Semicarbazones, thiosemicarbazone, thiazole and oxazole analogues as monoamine oxidase inhibitors: Synthesis, characterization, biological evaluation, molecular docking, and kinetic studies

Exploration of novel triazolo-thiadiazine hybrids of deferasirox as multi-target-directed anti-neuroinflammatory agents with structure-activity relationship (SAR): a new treatment opportunity for Alzheimer's disease

It is believed that inflammation influences several physiological processes, including the function of the central nervous system. Moreover, the impairment of lipid mechanisms/pathways is associated with neurodegenerative disorders and onset of Alzheimer's disease (AD). AD is a chronic neurodegenerative disease representing the major cause of dementia worldwide. In this case, the overexpression of different pharmacological targets has been confirmed to address neuronal inflammation and AD, with acetylcholinesterase (AChE), monoamine oxidase-B (MAO-B), cyclooxygenase-2 (COX-2) and 5-lipoxygenase (LOX-5) being the most explored targets. Currently, the available treatments are only capable of alleviating the symptoms and not capable of delivering disease-modifying effects. Thus, the current research objective is to synthesize triazolo-thiadiazine derivatives of the deferasirox drug as multi-target compounds that could concurrently inhibit ChEs, MAOs, LOX-5 and COX-2. The synthesized derivatives were confirmed by FTIR, 1H NMR, 13C NMR and DEPT-135 spectroscopic techniques. During in vitro investigations, compound 11 was found to be the most potent inhibitor of all the targeted enzymes. Briefly, this compound exhibited inhibitory values (IC50 ± SEM) of 0.31 ± 0.16, 0.13 ± 0.16 and 0.94 ± 0.16 μM against AChE, MAO-B and COX-2, respectively, suggesting that it is a lead molecule for the synthesis of more potential multi-targeted inhibitors. Several compounds, such as compound 9 and 13, showed dual inhibition potential in comparison to standard drugs. Furthermore, molecular docking analysis was performed to validate the in vitro results, where the potent compounds showed some significant interactions with the key amino acids present in the active site of the targeted enzymes. Furthermore, molecular dynamics (MD) simulation data and physicochemical properties supported deferasirox-substituted triazolo-thiadiazine as a promising horizon for the discovery and development of new molecules to treat multifactorial diseases associated with neuro-inflammation, such as AD.

New class of thio/semicarbazide-based benzyloxy derivatives as selective class of monoamine oxidase-B inhibitors

Sixteen thio/semicarbazide-based benzyloxy derivatives (BT1-BT16) were synthesized and evaluated for their inhibitory activities against monoamine oxidases (MAOs). Most compounds showed better inhibitory activity against MAO-B than against MAO-A. BT1, BT3, and BT5 showed the greatest inhibitory activity with an identical IC50 value of 0.11 µM against MAO-B, followed by BT6 and BT7 (IC50 = 0.12 µM) and BT2 (IC50 = 1.68 µM). The selectivity index of BT5 was the highest (363.64) for MAO-B, whereas that of BT1 was 88.73. BT1 and BT5 were reversible MAO-B inhibitors, based on the results of dialysis experiments. In inhibition kinetics, BT1 and BT5 were competitive MAO-B inhibitors with Ki values of 0.074 ± 0.0020 and 0.072 ± 0.0079 µM, respectively. Additionally, in the in-vitro parallel artificial membrane penetration assay, BT1 and BT5 crossed the blood-brain barrier. Cytotoxicity and possible neuroprotective effects of the lead compounds were assessed using IMR 32 cells. Levels of the antioxidant superoxide dismutase, catalase, and glutathione peroxidase in IMR 32 cells were increased by pretreatment with lead compounds. Five lead molecules (BT1, BT3, BT5, BT6, and BT7) were used for the docking studies. A significant pi-pi interaction with Tyr 326 was observed and molecular dynamics studies were performed for the most promising BT1-MAO-B complex. These results suggested that BT1 and BT5 could be used therapeutically for the treatment of various neurodegenerative diseases.

Synthesis of epoxyazadiradione-thiazole hybrid derivatives and evaluation of their cytotoxic activities

In an attempt to develop natural product-based anticancer agents, a series of novel epoxyazadiradione-thiazole hybrids (6a-j) were synthesised and evaluated for their anticancer activity. All the synthesised derivatives were assessed for in vitro cytotoxic activity against a panel of human cancer and normal cell lines and the results showed that most of the compounds exhibited significant cytotoxic activity against cancer cells and as well some of the compounds showed less cytotoxicity against normal cells. In particular, compound 4 showed potent cytotoxic activity against tongue cancer cell lines. In consideration of the potent activity, the compound 4 was further assessed for cell cycle analysis and the results showed that the compound arrests the cell cycle progression at the G0/G1 phase in the tongue cancer cell lines. Consequently, the annexin V/PI staining assay demonstrated that compound 4 induced early apoptosis against tongue cancer. Taken together, the results inferred that the epoxyazadiradione is promising anticancer candidate for developing novel anticancer drugs against tongue cancer.

Recent Literature on the Synthesis of Thiazole Derivatives and their Biological Activities

The thiazole ring is naturally occurring and is primarily found in marine and microbial sources. It has been identified in various compounds such as peptides, vitamins (thiamine), alkaloids, epothilone, and chlorophyll. Thiazole-containing compounds are widely recognized for their antibacterial, antifungal, anti-inflammatory, antimalarial, antitubercular, antidiabetic, antioxidant, anticonvulsant, anticancer, and cardiovascular activities. The objective of this review is to present recent advancements in the discovery of biologically active thiazole derivatives, including their synthetic methods and biological effects. This review comprehensively discusses the synthesis methods of thiazole and its corresponding biological activities within a specific timeframe, from 2017 until the conclusion of 2022.

Urease inhibitory kinetics, molecular docking, SAR and ADME studies of imine analogues

A series of synthesized imine derivatives (3a–m), including thio-semicarbazone, semicarbazone, thiazole and oxazole functional moieties, were examined for in vitro urease inhibition activity.