Synthesis, in vitro evaluation of thymidine phosphorylase inhibitory activity, and in silico study of 1,3,5-triazin-2,4-dione and its fused analogues

Based on structural similarities with the reference compounds, a series of 1,3,5-triazin-2,4-dione and their fused analogues was designed, synthesized and their in vitro thymidine phosphorylase inhibitory potential was evaluated. The monocyclic analogues were found to be inactive. Among the different fused derivatives synthesized, compounds having keto group (C=O) at C7/C4 and thioketo group (C=S) at C5/C2 position showed TP inhibitory activity comparable to positive control, 7-deazaxanthine (7-DX) (IC₅₀ value = 42.63 μM). Molecular docking of the target compounds into the enzyme thymidine phosphorylase was performed to illustrate the important structural information on the plausible ligand–enzyme-binding interactions.     

Synthesis and biological activity of novel Schiff bases derived from metronidazole

A number of novel Schiff bases (5a–i) and (7a–d) derived from metronidazole were synthesized. Reaction of 2-(2-methyl-5-nitro-imidazol-1-yl)-ethyl ester toluene-4-sulfonate with 4-hydroxybenzaldehyde and with 3-hydroxybenzaldehyde in the presence of a base afforded 4-(2-(2-methyl-5-nitro-1H-imidazol-1-yl)ethoxy)benzaldehyde (5) and 3-(2-(2-methyl-5-nitro-1H-imidazol-1-yl)ethoxy)benzaldehyde (7), respectively. The reaction of aldehydes 5 and 7 with a number of primary aromatic amines produced Schiff bases 5a–i and 7a–d, respectively. Structures of these compounds were confirmed through different spectroscopic methods such as ¹H-NMR, ¹³C-NMR, mass spectrometry, and also by elemental analyses. The prepared compounds were evaluated in vitro for their antigiardial, anti-trichomonal, antibacterial, and antifungal activities. Compounds 5e, 5g, 5i, 7a, 7b, 7c, and 7d exhibited remarkable antigiardial activity and were found to be more active than metronidazole with IC₅₀ of 7.2, 3.3, 1.5, 5.8, 4.5, 2.9, and 3.8 µg/mL, respectively. Compounds 5a and 5c also exhibited antigiradial activity with similar IC₅₀ values compared to the reference drug metronidazole with IC₅₀ of 7.2 µg/mL. The other compounds 5b, 5d, 5f, and 5 h also showed antigiardial activity but with higher IC₅₀ compared to the reference drug. Compounds were also tested for their anti-trichomonal activity, they, however, exhibited higher IC₅₀ compared to the reference drug metronidazole (7.4 µg/mL), except for compound 5a which exhibited anti-trichomonal activity with an IC₅₀ of 6.3 µg/mL. On the bases of preliminary screening, the newly synthesized compounds exhibited moderate to potent antimicrobial activities. Compound 5e inhibited the growth of Methicillin resistant Staphylococcus aureus (MRSA) and Bacillus cereus and compound 5c inhibited Candida Pathogenic fungus at 50 μg/mL compared with the positive control (Nystatin) which inhibits Candida at 25 μg/mL.     

Synthesis, anti-inflammatory, and structure antioxidant activity relationship of novel 4-quinazoline

The practice of medicinal chemistry is devoted to the discovery and development of new agents for treating disease. A new derivative of methyl 2-((E)-3-(3,4-dihydroxyphenyl)acrylamido)benzoate 2 was synthesized by reacting the amino group of methyl anthranilate 1 with caffeic acid in the presence of PCl₃. Cyclcondensation of 2 with hydrazine hydrate afforded the corresponding 2,3-dihydro-2-(3,4-dihydroxyphenyl) pyrazolo[5,1-b]quinazolin-9(1H)-one 3. The median lethal doses (LD_50s) of compounds 2 and 3 in mice were 1,135 and 495 mg/kg b.w., respectively. The anti-inflammatory, reducing power, chelating activity on Fe²⁺, free radical-scavenging, and total antioxidant activities were more pronounced in compound 2 compared to compound 3. On the other hand, antipyretic activity was more pronounced in compound 3 compared to compound 2. Antioxidant activity of compounds 2 and 3 increased with increased concentrations. Total antioxidant activity of compounds 2, 3 and both standards decreased in the order of α-tocopherol > compound 2 > trolox > BHA > BHT > compound 3. Administration of compounds 2 and 3 orally to the rats at dose of 50, 100, and 150 mg/kg b.w., for 10 days showed non-significant changes in serum level of GOT, GPT, ALP, γ-GT, and LDH as compared with the control group. In addition, oral administration of the compound 2 at a concentration of 100 and 150 mg/kg b.w. and compound 3 at a concentration of 150 mg/kg b.w. daily to normal rats for 10 days showed a significant increase in liver GSH, GPx, GR, and GST activities and significant decrease in TBARS level. But, administration of diclofenac sodium (30 mg/kg b.w.) orally to the rats daily for 10 days to rats showed significant increase in serum SGOT, SGPT, ALP, γ-GT, and LDH and significant decrease in liver GSH, GPx, GR, and GST activities. These findings suggest that compounds 2 and 3 exhibited good antioxidant and anti-inflammatory activity and also showed effects on liver enzymes.     

In vitro antimicrobial activity of o-phenylenediamine-tert-butyl-N-1,2,3-triazole carbamate analogs

In an attempt to design and synthesize effective antimicrobial agents using click chemistry, mono- and di-alkyne-substituted monoboc protected o-phenylenediamines were reacted with different substituted aryl azides which yielded 18 new compounds (4a–4k and 5a–5f, 5l). Structures of all newly synthesized compounds were established by ¹H and ¹³C NMR analysis. The intermediate compound 1 was also confirmed by X-ray crystallography. The title compounds were screened for their antibacterial activity against Gram +ve bacteria (Staphylococcus aureus and Enterococcus faecalis), Gram ?ve bacteria (Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa), and their antifungal profile were tested on (Candida tropicalis, Candida albicans, Candida krusei, and Cryptococcus neoformans) as well as on molds such as (Aspergillus niger, Aspergillus fumigatus). The compounds 4k and 5f both showed maximum potency against S. aureus (ATCC 25323) strain with MIC value of 6.25 µg/ml, which is comparable with standard drug ciprofloxacin (MIC 6.25 µg/ml) while remaining compounds showed moderate to weak activity. Further, all compounds showed average antifungal activity in the range of 100–200 µg/ml.     

New 4-thiazolidinones from 5-ethyl pyridine-2-ethanol: their antibacterial,antifungal, and antitubercular activity

New thiazolidinones 5a–o were prepared from Schiff base 4a–o and thioglycolic acid in the presence of ZnCl₂ from 4-[2-(5-ethylpyridin-2-yl)ethoxy]benzaldehyde. The structures of the synthesized compounds were assigned on the basis of elemental analysis, IR, ¹H NMR ¹³C NMR, and mass spectral data. All the compounds were screened against different strains of bacteria and fungi. Compounds 4e, 4n, 4m, 4o, 5e, 5f, 5j, and 5m possessed very good activity against bacterial and fungal species. These active compounds impelled us to study their antitubercular activity. Schiff base 4n and 4e showed M. tuberculosis MIC value 25 and 62.5 μg/ml, respectively. Thiazolidinone 5m displayed M. tuberculosis MIC at 25 μg/ml, which is better antitubercular activity compared with rifampicin.     

Synthesis, characterization, biological evaluation and in silico screening of oxadiazinanones

A series of novel oxadiazinan-5-one namely 2-methyl-2-phenyl-1,3,4-oxadiazinan-5-one (6), 2-(3-hydroxyphenyl)-2-methyl-1,3,4-oxadiazinan-5-one (7), 2-(4-hydroxyphenyl)-2-methyl-1,3,4-oxadiazinan-5-one (8), 2-(2,4-dihydroxyphenyl)-2-methyl-1,3,4-oxadiazinan-5-one (9) and 2-(2,5-dihydroxyphenyl)-2-methyl-1,3,4-oxadiazinan-5-one (10) have been synthesized by the reaction of acetophenone and its derivatives with cyanoacetic acid hydrazide. The structural assignments of the products were done on the basis of IR, ¹H NMR, ¹³C NMR, MS, and analytical data. The in vitro antioxidant and antimicrobial activity of all the synthesized compounds (6–10) was tested by the DPPH and disk diffusion method, respectively. The synthesized compounds were screened against Gram-positive and Gram-negative bacterial and fungal strains. Compound (7) showed the highest inhibition comparable with the standard antibiotic drugs Ciprofloxacin and Amphotericin B. The antibacterial activity of the synthesized compounds was further investigated with the help of in silico docking study using Discovery studio 3.1, Molego Virtual Docker and LigandScout to predict the active sites.     

Synthesis and evaluation of 2,4,6-trisubstituted pyrimidine derivatives as novel antileishmanial agents

A series of new 2,4,6-trisubstituted pyrimidine derivatives 8(a–j) were synthesized by reacting substituted chalcones containing imidazole 6(a–d) and benzimidazole 7(a–f) with guanidine hydrochloride in the presence of strong base. Substituted chalcones were synthesized by reacting 4-(1H-imidazol-1-yl)benzaldehyde or 4-(1H-benzo[d]imidazol-1-yl)benzaldehyde with different substituted acetophenones in the presence of 40 % NaOH in methanol. The synthesized compounds were confirmed by IR, ¹HNMR, and mass spectral data and screened for antileishmanial activity. Antileishmanial activity was performed against Leishmania donovani parasite, and percentage lysis inhibition were calculated by meglumine antimoliate taking a positive control and chloroform (0.1 % CHCl₃) treatment served as control. Among all the compounds, 8h and 8j exhibited 50–57 % inhibition against promastigotes, thus providing new structural lead for antileishmanials.     

Antibacterial and free radical scavenging potential of synthesized 7-hydroxy-2-aryl-6-aryldiazenyl-4H-chromen-4-ones

A series of 7-hydroxy-2-aryl-6-aryldiazenyl-4H-chromen-4-one derivatives (6a–m) was synthesized in quantitative yields and their structures were corroborated on the basis of FT-IR, ¹H, ¹³C NMR, ESI–MS, and elemental analysis data. The synthesized compounds were screened for in vitro antibacterial activities against a representative panel of Gram-positive and Gram-negative bacteria, as well as to evaluate their antioxidant potential using DPPH assay method. Bio-evaluation studies revealed that compounds 6c, 6d, 6e, 6j, and 6l exhibited moderate to good antibacterial activity against all the tested bacterial strains. Furthermore, from the antioxidant screening results, it has been observed that compounds 6c, 6e, and 6g manifested profound antioxidant potential (IC₅₀ <7.68 μM) in comparison to the standard antioxidant ascorbic acid.     

Synthesis,biological evaluation of certain pyrazolo[3,4-d]pyrimidines as novel anti-inflammatory and analgesic agents

In the present study, a series of pyrazolo[3,4-d]pyrimidin-4(5H)-ones linked at 5-position to thiazoline or thiazolidinone ring systems through imino linkage (5–8) was designed and synthesized. The compounds were assessed for their anti-inflammatory activity and analgesic in vivo. Also, their ability to inhibit ovine COX-1/COX-2 isozymes was evaluated using in vitro cyclooxygenase (COX) inhibition assay. The newly synthesized compounds 7, 8d, and 8e showed potent anti-inflammatory and analgesic activity. Moreover, compound 7 displayed preferential COX-2 inhibitory potency (IC₅₀ = 0.53 µM and COX-2 selectivity index = 10.07) which is more potent than the standard drug meloxicam. Interestingly, the tested compounds showed excellent gastrointestinal safety profile and were well tolerated by experimental animals with high safety margins than the reference drug meloxicam.     

Design, synthesis and molecular modelling of novel 4-thiazolidinones of potential activity against Gram positive bacteria

A series of novel 4-thiazolidinones (2–21) incorporating 2-(2,4,5-trichlorophenoxy)propanamide was synthesised. Reaction of 2-(2,4,5-trichlorophenoxy)propanohydrazide (1) with the corresponding carbonyl compounds afforded 2-(2,4,5-trichlorophenoxy)propanehydrazide hydrazones (2–11) which upon reaction with thioglycolic acid revealed 4-thiazolidinone derivatives (12–21). Structure elucidation of the synthesised compounds was done based on analytical and spectral data. The newly synthesised compounds were evaluated for their antimicrobial activity. Compounds 13 and 17 showed the equipotent activity with MIC value 6.25 μg ml^?1 compared with chloramphenicol as reference drug. Docking studies of the promising compounds was done on MurB using Dock6.4 docking program to study their observed activity.     

Synthesis of new 1-phenyl-2-(4-substituted-piperazin-1-yl)-propanol derivatives and evaluation of their antidepressant-like effects

In this study, we synthesized eight novel 1-phenyl-2-(4-substituted-piperazin-1-yl)-propanol derivatives and evaluated their antidepressant-like activities. The chemical structures of the synthesised compounds were elucidated by spectroscopy and elemental analyses. Potential antidepressant-like effects of the test compounds (20 mg kg^?1) were investigated using the tail-suspension test and modified forced swimming test (MFST) in mice. Additionally, the spontaneous locomotor activity of the mice was assessed using the activity cage apparatus. Both the reference drug fluoxetine (20 mg kg^?1) and the test compounds 3a–3e and 3g significantly shortened the immobility time of the mice in both the behavioural tests. These test compounds also increased the swimming time in MFST without any change in the climbing duration. Compounds 3c–3e and 3g were significantly more potent in inducing these effects than 3a and 3b. None of the compounds changed the locomotor activities of the animals, thus antidepressant-like effects of test compounds were specific. The findings support those of previous studies that reported antidepressant-like activities of aryl alkanol piperazine derivatives.     

Phosphorylated ganciclovir derivatives: design,synthesis and in vitro and in vivo immunomodulatory activity

Synthesis of a series of novel phosphorylated ganciclovir derivatives with bioactive amines/aminoacid esters as substituents was accomplished. These compounds were structurally characterized by IR, NMR (¹H, ¹³C, ³¹P), mass spectra and CHN analysis. The compounds (5a–m) have been evaluated for its in vitro and in vivo immunomodulatory activities. The amino acid ester-substituted ganciclovir derivatives, especially the 5g and 5i, increased the intracellular killing activity of the stimulated neutrophils. The in vivo experiment results show that the administration of compounds 5g and 5i (8 mg/kg body weight) to diet-induced immune impaired obese rats ameliorated the significant increase in immune cell counts (lymphocytes, neutrophils and monocytes). In addition, TNF-α, IL-6 and IL-1 secretions were considerably restored to normal by the compounds 5g and 5i with regulation in the release of C-reactive protein suggesting their potentiating effect on immune system dysfunction. These in vitro and in vivo results suggest that the phosphorylated ganciclovir derivatives 5g and 5i are strong immunomodulators.     

Design, synthesis and biological evaluation of some novel benzylidene-2-(4-phenylthiazol-2-yl) hydrazines as potential anti-inflammatory agents

A series of substituted benzylidene-2-(4-phenylthiazol-2-yl) hydrazines (2a–q) have been synthesized, characterized and evaluated for their anti-inflammatory activity by carrageenin-induced hind paw edema (acute inflammation) and cotton pellet granuloma (chronic inflammation) methods in rats. In carrageenin-induced hind paw edema method, compounds 2a, 2b, 2c, 2d, 2h, 2k and 2p at a dose of 20 mg kg^?1 body weight, p.o. showed excellent inhibitions (51.80–86.74 %) in between 1 and 4 h. Similarly, in cotton pellet granuloma method, compounds 2a, 2b, 2c, 2d, 2h, 2k and 2p at a dose of 20 mg kg^?1 body weight, p.o. inhibited the granuloma formation (71.71–90.19 % inhibition) which was comparable to that of standard drug, ibuprofen (90.36 % inhibition of paw volume at 3 h and 94.02 % inhibition of granuloma formation). Structure activity relationship studies showed excellent activity of the compounds containing electron withdrawing group (fluoro, chloro, bromo or nitro) in phenyl ring at C2 and/or C4 position of thiazole ring.     

Synthesis,antimicrobial, and antioxidant activity of benzofuran barbitone and benzofuran thiobarbitone derivatives

The synthesis of novel series of benzofuran derivatives, containing barbitone moiety, 5-[(2/4-substitutedphenyl)(5-substituted-1-benzofuran-2-yl) methylidene]pyrimidin-2,4,6(1H,3H,5H)-trione (4a–i) and thiobarbitone moiety, 5-[(2/4-substitutedphenyl)(5-substituted-1-benzofuran-2-yl)methylidene]-2-thioxodihydropyrimidin-4,6(1H, 5H)-dione (5a–i) have been reported. The target compounds (4a–i) and (5a–i) were synthesized by the Knoevenagel condensation of (5-substituted-1-benzofuran-2-yl)(2/4-substitutedphenyl) methanone (3a–i) with barbituric acid and thiobarbituric acid, respectively, in acid medium. These compounds were screened for the antimicrobial and antioxidant activities. From antimicrobial activity results it was found that compounds 4a, 5a, 4c, and 5c displayed good antibacterial and antifungal activity against all tested strains. Further, the synthesized compounds were studied for docking on the enzyme, Glucosamine-6-phosphate synthase and the compounds 4c and 5c have emerged has an active antimicrobial agent with least binding energy (?5.27 and ?4.85 kJ mol^?1). Compounds 4e, 4f, 5e, and 5f showed promising free radical scavenging activity and compounds 5a and 5b showed good chelating ability with Fe²⁺ ions.     

Efficient synthesis of piperazine-2,6-dione and 4-(1H-indole-2-carbonyl)piperazine-2,6-dione derivatives and their evaluation for anticancer activity

Condensation of iminodiacetic acid 1 with various amines i.e., cyclohexanamine, 1-(3-aminopropyl)imidazole, pyridin-2-ylmethanamine, pyridin-3-ylmethanamine, pyridin-4-ylmethanamine, 2-morpholinoethanamine, thiophen-2-ylmethanamine, 2-(thiophen-2-yl)ethanamine, furan-2-ylmethanamine, 2-(pyrrolidin-1-yl)ethanamine, and 1-(3-aminopropyl) pyrrolidin-2-one 2a–k under microwave irradiation gave the corresponding piperazine-2,6-dione derivatives 3a–k in quantitative yields. Piperazine-2,6-dione derivatives 3a–k on condensation with 1H-indole-2-carboxylic acid under microwave irradiation gave the corresponding 4-(1H-indole-2-carbonyl)piperazine-2,6-dione derivatives 4a–k in quantitative yields. All the synthesized compounds (3a–k & 4a–k) were purified by crystallization and characterized by spectroscopic means. On screening at a concentration of 10 μM, compounds 3k, 4e, 4i breast (T47D), 4j lung (NCI H-522), 3i colon (HCT-15), 4e ovary (PA-1), and 4g liver (HepG-2) exhibited good anticancer activity.     

Synthesis, structure, and biological assay of cinnamic amides as potential EGFR kinase inhibitors

A series of derivatives of cinnamic amide (compounds 2a–2v) were synthesized and evaluated for antiproliferative activities against the human breast cancer cell line MCF-7- and EGFR-inhibitory activities. The structures of compounds 2b and 2i were determined by single-crystal X-ray diffraction analysis. Compounds 2f and 2j showed moderate EGFR inhibitory activity with IC₅₀ values of 5.16 and 7.37 μM, respectively. Docking simulation of compound 2f was carried out to illustrate the binding mode of the molecule into the EGFR active site. Structure–activity relationship analysis found that the N-phenyl rings are required for enhancing the activities.     

Synthesis,characterization, DNA interaction,and antitumor activities of mixed-ligand metal complexes of kaempferol and 1,10-phenanthroline/2,2′-bipyridine

Four novel mixed-ligand metal complexes with the composition [Cu(Kae)(phen)]Cl·2H₂O (1), [Cu(Kae)(bpy)]Cl·H₂O (2), [Zn(Kae)(phen)]Cl·H₂O (3), and [Zn(Kae)(bpy)]Cl·H₂O (4), where Kae = kaempferol, phen = 1,10-phenanthroline, bpy = 2,2′-bipyridine were synthesized and characterized by elemental analysis, IR, UV, ¹H NMR, ¹³C NMR, HRMS ,and molar conductivity. The binding and cleavage abilities of complexes 1–4 with DNA have been studied by fluorescence spectroscopy, viscosity measurements, and gel electrophoresis under physiological conditions. The experimental results indicated that four complexes could bind to CT-DNA via an intercalative mode, and the complex 1 showed the strongest activity to cleavage DNA (pUC 19). The in vitro cytotoxicities of kaempferol and complexes 1–4 were also evaluated against human breast carcinoma cells by MTT assays. The results show that the cytotoxicities of complexes 1–4 are much higher than that of kaempferol alone, and the complex 1 shows the strongest ability to inhibit the growth of human breast carcinoma cells. The results suggest that the complex 1 may be a valuable tool in cancer chemotherapy agents.     

Synthesis and anti-HIV-1 screening of novel N′-(1-(aryl)ethylidene)-2-(5,5-dioxido-3-phenylbenzo[e]pyrazolo[4,3-c][1,2]thiazin-4(1H)-yl)acetohydrazides

A novel series of N′-(1-(aryl)ethylidene)-2-(5,5-dioxido-3-phenylbenzo[e]pyrazolo[4,3-c][1,2]thiazin-4(1H)-yl)acetohydrazides was synthesized. The synthesis was carried out by thermal method as well as ultrasonic bath to reduce reaction time and to enhance product yields. The synthesized compounds were characterized by spectroscopic techniques like NMR, infrared and EIMS. The structure of compound 5w was elucidated by X-ray crystallography. The titled compounds were evaluated for anti-human immunodeficiency virus type 1 (anti-HIV-1) and cytotoxic activities. Biological studies indicated that amongst these compounds, 5a, b, j, h and i showed the activity with median effective concentration (EC₅₀) values less than 20 μM. Compound 5i exhibited the most potent anti-HIV-1 activity (EC₅₀ = 3.2 μM) while 5h showed anti-HIV-1 activity (EC₅₀ = 3.8 μM) with no toxicity at all in primary human lymphocytes, CEM and VERO cells.     

Synthesis,molecular docking studies,and in vitro screening of barbiturates/thiobarbiturates as antibacterial and cholinesterase inhibitors

On the basis of observed biological activity of barbiturates/thiobarbiturates, a set of 13 hydrazinecarboxamide/hydrazinecarbothioamides derivatives were designed and synthesized in good to excellent yield with extensive structural characterization. These compounds were screened for antibacterial and cholinesterase inhibitory activities. Two of the compounds 1 and 2 showed moderate bactericidal activity. Compounds 10 and 4 were found to be the most active acetyl/butyryl cholinesterase inhibitor, respectively (AChEI; 10; IC₅₀ = 40.78 μM and BChEI; 4; IC₅₀ = 3.31 μM). In silico molecular docking studies were carried out to identify active interacting sites of drug and enzyme and to establish structure–activity relationships. When predicted cholinesterase binding energies were compared with the experimentally determined inhibitory concentrations (IC₅₀), most active compounds were also found to be the most favorable for binding. The binding scores of compounds 10 and 4 were ?10.2 and ?9.3 kcal/mol, respectively.     

Synthesis,pharmacological and biological screening of some novel pyrimidine derivatives

In the present study a new series of 4-substituted phenyl-6-(pyridin-2-yl)pyrimidin-2-ol (1–9) and 4-substituted phenyl-6-(pyridin-2-yl)pyrimidin-2-thiol (10–18) have been synthesized by cyclizing 3-substituted phenyl-1-(pyridin-2-yl)prop-2-en-1-one with urea/thiourea in the presence of NaOH as base (1a–18a). 3-Substituted phenyl-1-(pyridin-2-yl)prop-2-en-1-one was prepared by condensing 2-acetylpyridine with substituted benzaldehyde in the presence of 20 % NaOH as base. The structures of the newly synthesized compounds were characterized by elemental analysis, IR, ¹H NMR, ¹³C NMR, and mass spectroscopic studies. Newly synthesized compounds were screened for their anti-inflammatory, analgesic, cytotoxic, and antitubercular activities studies. Few of the compounds exhibited excellent anti-inflammatory activities compared to standard drug diclofenac sodium. Some compounds have shown moderate analgesic activities compared to standard drug pentazocine. Also, some compounds have exhibited moderate cytotoxic and antitubercular activities.