4-(3H)-quinazolinones N-3 substituted with a five membered heterocycle: A promising scaffold towards bioactive molecules.

The quinazolinone nucleus represents, among the class of fused heterocycles, a very important scaffold to obtain molecules with biological activities. A review of literature revealed how such kind of fused heterocycles, coming from natural or synthetic source, are associated with a wide range of biological activities. This review is mainly directed towards the 4-(3H)-quinazolinones N-3 substituted with a five membered heterocycle in which all the possible combinations of nitrogen, sulfur and oxygen atoms are present.

New complex polycyclic compounds: Synthesis, antiproliferative activity and mechanism of action.

Polycyclic or O-glycoconiugate polycyclic compounds 1a-g were previously tested for their in vitro antiproliferative activity. In this series of compounds, activity increases as log P decreases. Specifically, compounds 1d and 1g showed lower log P values together with the best antiproliferative profiles. With the aim of extending our understanding of the structure-activity relationship (SAR) of this class of compounds, we prepared new polycyclic derivatives 2a-c, which bear on each of the two phenyl rings hydrophilic substituents (OH, SO2NH2 or NHCOCH3). These substituents are able to form hydrogen bonds and to decrease the partition coefficient value as compared with compound 1d. Compound 2a was slightly more active than 1d, while 2b and 2c had antiproliferative activity comparable to that of 1d. Finally, the role of the two phenyl groups of polycycle derivatives 1 was also investigated. The analog 3, which bears two methyls instead of the two phenyls had a lower log P value (2.94 ± 1.22) than all the other compounds, but it had negligible antiproliferative activity at 10 µM. The analysis of the most active derivative 2a revealed a significant antiproliferative activity against the triple-negative breast cancer cell line MDA-MB231. After a 24 h treatment, an autophagic process was activated, as demonstrated by an increase in monodansylcadaverine-positive cells as well as by the appearance of the autophagic markers Beclin and LC3II. Prolonging the treatment to 48 h, 2a caused cytotoxicity through the activation of caspase-dependent apoptosis.

Novel 4-(3-phenylpropionamido), 4-(2-phenoxyacetamido) and 4-(cinnamamido) substituted benzamides bearing the pyrazole or indazole nucleus: synthesis, biological evaluation and mechanism of action.

Based on some common structural features of known compounds interfering with p53 pathways and our previously synthesized benzamides, we synthesized new ethyl 5-(4-substituted benzamido)-1-phenyl-1H-pyrazole-4-carboxylates 26a-c, ethyl 5-(4-substituted benzamido)-1-(pyridin-2-yl)-1H-pyrazole-4-carboxylates 27a-c and N-(1H-indazol-6-yl)-4-substituted benzamides 31a,b bearing in the 4 position of the benzamido moiety the 2-phenylpropanamido or 2-phenoxyacetamido or cinnamamido groups. A preliminary test to evaluate the antiproliferative activity against human lung carcinoma H292 cells highlighted how compound 26c showed the best activity. This last was therefore selected for further studies with the aim to find the mechanism of action. Compound 26c induces intrinsic apoptotic pathway by activating p53 and is also able to activate TRAIL-inducing death pathway by promoting increase of DR4 and DR5 death receptors, downregulation of c-FLIPL and caspase-8 activation.

The role of (E)-6-chloro-3-(3-methyl-1-phenyl-1H-pyrazol-5-yl)-2-styrylquinazolin-4(3H)-one in the modulation of cannabinoidergic system. A pilot study.

BACKGROUND: Compounds acting on endocannabinoid system regulate different neuronal processes through the cannabinoid receptors activation. The main aim of this study was determining whether the 2-styrylquinazolin-4(3H)-one 5, a structural analogue of rimonabant, was able to counteract the behavioural signs of the activation of the endocannabinoidergic system induced by CP 55.940. METHODS: Behavioural assessment was carried out using the tetrad task and the novel object recognition test. The endocannabinoidergic system activation was possible by the administration of CP 55.940 and 30min after rats were tested in the tetrad task for the evaluation of the antinociceptive-, cataleptic-, hypothermic- and locomotor- effects. The evaluation of the declarative memory was carried out through the novel object recognition test. The administration of the new compound was made at three different doses, 30min before CP 55.940 administration on a separate group of animals. RESULTS: Our results demonstrated that compound 5, at the highest dose, was able to counteract the effects exerted by CP 55.940, shown by an increase in body temperature, total distance travelled, latency to fall and decrease in tail flick latency, interfering conjointly in memory impairment. CONCLUSION: This study shows that compound 5 is able to counteract the cannabinoid activation induced by the agonist CP 55.940. Further investigations on its pharmacological profile are mandatory before considering it as a potential candidate for clinical studies and its possible employment as pharmacological agent for the management of different pathological conditions such as motor incoordination, obesity and brain related disorders.

Recent discoveries of anticancer flavonoids.

In this review we report the recent advances in anticancer activity of the family of natural occurring flavonoids, covering the time span of the last five years. The bibliographic data will be grouped, on the basis of biological information, in two great categories: reports in which the extract plants bioactivity is reported and the identification of each flavonoid is present or not, and reports in which the anticancer activity is attributable to purified and identified flavonoids from plants. Wherever possible, the targets and mechanisms of action as well as the structure-activity relationships of the molecules will be reported. Also, in the review it was thoroughly investigated the recent discovery on flavonoids containing the 2-phenyl-4H-chromen-4-one system even if some examples of unusual flavonoids, bearing a non-aromatic B-ring or other ring condensed to the base structure are reported.

Anthranilamide-based 2-phenylcyclopropane-1-carboxamides, 1,1'-biphenyl-4-carboxamides and 1,1'-biphenyl-2-carboxamides: Synthesis biological evaluation and mechanism of action.

Several anthranilamide-based 2-phenylcyclopropane-1-carboxamides 13a-f, 1,1'-biphenyl-4-carboxamides 14a-f and 1,1'-biphenyl-2-carboxamides 17a-f were obtained by a multistep procedure starting from the (1S,2S)-2-phenylcyclopropane-1-carbonyl chloride 11, the 1,1'-biphenyl-4-carbonyl chloride 12 or the 1,1'-biphenyl-2-carbonyl chloride 16 with the appropriate anthranilamide derivative 10a-f. Derivatives 13a-f, 14a-f and 17a-f showed antiproliferative activity against human leukemia K562 cells. Among these derivatives 13b, 14b and 17b exerted a particular cytotoxic effect on tumor cells. Derivative 17b showed a better antitumoral effect on K562 cells than 13b and 14b. Analyses performed to explore 17b mode of action revealed that it induced an arrest in G2/M phase of cell cycle which was consequent to DNA lesions as demonstrated by the increase in phospho-ATM and γH2AX, two known markers of DNA repair response system. The effect of 17b was also related to ROS generation, activation of JNK and induction of caspase-3 dependent apoptosis.

Synthesis and biofilm formation reduction of pyrazole-4-carboxamide derivatives in some Staphylococcus aureus strains.

The ability of several N-phenyl-1H-pyrazole-4-carboxamide derivatives and other pyrazoles opportunely modified at the positions 3, 4 and 5, to reduce the formation of the biofilm in some Staphylococcus aureus strains (ATCC 29213, ATCC 25923 and ATCC 6538) were investigated. All the tested compounds were able, although to a different extent, to reduce the biofilm formation of the three bacterial strains considered. Among these, the 1-(2,5-dichlorophenyl)-5-methyl-N-phenyl-1H-pyrazole-4-carboxamide 14 resulted as the best inhibitor of biofilm formation showing an IC50 ranging from 2.3 to 32 µM, against all the three strains of S. aureus. Compound 14 also shows a good protective effect in vivo by improving the survival of wax moth larva (Galleria mellonella) infected with S. aureus ATCC 29213. These findings indicate that 14d is a potential lead compound for the development of new anti-virulence agents against S. aureus infections.

Synthesis and antiproliferative activity of a natural like glycoconjugate polycyclic compound.

A natural like O-glycoconjugate polycyclic compound 4 was obtained by a multistep procedure starting from N-(3-methyl-1-(4-nitrophenyl)-1H-pyrazol-5-yl)acetamide. The glycosyl derivative 4 showed antiproliferative activity against all the tumoral cell lines of the NCI panel in the range 0.47-5.43 µM. Cytofluorimetric analysis performed on MDA-MB231, a very aggressive breast cancer cell line, which does not express estrogen, progesterone and HER-2/neu receptors, showed that 4 is able to induce prolonged cell cycle arrest at G2/M phase and morphological signs of differentiation. These events are correlated with down-regulation of both cyclin B1 and cdc2, the cyclins involved in G2/M transition, as well as up-regulation of cyclin-dependent kinase (CDK) inhibitor p21 Cip1/Waf1.

Discovery of a New Class of Sortase A Transpeptidase Inhibitors to Tackle Gram-Positive Pathogens: 2-(2-Phenylhydrazinylidene)alkanoic Acids and Related Derivatives.

A FRET-based random screening assay was used to generate hit compounds as sortase A inhibitors that allowed us to identify ethyl 3-oxo-2-(2-phenylhydrazinylidene)butanoate as an example of a new class of sortase A inhibitors. Other analogues were generated by changing the ethoxycarbonyl function for a carboxy, cyano or amide group, or introducing substituents in the phenyl ring of the ester and acid derivatives. The most active derivative found was 3-oxo-2-(2-(3,4dichlorophenyl)hydrazinylidene)butanoic acid (2b), showing an IC50 value of 50 µM. For a preliminary assessment of their antivirulence properties the new derivatives were tested for their antibiofilm activity. The most active compound resulted 2a, which showed inhibition of about 60% against S. aureus ATCC 29213, S. aureus ATCC 25923, S. aureus ATCC 6538 and S. epidermidis RP62A at a screening concentration of 100 µM.

Pharmaceutical Potential of Synthetic and Natural Pyrrolomycins.

The emergence of antibiotic resistance is currently considered one of the most important global health problem. The continuous onset of multidrug-resistant Gram-positive and Gram-negative bacterial strains limits the clinical efficacy of most of the marketed antibiotics. Therefore, there is an urgent need for new antibiotics. Pyrrolomycins are a class of biologically active compounds that exhibit a broad spectrum of biological activities, including antibacterial, antifungal, anthelmintic, antiproliferative, insecticidal, and acaricidal activities. In this review we focus on the antibacterial activity and antibiofilm activity of pyrrolomycins against Gram-positive and Gram-negative pathogens. Their efficacy, combined in some cases with a low toxicity, confers to these molecules a great potential for the development of new antimicrobial agents to face the antibiotic crisis.

Synthesis, antiproliferative activity and possible mechanism of action of novel 2-acetamidobenzamides bearing the 2-phenoxy functionality.

Several new 2-(2-phenoxyacetamido)benzamides 17a-v, 21 and 22 were synthesized by stirring in pyridine the acid chlorides 16a-e and the appropriate5-R-4-R1-2-aminobenzamide 15a-e and initially evaluated in vitro for antiproliferative activity against the K562 (human chronic myelogenous leukemia) cell line. Some of synthesized compounds were evaluated for their in vitro antiproliferative activity against the full NCI tumor cell line panel derived from nine clinically isolated cancer types (leukemia, non-small cell lung, colon, CNS, melanoma, ovarian, renal, prostate and breast). The most active compounds caused an arrest of K562 cells in the G0-G1 phase of cell cycle and induction of apoptosis, which was mediated by caspase activation.

Sortase A Inhibitors: Recent Advances and Future Perspectives.

Here, we describe the most promising small synthetic organic compounds that act as potent Sortase A inhibitors and cater the potential to be developed as antivirulence drugs. Sortase A is a polypeptide of 206 amino acids, which catalyzes two sequential reactions: (i) thioesterification and (ii) transpeptidation. Sortase A is involved in the process of bacterial adhesion by anchoring LPXTG-containing proteins to lipid II. Sortase A inhibitors do not affect bacterial growth, but they restrain the virulence of pathogenic bacterial strains, thereby preventing infections caused by Staphylococcus aureus or other Gram-positive bacteria. The efficacy of the most promising inhibitors needs to be comprehensively evaluated in in vivo models of infection, in order to select compounds eligible for the treatment of bacterial infections in humans.

Synthesis and antiproliferative activity of 3-(2-chloroethyl)-5-methyl-6-phenyl-8-(trifluoromethyl)-5,6-dihydropyrazolo[3,4-f][1,2,3,5]tetrazepin-4-(3H)-one.

Based on the encouraging results found for 3,5-dimethyl-6-phenyl-8-(trifluoromethyl)-5,6-dihydropyrazolo[3,4-f][1,2,3,5]tetrazepin-4-(3H)-one 7 previously tested by us, as well as the consideration that heterocycle fused tetrazepinones bearing the 2-chloroethyl substituent show a better cytotoxic profile than temozolomide and mitozolomide against human cancer cell lines which express the DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT), in this paper we report the multistep synthesis and the biological study of 3-(2-chloroethyl)-5-methyl-6-phenyl-8-(trifluoromethyl)-5,6-dihydropyrazolo[3,4-f][1,2,3,5]tetrazepin-4-(3H)-one 10. Like compound 7, it was active on P-glycoprotein expressing cells (MDR) HL60 and on K562 cell line that are resistant to apoptosis induced by different stimuli, showing GI50 values of 14 and 18 µM respectively. As an antiproliferative agent against the above cells compound 10 was about 2.2 times more active than compound 7. Compound 10 was also tested against WiDR cells which are overexpressing the DNA repair protein MGMT, showing a GI50 value of 2.3 µM. Finally, concerning the effect on cell cycle we observed an evident difference between compounds 7 and 10. In fact, compound 7 induces a block of cell cycle in G0-G1, therefore acting as phase-specific drug, in contrast, compound 10 is a not phase-specific agent. Both the compounds are able to increase the apoptotic sub G0-G1 peak of cell cycle.

Recent advanced in bioactive systems containing pyrazole fused with a five membered heterocycle.

In this review we report the recent advances in bioactive system containing pyrazole fused with a five membered heterocycle, covering the time span of the last decade. All of them are represented around the common structure of the pyrazole ring fused with another five membered heterocycle containing the nitrogen, sulfur and oxygen atoms in all their possible combinations. The classification we have used is based in terms of the therapeutic area providing, when possible, some general conclusions on the targets and mechanisms of action as well as the structure-activity relationships of the molecules.

Synthesis and antiproliferative activity of new derivatives containing the polycyclic system 5,7:7,13-dimethanopyrazolo[3,4-b]pyrazolo[3',4':2,3]azepino[4,5-f]azocine.

The reaction under reflux between 1-phenyl-3-R-5-methylaminopyrazoles and 2,5-hexanedione lead to 5,7:7,13-dimethanopyrazolo[3,4-b]pyrazolo[3',4':2,3]azepino[4,5-f]azocine derivatives 3b-g. These unusual molecules show the structural complexity of many biologically active natural products and are endowed with the chemical diversity that is required in drug discovery. The compounds 3b,e were reduced by hydrogen in the presence of Palladium on activated charcoal to give the dihydro derivatives 5b,e. Compounds 3b-f and 5b,e were selected by the NCI to evaluate their in vitro antiproliferative activity against 60 human cell lines derived from nine clinically isolated cancer types (leukaemia, lung, colon, melanoma, renal, ovarian, brain, breast, and prostate). The most active compound of this series, caused a block in G0-G1 phase of cell cycle. Analysis of pRb expression showed that this compound favours pRb dephosphorylation.

Non-classical transformation of benzendiazonium hydrogen sulfates. Access to 1,3-dimethylisochromeno[4,3-c]pyrazol-5(1H)-one, a potential benzodiazepine receptor ligand.

The compound 2-((1,3-dimethyl-1H-pyrazol-5-yl)(methyl)carbamoyl)benzene-diazonium hydrogen sulfate (10) was reacted with copper sulfate and sodium chloride, in the presence of ascorbic acid as reducing agent, to afford a mixture of the chlorinated epimers 4'-chloro-2,2',5'-trimethyl-2',4'-dihydrospiro[isoindoline-1,3'-pyrazol]-3-one (18) and (19), the epimers 4'-hydroxy-2,2',5'-trimethyl-2',4'-dihydrospiro[isoindoline-1,3'-pyrazol]-3-one (20) and (21), and N-(1,3-dimethyl-1H-pyrazol-5-yl)benzamide (22). Under the foregoing conditions, diazonium salt 10 affords neither the 2-chloro-N-(1,3-dimethyl-1H-pyrazol-5-yl)-N-methylbenzamide (23) nor the tricyclic derivative 24, the classical products of the Sandmeyer and Pschorr reactions, respectively. Finally, by heating 20 at 210 °C the compound 1,3-dimethylisochromeno[4,3-c]pyrazol-5(1H)-one (24) was obtained. The transformation under the above conditions of 2-((4-chloro-3-methyl-1-phenyl- 1H-pyrazol-5-yl)(methyl)carbamoyl)benzendiazonium hydrogen sulphate (11) afforded 4',4'-dichloro-2,5'-dimethyl-2'-phenyl-2',4'-dihydrospiro[isoindoline-1,3'-pyrazol]-3-one (29) as the sole reaction product.

2-cinnamamido, 2-(3-phenylpropiolamido), and 2-(3-phenylpropanamido)benzamides: synthesis, antiproliferative activity, and mechanism of action.

Several new benzamides 4a-q were synthesized by stirring in pyridine the acid chlorides 3a-q with the appropriate anthranilamide derivatives 2a-g. Some of the synthesized compounds were evaluated for their in vitro antiproliferative activity against a panel of 5 human cell lines (K562 human chronic myelogenous leukemia cells, MCF-7 breast cancer cells, HTC-116 and HT26 colon cancer cells and NCI H460 non-small cell lung cancer cells).

Synthesis and anti-staphylococcal activity of new 4-diazopyrazole derivatives.

Several new 4-diazopyrazole derivatives 6a-g and 9a-c were obtained by the reaction of 1-(R-substituted-phenyl)-3-(1,3-dimethyl-1H-pyrazol-5-yl)ureas 5a-g and N-(1,3-dimethyl-1H-pyrazol-5-yl)-2-(R-substituted-phenyl)acetamides 8a-c respectively with a sevenfold excess of nitrous acid in acetic acid solution. The compounds were assayed for their activity against the Staphylococcus aureus reference strains ATCC 25923, ATCC 29213 and ATCC 6538, as well as six veterinary strains. The best anti-staphylococcal profile was showed by [(R-substituted-phenyl)acetyl](4-diazonio-1,3-dimethyl-1H-pyrazol-5-yl)azanides 9a,c. Compound 9c was also able at 3.1 µg mL(-1) to inhibit of 45.7% the biofilm formation of the strains S. aureus ATCC 29213.

Synthesis, antiproliferative activity, and mechanism of action of a series of 2-{[(2E)-3-phenylprop-2-enoyl]amino}benzamides.

Several new 2-{[(2E)-3-phenylprop-2-enoyl]amino}benzamides 12a-s and 17t-v were synthesized by stirring in pyridine the (E)-3-(2-R1-3-R2-4-R3-phenyl)acrylic acid chlorides 11c-k and 11t-v with the appropriate anthranilamide derivatives 10a-c or the 5-iodoanthranilic acid 13. Some of the synthesized compounds were evaluated for their in vitro antiproliferative activity against the full NCI tumor cell line panel derived from nine clinically isolated cancer types (leukemia, non-small cell lung, colon, CNS, melanoma, ovarian, renal, prostate and breast). COMPARE analysis, effects on tubulin polymerization in cells and with purified tubulin, and effects on cell cycle distribution for 17t, the most active of the series, indicate that these new antiproliferative compounds act as antitubulin agents.

Synthesis of substituted 3-amino-N-phenyl-1H-indazole-1-carboxamides endowed with antiproliferative activity.

Several new N-phenyl-1H-indazole-1-carboxamides 1c-h and 4l,m were prepared by reacting phenyl isocyanate derivatives 3a,b with 3-amino-1H-indazole derivatives 2c,e,g or 1H-indazole 2l respectively. Chemical transformations of compounds 1a,b and 1g,h gave 3-acetamido-N-phenyl-1H-indazole-1-carboxamide derivatives 5a,b, and 3,5-diamino-N-phenyl-1H-indazole-1-carboxamide derivatives 4i,j respectively. Finally, 3,5-diacetamido-N-phenyl-1H-indazole-1-carboxamide derivatives 6a,b were prepared by acetylation of 4i,j. Some of synthesized compounds were evaluated for their in vitro antiproliferative activity against the full NCI tumor cell lines panel derived from nine clinically isolated cancer types (leukemia, non-small cell lung, colon, CNS, melanoma, ovarian, renal, prostate and breast). Compound 1c, the most active of the series, was able to inhibit cell growth showing GI(50) values in the 0.041-33.6 µM range, mean GI(50) 1.90 µM, being very effective against colon and melanoma cell lines. Cell cycle analysis in K562 cells showed that 1c causes a marked increase of cells in G0-G1 phase. Moreover, it increases the ratio between hypophosphorylated pRb and total pRb.