-2-yl)azetidin-2-one, 3-allylazetidin-2-one and 3-(buta-1,3-dien-1-yl)azetidin-2-one analogues of combretastatin A-4 (CA-4) were designed and synthesised as colchicine-binding site inhibitors (CBSI) in which the ethylene bridge of CA-4 was replaced with a β-lactam (2-azetidinone) scaffold. These compounds, together with related prodrugs, were evaluated for their antiproliferative activity, cell cycle effects and ability to inhibit tubulin assembly. The compounds demonstrated significant in vitro antiproliferative activities in MCF-7 breast cancer cells, particularly for compounds 9h, 9q, 9r, 10p, 10r and 11h, with IC50 values in the range 10-33 nM. These compounds were also potent in the triple-negative breast cancer (TBNC) cell line MDA-MB-231, with IC50 values in the range 23-33 nM, and were comparable with the activity of CA-4. The compounds inhibited the polymerisation of tubulin in vitro, with significant reduction in tubulin polymerization, and were shown to interact at the colchicine-binding site on tubulin. Flow cytometry demonstrated that compound 9q arrested MCF-7 cells in the G2/M phase and resulted in cellular apoptosis. The antimitotic properties of 9q in MCF-7 human breast cancer cells were also evaluated, and the effect on the organization of microtubules in the cells after treatment with compound 9q was observed using confocal microscopy. The immunofluorescence results confirm that β-lactam 9q is targeting tubulin and resulted in mitotic catastrophe in MCF-7 cells. In silico molecular docking supports the hypothesis that the compounds interact with the colchicine-binding domain of tubulin. Compound 9q is a novel potent microtubule-destabilising agent with potential as a promising lead compound for the development of new antitumour agents.

Computational Exploration of the Structural Requirements of Triazole Derivatives as Colchicine Binding Site Inhibitors

AbstractColchicine inhibits microtubule assembly by preventing tubulin polymerization, making the colchicine binding site a promising target against cancer. The present study focuses on the 3D‐QSAR analysis of 31 triazole analogs. The atom‐based and field‐based QSAR models exhibit significant statistical results for internal and external validations, with the atom‐based 3D‐QSAR model showing a Q2 of 0.658 and R2 of 0.998, and the field‐based 3D‐QSAR model showing a Q2 of 0.658 and R2 of 0.998. The 3D‐QSAR atom‐based pharmacophore model explains biological activity using a six‐point hypothesis (AHHRRR.1), while the field‐based 3D‐QSAR model explains activity based on steric, electrostatic, hydrophobic, and hydrogen bond donor/acceptor fields. Based on the 3D contour maps generated, five new compounds were designed and their ADME/Tox properties predicted. The results suggested that these compounds possess potent pharmacological characteristics. The results of the molecular docking analysis showed that Pred01 and Pred02 had higher docking scores (−6.2417Kcal/mol and −6.5049Kcal/mol, respectively) than compound 15, and they formed notable hydrogen bonds and hydrophobic interactions with active site residues. The MMGBSA results confirmed these findings and emphasized the essential role of van der Waals energy in the binding energy. Moreover, the dynamic stability of the complexes was further supported by MD simulations.

End-binding protein 1 regulates the metabolic fate of CD4+ T lymphoblasts and Jurkat T cells and the organization of the mitochondrial network.

The organization of the mitochondrial network is relevant for the metabolic fate of T cells and their ability to respond to TCR stimulation. This arrangement depends on cytoskeleton dynamics in response to TCR and CD28 activation, which allows the polarization of the mitochondria through their change in shape, and their movement along the microtubules towards the immune synapse. This work focus on the role of End-binding protein 1 (EB1), a protein that regulates tubulin polymerization and has been previously identified as a regulator of intracellular transport of CD3-enriched vesicles. EB1-interferred cells showed defective intracellular organization and metabolic strength in activated T cells, pointing to a relevant connection of the cytoskeleton and metabolism in response to TCR stimulation, which leads to increased AICD. By unifying the organization of the tubulin cytoskeleton and mitochondria during CD4+ T cell activation, this work highlights the importance of this connection for critical cell asymmetry together with metabolic functions such as glycolysis, mitochondria respiration, and cell viability.

Insights into the Pharmacological Activity of the Imidazo-Pyrazole Scaffold.

In previous studies, we synthesized different imidazo-pyrazoles 1 and 2 with interesting anticancer, anti-angiogenic and anti-inflammatory activities. To further extend the structure-activity relationships of imidazo-pyrazole scaffold and to identify novel antiproliferative/anti-inflammatory agents potentially active with multi-target mechanisms, a library of compounds 3-5 has been designed and synthesized. The chemical modifications characterizing the novel derivatives include: i) decoration of the catechol ring with groups with different electronic, steric and lipophilic properties (compounds 3); ii) insertion of a methyl group on C-6 of imidazo-pyrazole scaffold (compounds 4); iii) shift of the acylhydrazonic substituent from position 7 to 6 of the imidazo-pyrazole substructure (compounds 5). All synthesized compounds were tested against a panel of cancer and normal cell lines. Derivatives 3 a, 3 e, 4 c, 5 g and 5 h showed IC50 values in the low micromolar range against selected tumor cell lines and proved to have antioxidant properties, being able to inhibit ROS production in human platelet. In silico calculation predicted favourable drug-like and pharmacokinetic properties for the most promising compounds. Furthermore, molecular docking and molecular dynamic simulations suggested the ability of most active derivative 3 e to interact with colchicine binding site in the polymeric tubulin α/tubulin β/stathmin4 complex.

Clastogenic, aneugenic, and tubulin polymerization properties of di-(2-ethylhexyl) phthalate and dibutyl phthalate.

Phthalate compounds were found to disrupt the endocrine system and alter transcriptomes during human embryonic development. In our previous work, we have isolated and reported two such phthalates di-(2-ethylhexyl) phthalate (DEHP) and dibutyl phthalate (DBP) from Brevibacterium mcbrellneri bacteria and evaluated their bioactive properties. Naturally derived phthalates might be less toxic compared with synthesized molecules. We have investigated biologically isolated phthalates to understand the possible genotoxic effects in mice and further investigated in silico binding and polymerization of β-tubulin. Three sub-lethal concentrations of DEHP (150μM, 175μM, and 200μM) and DBP (10μM, 15μM, and 30μM) were studied. The results showed that the phthalates were found to be highly genotoxic in nature. However, the pattern of genotoxic effects was not found to be dose-dependent in the induction of chromosome aberrations (CA), micronuclei (MN), and changes in the mitotic index (MI) in cells. In silico studies of phthalates on polymerization of β-tubulin suggested that both DBP and DEHP were able to interact with the hydrogen bonds and make strong van der Waals interactions with β-tubulin thereby possibly causing destabilization of microtubule network. Our study suggests that these phthalates might be playing an important role in normal cell division thereby showing highly genotoxic effects.

Design, synthesis, and biological evaluation of 4-aryl-9H-carbazoles as tubulin polymerization inhibitors with potent anticancer activities

Some novel 4-aryl-9H-carbazoles were designed as potential tubulin polymerization inhibitors through structural optimization and bioisosteric strategy. These compounds showed effective antiproliferative activities against a diverse set of cancer cell lines, including HeLa, HepG2, and SGC-7901 cells. Among them, compound 13k exerted the strongest inhibitory effect on HeLa cells with an IC50 of 1.2 ± 0.09 μM. Mechanism studies indicated that 13k significantly inhibited tubulin polymerization in vitro and disrupted the dynamic homeostasis of microtubules in HeLa cells. Furthermore, 13k concentration-dependently caused G2/M phase cell cycle arrest and apoptosis in HeLa cells. Molecular docking analysis demonstrated the interaction of 13k at the colchicine binding site of tubulin. In addition, the prediction of physicochemical properties studies shows that 13k has good pharmacokinetic properties. These preliminary results suggested that 13k is a new tubulin polymerization inhibitor and worthy of further investigation.

Design, synthesis and tubulin polymerization inhibition activity of newly synthesized hydrazone-linked to combretastatin analogues as potential anticancer agents

A new series of hydrazone derivatives were synthesized by varying the active part (hydrazide group) of cis-vinyl amide derivatives, characterized by 1H NMR, 13C NMR spectral data and screened for their cytotoxic activity against MCF-7 breast cancer cell line. Results indicated that compounds 3 g, 3k and 4 were potent cytotoxic agents (IC50 = 4.02–5.36 μM) relative to CA-4 as a reference compound. The most active hydrazinyl compounds were further evaluated for the β-tubulin inhibition activity. Cellular cycle analysis of the inhibitory effect of N-(furan-2-ylmethylene)hydrazinyl 4 on each phase of the cell cycle of breast adenocarcinoma MCF-7 cells was investigated using flow cytometric analysis. Test compound elicited cellular cycle arrest at G2/M phase. Annexin V dual staining analysis results revealed that treatment of MCF-7 cells with N-(furan-2-ylmethylene)hydrazinyl 4 increase the percentage of apoptosis compared to negative untreated control. Besides, N-(furan-2-ylmethylene)hydrazinyl 4 induced apoptosis via decreased the level of mitochondrial membrane potential relative to untreated control cells as revealed by flow cytometry analysis. Moreover, molecular modeling investigations were conducted to clarify the manner in which the most potent compound binds within the tubulin's colchicine-binding pocket, thereby elucidating the reasons behind its exceptional cytotoxicity and its superior ability to inhibit tubulin when compared to CA-4.

The Sherpa hypothesis: Phenotype-Preserving Disordered Proteins stabilize the phenotypes of neurons and oligodendrocytes

Intrinsically disordered proteins (IDPs), which can interact with many partner proteins, are central to many physiological functions and to various pathologies that include neurodegeneration. Here, we introduce the Sherpa hypothesis, according to which a subset of stable IDPs that we term Phenotype-Preserving Disordered Proteins (PPDP) play a central role in protecting cell phenotypes from perturbations. To illustrate and test this hypothesis, we computer-simulate some salient features of how cells evolve and differentiate in the presence of either a single PPDP or two incompatible PPDPs. We relate this virtual experiment to the pathological interactions between two PPDPs, α-synuclein and Tubulin Polymerization Promoting Protein/p25, in neurodegenerative disorders. Finally, we discuss the implications of the Sherpa hypothesis for aptamer-based therapies of such disorders.

Exploration of quinoxaline-benzimidazole hybrids as apoptosis-inducing agents and tubulin polymerisation inhibitors

We herein report the design and synthesis of a new class of quinoxaline-benzimidazole hybrids based on the molecular hybridization concept and evaluation of their in vitro cytotoxicity profile against human cancer cell lines, i.e., colorectal, lung, skin, and mouse melanoma cell line. Among all the screened compounds, compound 5l (2-(1-(3, 4-dichlorobenzyl)-1H-benzo[d]imidazol-2-yl)quinoxaline) exhibited potent cytotoxicity against lung cancer cell line (A549) with an IC50 of 4.37 ± 0.09 µM with a cytospecificity towards cancer cells. Further, AO/EB, DAPI, DCFDA, and JC-1 staining techniques confirmed that 5l induced apoptosis in the A549 cell line. In addition, 5l in annexin V-FITC/PI assay induced early apoptosis. The clonogenic assay revealed that 5l inhibited colony formation in a dose-dependent manner. Cell cycle distribution analysis unveiled that 5l caused the arrest of G2/M phase of cell cycle. Moreover, 5l inhibited tubulin polymerization with an IC50 value of < 2.19 µM. Docking studies revealed that 5l has a prominent binding affinity towards colchicine binding site of α/β- tubulin with good protein-ligand interactions with a binding energy of -45.139 kcal/mol. In silico ADME/T prediction studies disclosed the favourable drug-like properties of 5l.