During the last five decades, a large number of BT (Benzothiazole) derivatives formed one of the eligible structures in medicinal chemistry as anticancer agents. Most of the studies reveal that various substitutions at specific positions on BT scaffold modulate the antitumor property. The potential of BTs encouraged us to synthesize a number of new 2-((5-substitutedbenzothiazol-2-yl)thio)-N’-(2-(4-(substitutedphenyl)ethylidene)acetohydrazide derivatives and investigate their probable anticancer activity. 4-Substitued benzaldehyde derivatives (1a–1e) were afforded by the reaction of appropriate secondary amine and 4-fluorobenzaldehyde in DMF. Equimolar quantitates of 5-substitutedbenzothiazole-2-thiol, ethyl chloroacetate and K₂CO₃ were refluxed in acetone to obtain 2-((5-substitutedbenzothiazol-2-yl)thio)acetate derivatives (2a,2b), which reacted with excess of hydrazine hydrate to get 2-((5-substitutebenzothiazol-2-yl)thio)acetohydrazides (3a,3b). In the last step, 2-((5-substitutedbenzothiazol-2-yl)thio)-N’-(4-substitutedbenzylidene)acetohydrazide derivatives (4a–4j) were synthesized by the reaction of 1a–1e and 3a–3b in EtOH. The anticancer activity of target compounds was evaluated in three steps. First, an MTT test (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) was performed to observe cytotoxic activity of the compounds against carcinogenic C6 (Rat brain glioma cell line), A549 (Human lung adenocarcinoma epithelial cell line), MCF-7 (Human breast adenocarcinoma cell line), and HT-29 (Human colorectal adenocarcinoma cell line) cancer cell lines. Healthy NIH3T3 (Mouse embryo fibroblast cell line) cells were also subjected to MTT assay to determine selectivity of the compounds towards carcinogenic cell lines. Secondly, inhibitory effects of selected compounds 4d, 4e, and 4h on DNA synthesis of C6 cells were investigated. Finally, flow cytometric analysis were performed to identify the death pathway of the carcinogenic cells.

Discovery of novel anticandidal agents with clarified mechanisms of action, could be a rationalist approach against diverse pathogenic fungal strains due to the rise of resistance to existing drugs. In support to this hypothesis, in this paper, a series of benzimidazole-oxadiazole compounds were synthesized and subjected to antifungal activity evaluation. In vitro activity assays indicated that some of the compounds exhibited moderate to potent antifungal activities against tested Candida species when compared positive control amphotericin B and ketoconazole. The most active compounds 4h and 4p were evaluated in terms of inhibitory activity upon ergosterol biosynthesis by an LC-MS-MS method and it was determined that they inhibited ergosterol synthesis concentration dependently. Docking studies examining interactions between most active compounds and lanosterol 14-α-demethylase also supported the in vitro results.

In the present work, 14 new 1-substituted-2-phenylhydrazone derivatives were synthesized to evaluate their inhibitory activity against hMAO enzymes. The structures of the newly synthesized hydrazones 2a–2n were characterized by IR, 1H-NMR, 13C-NMR, HR-MS spectroscopic methods. The inhibitory activity of compounds 2a–2n against hMAO-A and hMAO-B enzymes was elucidated by using an in-vitro Amplex Red® reagent assay based on fluorometric methods. According to the activity studies, 2a and 2b were found to be the most active compounds against hMAO-A enzyme, with IC50 values of 0.342 µM and 0.028 µM, respectively. The most active compounds 2a–2b were evaluated by means of enzyme kinetics and docking studies. Moreover, these compounds were subjected to cytotoxicity and genotoxicity tests to establish their preliminary toxicological profiles and were found to be non-cytotoxic and non-genotoxic. Consequently, the findings of this study display the biological importance of compounds 2a, 2b as selective, irreversible and competitive inhibitors of hMAO-A. Docking studies revealed that there is a strong interaction between hMAO-A and the most active compound 2b.

Alzheimer’s disease (AD), one of the main causes of aged dementia, is a progressive and degenerative neurological disorder characterized by loss of cognition and memory. Although the symptomatic treatment of AD, particularly acetylcholinesterase inhibitors (AChEIs) based on the ‘cholinergic hypothesis’, has been successful in clinic, at present there is no cure for this disease. In this study, we designed compounds carrying benzimidazole and triazole rings on the same chemical skeleton so as to investigate their potential acetylcholinesterase and butyrylcholinesterase activity. Furthermore, molecular modeling study was performed to determine the binding mode of the best inhibitor to the AChE. Among them, compounds 3d and 3h, which featured 3,4-dihydroxy substitution at the phenyl ring and 5(6)-chloro substitution at the benzimidazole ring were found to be potent inhibitors of AChE. The inhibition kinetics of the two most active derivatives 3d and 3h were further studied. The kinetic displayed increasing slope and increasing intercept, which is consistent with a mixed inhibition. The IC₅₀ and K_i values of 3d are 31.9 ± 0.1 nM and 26.2 nM, respectively. Compound 3h exhibited IC₅₀ of 29.5 ± 1.2 nM and K_i of 24.8 nM. The above data compared favorably with data for donepezil (21.8 ± 0.9 nM) the reference compound in our study.