Design and synthesis of novel nitrothiazolacetamide conjugated to different thioquinazolinone derivatives as anti-urease agents

The present article describes the design, synthesis, in vitro urease inhibition, and in silico molecular docking studies of a novel series of nitrothiazolacetamide conjugated to different thioquinazolinones. Fourteen nitrothiazolacetamide bearing thioquinazolinones derivatives (8a-n) were synthesized through the reaction of isatoic anhydride with different amine, followed by reaction with carbon disulfide and KOH in ethanol. The intermediates were then converted into final products by treating them with 2-chloro-N-(5-nitrothiazol-2-yl)acetamide in DMF. All derivatives were then characterized through different spectroscopic techniques (1H, 13C-NMR, MS, and FTIR). In vitro screening of these molecules against urease demonstrated the potent urease inhibitory potential of derivatives with IC50 values ranging between 2.22 ± 0.09 and 8.43 ± 0.61 μM when compared with the standard thiourea (IC50 = 22.50 ± 0.44 μM). Compound 8h as the most potent derivative exhibited an uncompetitive inhibition pattern against urease in the kinetic study. The high anti-ureolytic activity of 8h was confirmed against two urease-positive microorganisms. According to molecular docking study, 8h exhibited several hydrophobic interactions with Lys10, Leu11, Met44, Ala47, Ala85, Phe87, and Pro88 residues plus two hydrogen bound interactions with Thr86. According to the in silico assessment, the ADME-Toxicity and drug-likeness profile of synthesized compounds were in the acceptable range.

Discovery of phthalazino[1,2-b]-quinazolinone derivatives as multi-target HDAC inhibitors for the treatment of hepatocellular carcinoma via activating the p53 signal pathway

In view of histone deacetylases (HDACs) as a promising target for cancer therapy, a series of phthalazino[1,2-b]-quinazolinone units were hybrided with ortho-aminoanilide or hydroxamic acid to serve as multi-target HDAC inhibitors for the treatment of solid tumors. Among the target compounds, 8h possessed nano-molar IC50 values toward the tested cancer cells and HDAC subtypes, which was more potent than the HDAC inhibitor SAHA (vorinostat). Mechanism study revealed that compound 8h could suppress the HepG2 cell proliferation via prompting the acetylation of histone 3 (H3) and α-tubulin, and activating the p53 signal pathway as designed. In addition, compound 8h exhibited much stronger in vivo antitumor efficacy than SAHA in the HepG2 xenograft tumor model with negligible toxicity. As a novel multi-target HDAC inhibitor, compound 8h deserves further development as a potential anticancer agent.

Synthesis and preliminary structure-activity relationship study of 3-methylquinazolinone derivatives as EGFR inhibitors with enhanced antiproliferative activities against tumour cells

In this paper, a set of 3-methylquniazolinone derivatives were designed, synthesised, and studied the preliminary structure-activity relationship for antiproliferative activities. All target compounds performed significantly inhibitory effects against wild type epidermal growth factor receptor tyrosine kinase (EGFRwt-TK) and tumour cells (A431, A549, MCF-7, and NCI-H1975). In particular, compound 4d 3-fluoro-N-(4-((3-methyl-4-oxo-3,4-dihydroquinazolin-2-yl)methoxy)phenyl)benzamide showed higher antiproliferative activities against all tumour cells than Gefitinib (IC50 of 3.48, 2.55, 0.87 and 6.42 μM, respectively). Furthermore, compound 4d could induce apoptosis of MCF-7 cells and arrest in G2/M phase at the tested concentration. Molecular docking and ADMET studies showed that compound 4d could closely form many hydrogen bonds with EGFRwt-TK. Therefore, compound 4d is potential to develop as novel anti-cancer drug.

Synthesis and Evaluation of Antioxidant Properties of 2-Substituted Quinazolin-4(3H)-ones

Quinazolinones represent an important scaffold in medicinal chemistry with diverse biological activities. Here, two series of 2-substituted quinazolin-4(3H)-ones were synthesized and evaluated for their antioxidant properties using three different methods, namely DPPH, ABTS and TEACCUPRAC, to obtain key information about the structure-antioxidant activity relationships of a diverse set of substituents at position 2 of the main quinazolinone scaffold. Regarding the antioxidant activity, ABTS and TEACCUPRAC assays were more sensitive and gave more reliable results than the DPPH assay. To obtain antioxidant activity of 2-phenylquinazolin-4(3H)-one, the presence of at least one hydroxyl group in addition to the methoxy substituent or the second hydroxyl on the phenyl ring in the ortho or para positions is required. An additional ethylene linker between quinazolinone ring and phenolic substituent, present in the second series (compounds 25a and 25b), leads to increased antioxidant activity. Furthermore, in addition to antioxidant activity, the derivatives with two hydroxyl groups in the ortho position on the phenyl ring exhibited metal-chelating properties. Our study represents a successful use of three different antioxidant activity evaluation methods to define 2-(2,3-dihydroxyphenyl)quinazolin-4(3H)-one 21e as a potent antioxidant with promising metal-chelating properties.

Diastereoselective, Multicomponent Synthesis of Pyrrolopyrazinoquinazolinones via a Tandem Quinazolinone Rearrangement/Intramolecular Ring Closure of Tautomeric (Z)-Benzamidines

An expedient route to enantiopure, diastereomeric pyrrolopyrazinoquinazolinones was developed following the discovery of a domino quinazolinone rearrangement-intramolecular cyclization of N-H benzamidines. A Ugi-Mumm-Staudinger sequence employing an optically pure proline derivative gave quinazolinones that, upon N-Boc deprotection, rearranged to tautomeric Z-benzamidines. Subsequent spontaneous cyclization afforded 15 diastereomeric pyrazinoquinazolinone pairs in up to 83% overall yield and 89:11 d.r which were separated easily via routine chromatographic purification-the only one required in the entire process.

Novel iodinated quinazolinones bearing sulfonamide as new scaffold targeting radiation induced oxidative stress

Reactive oxygen species (ROS) play an integral role in the pathogenesis of most diseases. This work presents the design and synthesis of fourteen new diiodoquinazolinone derivatives bearing benzenesulfonamide moiety with variable acetamide tail and evaluation of their ability to activate nuclear factor erythroid 2-related factor 2 (Nrf2) using its classical target NAD(P)H: quinone oxidoreductase 1 (NQO1) in Hepa1c1c7 murine hepatoma cells. The N-(2-chloropyridin-3-yl)-2-((6,8-diiodo-4-oxo-3-(4-sulfamoylphenyl)-3,4-dihydroquinazolin-2-yl)thio) acetamide 17 was the most potent NQO1 inducer (CD = 25 µM) with free radical scavenging activity (IC50 = 28 µM) and in vivo median lethal dose (LD50) of 500 mg/Kg. The possible radioprotective activity of compound 17 was evaluated in (7 Gy) irradiated mice. Compound 17 showed a reduction in radiation induced oxidative stress as evidenced by the lower levels of ROS, malondialdehyde (MDA) and NQO1 in liver tissues. Moreover, compound 17 showed improvement in the complete blood count (CBC) of irradiated mice and decreased mortality over 30 days following irradiation. Additionally, docking studies inside the Nrf2-binding site of Kelch-like ECH associated protein 1 (Keap1), the main negative regulator of Nrf2, confirmed that 17 revealed the same interactions with the key amino acids as those of the co-crystallized ligand. This study identifies 17 as a novel antioxidant that protects against the harmful effect of radiation.

Design, synthesis, molecular docking, and some metabolic enzyme inhibition properties of novel quinazolinone derivatives

3-Amino-2-ethylquinazolin-4(3H)-one (3) was synthesized in two steps from the reaction of amide (2), which was obtained from the treatment of methyl anthranilate (1) with propionyl chloride, with hydrazine. From the reaction of 3-amino-2-ethylquinazolin-4(3H)-one (3) with various aromatic aldehydes, novel benzylidenaminoquinazolin-4(3H)-one (3a-n) derivatives were synthesized. The structures of the novel molecules were characterized using infrared spectroscopy, nuclear magnetic resonance spectroscopy (¹ H-NMR and ¹³ C-NMR), and high-resolution mass spectroscopy. The novel compounds were tested against some metabolic enzymes, including α-glucosidase (α-Glu), acetylcholinesterase (AChE), and human carbonic anhydrases I and II (hCA I and II). The novel compounds showed K_i values in the range of 244-988 nM for hCA I, 194-900 nM for hCA II, 30-156 nM for AChE, and 215-625 nM for α-Glu. The binding affinities of the most active compounds were calculated as -7.636, -6.972, -10.080, and -8.486 kcal/mol for hCA I, hCA II, AChE, and α-Glu enzymes, respectively. The aromatic ring of the quinazoline moiety plays a critical role in the inhibition of the enzymes.

Synthesis, biological evaluation and molecular docking studies of novel quinazolinones as antitubercular and antimicrobial agents

In the present study, a series of novel quinazolinone hybrids, viz. triazepino-quinazolinones 4, thiazolo-triazolo-quinazolinones 7 and triazolo-quinazolinones 8 have been synthesized from the key intermediate 3-(substituted phenyl)-2-hydrazinoquinazolin-4(3H)-ones 3. All the newly synthesized compounds were characterized by means of spectral (IR, ¹H NMR, ¹³C NMR) and elemental analysis. The target compounds were biologically screened for their in vitro antimicrobial and antitubercular activities against pathogenic strain. The results of bioassay demonstrated that some of the compounds exhibited pronounced antimicrobial activity comparable to that of standard drugs tested under similar conditions. Compounds 4c, 4e, 7e and 8b showed relatively very good inhibitory activity against pathogenic bacteria with minimum inhibitory concentration (MIC) of 2.6 μg/mL, 5.2 μg/mL, while the rest of the compounds showed moderate activity. Compounds 4c and 8b were found to be nearly equipotent with ciprofloxacin against P. aeruginosa with MIC 5.2 μg/mL, while compound 8b was more potent against pathogenic bacteria S. aureus. It is very remarkable that four compounds, 4c, 4e, 7e and 8b showed pronounced antifungal activity against selected pathogenic fungi, A. niger, C. albicans with MIC 2.6 μg/mL and 5.2 μg/mL. The antitubercular activity of synthesized compounds reveal that compound 8b showed better activity than the other compounds with a MIC of 5.2 μg/mL against M. tuberculosis (H₃₇Rv). Molecular docking studies of the compounds were performed to rationalize the inhibitory properties of these compounds and results showed that these compounds have good binding energy and better binding affinity within the active pocket, thus these compounds may be considered as potent inhibitors towards selective targets.

Novel quinazolinone inhibitors of the Pseudomonas aeruginosa quorum sensing transcriptional regulator PqsR

Rising numbers of cases of multidrug- and extensively drug-resistant Pseudomonas aeruginosa over recent years have created an urgent need for novel therapeutic approaches to cure potentially fatal infections. One such approach is virulence attenuation where anti-virulence compounds, designed to reduce pathogenicity without affording bactericidal effects, are employed to treat infections. P. aeruginosa uses the pqs quorum sensing (QS) system, to coordinate the expression of a large number of virulence determinants as well as bacterial-host interactions and hence represents an excellent anti-virulence target. We report the synthesis and identification of a new series of thiazole-containing quinazolinones capable of inhibiting PqsR, the transcriptional regulator of the pqs QS system. The compounds demonstrated high potency (IC50 < 300 nM) in a whole-cell assay, using a mCTX:PpqsA-lux-based bioreporter for the P. aeruginosa PAO1-L and PA14 strains. Structural evaluation defined the binding modes of four analogues in the ligand-binding domain of PqsR through X-ray crystallography. Further work showed the ability of 6-chloro-3((2-pentylthiazol-4-yl)methyl)quinazolin-4(3H)-one (18) and 6-chloro-3((2-hexylthiazol-4-yl)methyl)quinazolin-4(3H)-one (19) to attenuate production of the PqsR-regulated virulence factor pyocyanin. Compounds 18 and 19 showed a low cytotoxic profile in the A549 human epithelial lung cell line making them suitable candidates for further pre-clinical evaluation.

Synthesis and biofilm inhibition studies of 2-(2-amino-6-arylpyrimidin-4-yl)quinazolin-4(3H)-ones

Synthesis of novel 4(3H)-quinazolinonyl aminopyrimidine derivatives has been achieved via quinazolinonyl enones which in turn were obtained from 2-acyl-4(3H)-quinazolinone. They have been assayed for biofilm inhibition against Gram-positive (methicillin-resistant Staphylococcus aureus (MRSA)) and Gram-negative bacteria (Acinetobacter baumannii). The analogues with 2,4,6-trimethoxy phenyl, 4-methylthio phenyl, and 3-bromo phenyl substituents (5h, 5j & 5k) have been shown to inhibit biofilm formation efficiently in MRSA with IC50 values of 20.7-22.4 μM). The analogues 5h and 5j have demonstrated low toxicity in human cells in vitro and can be investigated further as leads.

A Novel Redox Modulator Induces a GPX4-Mediated Cell Death That Is Dependent on Iron and Reactive Oxygen Species

Redox modulators have been developed as an attractive approach to treat cancer. Herein, we report the synthesis, identification, and biological evaluation of a quinazolinedione reactive oxygen species (ROS) inducer, QD394, with significant cytotoxicity in pancreatic cancer cells. QD394 shows a transcriptomic profile remarkably similar to napabucasin, a cancer stemness inhibitor. Both small molecules inhibit STAT3 phosphorylation, increase cellular ROS, and decrease the GSH/GSSG ratio. Moreover, QD394 causes an iron- and ROS-dependent, GPX4 mediated cell death, suggesting ferroptosis as a major mechanism. Importantly, QD394 decreases the expression of LRPPRC and PNPT1, two proteins involved in mitochondrial RNA catabolic processes and both negatively correlated with the overall survival of pancreatic cancer patients. Pharmacokinetics-guided lead optimization resulted in the derivative QD394-Me, which showed improved plasma stability and reduced toxicity in mice compared to QD394. Overall, QD394 and QD394-Me represent novel ROS-inducing drug-like compounds warranting further development for the treatment of pancreatic cancer.

Radiomodulatory effect of a non-electrophilic NQO1 inducer identified in a screen of new 6, 8-diiodoquinazolin-4(3H)-ones carrying a sulfonamide moiety

Fifteen new quinazolinone derivatives bearing benzenesulfonamide moiety with variable acetamide tail were synthesized. The structures assigned to the products were concordant with the microanalytical and spectral data. Compounds 4-18 were screened for their ability to induce the antioxidant enzyme NAD(P)H: quinone oxidoreductase 1 (NQO1) in cells, a classical target for transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2). The 2-((6,8-diiodo-4-oxo-3-(4-sulfamoylphenyl)-3,4-dihydroquinazolin-2-yl)thio)-N-(3,4,5-trimethoxyphenyl) acetamide 15 showed the most potent NQO1 inducer activity in vitro. Compound 15 had low toxicity in mice (LD50 = 500 mg/kg). It also reduced the damaging effects of gamma radiation, as assessed by the levels of Nrf2, NQO1, reactive oxygen species (ROS) and malondialdehyde (MDA) in liver tissues. In addition, compound 15 showed amelioration in the complete blood count of irradiated mice and enhanced survival over a period of 30 days following irradiation. Molecular docking of 15 inside the Nrf2-binding site of Kelch-like ECH associated protein 1 (Keap1), the main negative regulator of Nrf2, showed the same binding interactions as that of the co-crystallized ligand considering the binding possibilities and energy scores. These findings suggest that compound 15 could be considered as a promising antioxidant and radiomodulatory agent.

Novel N-(Substituted) Thioacetamide Quinazolinone Benzenesulfonamides as Antimicrobial Agents

AIM

With the rapid emergence of antibiotic resistance, efforts are being made to obtain new selective antimicrobial agents. Hybridization between quinazolinone and benzenesulfonamide can provide new antimicrobial candidates. Also, the use of nanoparticles can help boost drug efficacy and lower side effects.

MATERIALS AND METHODS

Novel quinazolinone-benzenesulfonamide derivatives 5-18 were synthesized and screened for their antimicrobial activity against Gram-positive bacteria, Gram-negative bacteria, MRSA and yeast. The most potent compound 16 was conjugated with copper oxide nanoparticles 16-CuONPs by gamma irradiation (4.5 KGy). Characterization was performed using UV-Visible, TEM examination, XRD patterns and DLS. Moreover, compound 16 was used to synthesize two nanoformulations: 16-CNPs by loading 16 in chitosan nanoparticles and the nanocomposites 16-CuONPs-CNPs. Characterization of these nanoformulations was performed using TEM and zeta potential. Besides, the inhibitory profile against Staphylococcus aureus DNA gyrase was assayed. Cytotoxic evaluation of 16, 16-CNPs and 16-CuONPs-CNPs on normal VERO cell line was carried out to determine its relative safety. Molecular docking of 16 was performed inside the active site of S. aureus DNA gyrase.

RESULTS

Compound 16 was the most active in this series against all the tested strains and showed inhibition zones and MICs in the ranges of 25-36 mm and 0.31-5.0 µg/mL, respectively. The antimicrobial screening of the synthesized nanoformulations revealed that 16-CuONPs-CNPs displayed the most potent activity. The MBCs of 16 and the nanoformulations were measured and proved their bactericidal mode of action. The inhibitory profile against S. aureus DNA gyrase showed IC50 ranging from 10.57 to 27.32 µM. Cytotoxic evaluation of 16, 16-CNPs and 16-CuONPs-CNPs against normal VERO cell lines proved its relative safety (IC50= 927, 543 and 637 µg/mL, respectively). Molecular docking of 16 inside the active site of S. aureus DNA gyrase showed that it binds in the same manner as that of the co-crystallized ligand, ciprofloxacin.

CONCLUSION

Compound 16 could be considered as a new antimicrobial lead candidate with enhanced activity upon nanoformulation.

Synthesis, Evaluation and Proposed Binding Pose of Substituted Spiro-Oxindole Dihydroquinazolinones as IRAP Inhibitors

Insulin-regulated aminopeptidase (IRAP) is a new potential macromolecular target for drugs aimed for treatment of cognitive disorders. Inhibition of IRAP by angiotensin IV (Ang IV) improves the memory and learning in rats. The majority of the known IRAP inhibitors are peptidic in character and suffer from poor pharmacokinetic properties. Herein, we present a series of small non-peptide IRAP inhibitors derived from a spiro-oxindole dihydroquinazolinone screening hit (pIC50 5.8). The compounds were synthesized either by a simple microwave (MW)-promoted three-component reaction, or by a two-step one-pot procedure. For decoration of the oxindole ring system, rapid MW-assisted Suzuki-Miyaura cross-couplings (1 min) were performed. A small improvement of potency (pIC50 6.6 for the most potent compound) and an increased solubility could be achieved. As deduced from computational modelling and MD simulations it is proposed that the S-configuration of the spiro-oxindole dihydroquinazolinones accounts for the inhibition of IRAP.

Synthesis and evaluation of anticancer, antiphospholipases, antiproteases, and antimetabolic syndrome activities of some 3H-quinazolin-4-one derivatives

Some new 3H-quinazolin-4-one derivatives were synthesised and screened for anticancer, antiphospholipases, antiproteases, and antimetabolic syndrome activities. Compound 15d was more potent in reducing the cell viabilities of HT-29 and SW620 cells lines to 38%, 36.7%, compared to 5-FU which demonstrated cell viabilities of 65.9 and 42.7% respectively. The IC50 values of 15d were ∼20 µg/ml. Assessment of apoptotic activity revealed that 15d decreased the cell viability by down regulating Bcl2 and BclxL. Moreover, compounds, 8j, 8d/15a/15e, 5b, and 8f displayed lowered IC50 values than oleanolic acid against proinflammatory isoforms of hGV, hG-X, NmPLA2, and AmPLA2. In addition, 8d, 8h, 8j, 15a, 15b, 15e, and 15f showed better anti-α-amylase than quercetin, whereas 8g, 8h, and 8i showed higher anti-α-glucosidase activity than allopurinol. Thus, these compounds can be considered as potential antidiabetic agents. Finally, none of the compounds showed higher antiproteases or xanthine oxidase activities than the used reference drugs.

Novel sulphonamide benzoquinazolinones as dual EGFR/HER2 inhibitors, apoptosis inducers and radiosensitizers

A series of sulphonamide benzoquinazolinones 5-18 was synthesized and evaluated for cytotoxic activity against MDA-MB-231 cell line. The compounds showed IC₅₀ ranging from 0.26 to 161.49 µM. The promising compounds were evaluated for their inhibitory profile against epidermal growth factor (EGFR) and HER2 enzymes. Compound 10 showed more potent activity on both EGFR and HER2 than erlotinib (IC₅₀ 3.90 and 5.40 µM versus 6.21 and 9.42 µM). The pro-apoptotic activity of 10 was evaluated against caspase-3, Bax, B-cell lymphoma protein 2 (Bcl-2) expression levels, and cell cycle analysis. Compound 10 increased the level of caspase-3 by 10 folds, Bax level by 9 folds, decreased the level of the Bcl-2 by 0.14 and arrested the cell cycle in the G2/M phase. The radio-sensitizing activity of 10 was measured using a single dose of 8 Gy gamma radiation (IC₅₀ decreased from 0.31 to 0.22 µM). Molecular docking was performed on EGFR and HER2 receptors.

Synthesis, Antiproliferative, and Antioxidant Evaluation of 2-Pentylquinazolin-4(3H)-one(thione) Derivatives with DFT Study

The current study was chiefly designed to examine the antiproliferative and antioxidant activities of some novel quinazolinone(thione) derivatives 6–14. The present work focused on two main points; firstly, comparing between quinazolinone and quinazolinthione derivatives. Whereas, antiproliferative (against two cell lines namely, HepG2 and MCF-7) and antioxidant (by two methods; ABTS and DPPH) activities of the investigated compounds, the best quinazolinthione derivatives were 6 and 14, which exhibited excellent potencies comparable to quinazolinone derivatives 5 and 9, respectively. Secondly, we compared the activity of four series of Schiff bases which included the quinazolinone moiety (11a–d). In addition, the antiproliferative and antioxidant activities of the compounds with various aryl aldehyde hydrazone derivatives (11a–d) analogs were studied. The compounds exhibited potency that increased with increasing electron donating group in p-position (OH > OMe > Cl) due to extended conjugated systems. Noteworthy, most of antiproliferative and antioxidant activities results for the tested compounds are consistent with the DFT calculations.

Synthesis of tricyclic quinazolinone-iminosugars as potential glycosidase inhibitors via a Mitsunobu reaction

A series of novel tricyclic quinazolinone-iminosugars 1 (a-c) were synthesized from the benzyl protected sugars through three steps. Firstly, the benzyl protected sugar (aldehyde) 5 reacted with o-aminobenzamide by the iodine-induced oxidative condensation to afford the corresponding aldo-quizanolinone 6. Secondly, through the intramolecular cyclization of the unprotected OH and the amide NH in 6, the tricyclic compounds 7 and 8 were constructed by the key Mitsunobu reaction. Finally, removal of the benzyl group gave the target tricyclic quinazolinone-iminosugars 1. The protocol was effective for the preparation of the tricyclic iminosugars in satisfactory yield. Interestingly, an unusual C-2 epimerization was observed with d-mannose and d-ribose compounds under the conditions of the Mitsunobu reaction that generated the products having the trans configuration at the C-2 and C-3 positions. Unfortunately, such tricyclic quinazolinone-iminosugars showed no inhibitory effects on the tested five glycosidases.

Synthesis of New Furothiazolo Pyrimido Quinazolinones from Visnagenone or Khellinone and Antimicrobial Activity

Substituted-6-methyl-1-thioxo-1,2-dihydro-3H-furo[3,2-g]pyrimido[1,6-a]quinazolin-3-ones (5a,b) were synthesized from condensation of visnagenone (2a) or khellinone (2b) with 6-amino-thiouracil (3) in dimethylformamide or refluxing of (4a) or (4b) in dimethylformamide. Hence, compounds (5a,b) were used as the starting materials for preparing many new heterocyclic compounds such as; furo[3,2-g]pyrimido[1,6-a]quinazoline (6a,b), furo[3,2-g]thiazolo[2',3':2,3]pyrimido[1,6-a]quinazolinone (7a,b), substituted-benzylidene-furo[3,2-g]thiazolo[2',3':2,3]pyrimido[1,6-a]quinazoline-3,5-dione (8a⁻f), 3-oxo-furo[3,2-g]pyrimido[1,6-a]quinazoline-pentane-2,4-dione (9a,b), 1-(pyrazole)-furo[3,2-g]pyrimido[1,6-a]quinazolinone (10a,b), 2-(oxo or thioxo)-pyrimidine-furo[3,2-g]pyrimido[1,6-a]quinazolinone (11a⁻d), 1-(methylthio)-furo[3,2-g]pyrimido[1,6-a]quinazolinone (12a,b), 1-(methyl-sulfonyl)-furo[3,2-g]pyrimido[1,6-a]quinazolinone (13a,b) and 6-methyl-1-((piperazine) or morpholino)-3H-furo[3,2-g]pyrimido[1,6-a]quinazolin-3-one (14a⁻d). The structures of the prepared compounds were elucidated on the basis of spectral data (IR, ¹H-NMR, ¹³C-NMR, MS) and elemental analysis. Antimicrobial activity was evaluated for the synthesized compounds against Gram-positive, Gram-negative bacteria and fungi. The new compounds, furothiazolo pyrimido quinazolines 8a⁻f and 11a⁻d displayed results excellent for growth inhibition of bacteria and fungi.

Antitumor Activity of Quinazolinone Alkaloids Inspired by Marine Natural Products

Many fungal quinazolinone metabolites, which contain the methyl-indole pyrazino [1,2-b]quinazoline-3,6-dione core, have been found to possess promising antitumor activity. The purpose of this work was to synthesize the enantiomeric pairs of two members of this quinazolinone family, to explore their potential as antitumor and their ability to revert multidrug resistance. The marine natural product fiscalin B (4c), and antienantiomers (4b, 5b, and 5c) were synthesized via a one-pot approach, while the syn enantiomers (4a, 4d, 5a, and 5d) were synthetized by a multi-step procedure. These strategies used anthranilic acid (i), chiral N-protected α-amino acids (ii), and tryptophan methyl esters (iii) to form the core ring of pyrazino[2,1-b]quinazoline-3,6-dione scaffold. Four enantiomeric pairs, with different enantiomeric purities, were obtained with overall yields ranging from 7 to 40%. Compounds 4a–d and 5a–d were evaluated for their growth inhibitory effect against two tumor cell lines. Differences between enantiomeric pairs were noted and 5a–d displayed GI₅₀ values ranging from 31 to 52 μM, which are lower than those of 4a–d. Nevertheless, no effect on P-glycoprotein (P-gp) modulation was observed for all compounds. This study disclosed new data for fiscalin B (4c), as well as for its analogues for a future development of novel anticancer drug leads.

Isoxazolidine Conjugates of N3-Substituted 6-Bromoquinazolinones-Synthesis, Anti-Varizella-Zoster Virus, and Anti-Cytomegalovirus Activity

1,3-Dipolar cycloaddition of N-methyl C-(diethoxyphosphoryl) nitrone to N3-substituted 6-bromo-2-vinyl-3H-quinazolin-4-ones gave (3-diethoxyphosphoryl) isoxazolidines substituted at C5 with quinazolinones modified at N3. All isoxazolidine cycloadducts were screened for antiviral activity against a broad spectrum of DNA and RNA viruses. Several isoxazolidines inhibited the replication of both thymidine kinase wild-type and deficient (TK⁺ and TK^-) varicella-zoster virus strains at EC₅₀ in the 5.4⁻13.6 μΜ range, as well as human cytomegalovirus (EC₅₀ = 8.9⁻12.5 μΜ). Isoxazolidines trans-11b, trans-11c, trans-11e, trans-11f/cis-11f, trans-11g, trans-11h, and trans-11i/cis-11i exhibited moderate cytostatic activity towards the human lymphocyte cell line CEM (IC₅₀ = 9.6⁻17 μM).

Synthesis of 6-N-R-Tetrazolo[1,5-c]quinazolin-5(6H)-ones and Their Anticancer Activity

Chemical compounds with tetrazole ring are very interesting systems that can be valuable in pharmaceutical and clinical applications, especially as anticancer agents. In this work, novel 6-N-R-tetrazolo[1,5-c]quinazolin-5(6H)-ones were synthesized. A large set of IR, LC-, EI-MS, 1H, 13C NMR and elemental analysis data were collected and evaluated for their structures and purity. Details of synthesis, namely the N-alkylation, are discussed, including reactions with secondary and tertiary amides. Four new synthesized compounds (2.7, 3.2, 5.2, 5.3) were tested in vitro for anticancer activity at 10 μM against 60 cell lines of nine different cancer types: leukemia, melanoma, lung, colon, CNS, ovarian, renal, prostate, and breast cancers. Further synthesis of substances within the series of substituted tetrazolo[1,5-c]quinazoline systems will be attempted to develop improved compounds with better anticancer activity.

Design, synthesis, and biological evaluation of novel 3-substituted imidazo[1,2-a]pyridine and quinazolin-4(3H)-one derivatives as PI3Kα inhibitors

Phosphatidylinositol 3-kinase (PI3K) is a pivotal regulator of intracellular signaling pathways and considered as a promising target in the development of a therapeutic treatment of cancer. Among the different PI3K subtypes, the PIK3CA gene encoding PI3K p110α is frequently mutated and overexpressed in majority of human cancers. Therefore, the inhibition of PI3Kα has been considered to be an efficient approach for the treatment of cancer. In this study, two series compounds containing hydrophilic group in imidazo[1,2-a]pyridine and quinazolin-4(3H)-one were synthesized and their antiproliferative activities against five cancer cell lines, including HCT-116, SK-HEP-1, MDA-MB-231, SNU638 and A549, were evaluated. Compound 1i with most potent antiproliferative activity was selected for further biological evaluation. PI3K kinase assay showed that 1i has selectivity for PI3Kα distinguished from other isoforms. The western blot assay indicated that 1i is more effective than HS-173, an imidazopyridine-based PI3Ka inhibitor, in reducing the levels of phospho-Akt. All these results suggested that 1i is a potent PI3Kα inhibitor and could be considered as a potential candidate for the development of anticancer agents.

Novel 2,3-Dihydro-1H-pyrrolo[3,2,1-ij]quinazolin-1-ones: Synthesis and Biological Evaluation

Herein we describe the synthesis and evaluation of a series of novel 2,3-dihydro-1H-pyrrolo[3,2,1-ij]quinazolin-1-ones for in vitro cytotoxicity against three human cancer cell lines as well as for potential antimalarial activity against the chloroquine-sensitive strain 3D7 of Plasmodium falciparum. The title compounds were prepared via PdCl₂-mediated endo-dig cyclization of 2-aryl-8-(arylethynyl)-6-bromo-2,3-dihydroquinazolin-4(1H)-ones. The latter were prepared, in turn, via initial Sonogashira cross-coupling of 2-amino-5-bromo-3-iodobenzamide with aryl acetylenes followed by boric acid-mediated cyclocondensation of the intermediate 2-amino-3-(arylethynyl)-5-bromobenzamides with benzaldehyde derivatives. The 2,3-dihydro-1H-pyrrolo[3,2,1-ij]quinazolin-1-ones 4a-k were evaluated for potential in vitro cytotoxicity against the breast (MCF-7), melanoma (B16) and endothelioma (sEnd.2) cell lines. All of the compounds except 4h and 4i were found to be inactive against the three cancer cell lines. Compound 4h substituted with a 4-methoxyphenyl and 4-fluorophenyl groups at the 3- and 5-positions was found to exhibit significant cytotoxicity against the three cancer cell lines. The presence of phenyl and 3-chlorophenyl groups at the 3- and 5-posiitons of the pyrroloquinazolinone 4i, on the other hand, resulted in significant cytotoxicity against vascular tumour endothelial cells (sEnd.2), but reduced activity against the melanoma (B16) and breast cancer (MCF-7) cells except at higher concentrations. The 2,3-dihydro-1H-pyrrolo[3,2,1-ij]quinazolin-1-ones 4a-l were found to be inactive against the chloroquine sensitive 3D7 strain of Plasmodium falciparum.

Synthesis and Biological Evaluation of N-[2-(4-Hydroxyphenylamino)-pyridin-3-yl]-4-methoxy-benzenesulfonamide (ABT-751) Tricyclic Analogues as Antimitotic and Antivascular Agents with Potent in Vivo Antitumor Activity

Benzopyridothiadiazepine (2a) and benzopyridooxathiazepine (2b) were modified to produce tricyclic quinazolinone 15-18 or benzothiadiazine 26-27 derivatives. These compounds were evaluated in cytotoxicity and tubulin inhibition assays and led to potent inhibitors of tubulin polymerization. N-[2(4-Methoxyphenyl)ethyl]-1,2-dihydro-pyrimidino[2,1-b]quinazolin-6-one (16a) exhibited the best in vitro cytotoxic activity (GI50 10-66.9 nM) against the NCI 60 human tumor cell line and significant potency against tubulin assembly (IC50 0.812 μM). In mechanism studies, 16a was shown to block cell cycle in G2/M phase and to disrupt microtubule formation and displayed good antivascular properties as inhibition of cell migration, invasion, and endothelial tube formation. Compound 16a was evaluated in C57BL/6 mouse melanoma B16F10 xenograft model to validate its antitumor activity, in comparison with reference ABT-751 (1). Compound 16a displayed strong in vivo antitumor and antivascular activities at a dose of 5 mg/kg without obvious toxicity, whereas 1 needed a 10-fold higher concentration to reach similar effects.

Design, synthesis and biological evaluation of novel 2,3-dihydroquinazolin- 4(1H)-one derivatives as potential fXa inhibitors

Coagulation factor Xa (fXa) is a particularly attractive target for the development of effective and safe anticoagulants. In this study, novel 2,3-dihydroquinazolin-4(1H)-one derivatives were designed as potential fXa inhibitors based on anthranilamide structure which has been reported in our previous research. The experimental data showed that most of the designed compounds exhibited significant in vitro potency against fXa. Among them, compound 8e displayed the strongest potency against fXa with the IC₅₀ value of 21 nM and highly selectivity versus thrombin (IC₅₀ = 67 μM) and excellent in vitro antithrombotic activity with its 2 × PT value of 1.2 μM and 2 × aPTT value of 0.6 μM. In addition, 8e also displayed excellent in vivo antithrombotic activity in the rat arteriovenous shunt (AV-SHUNT) model. The bleeding risk evaluation showed that 8e had a similar safety profile as that of betrixaban. All results demonstrated that compound 8e could be considered as a potential fXa inhibitor for the prevention and treatment of thromboembolic diseases.

Synthesis 4-[2-(2-mercapto-4-oxo-4H-quinazolin-3-yl)-ethyl]-benzenesulfonamides with subnanomolar carbonic anhydrase II and XII inhibitory properties

Condensation of substituted anthranilic acids with 4-isothiocyanatoethyl-benzenesulfonamide led to series of heterocyclic benzenesulfonamides incorporating 2-mercapto-quinazolin-4-one tails. These sulfonamides were investigated as inhibitors of the human carbonic anhydrase (hCA, EC 4.2.1.1) isoforms hCA I and II (cytosolic isozymes), as well as hCA XII (a transmembrane, tumor-associated enzyme also involved in glaucoma-genesis). The new sulfonamides acted as medium potency inhibitors of hCA I (KIs of 28.5-2954nM), being highly effective as hCA II (KIs in the range of 0.62-12.4nM) and XII (KIs of 0.54-7.11nM) inhibitors. All substitution patterns present in these compounds (e.g., halogens, methyl and methoxy moieties, in positions 6, 7 and/or 8 of the 2-mercapto-quinazolin-4-one ring) led to highly effective hCA II/XII inhibitors. These compounds should thus be of interest as preclinical candidates in pathologies in which the activity of these enzymes should be inhibited, such as glaucoma (CA II and XII as targets) or some tumors in which the activity of isoforms CA II and XII is dysregulated.

New Isoxazolidine-Conjugates of Quinazolinones-Synthesis, Antiviral and Cytostatic Activity

A novel series of (3-diethoxyphosphoryl)isoxazolidines substituted at C5 with various quinazolinones have been synthesized by the 1,3-dipolar cycloaddition of N-methyl-C-(diethoxyphosphoryl)nitrone with N3-substitued 2-vinyl-3H-quinazolin-4-ones. All isoxazolidines were assessed for antiviral activity against a broad range of DNA and RNA viruses. Isoxazolidines trans-11f/cis-11f (90:10), trans-11h and trans-11i/cis-11i (97:3) showed weak activity (EC₅₀ = 6.84, 15.29 and 9.44 μM) toward VZV (TK⁺ strain) which was only one order of magnitude lower than that of acyclovir used as a reference drug. Phosphonates trans-11b/cis-11b (90:10), trans-11c, trans-11e/cis-11e (90:10) and trans-11g appeared slightly active toward cytomegalovirus (EC₅₀ = 27–45 μM). Compounds containing benzyl substituents at N3 in the quinazolinone skeleton exhibited slight antiproliferative activity towards the tested immortalized cells with IC₅₀ in the 21–102 μM range.

Synthesis of Bioactive 2-(Arylamino)thiazolo[5,4-f]-quinazolin-9-ones via the Hügershoff Reaction or Cu- Catalyzed Intramolecular C-S Bond Formation

A library of thirty eight novel thiazolo[5,4-f]quinazolin-9(8H)-one derivatives (series 8, 10, 14 and 17) was prepared via the Hügershoff reaction and a Cu catalyzed intramolecular C-S bond formation, helped by microwave-assisted technology when required. The efficient multistep synthesis of the key 6-amino-3-cyclopropylquinazolin-4(3H)-one (3) has been reinvestigated and performed on a multigram scale from the starting 5-nitroanthranilic acid. The inhibitory potency of the final products was evaluated against five kinases involved in Alzheimer's disease and showed that some molecules of the 17 series described in this paper are particularly promising for the development of novel multi-target inhibitors of kinases.

Quinazolines and quinazolinones as ubiquitous structural fragments in medicinal chemistry: An update on the development of synthetic methods and pharmacological diversification

Nitrogen-rich heterocycles, particularly quinazolines and quinazolinones, represent a unique class of diversified frameworks displaying a broad spectrum of biological functions. Over the past several years, intensive medicinal chemistry efforts have generated numerous structurally functionalized quinazoline and quinazolinone derivatives. Interest in expanding the biological effects, demonstrated by these motifs, is growing exponentially, as indicated by the large number of publications reporting the easy accessibility of these skeletons in addition to the diverse nature of synthetic as well as biological applications. Therefore, the main focus of the present review is to provide an ample but condensed overview on various synthetic approaches providing access to quinazoline and quinazolinone compounds with multifaceted biological activities. Furthermore, mechanistic insights, synthetic utilization, structure-activity relationships and molecular modeling inputs for the potent derivatives have also been discussed.

Identification and Development of 2,3-Dihydropyrrolo[1,2-a]quinazolin-5(1H)-one Inhibitors Targeting Bromodomains within the Switch/Sucrose Nonfermenting Complex

Bromodomain containing proteins PB1, SMARCA4, and SMARCA2 are important components of SWI/SNF chromatin remodeling complexes. We identified bromodomain inhibitors that target these proteins and display unusual binding modes involving water displacement from the KAc binding site. The best compound binds the fifth bromodomain of PB1 with a KD of 124 nM, SMARCA2B and SMARCA4 with KD values of 262 and 417 nM, respectively, and displays excellent selectivity over bromodomains other than PB1, SMARCA2, and SMARCA4.

Synthesis and biological evaluation of novel 2-phenylquinazoline-4-amine derivatives: identification of 6-phenyl-8H-benzo[g]quinazolino[4,3-b]quinazolin-8-one as a highly potent inducer of NAD(P)H quinone oxidoreductase 1

A novel series of quinazoline compounds (2-14) incorporating biologically active heterocyclic moieties were designed and synthesized. The structure of the newly synthesized compounds was recognized on the basis of elemental analyses, IR, 1H-NMR, 13C-NMR and mass spectral data. All compounds were evaluated for their ability to induce the cytoprotective enzyme NAD(P)H:quinone oxidoreductase 1 (NQO1) using a quantitative bioassay and a docking study was performed in the Kelch domain of Keap1 obtained from the Protein Data Bank (PDB ID: 4IQK) to explore the ability of the synthesized compounds to block the Nrf2-binding site of Keap1. All of the synthesized compounds showed concentration-dependent inducer activity with potencies in the low- or sub-micromolar range. Compound 12 was the most potent inducer in this new series, with a concentration that doubles the specific activity of NQO1 (CD value) of 70 nM. The identification of this compound offers a new chemical scaffold for future development of highly potent inducers.

DESIGN, SYNTHESIS, MOLECULAR DOCKING AND ANTI-BREAST CANCER ACTIVITY OF NOVEL QUINAZOLINONES TARGETING ESTROGEN RECEPTOR α

A new series of 6,8-dibromo-2-(4-chlorophenyl)-4-oxo-4H-quinazoline derivatives II-VI were syn- thesized, their chemical structures were confirmed by spectroscopic means and elemental analyses. All these compounds were tested in vitro against human breast cancer cell line (MCF-7) using resazurin reduction assay method and doxorubicin as a reference drug. Most of the tested compounds showed better activity than dox- orubicin. Compound IVh was the best active one, its IC₅₀ is 8.52 µg/mL. Molecular docking studies for the best active compounds IVb, IVc, IVf, IVh and Va were performed on the active site of estrogen receptor α (ERα) subtype to explore the estrogen receptor binding ability of these compounds. All the docked compounds showed good fitting score energy with the active site of ERα subtype and compound IVh showed the best docking score energy(-25.3 kcal/mol). Estrogen binding evaluation assay was performed for the docked compounds to ensure that their activity against MCF7 go through inhibition of ERα, they showed ERα inhibition at 41-85% and compound IVh was the most active one (85%).

Enantioselective synthesis of 3-arylquinazolin-4(3H)-ones via peptide-catalyzed atroposelective bromination

We report the development of a tertiary amine-containing β-turn peptide that catalyzes the atroposelective bromination of pharmaceutically relevant 3-arylquinazolin-4(3H)-ones (quinazolinones) with high levels of enantioinduction over a broad substrate scope. The structure of the free catalyst and the peptide-substrate complex were explored using X-ray crystallography and 2D-NOESY experiments. Quinazolinone rotational barriers about the chiral anilide axis were also studied using density functional theory calculations and are discussed in light of the high enantioselectivities observed. Mechanistic studies also suggest that the initial bromination event is stereodetermining, and the major monobromide intermediate is an atropisomerically stable, mono-ortho-substituted isomer. The observation of stereoisomerically stable monobromides stimulated the conversion of the tribromide products to other atropisomerically defined products of interest. For example, (1) a dehalogenation Suzuki-Miyaura cross-coupling sequence delivers ortho-arylated derivatives, and (2) a regioselective Buchwald-Hartwig amination procedure installs para-amine functionality. Stereochemical information was retained during these subsequent transformations.

Experimental and theoretical spectroscopic studies, HOMO-LUMO, NBO analyses and thione-thiol tautomerism of a new hybrid of 1,3,4-oxadiazole-thione with quinazolin-4-one

The hybrid 3-(4-chlorophenyl)-2-[(5-thioxo-4,5-dihydro-1,3,4-oxadiazol-2-yl)methylthio]quinazolin-4(3H)-one has been synthesized and characterized using elemental analysis, FTIR and NMR spectroscopy. The thione-thiol tautomeric equilibria has been studied using both DFT/B3LYP and HF methods at different basis sets. The results of calculations showed predominance of the thione form. The molecular structure and vibrational spectra of the stable tautomer are predicted using the same level of theory. The complete assignments of the vibrational modes were performed on the basis of potential energy distribution (PED). The 6-311++G(d,p) gave the best results compared to the experimental data. The chemical shift values of the two tautomers are calculated using GIAO method. The NH proton of the thione tautomer have chemical shift value closer to the experimental data compared to the SH proton of the thiol one. The electronic transitions are predicted using the TD-DFT calculations at B3LYP/6-311++G(d,p) level of theory. The calculated polarizability and first hyperpolarizability showed that the studied compound has better NLO properties than urea. The molecular electrostatic potential (MEP) analysis reveals the sites for electrophilic and nucleophilic attack in the molecule. NBO analysis is carried out to investigate the stabilization energy of various intramolecular charge transfer interactions within the studied molecule.

Halofuginone - the multifaceted molecule

Halofuginone is an analog of febrifugine-an alkaloid originally isolated from the plant Dichroa febrifuga. During recent years, halofuginone has attracted much attention because of its wide range of beneficial biological activities, which encompass malaria, cancer, and fibrosis-related and autoimmune diseases. At present two modes of halofuginone actions have been described: (1) Inhibition of Smad3 phosphorylation downstream of the TGFβ signaling pathway results in inhibition of fibroblasts-to-myofibroblasts transition and fibrosis. (2) Inhibition of prolyl-tRNA synthetase (ProRS) activity in the blood stage of malaria and inhibition of Th17 cell differentiation thereby inhibiting inflammation and the autoimmune reaction by activation of the amino acid starvation and integrated stress responses. This review deals with the history and origin of this natural product, its synthesis, its known modes of action, and it's various biological activities in pre-clinical animal models and in humans.

Optimization of potent and selective quinazolinediones: inhibitors of respiratory syncytial virus that block RNA-dependent RNA-polymerase complex activity

A quinazolinedione-derived screening hit 2 was discovered with cellular antiviral activity against respiratory syncytial virus (CPE EC50 = 2.1 μM), moderate efficacy in reducing viral progeny (4.2 log at 10 μM), and marginal cytotoxic liability (selectivity index, SI ∼ 24). Scaffold optimization delivered analogs with improved potency and selectivity profiles. Most notable were compounds 15 and 19 (EC50 = 300-500 nM, CC50 > 50 μM, SI > 100), which significantly reduced viral titer (>400,000-fold), and several analogs were shown to block the activity of the RNA-dependent RNA-polymerase complex of RSV.

Synthetic approaches, functionalization and therapeutic potential of quinazoline and quinazolinone skeletons: the advances continue

The presence of N-heterocycles as an essential structural motif in a variety of biologically active substances has stimulated the development of new strategies and technologies for their synthesis. Among the various N-heterocyclic scaffolds, quinazolines and quinazolinones form a privileged class of compounds with their diverse spectrum of therapeutic potential. The easy generation of complex molecular diversity through broadly applicable, cost-effective, practical and sustainable synthetic methods in a straightforward fashion along with the importance of these motifs in medicinal chemistry, received significant attention from researchers engaged in drug design and heterocyclic methodology development. In this perspective, the current review article is an effort to recapitulate recent developments in the eco-friendly and green procedures for the construction of highly challenging and potentially bioactive quinazoline and quinazolinone compounds in order to help medicinal chemists in designing and synthesizing novel and potent compounds for the treatment of different disorders. The key mechanistic insights for the synthesis of these heterocycles along with potential applications and manipulations of the products have also been conferred. This article also aims to highlight the promising future directions for the easy access to these frameworks in addition to the identification of more potent and specific products for numerous biological targets.

Synthesis and photophysical properties of the 2-(3-(2-Alkyl-6,8-diaryl-4-oxo-1,2,3,4-tetrahydroquinazolin-2-yl)propyl)-6,8-diarylquinazolin-4(3H)-ones

Iodine-catalyzed condensation of 2-amino-3,5-dibromobenzamide with cyclohexane-1,3-dione derivatives in refluxing toluene afforded the corresponding bisquinazolinones. Suzuki-Miyaura cross-coupling of the latter with arylboronic acids afforded tetraarylbisquinazolinones. The electronic absorption and emission properties of these tetraarylbisquinazolinones were measured in dimethylsulfoxide (DMSO) and acetic acid by means of UV-Vis and fluorescence spectroscopic techniques in conjunction with quantum chemical methods to understand the influence of substituents on intramolecular charge transfer (ICT).

Synthesis, anti-microbial and molecular docking studies of quinazolin-4(3H)-one derivatives

In this work, synthesis, antimicrobial activities and molecular docking studies of some new series of substituted quinazolinone 2a-h and 3a-d were described. Starting form 2-aminobenzamide derivatives 1, a new series of quinazolinone derivatives has been synthesized, in high yields, assisted by microwave and classical methods. Some of these substituted quinazolinones were tested for their antimicrobial activity against Gram-negative bacteria (Pseudomonas aeruginosa and Esherichia coli) and Gram-positive bacteria (Staphylococcus aureus, and Bacillus subtilis), and anti-fungal activity against (Aspergillus fumigatus, Saccharomyces cervevisiae, and Candida albicans) using agar well diffusion method. Among the prepared products, 3-benzyl-2-(4-chlorophenyl)quinazolin-4(3H)-one (3a) was found to exhibits the most potent in vitro anti-microbial activity with MICs of 25.6±0.5, 24.3±0.4, 30.1±0.6, and 25.1±0.5 µg/mL against Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Esherichia coli, respectively. Compound 3a was found to exhibits the most potent in vitro anti-fungal activity with MICs of 18.3±0.6, 23.1±0.4, and 26.1±0.5 µg/mL against Aspergillus fumigatus, Saccharomyces cervevisiae, and Candidaal bicans, respectively.

Design, synthesis, and antibacterial activity of novel Schiff base derivatives of quinazolin-4(3H)-one

Novel imine derivatives of quinazolin-4(3H)-one were designed and synthesized by using aminoethyl moieties to increase the amine bridge of quinazolin-4(3H)-one amine and then introducing various aromatic aldehydes. The target compounds were characterized by proton nuclear magnetic resonance spectroscopy ((1)H NMR), carbon nuclear magnetic resonance spectroscopy ((13)C NMR), mass spectrometry (MS), infrared spectroscopy (IR), elemental analysis, and X-ray diffraction crystallography. Bioassay results indicated that some of the compounds showed good to excellent antibacterial activities against tobacco bacterial wilt and tomato bacterial wilt. The 50% effective concentrations (EC50) of the compounds against tobacco and tomato bacterial wilts ranged from 63.73 μg/mL to 201.52 μg/mL and 38.64 μg/mL to 81.39 μg/mL, respectively, which are lower than that the positive control thiodiazole copper (216.70 and 99.80 μg/mL). These results indicated that novel Schiff base derivatives containing the 4(3H)-quinazolinone moiety can effectively control tobacco and tomato bacterial wilts.

[Design, synthesis and biological evaluation of novel para-substituted 1-benzyl-quinazoline-2, 4 (1H, 3H)-diones as human PARP-1 inhibitors]

Poly(ADP-ribose) polymerase-1 (PARP-1) has emerged as a promising anticancer drug target due to its key role in the DNA repair process. It can polymerize ADP-ribose units on its substrate proteins which are involved in the regulation of DNA repair. In this work, a novel series of para-substituted 1-benzyl-quinazoline-2, 4 (1H, 3H)-diones was designed and synthesized, and the inhibitory activities against PARP-1 of compounds 7a-7e, 8a-8f, 9a-9c and 10a-10c were evaluated. Of all the tested compounds, nine compounds displayed inhibitory activities with IC50 values ranging from 4.6 to 39.2 micromol x L(-1). In order to predict the binding modes of the potent molecules, molecular docking was performed using CDOCKER algorithm, and that will facilitate to further develop more potent PARP-1 inhibitors with a quinazolinedione scaffold.

Synthesis and bioactivity evaluation of novel arylimines containing a 3-aminoethyl-2-[(p-trifluoromethoxy)anilino]-4(3H)-quinazolinone moiety

Twenty-seven novel (E)-3-[2-arylideneaminoethyl]-2-[4-(trifluoromethoxy)anilino]-4(3H)-quinazolinone derivatives were synthesized by reacting various aromatic aldehydes with intermediate 6. The target compounds were characterized by (1)H NMR, (3)C NMR, IR, and elemental analysis. Bioassay results revealed that some of the compounds have strong antifungal activities against six fungi ( Gibberella zeae , Fusarium oxysporum , Clematis mandshurica , Paralepetopsis sasakii , Phytophthora infestans , and Sclerotinia sclerotiorum ) and three bacteria ( Xanthomonas oryzae , tomato bacterial wilt, and tobacco bacterial wilt). Notably, these compounds exhibited the highest activity against tomato bacterial wilt and X. oryzae, with 50% effective concentration (EC50) values ranging from 45.96 to 93.31 μg/mL and from 20.09 to 21.33 μg/mL, respectively, which are superior to those of the commercial antibacterial agents thiodiazole-copper (99.80 μg/mL) and bismerthiazol (92.61 μg/mL). These results indicate that novel arylimine derivatives containing the 4(3H)-quinazolinone moiety can effectively control tobacco bacterial wilt, tomato bacterial wilt, and X. oryzae. Evaluation of their bactericidal properties in field studies as well as the mechanisms underlying their enhanced antibacterial activity should be interesting topics for future investigations.

Structure-based design of novel HCV NS5B thumb pocket 2 allosteric inhibitors with submicromolar gt1 replicon potency: discovery of a quinazolinone chemotype

We describe the structure-based design of a novel lead chemotype that binds to thumb pocket 2 of HCV NS5B polymerase and inhibits cell-based gt1 subgenomic reporter replicons at sub-micromolar concentrations (EC50<200nM). This new class of potent thumb pocket 2 inhibitors features a 1H-quinazolin-4-one scaffold derived from hybridization of a previously reported, low affinity thiazolone chemotype with our recently described anthranilic acid series. Guided by X-ray structural information, a key NS5B-ligand interaction involving the carboxylate group of anthranilic acid based inhibitors was replaced by a neutral two-point hydrogen bonding interaction between the quinazolinone scaffold and the protein backbone. The in vitro ADME and in vivo rat PK profile of representative analogs are also presented and provide areas for future optimization of this new class of HCV polymerase inhibitors.

Synthesis and biological evaluation of thieno[3,2-d]- pyrimidinones, thieno[3,2-d]pyrimidines and quinazolinones: conformationally restricted 17b-hydroxysteroid dehydrogenase type 2 (17b-HSD2) inhibitors

In this study, a series of conformationally restricted thieno[3,2-d]pyrimidinones, thieno[3,2-d]pyrimidines and quinazolinones was designed and synthesized with the goal of improving the biological activity as 17b-hydroxysteroid dehydrogenase type 2 inhibitors of the corresponding amidothiophene derivatives. Two moderately active compounds were discovered and this allowed the identification of the biologically active open conformer as well as the extension of the enzyme binding site characterisation.

Palladium(II) complexes as biologically potent metallo-drugs: synthesis, spectral characterization, DNA interaction studies and antibacterial activity

Four novel mononuclear Pd(II) complexes have been synthesized with the biologically active Schiff base ligands (L1-L4) derived from 3-amino-2-methyl-4(3H)-quinazolinone. The structure of the complexes has been proposed by elemental analysis, molar conductance, IR, (1)H NMR, mass, UV-Vis spectrometric and thermal studies. The investigation of interaction of the complexes with calf thymus DNA (CT-DNA) has been performed with absorption and fluorescence spectroscopic studies. The nuclease activity was done using pUC19 supercoiled DNA by gel-electrophoresis. All the ligands and their Pd(II) complexes have also been screened for their antibacterial activity by discolor diffusion technique.

Survey of recent literature related to the biologically active 4(3H)-quinazolinones containing fused heterocycles

The present review focuses on the synthesis and biological evaluation of polycyclic 4(3H)-quinazolinones containing fused aromatic or heteroaromatic rings. The first part of the review is related to compounds with ring fused to the pyrimidine part of the quinazoline core. Most of the quinazolinone alkaloids belong to this class of molecules. The second part presents molecules bearing extra ring(s) fused to the benzo moiety of the quinazolinone skeleton. Their structural diversity opens new fields in the search of active molecules.

Synthesis of coumarins and 2,3-dihydroquinazolin-4(1H)-ones using trichloroacetic acid as a catalyst

Trichloroacetic acid was used as an efficient catalyst for the synthesis of coumarins from phenols and beta-ketoesters and in an efficient synthesis of 2,3-dihydroquinazolin-4(1H)-ones through the condensation of 2-aminobenzamide with aldehydes or ketones under solvent-free conditions. The remarkable advantages offered by this method are short reaction times, simple procedure, and an easy work-up without using any chromatographic methods.

Synthesis of some new thioxoquinazolinone derivatives and a study on their anticonvulsant and antimicrobial activities

OBJECTIVE

A series of ten novel derivatives of 3-substituted-2-thioxoquinazolin-4(3H)-ones have been synthesized from anthranilic acid via Mannich reaction with various secondary amines in presence of formaldehyde in ice cold condition.

MATERIALS AND METHODS

The structure of these compounds have been elucidated by spectral (FTIR, 1H-NMR and mass) analysis. The titled compounds were evaluated for antimicrobial and anticonvulsant activities. Antimicrobial activities were determined by cup plate method and MIC values using the micro dilution broth method against two Gram positive bacteria Staphylococcus aureus and Streptococcus aureus, two Gram negative bacteria Escherichia coli and Proteus vulgaris and against two fungi Candida albicans and Aspergillus niger. Amikacin and fluconazole were used as standard antibacterial and antifungal agents in the concentration of 10 µg/disc 20 µg/disc respectively.

RESULTS AND CONCLUSIONS

Amongst the compounds tested, compound 2-(2,3-dimethylphenyl) (3-(4-ethoxyphenyl)-4-oxo-2-thioxo-3,4-dihydroquinazolin-1-2H)-1ylmethyl amino)benzoic acid (PTQ-03) and 2-((2,3-dimethylphenyl)((3-(4-ethoxyphenyl)-4-oxo-2-thioxo-3,4-dihydroquinazolin-1(2H)-yl)methyl)amino)benzoic acid (ETQ-03) showed broad spectrum of activity against all the tested Gram positive bacteria, Gram negative bacteria and the fungi. Anti-convulsant activity of the compounds was evaluated by maximal electro shock (MES) convulsion method. The compounds sodium 2-(2-((2,6-Dichlorophenyl)(3-(4-oxo-2-thioxo-3,4-dihydroquinazolin-1(2H)-yl)methyl)amino) phenyl acetate (PTQ-04) and N-(4-Hydroxyphenyl)-N-((3-naphthalen-2-yl)-4-oxo-2-thioxo-3,4-dihydorquinazolin-1(2H)-ylmethyl)acetamide (NTQ-01) showed potent anticonvulsant activity.

Fluorinated quinazolinones as potential radiotracers for imaging kinesin spindle protein expression

Anti-mitotic anti-cancer drugs offer a potential platform for developing new radiotracers for imaging proliferation markers associated with the mitosis-phase of the cell-cycle. One interesting target is kinesin spindle protein (KSP)-an ATP-dependent motor protein that plays a vital role in bipolar spindle formation. In this work we synthesised a range of new fluorinated-quinazolinone compounds based on the structure of the clinical candidate KSP inhibitor, ispinesib, and investigated their properties in vitro as potential anti-mitotic agents targeting KSP expression. Anti-proliferation (MTT and BrdU) assays combined with additional studies including fluorescence-assisted cell sorting (FACS) analysis of cell-cycle arrest confirmed the mechanism and potency of these biphenyl compounds in a range of human cancer cell lines. Additional studies using confocal fluorescence microscopy showed that these compounds induce M-phase arrest via monoaster spindle formation. Structural studies revealed that compound 20-(R) is the most potent fluorinated-quinazolinone inhibitor of KSP and represents a suitable lead candidate for further studies on designing (18)F-radiolabelled agents for positron-emission tomography (PET).