Recognition of Natural Products as Potential Inhibitors of COVID-19 Main Protease (Mpro): In-Silico Evidences

SARS-CoV-2 (2019-nCoV) emerged in 2019 and proliferated rapidly across the globe. Scientists are attempting to investigate antivirals specific to COVID-19 treatment. The 2019-nCoV and SARS-CoV utilize the same receptor of the host which is COVID-19 of the main protease (Mpro).COVID-19 caused by SARS-CoV-2 is burdensome to overcome by presently acquired antiviral candidates. So the objective and purpose of this work was to investigate the plants with reported potential antiviral activity. With the aid of in silico techniques such as molecular docking and druggability studies, we have proposed several natural active compounds including glycyrrhizin, bicylogermecrene, tryptanthrine, β-sitosterol, indirubin, indican, indigo, hesperetin, crysophanic acid, rhein, berberine and β-caryophyllene which can be encountered as potential herbal candidate exhibiting anti-viral activity against SARS-CoV-2. Promising docking outcomes have been executed which evidenced the worthy of these selected herbal remedies for future drug development to combat coronavirus disease.

Docking techniques in pharmacology: How much promising?

In the drug development process, large numbers of molecules are failing at a later stage due to safety ö efficacy concerns which are generally investigated by conducting various experiments on animals but unfortunately, animal experimentation is associated with lots of limitations. Thus, there is an increasing interest in the development of alternative approaches that requires less number of animals. Docking is an alternative approach for screening of compounds before actually testing it on animals. It is the best option to predict the energetically favourable binding conformations of ligands in the active site cavity of particular receptor and has gained popularity in the scientific community to save time and money involved in the drug development process. The use of such techniques is increasing day by day among researchers due to availability of user friendly software's. Due to this, the number of papers related to docking has dramatically increased over the past decades. A variety of docking software's are currently available to predict the ligand binding pose in its particular receptor, but there is a lack of knowledge and confidence among scientists regarding accuracy of these softwares. There are many concerns to be taken care of, while carrying out any docking study such as selection of correct binding sites of the target protein, the selection of correct docking pose, lack of clarity over whether the compound is an antagonist or agonist, difficult to get best matching algorithms and scoring schemes. Many compounds show high dock score, but unfortunately fail in pre-clinical studies. These issues ought a chance to because for caution and concern before carrying out docking. Therefore, to ensure correct and effective application of docking techniques, it is necessary to understand the method's merits, demerits, the scope of application, and interpretation. In this review, we summarize fundamental concepts, why these techniques are needed, various docking methods and recent developments in this area. Further, current challenges and future perspectives of these tools are also discussed.

Synthesis and bioactivity of novel triazole incorporated benzothiazinone derivatives as antitubercular and antioxidant agent

In search of new active molecules against Mycobacterium tuberculosis (MTB) H37Ra and M. bovis BCG, a small focused library of benzothiazinone based 1,2,3-triazoles has been efficiently prepared via click chemistry approach. Several derivatives were found to be promising inhibitors of MTB and M. bovis BCG characterized by lower MIC values (27.34-29.37μg/mL). Among all the synthesized compounds, 6c and 6e is the most active compound against MTB and M. bovis BCG. The compounds were further tested for anti-proliferative activity against HeLa, A549 and A431 cell lines using MTT assay and showed no significant cytotoxic activity at the maximum concentration evaluated. Further, the synthesized compounds were found to have potential antioxidant activity with IC50 range=14.14-47.11μg/mL. Furthermore, to rationalize the observed biological activity data, the molecular docking study also been carried out against a potential target MTB DprE1, which revealed a significant correlation between the binding score and biological activity for these compounds. The results of the in vitro and in silico study suggest that the triazole incorporated benzothiazinone may possess the ideal structural requirements for further development of novel therapeutic agents.

Novel tacrine-1,2,3-triazole hybrids: In vitro, in vivo biological evaluation and docking study of cholinesterase inhibitors

A new series of tacrine-1,2,3-triazole hybrids were designed, synthesized, and evaluated as potent dual cholinesterase inhibitors. Most of synthesized compounds showed good in vitro inhibitory activities toward both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Among them, 7-chloro-N-((1-(4-methoxybenzyl)-1H-1,2,3-triazol-4-yl)methyl)-1,2,3,4-tetrahydroacridin-9-amine (5l) was found to be the most potent anti-AChE derivative (IC₅₀ = 0.521 μM) and N-((1-(4-methoxybenzyl)-1H-1,2,3-triazol-4-yl)methyl)-1,2,3,4-tetrahydroacridin-9-amine (5j) demonstrated the best anti-BChE activity (IC₅₀ = 0.055 μM). In vivo studies of compound 5l in Morris water maze task confirmed memory improvement in scopolamine-induced impairment. Also, molecular modeling and kinetic studies showed that compounds 5l and 5j bound simultaneously to the peripheral anionic site (PAS) and catalytic sites (CS) of the AChE and BChE.

Synthesis, anti-inflammatory, analgesic, COX-1/2 inhibitory activities and molecular docking studies of substituted 2-mercapto-4(3H)-quinazolinones

A new series of 2-substituted mercapto-4(3H)-quinazolinone 1-26 were synthesized and assessed for in vivo anti-inflammatory and analgesic activities and in vitro inhibition of cyclooxygenase COX-1/COX-2. A new series of 2-substituted mercapto-4(3H)-quinazolinone 1-26 were synthesized and assessed for in vivo anti-inflammatory and analgesic activities. The potent anti-inflammatory compounds were subjected to in vitro cyclooxygenase COX-1/COX-2 inhibition assays. Compounds 1, 3, 5, 11, 12, 13, 15, 17, and 25 exhibited potent anti-inflammatory effects, with half-maximal effective dose (ED50) values of 65.7-102.4 mg/kg, (0.16-0.36 mmol/kg), and strong analgesic activities, with ED50 values of 33.3-104.6 mg/kg, (0.07-0.34 mmol/kg). These values were compared with those of diclofenac sodium [ED50 values: 112.2 and 100.4 mg/kg, (0.35 and 0.31 mmol/kg)], and celecoxib [ED50 values: 84.3 and 71.6 mg/kg (0.22 and 0.19 mmol/kg)], respectively as reference drugs. Compounds 1, 11, 12, 13, 15, 17, and 25 exhibited effective COX-2 inhibitory activity, with half-maximal inhibitor concentration (IC50) values of 0.70-2.0 μM and selectivity index (SI) values of more than 50-142.9 compared with celecoxib as reference drugs (IC50 = 0.30 μM and COX-2 SI: >333). Potent COX-2 inhibitors, i.e., compounds 15, 11, and 17 were docked into the binding site pockets of COX-1 and COX-2. These compounds exhibited strong interactions at the COX-2 binding site and poor interactions at COX-1 active site pocket.

Indolinone-based acetylcholinesterase inhibitors: synthesis, biological activity and molecular modeling

A series of indolinone-based compounds bearing benzylpyridinium moiety was designed as dual-binding inhibitors of acetylcholinesterase (AChE). The target compounds 3a-u were synthesized by condensation of oxindole and pyridin-4-carbalehyde, and subsequent N-benzylation. The anti-cholinesterase activity evaluation of synthesized compounds revealed that most of them had very potent inhibitory activity against AChE, superior to standard drug donepezil. Particularly, 2-chlorobenzyl derivative 3c was the most potent compound against AChE with IC50 value of 0.44 nM, being 32-fold more potent than donepezil. Also, most of compounds were more potent than standard drug donepezil against butyrylcholinesterase (BuChE). Docking study revealed that the hydrophobic aromatic part (indoline) of representative compound 3c binds to the PAS and the N-benzylpyridinium residue binds to the CAS of AChE.

Synthesis, SAR and molecular docking studies of benzo[d]thiazole-hydrazones as potential antibacterial and antifungal agents

A series of new benzo[d]thiazole-hydrazones analogues were synthesized and screened for their in vitro antibacterial and antifungal activities. The results revealed that compounds 13, 14, 15, 19, 20, 28 and 30 exhibited superior antibacterial potency compared to the reference drug chloramphenicol and rifampicin. Compounds 5, 9, 10, 11, 12, 28 and 30 were found to be good antifungal activity compared to the standard drug ketoconazole. A preliminary study of the structure-activity relationship (SAR) revealed that the antimicrobial activity depended on the effect of different substituents on the phenyl ring. The electron donating (OH and OCH₃) groups presented in the analogues, increase the antibacterial activity (except compound 12), interestingly, while the electron withdrawing (Cl, NO₂, F and Br) groups increase the antifungal activity (except compound 19 and 20). In addition, analogues containing thiophene (28) and indole (30) showed good antimicrobial activities. Whereas, aliphatic analogues (24-26) shown no activities in both bacterial and fungal stains even in high concentrations (100µg/mL). Molecular docking studies were performed for all the synthesized compounds of which compounds 11, 19 and 20 showed the highest glide G-score.

Novel 2-indolinone thiazole hybrids as sunitinib analogues: Design, synthesis, and potent VEGFR-2 inhibition with potential anti-renal cancer activity

Novel 2-indolinone thiazole hybrids were designed and synthesized as VEGFR-2 inhibitors based on sunitinib, an FDA-approved anticancer drug. The proposed structures of the prepared 2-indolinone thiazole hybrids were confirmed based on their spectral data and CHN analyses. The target compounds were screened in vitro for their anti-VEGFR-2 activity. All tested compounds exhibited a potent submicromolar inhibition of VEGFR-2 kinase with IC₅₀ values ranging from 0.067 to 0.422 μM, relative to sunitinib reference drug (IC₅₀ = 0.075 ± 0.002 μM). Compounds 5, 15a, 15b, 17, 19c displayed excellent VEGFR-2 inhibitory activity, comparable or nearly equipotent to sunitinib. Compound 13b stood out as the most potent against VEGFR-2 showing IC₅₀ value of 0.067 ± 0.002 μM, lower than that of sunitinib. In addition, the most potent derivatives were assessed for their anticancer activity against two renal cancer cell lines. Compound 13b (IC₅₀ = 3.9 ± 0.13 μM) was more potent than sunitinib (IC₅₀ = 4.93 ± 0.16 μM) against CAKI-1 cell line. Moreover, thiazole 15b displayed excellent anticancer activity against CAKI-1 cell line (IC₅₀ = 3.31 ± 0.11 μM), superior to that of sunitinib (IC₅₀ = 4.93 ± 0.16 μM). Thiazole 15b was also equipotent to sunitinib (IC₅₀ = 1.23 ± 0.04 μM) against A498 cell line. Besides, compound 15b revealed a safety profile much better than that of sunitinib against normal human renal cells. Furthermore, a docking study revealed a proper fitting of the most active compounds into the ATP binding site of VEGFR-2, rationalizing their potent anti-VEGFR-2 activity.

Design, synthesis and biological evaluation of type-II VEGFR-2 inhibitors based on quinoxaline scaffold

In an effort to develop ATP-competitive VEGFR-2 selective inhibitors, a series of new quinoxaline-based derivatives was designed and synthesized. The target compounds were biologically evaluated for their inhibitory activity against VEGFR-2. The design of the target compounds was accomplished after a profound study of the structure activity relationship (SAR) of type-II VEGFR-2 inhibitors. Among the synthesized compounds, 1-(2-((4-methoxyphenyl)amino)-3-oxo-3,4 dihydroquinoxalin-6-yl)-3-phenylurea (VIIa) displayed the highest inhibitory activity against VEGFR-2. Molecular modeling study involving molecular docking and field alignment was implemented to interpret the variable inhibitory activity of the newly synthesized compounds.

Pectin co-functionalized dual layered solid lipid nanoparticle made by soluble curcumin for the targeted potential treatment of colorectal cancer

The investigation is to increase the cytotoxicity of soluble curcumin (SC) by loading it onto pectin and skimmed milk powder (SMP) dual layered solid lipid nanoparticles (DL-SLN). The DL-SLN exhibited significantly higher encapsulation efficiency (83.94 ± 6.16), better stability (90 days), and sustained the drug release in different gastro intestional (GI) environments upto 72 h. Molecular docking revealed that the Vander Waals (57420.669 Kcal^-mol^-1) and electrostatic (-197.533) bonds were involved in the DL-SLN complex formation. The in vivo toxicity of DL-SLN was performed by the zebrafish model, the cell cycle arrest at G₂/M phase (64.34 %) by flow cytometry, and western blot investigation was recognized molecular level cell death using SW480 cells. Pharmacokinetic (PK) evaluation (Cmax-5.78 ± 3.26 μg/mL; Tmax-24 h) and organ distribution studies confirmed that the co-functionalized pectin based SLN could efficiently improve the oral bioavailability (up to 72 h) of curcumin (CMN) on colon-targeted release.

Design, synthesis of 2,3-disubstitued 4(3H)-quinazolinone derivatives as anti-inflammatory and analgesic agents: COX-1/2 inhibitory activities and molecular docking studies

A new series, 2-substituted mercapto-3-[2-(pyridin-2-yl)ethyl]-4(3H)-quinazolinone 1-21, was synthesized and evaluated for in vivo anti-inflammatory and analgesic activities and in vitro COX-1/COX-2 inhibition. Compounds 1, 4, 5, 6, 8, 10, 13, 14, 15, 16, and 17 exhibited potent anti-inflammatory and analgesic properties, with ED50 values of 50.3-112.1mg/kg and 12.3-111.3mg/kg, respectively. These values may be compared with those of diclofenac sodium (ED50=112.2 and 100.4mg/kg) and celecoxib (ED50=84.3 and 71.6mg/kg). Compounds 4 and 6 possessed strong COX-2 inhibitory activity with IC50 (0.33μM and 0.40μM, respectively) and selectivity index (SI>303.0 and >250.0, respectively) values that are similar to those of the reference drug celecoxib (IC50 0.30μM and COX-2 SI>333). Compounds 5, 8, and 13 demonstrated effective COX-2 inhibitory activity with IC50 values of 0.70-0.80μM and COX-2 SI>125-142. Potent COX-2 inhibitors, such as compounds 4, 6, and 13, were docked into the active site pockets of COX-1 and COX-2, with the greatest recognition occurring at the COX-2 binding site and insignificant interactions at the binding site of the COX-1 pocket.

Synthesis and molecular docking study of some 5,6-dichloro-2-cyclopropyl-1H-benzimidazole derivatives bearing triazole, oxadiazole, and imine functionalities as potent inhibitors of urease

A new series of benzimidazole compounds including hydrazinecarbothioamide, 1,2,4-triazole, 1,3,4-oxadiazole and imine function were synthesized starting from 5,6-dichloro-2-cyclopropyl-1H-benzimidazole. All of the benzimidazole derivatives exhibited good urease inhibitor activity. Compound 6a proved to be the most potent showing an enzyme inhibitory activity with an IC₅₀=0.06µM. Molecular docking studies were also conducted on enzyme extracted from Jack bean urease to identify the binding mode of the newly synthesized compounds.

Design, synthesis, docking study, α-glucosidase inhibition, and cytotoxic activities of acridine linked to thioacetamides as novel agents in treatment of type 2 diabetes

A novel series of acridine linked to thioacetamides 9a-o were synthesized and evaluated for their α-glucosidase inhibitory and cytotoxic activities. All the synthesized compounds exhibited excellent α-glucosidase inhibitory activity in the range of IC₅₀ = 80.0 ± 2.0-383.1 ± 2.0 µM against yeast α-glucosidase, when compared to the standard drug acarbose (IC₅₀ = 750.0 ± 1.5 µM). Among the synthesized compounds, 2-((6-chloro-2-methoxyacridin-9-yl)thio)-N-(p-tolyl) acetamide 9b displayed the highest α-glucosidase inhibitory activity (IC₅₀ = 80.0 ± 2.0 μM). The in vitro cytotoxic assay of compounds 9a-o against MCF-7 cell line revealed that only the compounds 9d, 9c, and 9n exhibited cytotoxic activity. Cytotoxic compounds 9d, 9c, and 9n did not show cytotoxic activity against the normal human cell lines HDF. Kinetic study revealed that the most potent compound 9b is a competitive inhibitor with a K_i of 85 μM. Furthermore, the interaction modes of the most potent compounds 9b and 9f with α-glucosidase were evaluated through the molecular docking studies.

Synthesis, biological evaluation and docking study of 3-aroyl-1-(4-sulfamoylphenyl)thiourea derivatives as 15-lipoxygenase inhibitors

A series of 3-aroyl-1-(4-sulfamoylphenyl)thiourea derivatives containing sulfonamide moiety were designed and synthesized as 15-lipoxygenase (15-LOX) inhibitors. Most synthesized compounds showed potent activity against soybean 15-LOX with IC50 values less than 25 μM. The most potent compound 4c (3-methylbenzoyl derivative) with IC50 value of 1.8 μM was 10-fold more potent than quercetin. Interestingly, compound 4c also showed the highest antioxidant activity, as determined by ferric reducing antioxidant power (FRAP) assay. Its capacity for reducing ferric ion was more than ascorbic acid. The viability assay of the selected compound 4c against oxidative stress-induced cell death in differentiated PC12 cells revealed that compound 4c significantly protected neurons against cell death in low concentrations.

Design, synthesis, and biological evaluation of novel dipeptide-type SARS-CoV 3CL protease inhibitors: structure-activity relationship study

This work describes the design, synthesis, and evaluation of low-molecular weight peptidic SARS-CoV 3CL protease inhibitors. The inhibitors were designed based on the potent tripeptidic Z-Val-Leu-Ala(pyrrolidone-3-yl)-2-benzothiazole (8; K_i = 4.1 nM), in which the P3 valine unit was substituted with a variety of distinct moieties. The resulting series of dipeptide-type inhibitors displayed moderate to good inhibitory activities against 3CL^pro. In particular, compounds 26m and 26n exhibited good inhibitory activities with K_i values of 0.39 and 0.33 μM, respectively. These low-molecular weight compounds are attractive leads for the further development of potent peptidomimetic inhibitors with pharmaceutical profiles. Docking studies were performed to model the binding interaction of the compound 26m with the SARS-CoV 3CL protease. The preliminary SAR study of the peptidomimetic compounds with potent inhibitory activities revealed several structural features that boosted the inhibitory activity: (i) a benzothiazole warhead at the S1′ position, (ii) a γ-lactam unit at the S1-position, (iii) an appropriately hydrophobic leucine moiety at the S2-position, and (iv) a hydrogen bond between the N-arylglycine unit and a backbone hydrogen bond donor at the S3-position.

Synthesis, biological evaluation, and docking studies of novel thiourea derivatives of bisindolylmethane as carbonic anhydrase II inhibitor

This article describes discovery of 29 novel bisindolylmethanes consisting of thiourea moiety, which had been synthesized through three steps. These novel bisindolylmethane derivatives evaluated for their potential inhibitory activity against carbonic anhydrase (CA) II. The results for in vitro assay of carbonic anhydrase II inhibition activity showed that some of the compounds are capable of suppressing the activity of carbonic anhydrase II. Bisindoles having halogen at fifth position showed better inhibitory activity as compared to unsubstituted bisindoles. Derivatives showing inhibition activity docked to further, understand the binding behavior of these compounds with carbonic anhydrase II. Docking studies for the active compound 3j showed that nitro substituent at para position fits into the core of the active site. The nitro substituent of compound 3j is capable of interacting with Zn ion. This interaction believed to be the main factor causing inhibition activity to take place.

Synthesis and structure-activity relationship study of benzofuran-based chalconoids bearing benzylpyridinium moiety as potent acetylcholinesterase inhibitors

A series of benzofuran-based chalconoids 6a-v were designed and synthesized as new potential AChE inhibitors. The in vitro assay of synthesized compounds 6a-v showed that most compounds had significant anti-AChE activity at micromolar or sub-micromolar levels. Among the tested compounds, 3-pyridinium derivative 6m bearing N-(2-bromobenzyl) moiety and 7-methoxy substituent on the benzofuran ring exhibited superior activity. This compound with IC₅₀ value of 0.027 μM was as potent as standard drug donepezil.

Synthesis of novel chromenones linked to 1,2,3-triazole ring system: Investigation of biological activities against Alzheimer's disease

In this work, novel chromenones linked to 1,2,3-triazole ring system were synthesized and evaluated for their anti-ChE activity. Among them, N-((1-(2-chlorobenzyl)-1H-1,2,3-triazol-5-yl)methyl)-8-methoxy-2-oxo-2H-chromene-3-carboxamide (6m) showed good anti-acetylcholinesterase activity (IC₅₀=15.42μM). Also, compound 6m demonstrated neuroprotective effect against H₂O₂-induced cell death in PC12 neurons, however, it showed no beta-secretase (BACE1) inhibitory activity. Docking and kinetic studies separately confirmed dual binding activity of compound 6m since it targeted both the catalytic active site (CAS) and the peripheral anionic site (PAS) of AChE.

Anticancer and DNA binding studies of potential amino acids based quinazolinone analogs: Synthesis, SAR and molecular docking

A novel series of amino acids conjugated quinazolinone-Schiff's bases were synthesized and screened for their in vitro anticancer activity and validated by molecular docking and DNA binding studies. In the present investigations, compounds 32, 33, 34, 41, 42 and 43 showed most potent anticancer activity against tested cancer cell lines and DNA binding study using methyl green comparing to doxorubicin and ethidium bromide as a positive control respectively. The structure-activity relationship (SAR) revealed that the tryptophan and phenylalanine derived electron donating groups (OH and OCH₃) favored DNA binding studies and anticancer activity whereas; electron withdrawing groups (Cl, NO₂, and F) showed least anticancer activity. The molecular docking study, binding interactions of the most active compounds 33, 34, 42 and 43 stacked with A-T rich regions of the DNA minor groove by surface binding interactions were confirmed.

Novel tetrazoloquinoline-rhodanine conjugates: Highly efficient synthesis and biological evaluation

In search of new active molecules against Mycobacterium tuberculosis (MTB) H37Ra and Mycobacterium bovis BCG, a small focused library of rhodanine incorporated tetrazoloquinoline has been efficiently synthesized by using [HDBU][HSO4] acidic ionic liquid. The compound 3c found to be promising inhibitor of MTB H37Ra and M. bovis BCG characterized by lower MIC values 4.5 and 2.0 μg/mL, respectively. The active compounds were further tested for cytotoxicity against HeLa, THP-1, A549 and PANC-1 cell lines using MTT assay and showed no significant cytotoxic activity at the maximum concentration evaluated. Again, the synthesized compounds were found to have potential antifungal activity. Furthermore, to rationalize the observed biological activity data, the molecular docking study also been carried out against a potential target Zmp1 enzyme of MTB H37Ra, which revealed a significant correlation between the binding score and biological activity for these compounds. The results of in vitro and in silico study suggest that these compounds possess ideal structural requirement for the further development of novel therapeutic agents.

A cascade synthesis, in vitro cholinesterases inhibitory activity and docking studies of novel Tacrine-pyranopyrazole derivatives

In this work, we describe the preparation of some new Tacrine analogues modified with a pyranopyrazole moiety. A one-pot multicomponent reaction of 3-methyl-1H-pyrazol-5(4H)-one, aryl(or hetero)aldehydes, malononitrile and cyclohexanone involving a Friedländer condensation led to the title compounds. The synthesized heterocyclic analogues of this molecule were evaluated in vitro for their AChE and BChE inhibitory activities in search for potent cholinesterase enzyme inhibitors. Most of the synthesized compounds displayed remarkable AChE inhibitory activities with IC₅₀ values ranging from 0.044 to 5.80 µM, wherein compounds 5e and 5j were found to be most active inhibitors against AChE with IC₅₀ values of 0.058 and 0.044 µM respectively. Molecular modeling simulation on AChE and BChE receptors, showed good correlation between IC₅₀ values and binding interaction template of the most active inhibitors docked into the active site of their relevant enzymes.

Discovery of novel cyclic peptide inhibitors of dengue virus NS2B-NS3 protease with antiviral activity

NS2B-NS3 protease is an essential enzyme for the replication of dengue virus (DENV), which continues to be a serious threat to worldwide public health. We designed and synthesized a series of cyclic peptides mimicking the substrates of this enzyme, and assayed their activity against the DENV-2 NS2B-NS3 protease. The introduction of aromatic residues at the appropriate positions and conformational restriction generated the most promising cyclic peptide with an IC₅₀ of 0.95μM against NS2B-NS3 protease. Cyclic peptides with proper positioning of additional arginines and aromatic residues exhibited antiviral activity against DENV. Furthermore, replacing the C-terminal amide bond of the polybasic amino acid sequence with an amino methylene moiety stabilized the cyclic peptides against hydrolysis by NS2B-NS3 protease, while maintaining their enzyme inhibitory activity and antiviral activity.

Structural alterations based on naproxen scaffold: Synthesis, evaluation of antitumor activity and COX-2 inhibition, and molecular docking

A new series of non-carboxylic naproxen analogues, bearing a variety of ring systems, such as oxadiazoles 3a-c and 6a-c, cycloalkanes 4a-d, cyclic imides 5a-c, and triazoles 7-9 and 10a-c, was synthesized. In addition, in vitro antitumor activity and cyclooxygenase isozymes (COX-1/COX-2) inhibition assay of the target compounds 3-10 was studied. The results of the antitumor activity assays indicated that compounds 4b, 6c, 10b, and 10c exhibited the greatest antitumor activities against the tested cell lines MCF-7, MDA-231, HeLa, and HCT-116, with an IC₅₀ range of 4.83-14.49 μM. By comparison, the reference drugs doxorubicin, afatinib, and celecoxib yielded IC₅₀ values of 3.18-26.79, 6.20-11.40, and 22.79-42.74 μM, respectively. Furthermore, in vitro COX-1/COX-2 inhibition testing showed that the compounds 4b, 6c, 10b, and 10c exhibited effective COX-2 inhibition, with IC₅₀ values of 0.40-1.20 μM, and selectivity index (SI) values of >62.50-20.83, using celecoxib as a reference drug (IC₅₀ = 0.11 μM; COX-2 SI: >227.20). Compounds 6c and 10c, which were potent COX-2 inhibitors, were docked into the COX-2 binding site, where these compounds exhibited strong interactions.

Design, synthesis, molecular docking of new lipophilic acetamide derivatives affording potential anticancer and antimicrobial agents

Fifteen new substituted N-2-(2-oxo-3-phenylquinoxalin-1(2H)-yl) acetamides 5a-f, 6a-f, and 8a-c were synthesized by reacting ethyl 2-(2-oxo-3-phenylquinoxalin-1(2H)-yl)acetate with various primary amines including benzylamines, sulfonamides, and amino acids. The in vitro antimicrobial screening of the target compounds was screened to assess their antibacterial and antifungal activity. As a result, seven compounds namely; 5a, 5c, 5d, 6a, 6c, 8b and 8c showed a promising broad spectrum antibacterial activity against both Gram-positive and Gram-negative strains. Among these, the analogs 5c and 6d were nearly as equiactive as ciprofloxacin drug. Meanwhile, four compounds namely; 5c, 6a, 6f and 8c exhibited appreciable antifungal activity with MIC values range 33-40 mg/mL comparable with clotrimazole (MIC 25 mg/mL). In addition, the anticancer effects of the synthesized compounds were evaluated against three cancer lines. The data obtained revealed the benzylamines and sulpha derivatives were the most active compounds especially 5f and 6f ones. Further EGFR enzymatic investigation was carried out for these most active compounds 5f and 6f resulting in inhibitory activity by 1.89 and 2.05 µM respectively. Docking simulation was performed as a trial to study the mechanisms and binding modes of these compounds toward the enzyme target, EGFR protein kinase enzyme. The results revealed good compounds placement in the active sites and stable interactions similar to the co-crystallized reference ligand. Collectively, the analogs 5f and 6f could be further utilized and optimized as good cytotoxic agents.

Synthesis and antimycobacterial activity of 1-(β-d-Ribofuranosyl)-4-coumarinyloxymethyl- / -coumarinyl-1,2,3-triazole

A series of β-d-ribofuranosyl coumarinyl-1,2,3-triazoles have been synthesized by Cu-catalyzed cycloaddition reaction between azidosugar and 7-O-/7-alkynylated coumarins in 62-70% overall yields. The in vitro antimycobacterial activity evaluation of the synthesized triazolo-conjugates against Mycobacterium tuberculosis revealed that compounds were bactericidal in nature and some of them were found to be more active than one of the first line antimycobacterial drug ethambutol against sensitive reference strain H37Rv, and 7 to 420 times more active than all four first line antimycobacterial drugs (isoniazid, rifampicin, ethambutol and streptomycin) against multidrug resistant clinical isolate 591. Study of in silico pharmacokinetic profile indicated the drug like characters for the test molecules. Further, transmission electron microscopic experiments revealed that these compounds interfere with the constitution of bacterial cell wall possibly by targeting mycobacterial InhA and DNA gyrase enzymes. Study conducted on the activities of the test compounds on bacterial InhA and DNA gyrase revealed that the most bactericidal test compound, N¹-(β-d-ribofuranosyl)-C⁴-(4-methylcoumarin-7-oxymethyl)-1,2,3-triazole (6b) and its corresponding directly linked conjugate N¹-(β-d-ribofuranosyl)-C⁴-(4-methylcoumarin-7-yl)-1,2,3-triazole (11b) significantly inhibited the activity of both the enzymes. The results were further supported by molecular docking studies of the compound 6b and 11b with bacterial InhA and DNA gyrase B enzymes. Further, the cytotoxicity study of some of the better active compounds on THP-1 macrophage cell line using MTT assay showed that the synthesized compounds were non-cytotoxic.