Synthesis, cytotoxicity, docking study, and tubulin polymerization inhibitory activity of novel 1-(3,4-dimethoxyphenyl)-5-(3,4,5-trimethoxyphenyl)-1H-1,2,4-triazole-3-carboxanilides

1-Benzyl-5-bromo-3-hydrazonoindolin-2-ones as Novel Anticancer Agents: Synthesis, Biological Evaluation and Molecular Modeling Insights

Human health is experiencing several obstacles in the modern medical era, particularly cancer. As a result, the cancer therapeutic arsenal should be continually expanded with innovative small molecules that preferentially target tumour cells. In this study, we describe the development of two small molecule series (7a–d and 12a–e) based on the 1-benzyl-5-bromoindolin-2-one scaffold that connected through a hydrazone linker to a 4-arylthiazole (7a–d) or 4-methyl-5-(aryldiazenyl)thiazole (12a–e) moiety. The anticancer activity of all the reported indolin-2-one derivatives was assessed against breast (MCF-7) and lung (A-549) cancer cell lines. The 4-arylthiazole-bearing derivatives 7c and 7d revealed the best anticancer activity toward MCF-7 cells (IC50 = 7.17 ± 0.94 and 2.93 ± 0.47, respectively). Furthermore, the VEGFR-2 inhibitory activity for 7c and 7d was evaluated. Both molecules disclosed good inhibitory activity, and their IC50 values were equal to 0.728 µM and 0.503 µM, respectively. Additionally, the impacts of 7d on the cell cycle phases as well as on the levels of different apoptotic markers (caspase-3, caspase-9, Bax, and Bcl-2) were assessed. Molecular docking and dynamic simulations are carried out to explore the binding mode of 7d within the VEGFR-2 active site.

Synthesis and Biological Activity Screening of Newly Synthesized Trimethoxyphenyl-Based Analogues as Potential Anticancer Agents

A group of novel trimethoxyphenyl (TMP)-based analogues were synthesized by varying the azalactone ring of 2-(3,4-dimethoxyphenyl)-4-(3,4,5-trimethoxybenzylidene)oxazolone 1 and characterized using NMR spectral data as well as elemental microanalyses. All synthesized compounds were screened for their cytotoxic activity utilizing the hepatocellular carcinoma (HepG2) cell line. Compounds 9, 10 and 11 exhibited good cytotoxic potency with IC₅₀ values ranging from 1.38 to 3.21 μM compared to podophyllotoxin (podo) as a reference compound. In addition, compounds 9, 10 and 11 exhibited potent inhibition of β-tubulin polymerization. DNA flow cytometry analysis of compound 9 shows cell cycle disturbance at the G2/M phase and a significant increase in Annexin-V-positive cells compared with the untreated control. Compound 9 was further studied regarding its apoptotic potential in HepG2 cells; it decreased the level of MMP and Bcl-2 as well as boosted the level of p53 and Bax compared with the control HepG2 cells.

Development of novel isatin thiazolyl-pyrazoline hybrids as promising antimicrobials in MDR pathogens

Microbial Multidrug Resistance (MDR) is an emerging global crisis. Derivatization of natural or synthetic scaffolds is among the most reliable strategies to search for and obtain novel antimicrobial agents for the treatment of MDR infections. Here, we successfully manipulated the synthetically flexible isatin moieties to synthesize 22 thiazolyl-pyrazolines hybrids, and assessed their potential antimicrobial activities in vitro against various MDR pathogens, using the broth microdilution calorimetric XTT reduction method. We chose 5 strains to represent the major MDR microorganisms, viz: Methicillin-resistant S. aureus (MRSA), and Vancomycin-resistant E. faecalis (VRE) as Gram-positive bacteria; Carbapenem-resistant K. pneumonia (CRKP), and Extended-spectrum beta-lactamase E. coli (ESBL-E), as Gram-negative bacteria; and Fluconazole-resistant C. albicans (FRCA), as a yeast-like unicellular fungus. The cytotoxicity of compounds 9f and 10h towards mammalian lung fibroblast (MRC-5) cells demonstrated their potential satisfactory safety margin as represented by their relatively high IC₅₀ values. The target compounds showed promising anti-MDR activities, suggesting they are potential leads for further development and in vivo studies.

As promising antimicrobials against MDR pathogens, two novel series of isatin thiazolyl-pyrazoline conjugates were developed. Compounds 9f and 10h were the most effective against the tested MDR strains.

1,3,4-Oxadiazole N-Mannich Bases: Synthesis, Antimicrobial, and Anti-Proliferative Activities

The reaction of 5-(3,4-dimethoxyphenyl)-1,3,4-oxadiazole-2(3H)-thione 3 with formaldehyde solution and primary aromatic amines or 1-substituted piperazines, in ethanol at room temperature yielded the corresponding N-Mannich bases 3-arylaminomethyl-5-(3,4-dimethoxyphenyl)-1,3,4-oxadiazole-2(3H)-thiones 4a-l or 3-[(4-substituted piperazin-1-yl)methyl]-5-(3,4-dimethoxyphenyl)-1,3,4-oxadiazole-2(3H)-thiones 5a-d, respectively. The in vitro inhibitory activity of compounds 4a-l and 5a-d was assessed against pathogenic Gram-positive, Gram-negative bacteria, and the yeast-like pathogenic fungus Candida albicans. The piperazinomethyl derivatives 5c and 5d displayed broad-spectrum antibacterial activities the minimal inhibitory concentration (MIC) 0.5-8 μg/mL) and compounds 4j, 4l, 5a, and 5b showed potent activity against the tested Gram-positive bacteria. In addition, the anti-proliferative activity of the compounds was evaluated against prostate cancer (PC3), human colorectal cancer (HCT-116), human hepatocellular carcinoma (HePG-2), human epithelioid carcinoma (HeLa), and human breast cancer (MCF7) cell lines. The optimum anti-proliferative activity was attained by compounds 4l, 5a, 5c, and 5d.

OMA1520 and OMA1774, novel 1,2,4-triazole bearing analogs of combretastatin A-4, inhibit hepatocellular carcinoma: Histological and immunohistochemical studies

Combretastatin A-4 (CA-4) received significant interest as a potential anticancer agent in recent years. Several CA-4 analogs were synthesized and investigated to enhance the activity or solve the in vivo decreased activity of CA-4.

AIM

The present study aims to investigate the chemotherapeutic and the antiproliferative effects of the mono and the dual therapy of the newly synthesized CA-4 analogs OMA1520 and OMA1774 against hepatocellularcarcinoma (HCC) induced in male adult rats by N-methylnitrosourea (MNU).

METHODS

50 male rats were divided into 5 groups of 10 animals in each group. Group I: normal healthy control; group II: MNU treated group, group III: MNU animals treated by OMA1520, group IV: MNU animals treated by OMA1774, and group V: MNU animals treated by both OMA1520 and OMA1774. The rats were assessed for liver cancer progression or inhibition by evaluating the histopathological, immunohistochemical, biochemical, and antioxidant enzyme status.

RESULTS

The present work indicated that OMA1520 and OMA1774 possessed substantial chemotherapeutic efficiency against HCC. The histological and immunohistochemical examinations of liver tissues confirmed the biochemical sera data. Also, they diminished the cytotoxic effects of MNU and restored the normal histological hepatic architecture. Both analogs restored the normal levels of liver enzymes and functions and revealed potential antioxidant effects. OMA1520 and OMA1774 reduced the inflammatory and tumor markers' elevated expressions in serum.

CONCLUSION

Substantial evidence in our results suggests that both CA-4 analogs could be possible alternative anticancer agents, and their co-administration provides a synergistic activity.

Tubulin inhibitors: Discovery of a new scaffold targeting extra-binding residues within the colchicine site through anchoring substituents properly adapted to their pocket by a semi-flexible linker

Bis-hydrazides 13a-h were designed and synthesized as potential tubulin inhibitors selectively targeting the colchicine site between α- and β-tubulin subunits. The newly designed ring-B substituents were assisted at their ends by 'anchor groups' which are expected to exert binding interaction(s) with new additional amino acid residues in the colchicine site (beyond those amino acids previously reported to interact with reference inhibitors as CA-4 and colchicine). Conformational flexibility of bis-hydrazide linker assisted these 'extra-binding' properties through reliving ligands' strains in the final ligand-receptor complexes. Compound 13f displayed the most promising computational and biological study results in the series: MM/GBSA binding energy of -62.362 kcal/mol (extra-binding to Arg α:221, Thr β:353 & Lys β:254); 34% NCI-H522 cells' death (at 10 µM), IC₅₀ = 0.073 µM (MTT assay); significant cell cycle arrest at G2/M phase; 11.6% preG1 apoptosis induction and 83.1% in vitro tubulin inhibition (at concentration = IC₅₀). Future researchers in bis-hydrazide tubulin inhibitors are advised to consider the 2-chloro-N-(4-substituted-phenyl)acetamide derivatives as compound 13f due to extra-binding properties of their ring B.

Application of triazoles as bioisosteres and linkers in the development of microtubule targeting agents

The triazole ring system has emerged as an exciting prospect in the optimization studies of promising lead molecules in the quest for new drugs for clinical usage. Several marketed drugs possess these versatile moieties that are used in a wide range of medical indications. This stems from the unique intrinsic properties of triazoles, which impart stability to the basic pharmacophoric unit with an added advantage of being a bioisostere of different chemical functionalities. In the last decade, the use of triazoles as bioisosteres and linkers in the development of microtubule targeting agents has been extensively investigated. The present review highlights the advances in this promising area of drug discovery and development.

Synthesis, Biological Evaluation, and Molecular Docking of Combretastatin and Colchicine Derivatives and their hCE1-Activated Prodrugs as Antiviral Agents

Recent studies indicate that tubulin can be a host factor for vector-borne flaviviruses like dengue (DENV) and Zika (ZIKV), and inhibitors of tubulin polymerization such as colchicine have been demonstrated to decrease virus replication. However, toxicity limits the application of these compounds. Herein we report prodrugs based on combretastatin and colchicine derivatives that contain an ester cleavage site for human carboxylesterase, a highly abundant enzyme in monocytes and hepatocytes targeted by DENV. Relative to their parent compounds, the cytotoxicity of these prodrugs was reduced by several orders of magnitude. All synthesized prodrugs containing a leucine ester were hydrolyzed by the esterase in vitro. In contrast to previous reports, the phenylglycine esters were not cleaved by human carboxylesterase. The antiviral activity of combretastatin, colchicine, and selected prodrugs against DENV and ZIKV in cell culture was observed at low micromolar and sub-micromolar concentrations. In addition, docking studies were performed to understand the binding mode of the studied compounds to tubulin.