Medicinal Chemistry - Volume 17, Issue 8, 2021

Background: From the point of view of medicinal chemistry, compounds containing phenolic and pyrazolic moiety are significant since they are often constituents of bioactive compounds. Objective: The aims of this study were to synthesize pyrazole derivatives of medically relevant phenolic acids, confirm their structure, and evaluate their antioxidative and anti-LOX activities. Methods: Phenolic pyrazole derivatives were obtained, starting from esters of medically relevant phenolic acids. The structures of all obtained compounds were determined by NMR and IR spectroscopy, and UV-Vis spectrophotometry. In addition, the single-crystal X-ray diffraction was used. Pyrazole derivatives were tested for their in vitro antioxidative (DPPH assay), and lipoxygenase (LOX) inhibitory activities. Radical quenching mechanism was estimated using DFT and thermodynamic approach, while molecular docking was used to estimate the binding mode within the enzyme. Results: Pyrazole derivatives were obtained in high yields. The crystal structure of a new compound 3e was determined. Pyrazole derivative with catechol moiety 3d exhibited excellent radical scavenging activity, while compound 3b exhibited the best anti-LOX activity. Molecular docking study revealed that there is no direct interaction of any ligand with the active site of LOX-Ib, but pyrazoles 3a-e behave as inhibitors blocking the approach of linoleic acid to the active site. Conclusion: In this research, protocatechuic and vanillic acid pyrazole derivatives have been obtained for the first time. In vitro antioxidative assay suggests that pyrazole derivate of protocatechuic acid is a powerful radical scavenger, while anti-LOX assay indicates a pyrazole derivative with 4-hydroxyphenyl moiety.

Background: Malaria greatly affects the world health, having caused more than 228 million cases only in 2018. The emergence of drug resistance is one of the main problems in its treatment, demonstrating the need for the development of new antimalarial drugs. Objective: Synthesis and in vitro antiplasmodial evaluation of triazole compounds derived from isocoumarins and a 3,4-dihydroisocoumarin. Methods: The compounds were synthesized in 4 to 6-step reactions with the formation of the triazole ring via the Copper(I)-catalyzed 1,3-dipolar cycloaddition between isocoumarin or 3,4- dihydroisocoumarin azides and terminal alkynes. This key reaction provided compounds with an unprecedented connection of isocoumarin or 3,4-dihydroisocoumarin and the 1,2,3-triazole ring. The products were tested for their antiplasmodial activity against a Plasmodium falciparum chloroquine resistant and sensitive strains (W2 and 3D7, respectively). Results: Thirty-one substances were efficiently obtained by the proposed routes with an overall yield of 25-53%. The active substances in the antiplasmodial test displayed IC50 values ranging from 0.68-2.89 μM and 0.85-2.07 μM against W2 and 3D7 strains, respectively. Conclusion: This study demonstrated the great potential of isocoumarin or 3,4-dihydroisocoumarin derivatives because practically all the tested substances were active against Plasmodium falciparum.

Background: One of the best methods to treat Alzheimer disease (AD) is through the effective use of cholinesterase inhibitors as vital drugs due to the identification of acetylcholine deficit in the AD patients. Objective: The present study aims the investigation of spiro heterocyclic compounds as potential AD agents supported by their metal chelation capacity, POM analyses and DFT studies, respectively. Methods: The cholinesterase inhibition and metal chelation ability were performed on ELISA microtiter assay. Whereas, the B3LYP method with 6-31+G(d,p) basis set was implemented to study HOMOLUMO energy calculations. The pharmacokinetic properties of the synthesized molecules were studied through Petra, Osiris and Molinspiration (POM). Results: The six spiro (1-6) skeletons were tested for their inhibitory potential and metal-chelation capacity. Our findings revealed that the tested spiro skeletons exerted none or lower than 50% inhibition against both cholinesterases, while compound 4 proved to be the most active molecule with 57.21±0.89% of inhibition toward BChE. The spiro molecule 3 exhibited the highest metal-chelation capacity (9.12±5.26%). Molecular docking model for the most active molecule exhibited promising bindings with AChE and BChE’s active site pertained to hydrophobic hydrogen bonds and positive ionizable interactions. The POM analyses gave the information about the flexibility at the site of coordination of spiro compounds (1-6). Conclusion: The screening of spirocompounds (1-6) against cholinesterases revealed that some of them show considerable potential to inhibit AChE and BChE. Herein, we propose that the spiro molecules after further derivatization could serve interesting AD inhibitor drugs.

Background: Alzheimer´s disease (AD) is characterized by a progressive neuronal degeneration caused by two pathological hallmarks, hyperphosphorylated tau protein aggregated into tau filaments and amyloid precursor protein derived beta amyloid peptides aggregated into extracellular amyloid plaques. All attempts so far to find effective drugs failed in clinical trials. AD is a multifactorial disease, so that selective drugs to target one AD-relevant structure alone may not be sufficient. Objective: We built novel furopyridines with various substitution patterns to evaluate them as protein kinases inhibitors of enzymes related to tau pathology. Methods: Furopyridine derivatives were synthesized and purified using column chromatography. The protein kinase inhibitory properties were determined in ATP-competition assays with determined affinity constants for the most active compounds. Results: The compounds were prepared in simple two-component reactions of substituted 1,4- dihydropyridines and respective quinones to obtain various substitutions of the molecular furopyridine scaffold. The substituent effects on the determined kinase inhibitory properties of cdk1, cdk2, Fyn, JNK3 and gsk-3β are discussed. Conclusion: Various 3-substitutions were found most sensitive for the protein kinase inhibition depending on the length, nature and a substituent positioning within. We identified compounds as inhibitors of several kinases as a tool to potentially combat the disease progress in a multitargeting approach.

Background: Arylnaphthalene lignan lactones are a class of natural products containing the phenyl-naphthyl skeleton. Some arylnaphthalene lignan lactones have been used in clinical practice as antitumor agents, due to their cytotoxicity and inhibitory activities against DNA topoisomerase I (Topo I) and topoisomerase II (Topo II). Objective: This study presents the design and synthesis of arylnaphthalene lignan lactones derivatives. The inhibitory activities against Topo I and Topo IIα and antitumor activities of these compounds were assayed. Methods: A series of arylnaphthalene lignan lactones derivatives have been designed and synthesized, using the Diels-Alder reaction and Suzuki reaction as the key steps. Their antiproliferation activities were evaluated by sulforhodamine B assay on human breast cancer MDAMB-231, MDA-MB-435 and human cervical cancer HeLa cells. DNA relaxation assays were employed to examine the inhibitory activity of compounds 1-22 on Topo I and Topo IIα in vitro. Flow cytometry analysis was performed to study the drug effects on cell cycle progressions. Results: Seven compounds exhibited the modest anti-proliferation activity with IC50 values between 1.36 and 20 μM. Compounds 3, 19 and 22 showed potent inhibitory activities with IC50 values less than 1 μM. DNA relaxation assay revealed that compound 22 showed potent inhibitory activity against Topo IIα in vitro. Compound 22 also induced DNA breaks in MDA-MB-435 cells evidenced by comet tails and the accumulation of γ-H2AX foci. The ability of 22 in inducing DNA breaks mediated by Topo IIα resulted in G2/M phase arrest and apoptosis. Conclusion: This work indicates that arylnaphthalene lignan lactones derivatives represent a novel type of Topo IIα inhibitory scaffold for developing new antitumor chemotherapeutic agents.

Aims: The present study was conducted to examine the inhibitory effects of synthesized sulfonylhydrazones on the expression of CD73 (ecto-5′-NT). Background: CD73 (ecto-5′-NT) represents the most significant class of ecto-nucleotidases, which are mainly responsible for the dephosphorylation of adenosine monophosphate to adenosine. Inhibition of CD73 played an important role in the treatment of cancer, autoimmune disorders, precancerous syndromes, and some other diseases associated with CD73 activity. Objective: Keeping in view the significance of CD73 inhibitor in the treatment of cervical cancer, a series of sulfonylhydrazones (3a-3i) derivatives synthesized from 3-formylchromones were evaluated. Methods: All sulfonylhydrazones (3a-3i) were evaluated for their inhibitory activity towards CD73 (ecto-5′-NT) by the malachite green assay and their cytotoxic effect was investigated on the HeLa cell line using MTT assay. Secondly, the most potent compound was selected for cell apoptosis, immunofluorescence staining, and cell cycle analysis. After that, CD73 mRNA and protein expression were analyzed by real-time PCR and Western blot. Results: Among all compounds, 3h, 3e, 3b, and 3c were found to be the most active against rat-ecto- 5′-NT (CD73) enzyme with IC50 (μM) values of 0.70 ± 0.06 μM, 0.87 ± 0.05 μM, 0.39 ± 0.02 μM, and 0.33 ± 0.03 μM, respectively. These derivatives were further evaluated for their cytotoxic potential against cancer cell line (HeLa). Compounds 3h and 3c showed the cytotoxicity at IC50 value of 30.20 ± 3.11 μM and 86.02 ± 7.11 μM, respectively. Furthermore, compound 3h was selected for cell apoptosis, immunofluorescence staining, and cell cycle analysis, which showed a promising apoptotic effect in HeLa cells. Additionally, compound 3h was further investigated for its effect on the expression of CD73 using qRT-PCR and western blot. Conclusion: Among all synthesized compounds (3a-3i), Compound 3h (E)-N'-((6-ethyl-4-oxo-4Hchromen- 3-yl) methylene)-4-methylbenzenesulfonohydrazide was identified as the most potent compound. Additional expression studies conducted on the HeLa cell line proved that this compound successfully decreased the expression level of CD73 and thus, inhibited the growth and proliferation of cancer cells.

Background: There is a great need to discover more drugs with antimycobacterial activities to fight lung cancer and tuberculosis (two of the deadliest diseases worldwide). To our knowledge, the present study is the first to report the antimycobacterial activity of imidazole-fused heterocycles. Objective: Construction of some bis-imidazole fused heterocycles with potential anti-tubercular and/or potent antitumor activities. Methods: A series of bis-imidazole fused derivatives 6-8 and 13-16 was constructed using bisphenacyl bromide derivative 2 as a synthetic platform. Compound 2 was also used to access bisquinoxaline 20, bis-benzothiazine derivatives 23, and bis-thiazolopyrimidine derivatives 26. The new bis-imidazole derivatives were evaluated for their anticancer activity against the lung carcinoma cell line (A-549) using Cisplatin as a reference drug. The new compounds were also screened for their anti-tubercular activity against M. tuberculosis (ATCC 25177) using Isoniazid as a reference drug. Results: Among the new bis-imidazole derivatives, three examples showed remarkable antitumor activities while five other compounds showed high antimycobacterial activity. Conclusion: A novel series of bis-imidazole fused heterocycles was developed. Multiple prototypes of this new series showed remarkable anti-tubercular and/or potent antitumor activities.

Background: Diabetes mellitus is one of the most chronic metabolic disorders. Since past few years, our research group had synthesized and evaluated libraries of heterocyclic compounds against α and β-glucosidase enzymes and found encouraging results. The current study comprises of evaluation of indane-1,3-dione as antidiabetic agents based on our previously reported results obtained from closely related moiety isatin and its derivatives. Objective: A library of twenty three indane-1,3-dione derivatives (1-23) was synthesized and evaluated for α and β-glucosidase inhibitions. Moreover, in silico docking studies were carried out to investigate the putative binding mode of selected compounds with the target enzyme. Methods: The indane-1,3-dione derivatives (1-23) were synthesized by Knoevenagel condensation of different substituted benzaldehydes with indane-1,3-dione under basic condition. The structures of synthetic molecules were deduced by using different spectroscopic techniques, including ¹H-, ¹³C-NMR, EI-MS, and CHN analysis. Compounds (1-23) were evaluated for α and β-glucosidase inhibitions by adopting the literature protocols. Result: Off twenty three, eleven compounds displayed good to moderate activity against α- glucosidase enzyme, nonetheless, all compounds exhibited less than 50% inhibition against β- glucosidase enzyme. Compounds 1, 14, and 23 displayed good activity against α-glucosidase enzyme with IC50 values of 2.80 ± 0.11, 0.76 ± 0.01, and 2.17 ± 0.18 μM, respectively. The results have shown that these compounds have selectively inhibited the α-glucosidase enzyme. The in silico docking studies also supported the above results and showed different types of interactions of synthetic molecules with the active site of enzyme. Conclusion: The compounds 1, 14, and 23 have shown good inhibition against α-glucosidase and may potentially serve as lead for the development of new therapeutic representatives.

Background: The inhibition of α-amylase enzyme is one of the best therapeutic approach for the management of type II diabetes mellitus. Chalcone possesses a wide range of biological activities. Objective: In the current study chalcone derivatives (1-16) were synthesized and evaluated their inhibitory potential against α-amylase enzyme. Methods: For that purpose, a library of substituted (E)-1-(naphthalene-2-yl)-3-phenylprop-2-en-1-ones was synthesized by Claisen-Schmidt condensation reaction of 2-acetonaphthanone and substituted aryl benzaldehyde in the presence of base and characterized via different spectroscopic techniques such as EI-MS, HRESI-MS, ¹H-, and ¹³C-NMR. Results: Sixteen synthetic chalcones were evaluated for in vitro porcine pancreatic α-amylase inhibition. All the chalcones demonstrated good inhibitory activities in the range of IC50 = 1.25 ± 1.05 to 2.40 ± 0.09 μM as compared to the standard commercial drug acarbose (IC50 = 1.34 ± 0.3 μM). Conclusion: Chalcone derivatives (1-16) were synthesized, characterized, and evaluated for their α- amylase inhibition. SAR revealed that electron donating groups in the phenyl ring have more influence on enzyme inhibition. However, to insight the participation of different substituents in the chalcones on the binding interactions with the α-amylase enzyme, in silico (computer simulation) molecular modeling analyses were carried out.

Background: The role of zinc in diabetes has been a subject of considerable interest due to the insulin-mimetic properties associated with this mineral. On the other hand, phenolic acids are known as plant-derived polyphenols with antioxidative and antidiabetic pharmacological credence. Objective: This study was conducted in order to develop a novel therapeutic nutraceutical with an improved and multi-mode antidiabetic and antioxidative pharmacological property using cinnamic acid and Zn(II) mineral framework. Methods: A Zn(II) acetate complex of cinnamic acid was synthesized and characterized using FT-IR and ¹HNMR spectroscopy. Cytotoxicity evaluation was done using Chang liver cells and differentiated L6 myotubes. DPPH and ABTS scavenging, as well as Fe³⁺ reducing effects, were used to evaluate the antioxidant capacity. The antiglycation, as well as α-glucosidase and α-amylase inhibitory properties, were evaluated. Insulin mimetic property was evaluated as glucose uptake in L6 myotubes, while the complex was docked against GLUT-4 and PKB. Results: FTIR and ¹HMR suggested that Zn(II) complexed with cinnamic acid through a Zn(O4) coordination mode, thus affording the resulting complex 2 cinnamic acid molecules. Hence, complexation increased (p #130; 0.05) the antiglycation effect of cinnamic acid (IC50 = 29.3 μM) by 2 folds (IC50 = 13.9 μM). Also, Zn(II) conferred a potent glucose uptake (EC50 = 31 μM) and α-glucosidase inhibitory (IC50 = 59.4 μM) property on cinnamic acid; hence the activity of the complex was 162 and 2.1 folds higher than (p #130; 0.05) its precursor, respectively. Further molecular docking studies showed that the complex had a stronger interaction with insulin signaling proteins (GLUT-4 and PKB) than its precursor. Interestingly, the complex showed no severe cytotoxicity. Conclusion: Data suggested a structure-activity relationship. Complexation of Zn(II) to cinnamic acid resulted in a complex with improved and multi-facet pharmacological effects, which may be further studied as a safe glycemic control nutraceutical for T2D and glycation-induced complications.

Background: Coumarins are naturally occurring biologically active heterocyclic molecules endowed with a wide range of biological properties, including antibacterial, antifungal, and antitumor activities. Objective: The present work was aimed to synthesize new coumarin-containing compounds and to investigate their cytotoxic activity. Methods: Coumarin peptide and coumarin amino alcohols were prepared by treating epoxidecontaining coumarin derivatives with suitable aromatic amines and peptides in trifluoroethanol as a solvent at 50°C. These derivatives were evaluated for their cytotoxic activity on three different cell lines: HeLa, MDA-MB-231 and L-132. Cell viability was determined by MTT (3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Results: A new protocol was developed for the synthesis of thirteen novel coumarin peptide and coumarin amino alcohol derivatives. Among the tested compounds, three derivatives showed significant activity against all the tested cell lines. Docking studies indicated favorable interactions of the disubstituted peptide coumarin derivatives with the Asp 351 and Thr 347 amino acids at the active site of the human estrogen receptor. Conclusions: The results suggest that the synthesized compounds may be promising candidates in the research of new antitumor compounds.