Synthesis & Anticancer Evaluation of New Substituted 2-(3,4- Dimethoxyphenyl)benzazoles

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.

A new series of benzoxazole-based SIRT1 modulators for targeted therapy of non-small-cell lung cancer

In an attempt to identify potential anticancer agents for non-small-cell lung cancer (NSCLC) targeting sirtuin 1 (SIRT1), the synthesis of a new series of benzoxazoles (3a - i) was carried out through a facile and versatile synthetic route. The compounds were evaluated for their cytotoxic effects on A549 human lung adenocarcinoma and NIH/3T3 mouse embryonic fibroblast cells using the MTT assay. 2-[(5-Nitro-1H-benzimidazol-2-yl)thio]-N-(2-methylbenzoxazol-5-yl)acetamide (3e) and 2-[(5-chloro-1H-benzimidazol-2-yl)thio]-N-(2-methylbenzoxazol-5-yl)acetamide (3g) were the most potent and selective anticancer agents in this series against the A549 cell line, with IC₅₀ values of 46.66 ± 11.54 and 55.00 ± 5.00 µM, respectively. The flow cytometry-based apoptosis detection assay was performed to determine their effects on apoptosis in A549 cells. Both compounds induced apoptosis in a dose-dependent manner. The effects of compounds 3e and 3g on SIRT1 activity were determined. On the basis of in vitro studies, it was observed that compound 3g caused a significant decrease in SIRT1 levels in a dose-dependent manner, whereas compound 3e increased the SIRT1 levels. According to molecular docking studies, the substantial alteration in the type of action could be attributed to the difference between the interactions of compounds 3e and 3g with the same residues in the active site of SIRT1 (PDB code: 4IG9). On the basis of in silico ADME (absorption, distribution, metabolism, and excretion) studies, these compounds are predicted to possess favorable ADME profiles. According to the in vitro and in silico studies, compounds 3e and 3g, small-molecule SIRT1 modulators, were identified as potential orally bioavailable anticancer agents for the targeted therapy of NSCLC.

Synthesis and Structure Elucidation of New Benzimidazole Amidoxime Derivatives

OBJECTIVES

In our previous studies we synthesized some potent antiparasitic, anticancer and antimicrobial amidine derivatives. Despite all their potent activities, it is well known that due to their cationic charge, amidine derivatives pose a serious problem in terms of bioavailability. The main purpose of this study is to prepare amidoxime derivatives of previously synthesized potent amidine derivatives as prodrugs in order to increase their bioavailabilities.

MATERIALS AND METHODS

The targeted benzimidazole amidoximes were synthesized from their nitrile derivatives. The nitrile groups of these benzimidazole carbonitriles were converted to N-hydroxy benzamidine derivatives (amidoxime derivatives, 20-29) in the presence of NH₂OH.HCI and KO-t-Bu in dimethyl sulfoxide. Structures of newly synthesized amidoxime derivatives were elucidated with 1H-NMR, 13C-NMR and some 2D NMR techniques like COSY, NOESY, HSQC and HMBC.

RESULTS

A new series of benzimidazole amidoximes were synthesized and their structural elucidations were done in this study.

CONCLUSION

In order to solve the potential bioavailability problem of potent amidine derivatives, we prepared the prodrugs of those potent amidine derivatives as their amidoxime derivatives. In vivo studies of both previous amidine derivatives and amidoxime prodrugs of those amidines which were synthesized in this study are planned to perform in our ongoing studies.