Discovery of novel octahydroquinazoline scaffolds endowed with dual inhibition of tubulin polymerization/Eg5 against HCC: Apoptotic and radio-chemotherapeutic studies.

Mitotic kinesin Eg5 isozyme as a motor protein plays a critical role in cell division of tumor cells. Kinesin Eg5 selective inhibitors and Colchicine binding site suppressors are essential targets for many anticancer drugs and radio chemotherapies. On this work, a new series of octahydroquinazoline as anti-mitotic candidates 2-13 has been synthesized with dual inhibition of tubulin polymerization/Eg5 against HCC cell line. All octahydroquinazolines have been in vitro assayed against HepG-2 cytotoxicity, Eg5 inhibitory and anti-tubulin polymerization activities. The most active analogues 7, 8, 9, 10, and 12 against HepG-2 were further subjected to in vitro cytotoxic assay against HCT-116 and MCF-7 cell lines. Chalcones 9, 10, and 12 displayed the most cytotoxic potency and anti-tubulin aggregation in comparable with reference standard colchicine and potential anti-mitotic Eg5 inhibitory activity in comparison with Monastrol as well. Besides, they exhibited cell cycle arrest at the G2/M phase. Moreover, good convinced apoptotic activities have been concluded as overexpression of caspase-3 levels and tumor suppressive gene p53 in parallel with higher induction of Bax and inhibition of Bcl-2 biomarkers. Octahydroquinazoline 10 displayed an increase in caspase-3 by 1.12 folds compared to standard colchicine and induce apoptosis and demonstrated cell cycle arrest in G2/M phase arrest by targeting p53 pathway. Analogue 10 has considerably promoted cytotoxic radiation activity and boosted apoptotic induction in HepG-2 cells by 1.5 fold higher than standard colchicine.

Design and synthesis of novel benzoazoninone derivatives as potential CBSIs and apoptotic inducers: In Vitro, in Vivo, molecular docking, molecular dynamics, and SAR studies.

Apparently, tubulin inhibitors binding to the colchicine-binding site (CBS) currently have outstanding attention for cancer treatment. So, a series of benzo[b]azonin-2-one derivatives having the same pharmacophoric features as colchicine binding site inhibitors (CBSIs) were synthesized targeting the CBS of ß-tubulin. The antiproliferative activities of the newly synthesized compounds were assessed against five different cancer cell lines; HepG-2, MCF-7, MDA-MB-231, HCT-116, and Caco-2. Compounds 7a and 7d displayed promising inhibitory activities against all tested cell lines. They were further estimated towards ß-tubulin at CBS along with colchicine (Col) as a reference drug. It was shown that the assessed candidates (7a and 7d) and Col exhibited CBSI activities of 5492, 3771, and 486c.p.m./mg protein, respectively, at a concentration of 10 µM. Furthermore, compound 7d was picked out to assess its effects on apoptosis and cell-cycle profile using Annexin V-FITC and PI staining assay. In addition, the apoptotic activity of 7d was investigated using gene expression analysis of apoptosis-related genes of P53, Bax, Caspases 3 and 9, and Bcl-2 in both treated and untreated cells. Moreover, compound 7d was further assessed through in vivo studies using solid Ehrlich carcinoma (SEC)-bearing mice. Furthermore, both molecular docking and molecular dynamics simulations (for 150 ns) were performed to investigate their mechanism of action as potential CBSIs and give more insights into the behavior of the examined candidates within the ß-tubulin subunit of the CBS. On the other hand, in silico ADMET studies were carried out to assess the pharmacokinetic features, drug/lead likeness, and toxicity parameters of the newly synthesized derivatives. Finally, to anticipate the possible changes in the antimitotic activities upon future structural modifications of the investigated compounds, a structure-activity relationship study (SAR) was accomplished.

Discovery and biological evaluation of 4,6-pyrimidine analogues with potential anticancer agents as novel colchicine binding site inhibitors.

Novel 4,6-pyrimidine analogues were designed and synthesized as colchicine binding site inhibitors (CBSIs) with potent antiproliferative activities. Among them, compound 17j has the most potent activities against 6 human cancer cell lines with IC50 values from 1.1 nM to 4.4 nM, which was 76 times higher than the lead compound 3 in A549 cells. The co-crystal structure of 17j in complex with tubulin confirms the key binding mode at the colchicine binding site. Moreover, 17j inhibited the tubulin polymerization in biochemical assays, depolymerized cellular microtubules, induced the G2/M arrest, inhibited the cell migration, and promoted the initiation of apoptosis. In vivo, 17j effectively inhibits primary tumor growth with tumor growth inhibition rates of 42.51% (5 mg/kg) and 65.42% (10 mg/kg) in A549 xenograft model. Taken together, 17j represents a promising new generation of CBSIs.

Epidemiological Analysis of Cassava Mosaic and Brown Streak Diseases, and Bemisia tabaci in the Comoros Islands.

A comprehensive assessment of cassava brown streak disease (CBSD) and cassava mosaic disease (CMD) was carried out in Comoros where cassava yield (5.7 t/ha) is significantly below the African average (8.6 t/ha) largely due to virus diseases. Observations from 66 sites across the Comoros Islands of Mwali, Ngazidja, and Ndzwani revealed that 83.3% of cassava fields had foliar symptoms of CBSD compared with 95.5% for CMD. Molecular diagnostics confirmed the presence of both cassava brown streak ipomoviruses (CBSIs) and cassava mosaic begomoviruses (CMBs). Although real-time RT-PCR only detected the presence of one CBSI species (Cassava brown streak virus, CBSV) the second species (Ugandan cassava brown streak virus, UCBSV) was identified using next-generation high-throughput sequencing. Both PCR and HTS detected the presence of East African cassava mosaic virus (EACMV). African cassava mosaic virus was not detected in any of the samples. Four whitefly species were identified from a sample of 131 specimens: Bemisia tabaci, B. afer, Aleurodicus dispersus, and Paraleyrodes bondari. Cassava B. tabaci comprised two mitotypes: SSA1-SG2 (89%) and SSA1-SG3 (11%). KASP SNP genotyping categorized 82% of cassava B. tabaci as haplogroup SSA-ESA. This knowledge will provide an important base for developing and deploying effective management strategies for cassava viruses and their vectors.

Computational repurposing of benzimidazole anthelmintic drugs as potential colchicine binding site inhibitors.

Background: Although some benzimidazole-based anthelmintic drugs are found to possess anticancer activity, their modes of binding interactions have not been reported. Methodology: In this study, we aimed to investigate the binding interactions and electronic configurations of nine benzimidazole-based anthelmintics against one of the well-known cancer targets (tubulin protein). Results: Binding affinities of docked benzimidazole drugs into colchicine-binding site were calculated where flubendazole > oxfendazole > nocodazole > mebendazole. Flubendazole was found to bind more efficiently with tubulin protein than other drugs. Quantum mechanics studies revealed that the electron density of HOMO of flubendazole and mebendazole together with their molecular electrostatic potential map are closely similar to that of nocodazole. Conclusion: Our study has ramifications for considering repurposing of flubendazole as a promising anticancer candidate.

Design and synthesis of (2-(phenylamino)thieno[3,2-d]pyrimidin-4-yl)(3,4,5-trimethoxyphenyl)methanone analogues as potent anti-tubulin polymerization agents.

Anti-tubulin polymerization agents can disrupt tumor-vascular to exhibit anti-cancer potency. In this study, a series of substituted (2-(phenylamino)thieno[3,2-d]pyrimidin-4-yl)(3,4,5-trimethoxyphenyl)methanone analogues were designed and synthesized as anti-tubulin polymerization agents that interact with colchicine binding site. The anti-proliferative assay indicated that most of the target compounds displayed moderate to high potencies towards five tumor cell lines. The structure-activity relationship of these analogues was summarized. The most potent compound 14 was selected to assay its inhibition on the tubulin polymerization. 14 displayed potent inhibition against tubulin polymerization with an IC50 value of 4.1 ±â€¯0.1 µM. The colchicine competition assay demonstrated that 14 inhibited tubulin polymerization by binding to the colchicine-binding site of tubulin. The molecular modeling study elucidated the binding mode of 14 in the colchicine binding site. The result of confocal immunofluorescent study proved that 14 can quickly disrupt the microtubules of Hela cells in a concentration dependent manner. Some experiments at cellular level were conducted to investigate the effects of 14 on cellular morphology, cell colony formation, cell cycle distribution, cell apoptosis and mitochondrial changes. The results demonstrated that 14 is a potent anti-tubulin agent with strong concentration dependent effect of inhibition of colony formation, induction of G2/M arrest and induction of apoptosis through mitochondrial pathway.

BZML, a novel colchicine binding site inhibitor, overcomes multidrug resistance in A549/Taxol cells by inhibiting P-gp function and inducing mitotic catastrophe.

Multidrug resistance (MDR) interferes with the efficiency of chemotherapy. Therefore, developing novel anti-cancer agents that can overcome MDR is necessary. Here, we screened a series of colchicine binding site inhibitors (CBSIs) and found that 5-(3, 4, 5-trimethoxybenzoyl)-4-methyl-2-(p-tolyl) imidazol (BZML) displayed potent cytotoxic activity against both A549 and A549/Taxol cells. We further explored the underlying mechanisms and found that BZML caused mitosis phase arrest by inhibiting tubulin polymerization in A549 and A549/Taxol cells. Importantly, BZML was a poor substrate for P-glycoprotein (P-gp) and inhibited P-gp function by decreasing P-gp expression at the protein and mRNA levels. Cell morphology changes and the expression of cycle- or apoptosis-related proteins indicated that BZML mainly drove A549/Taxol cells to die by mitotic catastrophe (MC), a p53-independent apoptotic-like cell death, whereas induced A549 cells to die by apoptosis. Taken together, our data suggest that BZML is a novel colchicine binding site inhibitor and overcomes MDR in A549/Taxol cells by inhibiting P-gp function and inducing MC. Our study also offers a new strategy to solve the problem of apoptosis-resistance.