Design,synthesis and in vitro antiplasmodial activity of some bisquinolines against chloroquine‐resistant strain

A series of novel bisquinoline compounds comprising N¹‐(7‐chloroquinolin‐4‐yl) ethane‐1,2‐diamine and 7‐chloro‐N‐(2‐(piperazin‐1‐yl)ethyl)quinolin‐4‐amine connected with 7‐chloro‐4‐aminoquinoline containing various amino acids is described. We have bio‐evaluated the compounds against both chloroquine‐sensitive (3D7) and chloroquine‐resistant (K1) strains of Plasmodium falciparum in vitro. Among the series, compounds 4 and 7 exhibited 1.8‐ and 10.6‐fold superior activity as compared to chloroquine (CQ; IC₅₀ = 0.255 ± 0.049 μm ) against the K1 strain with IC₅₀ values 0.137 ± 0.014 and 0.026 ± 0.007 μm , respectively. Furthermore, compound 7 also displayed promising activity against the 3D7 strain (IC₅₀ = 0.024 ± 0.003 μm ) of P. falciparum when compared to CQ. All the compounds in the series displayed resistance factor between 0.57 and 4.71 as against 51 for CQ. These results suggest that bisquinolines can be explored for further development as new antimalarial agents active against chloroquine‐resistant P. falciparum.     

Synthesis and biological evaluation of some pyrazole derivatives as anti-malarial agents

Novel series of pyrazole derivatives were synthesized and tested for their in vivo anti‐malarial activity using mice infected with chloroquine sensitive P. berghei at a dose level of 50 µmol/kg. The most active compounds were further tested in vitro against chloroquine resistant (RKL9) strain of P. falciparum. The in vivo anti‐malarial activity study indicated that compounds 2a, 2b, 8a and 8b had mean percent suppression of 85%, 83%, 95% and 97%, respectively at equimolar dose level of the standard drug chloroquine diphosphate. Moreover, compounds 2a, 2b, 8a and 8b showed in vitro IC₅₀ values lower (p < 0.05) than that of the standard drug chloroquine phosphate (0.188 ± 0.003 µM) using the RKL9 strain. Compound 8b was the most active with IC₅₀ of 0.033 ± 0.014 µM. Generally, among the tested compounds, those containing a free carboxylic acid functional group on the pyrazole ring were the most active and this finding was supported by the docking results performed for the active compounds. The acute toxicity studies of the active compounds revealed that they have a good safety profile.     

New Compounds Hybrids 1H‐1,2,3‐Triazole‐Quinoline Against Plasmodium falciparum

Malaria is one of the most prevalent parasitic diseases in the world. The global importance of this disease, current vector control limitations, and the absence of an effective vaccine make the use of therapeutic antimalarial drugs the main strategy to control malaria. Chloroquine is a cost‐effective antimalarial drug with a relatively robust safety profile, or therapeutic index. However, chloroquine is no longer used alone to treat patients with Plasmodium falciparum due to the emergence and spread of chloroquine‐resistant strains, which have also been reported for Plasmodium vivax. However, the activity of 1,2,3‐triazole derivatives against chloroquine‐sensitive and chloroquine‐resistant strains of P. falciparum has been reported in the literature. To enhance the anti‐P. falciparum activity of quinoline derivatives, we synthesized 11 new quinoline‐1H‐1,2,3‐triazole hybrids with different substituents in the 4‐positions of the 1H‐1,2,3‐triazole ring, which were assayed against the W2‐chloroquine‐resistant P. falciparum clone. Six compounds exhibited activity against the P. falciparum W2 clone, chloroquine‐resistant, with IC₅₀ values ranging from 1.4 to 46 μm . None of these compounds was toxic to a normal monkey kidney cell line, thus exhibiting good selectivity indexes, as high 351 for one compound ( 11 ).     

Synthesis and Biological Evaluation of Tricyclic Guanidine Analogues of Batzelladine K for Antimalarial,Antileishmanial, Antibacterial,Antifungal, and Anti‐HIV Activities

Fifty analogues of batzelladine K were synthesized and evaluated for in vitro antimalarial (Plasmodium falciparum), antileishmanial (Leishmania donovani), antimicrobial (panel of bacteria and fungi), antiviral (HIV‐1) activities. Analogues 14h and 20l exhibited potential antimalarial activity against chloroquine‐sensitive D6 strain with IC₅₀ 1.25 and 0.88 μm and chloroquine‐resistant W2 strain with IC₅₀ 1.64 and 1.07 μm , respectively. Analogues 12c and 14c having nonyl substitution showed the most potent antileishmanial activity with IC₅₀ 2.39 and 2.78 μm and IC₉₀ 11.27 and 12.76 μm , respectively. Three analogues 12c , 14c, and 14i were the most active against various pathogenic bacteria and fungi with IC₅₀ < 3.02 μm and MIC/MBC/MFC <6 μm . Analogue 20l having pentyl and methyl substituents on tricycle showed promising activities against all pathogens. However, none was found active against HIV‐1. Our study demonstrated that the tricyclic guanidine compounds provide new structural class for broad spectrum activity.     

Synthesis of new arylazopyrazoles as apoptosis inducers: Candidates to inhibit proliferation of MCF‐7 cells

New 4‐arylazo‐3,5‐diamino‐1H‐pyrazole derivatives substituted in the 4‐aryl ring with the acetyl moiety were designed and synthesized. The antiproliferative activity of the novel arylazopyrazoles was examined against the MCF‐7 cell line. Among all target compounds, 8b (IC₅₀ 3.0 µM) and 8f (IC₅₀ 4.0 µM) displayed higher cytotoxicity as compared with the reference standard imatinib (IC₅₀ 7.0 µM). Further studies to explore the mechanism of action were performed on the most active hit of our library, 8b , via anti‐CDK2 kinase activity. It demonstrated good inhibitory effects for CDK2 (IC₅₀ 0.24 µM) with 62.5% inhibition, compared with imatinib. The cell cycle analysis in the MCF‐7 cell line revealed apoptosis induction by 8b and cell cycle arrest at the S phase. Docking in the CDK2 active site and pharmacophore modeling confirmed the affinity of 8b to the CDK2 active site. Absorption, distribution, metabolism, and excretion studies revealed that our target compounds are orally bioavailable, with no permeation through the blood–brain barrier.     

Synthesis,biological evaluation,and docking studies of some 5‐chloro‐2(3H)‐benzoxazolone Mannich bases derivatives as cholinesterase inhibitors

A series of N‐substituted‐5‐chloro‐2(3H)‐benzoxazolone derivatives were synthesized and evaluated for their acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) inhibitory, and antioxidant activities. The structures of the title compounds were confirmed by spectral and elemental analyses. The cholinesterase (ChE) inhibitory activity studies were carried out using Ellman's colorimetric method. The free radical scavenging activity was also determined by in vitro ABTS (2,2‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid)) assay. The biological activity results revealed that all of the title compounds displayed higher AChE inhibitory activity than the reference compound, rivastigmine, and were selective for AChE. Among the tested compounds, compound 7 exhibited the highest inhibition against AChE (IC₅₀ = 7.53 ± 0.17 μM), while compound 11 was found to be the most active compound against BuChE (IC₅₀ = 17.50 ± 0.29 μM). The molecular docking study of compound 7 showed that this compound can interact with the catalytic active site (CAS) of AChE and also has potential metal chelating ability and a proper log P value. On the other hand, compound 2 bearing a methyl substituent at the ortho position on the phenyl ring showed better radical scavenging activity (IC₅₀ = 1.04 ± 0.04 mM) than Trolox (IC₅₀ = 1.50 ± 0.05 mM).

     

Piperazine‐linked 4‐aminoquinoline‐chalcone/ferrocenyl‐chalcone conjugates: Synthesis and antiplasmodial evaluation

A series of piperazine‐linked 4‐aminoquinoline‐chalcone/ferrocenyl‐chalcone conjugates were prepared with a view to evaluate their activities against Plasmodium falciparum. The synthesized conjugates had in vitro IC₅₀ values from 0.41 to 2.38 μm against chloroquine‐resistant and mefloquine‐sensitive W2 strain of P. falciparum. The submicromolar activities of most of the synthesized conjugates suggest that such molecular frameworks can act as therapeutic templates for the design and synthesis of new antimalarials.     

Tetramethylpiperidine‐substituted phenazines as novel anti‐plasmodial agents

Two novel derivatives of clofazimine [3‐(p‐chloroanilino)‐10‐(p‐chlorophenyl)‐2,10‐dihydro‐2‐isopropylimino)phenazine] and the tetramethylpiperidine (TMP)‐substituted phenazines, B4119 [3‐(3‐chloro‐4‐fluoroanilino)‐10‐(3‐chloro‐4‐fluorophenyl)‐2,10‐dihydro‐2(2,2,6,6‐tetramethylpiper‐4‐ylimino)phenazine] and B4158 [3‐(4‐isopropylanilino)‐10‐(4‐isopropylphenyl)‐2,10‐dihydro‐2‐(2,2,6,6‐tetramethylpiper‐4‐ylimino)phenazine] (1–8 μM), were evaluated for activity against chloroquin‐, quinine‐, and sulfadoxine/pyrimethamine‐sensitive and ‐resistant strains of Plasmodium falciparum in vitro, as well as for their effects on polymerisation of haeme to β‐hematin. By using microscopic and flow cytometric methods, it was found that B4119 and B4158, but not clofazimine, inhibited the growth of sensitive, as well as resistant strains of P. falciparum with IC₅₀ values between 0.22 and 0.7 μM, indicating lack of cross‐resistance. Augmentation of anti‐plasmodial activity was observed when B4119 and B4158 were used in combination with chloroquin or mefloquine. Inhibition of the growth of P. falciparum was associated with interference with haeme polymerisation to β‐hematin in vitro, while administration of B4119 to P. berghei‐infected mice was accompanied by a significant reduction in parasitemia and improved therapeutic activity was observed when this agent was combined with chloroquin. The data presented in this study demonstrate that the TMP‐substitution at position 2 on the phenazine nucleus of riminophenazines confers anti‐plasmodial activity on these compounds. These may prove to be useful forerunners in the design of novel anti‐plasmodial pharmacologic agents. Drug Dev. Res. 50:195–202, 2000. © 2000 Wiley‐Liss, Inc.     

Synthesis and Antitumor Activity of Novel Nitrogen Mustard‐Linked Chalcones

A series of nitrogen mustard‐linked chalcones were synthesized and evaluated for their antitumor activity in vitro against the K562 and HepG2 cell lines. The aldol condensation of [N,N‐bis(chloroethyl)‐3‐amino]‐acetophenone ( 2 ) with aromatic aldehydes afforded the nitrogen mustard‐linked chalcones. Among the analogs tested, compounds 5e and 5k exhibited significant anti‐proliferation activities against K562 cells with IC₅₀ values of 2.55 and 0.61 µM, respectively, which revealed higher cell toxicity than the standard drugs cisplatin (IC₅₀ > 200 µM) and adriamycin (IC₅₀ = 14.88 µM). The methoxyl and N,N‐dimethyl groups on the B‐ring of the chalcone frame enhanced the inhibitory activities against both the K562 and HepG2 cell lines. The structure–activity relationship study indicated that the inhibitory activities significantly varied with the position(s) and species of the substituted group(s).     

Design and Synthesis of a New Class of 4‐Aminoquinolinyl‐ and 9‐Anilinoacridinyl Schiff Base Hydrazones as Potent Antimalarial Agents

A series of novel 4‐aminoquinolinyl and 9‐anilinoacridinyl Schiff base hydrazones have been synthesized and evaluated for their antimalarial activity. All compounds were evaluated in vitro for their antimalarial activity against chloroquine‐sensitive strain 3D7 and the chloroquine‐resistant K1 strain of Plasmodium falciparum and for cytotoxicity toward Vero cells. Compounds 17 , 20 , and 21 displayed good activity against the 3D7 strain with IC₅₀ values ranging from 19.69 to 25.38 nm . Moreover, compounds 16 , 17 , 21 , 24 , 32, and 33 exhibited excellent activities (21.64–54.26 nm ) against K1 strain and several compounds displayed β‐hematin inhibitory activity, suggesting that they act on the heme crystallization process such as CQ. Compounds were also found to be non‐toxic with good selectivity index.     

Design,syntheses, and evaluation of novel 1,1‐dihalo‐2,3‐diphenylcyclopropanes as potential cyclooxygenase‐2 (COX‐2) inhibitors with analgesic‐antiinflammatory activity

A group of (Z)‐ and (E)‐1,1‐dihalo‐2‐(4‐substituted‐phenyl)‐3‐phenylcyclopropane [ (Z)‐10 , (E)‐11 ] stereoisomers having a variety of substituents (H, Br, Cl, F, NO₂, SO₂Me) at the para‐position of the C‐2 phenyl ring in conjunction with either two chloro or bromo substituents at C‐1 were synthesized for in vivo evaluation as analgesic and antiinflammatory (AI) agents, and as potential selective cyclooxygenase‐2 (COX‐2) inhibitors. This group of compounds ( 10‐11 ) exhibited significant analgesic activity since 4% NaCl‐induced abdominal constriction was reduced by 44–73% at 30 min, and 48–77% at 60 min, post‐drug administration relative to the reference drugs aspirin and celecoxib (58 and 32% inhibition at 30 min post‐drug administration) for a 50 mg/kg intraperitoneal dose. In the 1,1‐dichloro group of compounds, a Cl or MeSO₂ substituent at the para‐position of the C‐2 phenyl ring generally provided superior analgesic activity. The most active analgesic compound, (E)‐1,1‐dichloro‐2‐(4‐methanesufonylphenyl)‐3‐phenylcyclopropane ( 11h ) inhibited abdominal constriction by 72 and 77% at 30 and 60 min post‐drug administration, respectively. AI activities, determined using the carrageenan‐induced rat paw edema assay, showed that this class of ( Z)‐10 and ( E)‐11 compounds exhibited AI activities in the inactive‐to‐moderate activity range (1.5–45% inhibition) for a 50 mg/kg oral dose. The AI potency order, with respect to the para‐substitutent on the C‐2 phenyl ring, for the ( Z)‐10 compounds was NO₂ > MeSO₂ ≈ H ≥ Cl, and for the ( E)‐11 compounds was H ≥ MeSO₂ > Cl ≈ Br. (E)‐1,1‐dibromo‐2‐(4‐methanesufonylphenyl)‐3‐phenylcyclopropane ( 11l ), which was the most active AI compound, reduced inflammation by 45 and 37% at 3 and 5 h post‐drug administration, respectively. The ( E)‐11 stereoisomer was generally a more potent AI agent than the corresponding ( Z)‐10 stereoisomer. In vitro COX‐1 and COX‐2 inhibition studies showed that (E)‐1,1‐dichloro‐2‐(4‐nitrophenyl)‐3‐phenylcyclopropane ( 11c ) inhibited COX‐1 (IC₅₀ = 278.8 μM) and COX‐2 (IC₅₀ = 80.5 μM) for a COX‐2 selectivity index of 3.5, whereas (E)‐1,1‐dichloro‐2‐(4‐methanesulfonylphenyl)‐3‐phenylcyclopropane ( 11h ) was a more potent inhibitor of COX‐1 and COX‐2, but it was more selective for COX‐1 (COX‐1 IC₅₀ = 0.59 μM, COX‐2 IC₅₀ = 3.04 μM). A molecular modeling (docking) study for (E)‐1,1‐dichloro‐2‐(4‐methanesulfonylphenyl)‐3‐phenylcyclopropane ( 11h ) on the active site of the human COX‐2 isozyme shows it binds in the center of the active site with the 1,1‐dichloro substituents oriented in the direction of the mouth of the channel towards Arg¹²⁰, and the C‐2 MeSO₂ moiety oriented towards the apex of the active site with the S‐atom of the MeSO₂ substituent positioned about 6.56 Å inside the entrance to the secondary pocket (Val⁵²³) of COX‐2. In contrast, the corresponding (Z)‐10h stereoisomer assumes a different position in the COX‐2 binding site where the S‐atom of the MeSO₂ moiety is near (4.02 Å) the Ser⁵³⁰ OH, but a much greater distance from the COX‐2 secondary pocket (Val⁵²³). The results from these docking studies are consistent with the observation that (E)‐11h is an inhibitor of both COX isozymes, whereas the (Z)‐10h stereoisomer is an inactive COX inhibitor (COX‐1 IC₅₀ > 100 μM, COX‐2 IC₅₀ > 200 μM). Drug Dev. Res. 55:79–90, 2002. © 2002 Wiley‐Liss, Inc.     

Design,synthesis, and antiprotozoal evaluation of new 2,9‐bis[(substituted‐aminomethyl)phenyl]‐1,10‐phenanthroline derivatives

A series of new 2,9‐bis[(substituted‐aminomethyl)phenyl]‐1,10‐phenanthroline derivatives was synthesized, and the compounds were screened in vitro against three protozoan parasites (Plasmodium falciparum, Leishmania donovani, and Trypanosoma brucei brucei). Biological results showed antiparasitic activity with IC₅₀ values in the μm range. The in vitro cytotoxicity of these molecules was assessed by incubation with human HepG2 cells; for some derivatives, cytotoxicity was observed at significantly higher concentrations than antiparasitic activity. The 2,9‐bis[(substituted‐aminomethyl)phenyl]‐1,10‐phenanthroline 1h was identified as the most potent antimalarial candidate with ratios of cytotoxic‐to‐antiparasitic activities of 107 and 39 against a chloroquine‐sensitive and a chloroquine‐resistant strain of P. falciparum, respectively. As the telomeres of the parasite P. falciparum are the likely target of this compound, we investigated stabilization of the Plasmodium telomeric G‐quadruplexes by our phenanthroline derivatives through a FRET melting assay. The ligands 1f and 1m were noticed to be more specific for FPf8T with higher stabilization for FPf8T than for the human F21T sequence.     

Novel pyridine‐2,4,6‐tricarbohydrazide thiourea compounds as small key organic molecules for the potential treatment of type‐2 diabetes mellitus: In vitro studies against yeast α‐ and β‐glucosidase and in silico molecular modeling

A range of novel pyridine‐2,4,6‐tricarbohydrazide thiourea compounds ( 4a–i ) were synthesized in good to excellent yields (63–92%). The enzyme inhibitory potentials of these compounds were investigated against α‐ and β‐glucosidases because these enzymes play a crucial role in treating type‐2 diabetes mellitus (T2DM). As compared to the reference compound acarbose (IC₅₀ 38.22 ± 0.12 μM), compounds 4i (IC₅₀ 25.49 ± 0.67 μM), 4f (IC₅₀ 28.91 ± 0.43 μM), 4h (IC₅₀ 30.66 ± 0.52 μM), and 4e (IC₅₀ 35.01 ± 0.45 μM) delivered better inhibition against α‐glucosidase and were quite inactive/completely inactive against β‐glucosidase. The structure–activity relationship of these compounds was developed and elaborated with the help of molecular docking studies.     

Synthesis and in‐vitro Cytotoxic Evaluation of Novel Pyridazin‐4‐one Derivatives

A new series of N‐aryl‐4‐oxo‐1,4‐dihydro‐pyridazine‐3‐carboxylic acids has been synthesized by condensation of aryldiazonium with 4‐hydroxy‐6‐methyl‐2‐pyrone. Some of these compounds exhibited in‐vitro cytotoxic activity with moderate to excellent growth inhibition against the murine P815 mastocytoma cell line. Compound 5b showed an important cytotoxic activity against cell line P815 (IC₅₀ = 0.40 μg/mL).     

Antimalarial activity of newly synthesized chalcone derivatives in vitro

Twenty‐seven novel chalcone derivatives were synthesized using Claisen‐Schmidt condensation and their antimalarial activity against asexual blood stages of Plasmodium falciparum was determined. Antiplasmodial IC₅₀ (half‐maximal inhibitory concentration) activity of a compound against malaria parasites in vitro provides a good first screen for identifying the antimalarial potential of the compound. The most active compound was 1‐(4‐benzimidazol‐1‐yl‐phenyl)‐3‐(2, 4‐dimethoxy‐phenyl)‐propen‐1‐one with IC₅₀ of 1.1 μg/mL, while that of the natural phytochemical, licochalcone A is 1.43 μg/mL. The presence of methoxy groups at position 2 and 4 in chalcone derivatives appeared to be favorable for antimalarial activity as compared to other methoxy‐substituted chalcones. Furthermore, 3, 4, 5‐trimethoxy groups on chalcone derivative probably cause steric hindrance in binding to the active site of cysteine protease enzyme, explaining the relative lower inhibitory activity.     

The application of tandem aza-wittig reaction to synthesize artemisinin-guanidine hybrids and their anti-tumor activity

Three series of novel artemisinin–guanidine hybrids 4a–4f , 8a–8h and 9a–9h have been facilely synthesized via four‐component reaction (aza‐Wittig reaction) and evaluated for their anti‐tumor activities against A549, HT‐29 and MDA‐MB‐231 cell lines in vitro. All of the tested compounds showed enhanced anti‐tumor activities with IC₅₀ values ranging from 0.02 µM to 12.0 µM as compared to DHA (dihydroartemisinin). Among them, artemisinin derived dimers, compounds 9b (IC₅₀ = 0.05 µM), 9d (IC₅₀ = 0.06 µM) and 9f (IC₅₀ = 0.02 µM) were found to be most active against HT29 cells.     

Synthesis,molecular docking studies,and biological evaluation of novel alkyl bis(4‐amino‐5‐cyanopyrimidine) derivatives

A series of bis(4‐amino‐5‐cyano‐pyrimidines) was synthesized and evaluated as dual inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). To further explore the multifunctional properties of the new derivatives, their antioxidant and antibacterial activities were also tested. The results showed that most of these compounds could effectively inhibit AChE and BChE. Particularly, compound 7c exhibited the best AChE inhibitory activity (IC₅₀ = 5.72 ± 1.53 μM), whereas compound 7h was identified as the most potent BChE inhibitor (IC₅₀ = 12.19 ± 0.57 μM). Molecular modeling study revealed that compounds 7c, 7f , and 7b showed a higher inhibitory activity than that of galantamine against both AChE and BChE. Anticholinesterase activity of compounds 7h, 7b , and 7c was significant in vitro and in silico for both enzymes, since these compounds have hydrophobic rings (Br‐phenyl, dimethyl, and methoxyphenyl), which bind very well in both sites. In addition to cholinesterase inhibitory activities, these compounds showed different levels of antioxidant activities. Indeed, in the superoxide–dimethyl sulfoxide alkaline assay, compound 7j showed very high inhibition (IC₅₀ = 0.37 ± 0.28 μM). Also, compound 7l exhibited strong and good antibacterial activity against Staphylococcus epidermidis and Staphylococcus aureus, respectively. Taking into account the results of biological evaluation, further modifications will be designed to increase potency on different targets. In this study, the obtained results can be a new starting point for further development of multifunctional agents for the treatment of Alzheimer's disease.     

Synthesis and Biological Evaluation of Novel 5,8‐Disubstituted‐2‐methyl‐2,3,4,5‐tetrahydro‐1H‐pyrido[4,3‐b] indoles as 5‐HT6 and H1 Receptors Antagonists

Synthesis, biological evaluation, and structure‐activity relationships (SAR) for a series of novel γ‐carboline analogues of Dimebon are described. Among the studied compounds, tetrahydro‐γ‐carboline 5b (2,8‐dimethyl‐5‐[cis‐2‐pyridin‐3‐ylvinyl]‐2,3,4,5‐tetrahydro‐carboline) has been identified as the most potent small molecule antagonist, in particular against histamine H₁ and serotonin 5‐HT₆ receptors (IC₅₀ < 0.45 μM and IC₅₀ = 0.73 μM, respectively). A thorough comparative SAR study performed for the tested compounds has revealed significant correlations between the nature of side substituents and the related antagonistic activity.     

New 2,4‐disubstituted‐2‐thiopyrimidines as VEGFR‐2 inhibitors: Design,synthesis, and biological evaluation

A new series of 2,4‐disubstituted‐2‐thiopyrimidines 6a–t, 9a , and 9b was efficiently designed and synthesized as antiangiogenic and cytotoxic agents. Compounds 6j, 6l , and 6d showed IC₅₀ values of 1.23, 3.78, and 3.84 μM, respectively, against the vascular endothelial growth factor receptor‐2 (VEGFR‐2). Most of the synthesized 2‐thiouracils showed antiproliferative activity against the HepG2 cell line (hepatocellular carcinoma) in the micromolar range, for instance, 9b, 6l, 6m, 6n , and 6j displayed IC₅₀ = 7.92, 8.35, 8.51, 9.59, and 13.06 μM, respectively, relative to sorafenib ( III ; IC₅₀ = 10.99 μM). Also, compounds 6j, 9a, 6m , and 6s (IC₅₀ = 15.21, 16.96, 17.68, and 18.15 μM, respectively) are the most potent compounds against the UO‐31 cell line. Further evaluation of the effect of the synthesized candidates on VEGFR‐2 in the HepG2 cell line demonstrated that compounds 6j and 6l exhibit VEGFR‐2 inhibitory activity of 87% and 84%, respectively, relative to sorafenib ( III ; 92%). In silico docking of the synthesized hits into the binding site of VEGFR‐2 showed their ability to perform the main binding interactions with the key amino acids in the binding site. Studying the in silico predicted ADME (absorption, distribution, metabolism, and excretion) parameters for the synthesized thiouracils demonstrated that they have favorable pharmacokinetic and drug‐likeness properties. These results demonstrate that the 2,4‐disubstituted thiouracils 6 and 9 have not only favorable antiangiogenic and antiproliferative activity but also satisfy the criteria required for the development of orally bioavailable drugs. Consequently, they represent a biologically active scaffold that should be further optimized for future discovery of potential hits.     

Facile synthesis and in-vitro antimalarial activity of novel α-hydroxy hydrazonates

A series of previously unreported α‐hydroxy hydrazonates were synthesized and tested for their antimalarial properties. Structure optimization of the antiplasmodially active α‐hydroxy hydrazonate III furnished derivatives with strong in‐vitro antimalarial activity against 3D7 strains of Plasmodium falciparum with IC₅₀ values lower than 2.0 µM.