Identification of Essential 2D and 3D Chemical Features for Discovery of the Novel Tubulin Polymerization Inhibitors

Kinetic studies, molecular docking, and antioxidant activity of novel 1,3-diphenyl pyrazole-thiosemicarbazone with anti-tyrosinase and anti-melanogenesis properties

This study reports the Design Hypothesis of a novel series of 1,3-diphenyl pyrazole-thiosemicarbazone as novel tyrosinase inhibitors (TYRI). The designed compounds were prepared and their TYRI activity and mechanisms were studied. The results showed that the selected compounds exhibited potent tyrosinase inhibitory activities greater than that of kojic acid (KA). Lead candidates, denoted as 6g and 6n, with a para-hydroxyphenyl group attached to the 3-position of the pyrazole ring demonstrated IC50 values of 2.09 and 3.18 µM, respectively. The potency of these compounds was approximately 5-8 times higher than that of KA. The in vitro melanin content of 6g or 6n-treated melanoma cells resulted in significant efficacy in melanin reduction. The DPPH assay result revealed that the tyrosinase inhibition mechanism for these derivatives was independent of a redox effect and corresponded to the interaction with tyrosinase. According to the Lineweaver-Burk plot, the most potent compounds, 6g and 6n, exhibit a mixed type of inhibition, primarily noncompetitive inhibition. In silico molecular docking studies were employed to determine the binding mode and explore the Design Hypothesis in detail. The results suggested that these compounds could be considered promising leads for the further development of novel inhibitors to treat disorders related to tyrosinase.

Design, synthesis, biological evaluation, and molecular modeling studies of pyrazole-benzofuran hybrids as new α-glucosidase inhibitor

In this work, new derivatives of biphenyl pyrazole-benzofuran hybrids were designed, synthesized and evaluated in vitro through enzymatic assay for inhibitory effect against α-glucosidase activity. Newly identified inhibitors were found to be four to eighteen folds more active with IC₅₀ values in the range of 40.6 ± 0.2-164.3 ± 1.8 µM, as compared to the standard drug acarbose (IC₅₀ = 750.0 ± 10.0 μM). Limited Structure-activity relationship was established. A kinetic binding study indicated that most active compound 8e acted as the competitive inhibitors of α-glucosidase with K_i = 38 μM. Molecular docking has also been performed to find the interaction modes responsible for the desired inhibitory activity. As expected, all pharmacophoric features, used in the design of the hybrid, are involved in the interaction with the active site of the enzyme. In addition, molecular dynamic simulations showed compound 8e oriented vertically into the active site from mouth to the bottom and stabilized the enzyme domains by interacting with the interface of domain A and domain B and the back side of the active site while acarbose formed non-binding interaction with the residue belong to the domain A of the enzyme.

Design, synthesis, and bio-evaluation of new isoindoline-1,3-dione derivatives as possible inhibitors of acetylcholinesterase

Background and purpose:

Alzheimer’s disease is considered one of the lead causes of elderly death around the world. A significant decrease in acetylcholine level in the brain is common in most patients with Alzheimer’s disease, therefore acetylcholinesterase (AChE) inhibitors such as donepezil and rivastigmine are widely used for patients with limited therapeutic results and major side effects.

Experimental approach:

A series of isoindoline-1,3-dione -N-benzyl pyridinium hybrids were designed, synthesized and evaluated as anti-Alzheimer agents with cholinesterase inhibitory activities. The structure of the compounds were confirmed by various methods of analysis such as HNMR, CNMR, and FT-IR. Molecular modeling studies were also performed to identify the possible interactions between neprilysin and synthesized compounds.

Findings/Results:

The biological screening results indicated that all synthesized compounds displayed potent inhibitory activity with IC₅₀ values ranging from 2.1 to 7.4 μM. Among synthesized compounds, para-fluoro substituted compounds 7a and 7f exhibited the highest inhibitory potency against AChE (IC₅₀ = 2.1 μM). Molecular modeling studies indicated that the most potent compounds were able to interact with both catalytic and peripheral active sites of the enzyme. Also, some of the most potent compounds (7a, 7c, and 7f) demonstrated a neuroprotective effect against H₂O₂-induced cell death in PC12 neurons.

Conclusion and implications:

The synthesized compounds demonstrated moderate to good AChE inhibitory effect with results higher than rivastigmine.

Design and synthesis of novel pyrazole-phenyl semicarbazone derivatives as potential α-glucosidase inhibitor: Kinetics and molecular dynamics simulation study

A series of novel pyrazole-phenyl semicarbazone derivatives were designed, synthesized, and screened for in vitro α-glucosidase inhibitory activity. Given the importance of hydrogen bonding in promoting the α-glucosidase inhibitory activity, pharmacophore modification was established. The docking results rationalized the idea of the design. All newly synthesized compounds exhibited excellent in vitro yeast α-glucosidase inhibition (IC₅₀ values in the range of 65.1-695.0 μM) even much more potent than standard drug acarbose (IC₅₀ = 750.0 μM). Among them, compounds 8o displayed the most potent α-glucosidase inhibitory activity (IC₅₀ = 65.1 ± 0.3 μM). Kinetic study of compound 8o revealed that it inhibited α-glucosidase in a competitive mode (Ki = 87.0 μM). Limited SAR suggested that electronic properties of substitutions have little effect on inhibitory potential of compounds. Cytotoxic studies demonstrated that the active compounds (8o, 8k, 8p, 8l, 8i, and 8a) compounds are also non-cytotoxic. The binding modes of the most potent compounds 8o, 8k, 8p, 8l and 8i was studied through in silico docking studies. Molecular dynamic simulations have been performed in order to explain the dynamic behavior and structural changes of the systems by the calculation of the root mean square deviation (RMSD) and root mean square fluctuation (RMSF).