Thiohydantoin derivatives incorporating a pyrazole core: Design,synthesis and biological evaluation as dual inhibitors of topoisomerase-I and cycloxygenase-2 with anti-cancer and anti-inflammatory activities

A new series of hybrid structures 14a–l containing thiohydantoin as anti-cancer moiety and pyrazole core possessing SO₂Me pharmacophore as selective COX-2 moiety was designed and synthesized to be evaluated for both anti-inflammatory and anti-cancer activities. The synthesized compounds were evaluated for their COX inhibition, in vivo anti-inflammatory activity, ulcerogenic liability, in vitro cytotoxic activity and human topoisomerase-1 inhibition. All compounds were more selective for COX-2 isozyme and showed good in vivo anti-inflammatory activity. Also, all derivatives were significantly less ulcerogenic (ulcer indexes = 2.64–3.87) than ibuprofen (ulcer index = 20.25) and were of acceptable ulcerogenicity when compared with the non-ulcerogenic reference drug celecoxib (ulcer index = 2.99). Regarding anti-cancer activity, most of the target derivatives showed activities against A-549, MCF-7 and HCT-116 cell lines (IC₅₀ = 5.32–17.90, 3.67–19.04 and 3.19–14.87 µM respectively) in comparison with doxorubicin (IC₅₀ = 0.20, 0.50 and 2.44 µM respectively). Compound 14a inhibited the human topoisomerase-1 with IC₅₀ = 29.7 µg/ml while 14b and 14c showed more potent inhibitory activity with IC₅₀ = 26.5 and 23.3 µg/ml. respectively in comparison with camptothecin (IC₅₀ = 20.2 µg/ml). Additionally, COX-2 and human topoisomerase-1 docking studies were carried out to explain the interaction of the synthesized hybrid structures 14a–l with the target enzymes.     

Anti-inflammatory drug approach: Synthesis and biological evaluation of novel pyrazolo[3,4-d]pyrimidine compounds

In this study, the acid chlorides of pyrazolo[3,4-d]pyrimidine compounds were prepared and reacted with a number of nucleophiles. The novel compounds were experimentally tested via enzyme assay and they showed cyclooxygenase-2 inhibition activity in the middle micro molar range (4b had a COX-1 IC₅₀ of 26 µM and a COX-2 IC₅₀ of 34 µM, 3b had a COX-1 IC₅₀ of 19 µM and a COX-2 IC₅₀ of 31 µM, 3a had a COX-2 IC₅₀ of 42 µM). These compounds were analyzed via docking and were predicted to interact with some of the COX-2 key residues. Our best hit, 4d (COX-1 IC₅₀ of 28 µM, COX-2 IC₅₀ of 23 µM), appears to adopt similar binding modes to the standard COX-2 inhibitor, celecoxib, proposing room for possible selectivity. Additionally, the resultant novel compounds were tested in several in vivo assays. Four compounds 3a (COX-2 IC₅₀ of 42 µM), 3d, 4d and 4f were notable for their anti-inflammatory activity that was comparable to that of the clinically available COX-2 inhibitor celecoxib. Interestingly, they showed greater potency than the famous non-steroidal anti-inflammatory drug, Diclofenac sodium. In summary, these novel pyrazolo[3,4-d]pyrimidine analogues showed interesting anti-inflammatory activity and could act as a starting point for future drugs.     

Design,synthesis of novel isoindoline hybrids as COX-2 inhibitors: Anti-inflammatory,analgesic activities and docking study

A group of novel isoindoline hybrids incorporating oxime, hydrazone, pyrazole, chalcone or aminosulfonyl pharmacophores (9–14) was designed and characterized by spectral data and elemental analyses results. All newly synthesized compounds were evaluated as COX-2 inhibitors, anti-inflammatory and analgesic agents. Six hybrid derivatives (10b, 10c, 11a, 11d, 13, 14) were moderate COX-2 inhibitors (IC₅₀ = 0.11–0.18 µM) close to standard celecoxib (IC₅₀ = 0.09 µM). The most active compounds showed outstanding in vivo anti-inflammatory activity (% edema inhibition = 41.7–50, 1 h; 40.7–67.4, 3 h; 20–46.7, 6 h) better than reference drug diclofenac (% edema inhibition = 29.2, 1 h; 22.2, 3 h; 20, 6 h). Most compounds showed significant peripheral and/or central analgesic activity. The moderate selective COX-2 inhibitor; dimethoxychalcone 11d (SI = 103) displayed excellent anti-inflammatory activity (% edema inhibition = 45.8–59.3) and increased thermal pain threshold (50–92.85%) comparable to piroxicam (75%). Molecular docking studies have been established.     

Novel aryl carboximidamide and 3-aryl-1,2,4-oxadiazole analogues of naproxen as dual selective COX-2/15-LOX inhibitors: Design,synthesis and docking studies

A series of novel naproxen analogues containing 3-aryl-1,2,4-oxadiazoles moiety (4b-g) and their reaction intermediates aryl carboximidamides moiety (3b-g) was synthesized and evaluated in vitro as dual COXs/15-LOX inhibitors. Compounds 3b-g exhibited superior inhibitory activity than celecoxib as COX-2 inhibitors. Compounds 3b-d and 3g were the most potent COX-2 inhibitors with IC₅₀ range of 6.4 – 8.13 nM and higher selectivity indexes (3b, SI = 26.19; 3c, SI = 13.73; 3d, SI = 29.27; 3g, SI = 18.00) comparing to celecoxib (IC₅₀ = 42.60 nM, SI = 8.05). Regarding 15-LOX inhibitory activity, compounds belonging to aryl carboximidamide backbone 3b-e and 3g were the most potent with IC₅₀ range of 1.77–4.91 nM comparing to meclofenamate sodium (IC₅₀ = 5.64 µM). Data revealed that The levels of NO released by aryl carboximidamides 3b-g were more higher than 3-aryl-1,2,4-oxadiazole derivatives 4b-g, which correlated well with their COX-2 inhibitory activities.     

Novel class of benzimidazole-thiazole hybrids: The privileged scaffolds of potent anti-inflammatory activity with dual inhibition of cyclooxygenase and 15-lipoxygenase enzymes

The present study includes design and synthesis of new molecular hybrids of 2-methylthiobenzimidazole linked to various anti-inflammatory pharmacophores through 2-aminothiazole linker, to investigate the effect of such molecular variation on cyclooxygenase (COX) and 15-lipoxygenase (15-LOX) enzymes inhibition as well as in vivo anti-inflammatory activity. The chemical structures of new hybrids were confirmed using different spectroscopic tools and elemental analyses. Benzimidazole-thiazole hybrids linked to acetyl moiety 13, phenyl thiosemicarbazone 14, 1,3-thiazolines 15a-c and 4-thiazolidinone 16 exhibited significant COX-2 inhibition (IC₅₀ = 0.045–0.075 µM) with significant COX-2 selectivity indices (SI = 142–294). All hybrids revealed potent 15-LOX inhibitory activity (IC₅₀ = 1.67–6.56 µM). Benzimidazole-thiazole hybrid 15b was the most potent dual COX-2 (IC₅₀ = 0.045 µM, SI = 294) inhibitor approximate to celecoxib (COX-2; IC₅₀ = 0.045 µM, SI = 327), with double inhibitory activity versus 15-LOX enzyme (IC₅₀ = 1.67 µM) relative to quercetin (IC₅₀ = 3.34 µM). Three hybrids (14, 15b & 16) were selected for in vivo screening using carrageenan-induced paw edema method. Benzimidazole-thiazole hybrid linked to 4-thiazolidinone 16 showed the maximum edema inhibition at both 3 h and 4 h intervals as well (~119% and 102% relative to indomethacin, respectively). The gastric ulcerogenic effect of benzimidazole-thiazole hybrid 16 was estimated compared with indomethacin showing superior gastrointestinal safety profile. In bases of molecular modeling; all new active hybrids were subjected to docking simulation into active sites of COX-2 and 15-LOX enzymes to study the binding mode of these novel potent dual COX-2/15-LOX inhibitors.     

New benzimidazothiazole derivatives as anti-inflammatory,antitumor active agents: Synthesis,in-vitro and in-vivo screening and molecular modeling studies

A new series of benzimidazothiazole derivatives has been synthesized. The structure of the products was confirmed by spectroscopic techniques such as IR, NMR and mass spectroscopy. The tested compounds were evaluated for their anti-inflammatory activity either in vitro through the COX enzyme inhibition assay, or in vivo through carrageenan paw edema technique. Results revealed that compound 25 and 29 represented the most active ones among the entire series with % inhibition 72.19, 72.07 for COX-1, and 87.46, 87.38 for COX-2, respectively. Interestingly, all synthesized compounds exhibited IC₅₀ values less than both reference drugs celecoxib and naproxen, indicating their superior potency. For compound 25, it showed about 340 and 198 times more potent than celecoxib and naproxen respectively as COX-1 inhibitor (IC₅₀ value 0.044 vs. 15.000 and 8.700 µM), and 10 and 115 times more potent than the same drugs as COX-2 inhibitor (IC₅₀ value 4.52 vs. 40.00 and 520.00 nM). The antitumor activity of the products was also evaluated and the results obtained are consistent with those obtained by the anti-inflammatory screening where compounds 25 and 29 proved to be the most active ones among the other compounds with %GI ranging from 31.5 to 62.5% and they exhibited the lowest IC₅₀ values as well. The ADMET analysis of the tested compounds was also performed in addition to the molecular modeling studies that included flexible alignment, surface and electrostatic maps in addition to the Lipinisk's rule of five.     

Novel pyrimidine-pyridine hybrids: Synthesis,cyclooxygenase inhibition,anti-inflammatory activity and ulcerogenic liability

Some derivatives containing pyrido[2,3-d:6,5d′]dipyrimidine-4,5-diones (9a-f), tetrahydropyrido[2,3-d]pyrimidine-6-carbonitriles (11a-c) and 6-(4-acetylphenyl)-2-thioxo-2,3,5,6,7,8-hexahydro-1H-pyrimido[4,5-d]pyrimidin-4-one (12) were synthesized from 6-amino-2-thioxo-2,3-dihydro-1H-pyrimidin-4-one (8). The anti-inflammatory effect of these candidates was determined and the ulcer indices were calculated for active compounds. 7-Amino-5-(3,4,5-trimethoxyphenyl)-4-oxo-2-thioxo-1,2,3,4-tetrahydropyrido[2,3-d] pyrimidine-6-carbonitrile (11c) exhibited better edema inhibition than celecoxib. Moreover, compounds 9b, 9d and 11c revealed better COX-2 inhibitory activity in a range (IC₅₀ = 0.25–0.89 µM) than celecoxib (IC₅₀ = 1.11 µM). Regarding ulcerogenic liability, all of the compounds under the study were less ulcerogenic than indomethacin. Molecular docking studies had been carried on active candidates 9d and 11c to explore action mode of these candidates as leads for discovering other anti-inflammatory agents.     

Novel quinoline incorporating 1,2,4-triazole/oxime hybrids: Synthesis,molecular docking,anti-inflammatory,COX inhibition,ulceroginicity and histopathological investigations

A series of novel quinolines incorporating 1,2,4-triazole/oxime hybrids were prepared. They showed remarkable anti-inflammatory activity and exhibited very low incidence of gastric ulceration, compared to indomethacin. Most of the compounds tested showed remarkable inhibition of the COX-1 isozyme, with IC₅₀’s ranging from 0.48 to 28 µM. Compounds 7c and 9g showed high safety profiles with normal stomach tissue integrity. Docking studies supported the observed in vitro inhibitory activity towards the COX enzymes that may explain their promising anti-inflammatory activity relative to indomethacin. Moreover, differences between the COX-1 and COX-2 isozymes in observed energy scores, as well as in the number of interactions with some of the compounds tested, might predict their higher selectivity towards COX-1 rather than COX-2. Compound 9e was found to inhibit both COXs non-competitively with K_i values of 81 µM and 94.6 µM.     

Synthesis,biological evaluation and docking study of 1,3,4-thiadiazole-thiazolidinone hybrids as anti-inflammatory agents with dual inhibition of COX-2 and 15-LOX

Selective inhibition of both cyclooxygenase-2 (COX-2) and 15-lipooxygenase (15-LOX) may provide good strategy for alleviation of inflammatory disorders while minimizing side effects associated with current anti-inflammatory drugs. The present study describes the synthesis, full characterization and biological evaluation of a series of thiadiazole-thiazolidinone hybrids bearing 5-alk/arylidene as dual inhibitors of these enzymes. Our design was based on merging pharmacophores that exhibit portent anti-inflammatory activities in one molecular frame. 5-(4-hydroxyphenyl)-1,3,4-thiadiazol-2-amine (3) was efficiently synthesized, chloroacetylated and cyclized to give the key 4-thiazolidinone (5). Knovenagel condensation of 5 with different aldehydes afforded the final compounds 6a-m, 7, 8 and 9. These compounds were subjected to in vitro COX-1/COX-2, 15-LOX inhibition assays. Compounds (6a, 6f, 6i, 6l, 6m and 9) with promising potency (IC₅₀ = 70–100 nM) and selectivity index (SI = 220-55) were further tested for in vivo anti-inflammatory activity and effect on gastric mucosa. The most promising compound (6l) inhibits COX-2 enzyme at a nanomolar concentration (IC₅₀ = 70 nM, SI = 220) with simultaneous inhibition of 15-LOX (IC₅₀ = 11 µM). These results are comparable to the potency and selectivity of the standard drugs of both enzymes; celecoxib (COX-2 IC₅₀ = 49 nM, SI = 308) and zileuton (15-LOX IC₅₀ = 15 µM) in one construct. Interestingly three compounds (6a, 6l and 9) exhibited equivalent to or even higher than that of celecoxib in vivo anti-inflammatory activity at 3 h interval with good GIT safety profile. Molecular docking study conferred binding sites of these compounds on COX-2 and 15-LOX. Such type of compounds would represent valuable leads for further investigation and derivatization.     

1,2,3-triazole tethered Indole-3-glyoxamide derivatives as multiple inhibitors of 5-LOX,COX-2 & tubulin: Their anti-proliferative & anti-inflammatory activity

To evaluate the role of COX-2 and 5-LOX as dual inhibitors in controlling the cancer cell proliferation, a set of two series having 42 compounds of 1, 2, 3-Tethered Indole-3-glyoxamide derivatives were synthesized by employing click chemistry approach and were also evaluated for their in vitro cyclooxygenase-1 (COX-1), cyclooxygenase-2 (COX-2), 5-lipoxygenase (5-LOX) inhibitory activities with in vivo anti-inflammatory and in vitro anti-proliferative potencies. Among the compounds tested, compounds 11q and 13s displayed excellent inhibition of COX-2 (IC₅₀ 0.12 µM) with good COX-2 selectivity index (COX-2/COX-1) of 0.058 and 0.046 respectively. Compounds 11q and 13s also demonstrated comparable 5-LOX inhibitory activity with IC₅₀ 7.73 and 7.43 µM respectively to that of standard Norhihydroguaiaretic acid (NDGA: IC₅₀ 7.31 µM). Among all the selected cell lines, prostate cancer cell line DU145 was found to be susceptible to this class of compounds. Among all the tested compounds, compounds 11g, 11i, 11k, 11q, 13r, 13s and 13u demonstrated excellent to moderate anti-proliferative activity with IC_50s ranging between 6.29 and 18.53 µM. Compounds 11q and 11g demonstrated better anti-proliferative activities against DU145 cancer cell line with IC₅₀ values 8.17 and 8.69 µM respectively when compared to the standard drug etoposide (VP16; IC₅₀ 9.80 µM). Compounds 11g, 11k, 11q, 13s and 13u showed good dual COX-2/5-LOX inhibitory potentials with excellent anti-proliferative activity. Results from carrageenan-induced hind paw edema demonstrated that compounds 11b, 11l, 11q and 13q exhibited significant anti-inflammatory activity with 69–77% inhibition at 3 h, 75–82% inhibition at 5 h when compared to the standard drug indomethacin (66.6% at 3 h and 77.94% at 5 h). Ulcerogenic study revealed that compounds 11q and 13q did not cause any gastric ulceration. In vitro tubulin assay resuted that compound 11q interfered with microtubulin dynamic and act as tubulin polymerization inhibitor. In silico molecular docking studies demonstrated that compounds 11q and 13s are occupying the colchicines binding site of tubulin polymer and 11q illustrated very good binding affinities towards COX-2 and 5-LOX.     

Novel N-substituted 5-aminosalicylamides as dual inhibitors of cyclooxygenase and 5-lipoxygenase enzymes: Synthesis,biological evaluation and docking study

Three new series of 5-aminosalicylic acid derivatives; series I (14, 16–18), series II (19–30) and series III (31–41) were synthesized as potential dual COX-2/5-LOX inhibitors. Their chemical structures were confirmed using spectroscopic tools including IR, ¹H NMR, ¹³C NMR, mass spectroscopy and elemental analyses. The anti-inflammatory activity for all target compounds was evaluated in vivo using carrageenan-induced paw edema. Compound 36 showed the highest anti-inflammatory activity (114.12%) relative to reference drug indomethacin at 4 h interval. Selected derivatives were evaluated in vitro to inhibit ovine COX-1, human recombinant COX-2 and 5-LOX enzymes. Compounds 34 & 35 exhibited significant COX-2 inhibition (IC₅₀ = 0.10 µM) with significant COX-2 selectivity indices (SI = 135 & 145 respectively) approximate to celecoxib (IC₅₀ = 0.049 µM, SI = 308.16) and exceeding indomethacin (IC₅₀ = 0.51 µM, SI = 0.08). Interestingly, all compounds showed superior 5-LOX inhibitory activity about 2–5 times relative to zileuton. Compound 16 was the superlative 5-LOX inhibitor that revealed (IC₅₀ = 3.41 µM) relative to zileuton (IC₅₀ = 15.6 µM). Compounds 34, 35, 36 and 41 showed significant dual COX-2/5-LOX inhibitions. The gastric ulcerogenic effect of compound 36 was examined on gastric mucosa of albino rats and they showed superior GI safety profile compared with indomethacin. Molecular docking studies of the compounds into the binding sites of COX-1, COX-2 and 5-LOX allowed us to shed light on the binding mode of these novels dual COX and 5-LOX inhibitors.     

Synthesis and biological evaluation of new pyrazolone Schiff bases as monoamine oxidase and cholinesterase inhibitors

In the current work, Schiff base derivatives of antipyrine were synthesized. The chemical characterization of the compounds was confirmed using IR, ¹H NMR, ¹³C NMR and mass spectroscopies. The inhibitory potency of synthesized compounds was investigated towards acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), and monoamine oxidases A and B (MAO-A and MAO-B) enzymes. Some of the compounds displayed significant inhibitory activity against AChE and MAO-B enzymes, respectively. According to AChE enzyme inhibition assay, compounds 3e and 3g were found as the most potent derivatives with IC₅₀ values of 0.285 µM and 0.057 µM, respectively. Also, compounds 3a (IC₅₀ = 0.114 µM), 3h (IC₅₀ = 0.049 µM), and 3i (IC₅₀ = 0.054 µM) were the most active derivatives against MAO-B enzyme activity. So as to understand inhibition type, enzyme kinetics studies were carried out. Furthermore, molecular docking studies were performed to define and evaluate the interaction mechanism between compounds 3g and 3h and related enzymes. ADME (Absorption, Distribution, Metabolism, and Excretion) and BBB (Blood, Brain, Barier) permeability predictions were applied to estimate pharmacokinetic profiles of synthesized compounds.     

New indole based hybrid oxadiazole scaffolds with N-substituted acetamides: As potent anti-diabetic agents

Current study is based on the sequential conversion of indolyl butanoic acid (1) into ethyl indolyl butanoate (2), indolyl butanohydrazide (3), and 1,3,4-oxadiazole-2-thiol analogs (4) by adopting chemical transformations. In a parallel series of reactions, 2-bromo-N-phenyl/arylacetamides (7a-l) were synthesized by reacting different amines derivatives (5a-l) with 2-bromoacetyl bromide (6) to serve as electrophile. Then, the synthesized electrophiles (7a-l) were treated with nucleophilic 1,3,4-oxadiazole-2-thiol analog (4) to afford a range of N-substituted derivatives (8a-l). The structural confirmation of all the synthetic compounds was carried out by IR, ¹H-, ¹³C NMR, EI-MS, and CHN analysis data. All synthesized molecules (8a-l) were tested for their antidiabetic potential via inhibition of the α-glucosidase enzyme followed by their in silico study. Their cytotoxicity profile was also ascertained via hemolytic activity and all of them possessed very low cytotoxicity. Compounds 8h and 8l were found most active having IC₅₀ values 9.46 ± 0.03 µM and 9.37 ± 0.03 µM, respectively. However, all other molecules also exhibited good to moderate inhibition potential with IC₅₀ values between 12.68 ± 0.04–37.82 ± 0.07, compared to standard acarbose (IC₅₀ = 37.38 ± 0.12 µM), hence can be used as lead molecules for further research in order to get better antidiabetic agents.     

Potent ACE inhibitors from 5-hydroxy indanone derivatives

A novel triazole derivatives(±)-2-(hydroxymethyl)-7,8-dihydro-1H-indeno[5,4-b]furan-6(2H)-one (12a–j) were designed and synthesized by the reaction between racemic azide and terminal acetylenes under click chemistry reaction conditions followed by biological evaluation as angiotensin converting enzyme (ACE) inhibitors. β-Amino alcohol derivatives of 1-indanone (15a–l) were synthesized from 5-hydroxy indanone, it was reacted with epichlorohydrin and followed by oxirane ring opening with various piperazine derivatives. Among the newly synthesized compounds 12b (IC₅₀: 1.388024 µM), 12g (IC₅₀: 1.220696 µM), 12j (IC₅₀: 1.312428 µM) and 15k (IC₅₀: 1.349671 µM) and 15l (IC₅₀: 1.330764 µM) emerged as most active non-carboxylic acid ACE inhibitors with minimal toxicity comparable to clinical drug Lisinopril.     

Design,synthesis, in vitro,and in silico studies of novel diarylimidazole-1,2,3-triazole hybrids as potent α-glucosidase inhibitors

In this work, new derivatives of diarylimidazole-1,2,3-triazole 7a-p were designed, synthesized, and evaluated for their in vitro α-glucosidase inhibitory activity. All compounds showed potent inhibitory activity in the range of IC₅₀ = 90.4–246.7 µM comparing with acarbose as the standard drug (IC₅₀ = 750.0 µM). Among the synthesized compounds, compounds 7b, 7c, and 7e were approximately 8 times more potent than acarbose. The kinetic study of those compounds indicated that they acted as the competitive inhibitors of α-glucosidase. Molecular docking studies were also carried out for compounds 7b, 7c, and 7e using modeled α-glucosidase to find the interaction modes responsible for the desired inhibitory activity.     

Synthesis,biological evaluation and docking study of N-(2-(3,4,5-trimethoxybenzyl)benzoxazole-5-yl) benzamide derivatives as selective COX-2 inhibitor and anti-inflammatory agents

A series of N-(2-(3,4,5-trimethoxybenzyl)-benzoxazole-5-yl)benzamide derivatives (3a–3n) was synthesized and evaluated for its in vitro inhibitory activity against COX-1 and COX-2. The compounds with considerable in vitro activity (IC₅₀ < 1 µM), were evaluated in vivo for their anti-inflammatory and ulcerogenic potential. Out of the fourteen newly synthesized compounds; 3b, 3d, 3e, 3h, 3l and 3m were found to be most potent COX-2 inhibitors in in vitro enzymatic assay with IC₅₀ in the range of 0.14–0.69 µM. In vivo anti-inflammatory activity of these six compounds (3b, 3d, 3e, 3h, 3l and 3m) was assessed by carrageenan induced rat paw edema method. The compound 3b (79.54%), 3l (75.00%), 3m (72.72%) and 3d (68.18%) exhibited significant anti-inflammatory activity than standard drug ibuprofen (65.90%). Ulcerogenic activity with histopathological studies was performed, and the screened compounds demonstrated significant gastric tolerance than ibuprofen. Molecular Docking study was also performed with resolved crystal structure of COX-2 to understand the interacting mechanisms of newly synthesized inhibitors with the active site of COX-2 enzyme and the results were found to be in line with the biological evaluation studies of the compounds.     

Flurbiprofen derivatives as novel α-amylase inhibitors: Biology-oriented drug synthesis (BIODS), in vitro,and in silico evaluation

Novel derivatives of flurbiprofen 1–18 including flurbiprofen hydrazide 1, substituted aroyl hydrazides 2–9, 2-mercapto oxadiazole derivative 10, phenacyl substituted 2-mercapto oxadiazole derivatives 11–15, and benzyl substituted 2-mercapto oxadiazole derivatives 16–18 were synthesized and characterized by EI-MS, ¹H and ¹³C NMR spectroscopic techniques. All derivatives 1–18 were screened for α-amylase inhibitory activity and demonstrated a varying degree of potential ranging from IC₅₀ = 1.04 ± 0.3 to 2.41 ± 0.09 µM as compared to the standard acarbose (IC₅₀ = 0.9 ± 0.04 µM). Out of eighteen compounds, derivatives 2 (IC₅₀ = 1.69 ± 0.1 µM), 3 (IC₅₀ = 1.04 ± 0.3 µM), 9 (IC₅₀ = 1.25 ± 1.05 µM), and 13 (IC₅₀ = 1.6 ± 0.18 µM) found to be excellent inhibitors while rest of the compounds demonstrated comparable inhibition potential. A limited structure-activity relationship (SAR) was established by looking at the varying structural features of the library. In addition to that, in silico study was conducted to understand the binding interactions of the compounds (ligands) with the active site of α-amylase enzyme.     

New phenolic cinnamic acid derivatives as selective COX-2 inhibitors. Design,synthesis, biological activity and structure-activity relationships

Selective inhibition of cyclooxygenase (COX)-2 enzyme is an important achievement when looking for potent anti-inflammatory agents, with fewer gastrointestinal side effects. In this work, a new series of cinnamic acid derivatives, namely hexylamides, have been designed, synthesized and evaluated in human blood for their inhibitory activity of COX-1 and COX-2 enzymes. From this, new structure-activity relationships were built, showing that phenolic hydroxyl groups are essential for both COX-1 and COX-2 inhibition. Furthermore, the presence of bulky hydrophobic di-tert-butyl groups in the phenyl ring strongly contributes for selective COX-2 inhibition. In addition, a correlation with the theoretical log P has been carried out, showing that lipophilicity is particularly important for COX-2 inhibition. Further, a plasma protein binding (PPB) prediction has been performed revealing that PPB seems to have no influence in the activity of the studied compounds. From the whole study, effective selective inhibitors of COX-2 were found, namely compound 9 (IC₅₀ = 3.0 ± 0.3 μM), 10 (IC₅₀ = 2.4 ± 0.6 μM) and 23 (IC₅₀ = 1.09 ± 0.09 μM). Those can be considered starting point hit compounds for further optimization as potential non-steroidal anti-inflammatory drugs.     

Rational design,molecular docking and synthesis of novel homopiperazine linked imidazo[1,2-a]pyrimidine derivatives as potent cytotoxic and antimicrobial agents

Designed and synthesized novel homopiperazine linked imidazo[1,2-a]pyrimidine derivatives (10a–i, 11a–g, 12), and evaluated them for their in vitro cytotoxicity against HeLa cells (cervical cancer), A549 cells (lung cancer) cells, by MTT assay. Compound 12 (IC₅₀ = 4.14 µM) and compound 10c (IC₅₀ = 5.98 µM) were found to be 2.5 fold, and 1.74 fold more potent when compared with standard Etoposide (IC₅₀ = 10.44 µM), against A549 (lung cancer cells). Compound 12 also found to be 1.57 and 1.13 fold potent against DU145 (IC₅₀ = 6.24 µM) and HeLa (IC₅₀ = 6.54 µM), respectively when compared with Etoposide (DU145, IC₅₀ = 9.8 µM; HeLa, IC₅₀ = 7.43 µM). Compound 10f (IC₅₀ = 6.12 µM) was found to be 1.31 fold more potent than Etoposide (IC₅₀ = 7.43 µM) against HeLa cell lines.Moreover compounds 10a and 11a showed cytotoxicity at low micro-molar concentrations against A549 cells. Synthesized compounds were also evaluated for their antimicrobial activity by Cup plate diffusion method. Compounds 10c, 11b, 11d and 11f displayed remarkable antimicrobial activity relating to their standard drugs Gentamycin, Amphotericin B and Ampicillin. Significantly, compound 10c showed broad spectrum activity against tested microbial strains. All the designed compounds were well occupied the binding site of the colchicine and interacted with both α- and β-tubuline interface (PDB ID: 3E22), which demonstrates that synthesized compounds are promising tubulin inhibitors. Also, the synthesized compounds occupied the catalytic triad and adenine-binding site, in the active site of β-ketoacyl-acyl carrier protein synthase III enzyme (PDB ID: 1MZS). The molecular docking results provided the useful information for the future design of more potent inhibitors. These preliminary results convinced further investigation and modifications on synthesized compounds aiming towards the development of potential cytotoxic as well as antimicrobial agents.     

Synthesis,biological evaluation and docking study of a new series of di-substituted benzoxazole derivatives as selective COX-2 inhibitors and anti-inflammatory agents

A new series of substituted-N-(3,4-dimethoxyphenyl)-benzoxazole derivatives 13a–13p was synthesized and evaluated in vitro for their COX (I and II) inhibitory activity, in vivo anti-inflammatory and ulcerogenic potential. Compounds 13d, 13h, 13k, 13l and 13n exhibited significant COX-2 inhibitory activity and selectivity towards COX-2 over COX-1. These selected compounds were screened for their in vivo anti-inflammatory activity by carrageenan induced rat paw edema method. Among these compounds, 13d was the most promising analogs of the series with percent inhibition of 84.09 and IC₅₀ value of 0.04?µM and 1.02?µM (COX-2 and COX-1) respectively. Furthermore, ulcerogenic study was performed and tested compounds (13d, 13h, 13k, 13l) demonstrated a significant gastric tolerance than ibuprofen. Molecular docking study was also performed with resolved crystal structure of COX-2 to understand the binding mechanisms of newly synthesized inhibitors in the active site of COX-2 enzyme and the results were found to be concordant with the biological evaluation studies of the compounds. These newly synthesized inhibitors also showed acceptable pharmacokinetic profile in the in silico ADME/T analyses.