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By the antiviral screening of an in house library of pyrazoline compounds, 4-(3-(4-phenoxyphenyl)-5-phenyl-4,5-dihydro-1H-pyrazol-1-yl)benzenesulfonamide (5a) was identified as a promising hit compound for the development of anti- Yellow Fever Virus (YFV) agents. Structural optimization studies were focused on the development of 5a analogues which retain the potency as YFV inhibitors and show a reduced cytotoxicity. The synthesized 1-3,5-triphenyl-pyrazolines (4a-j, 5a-j, 6a-j) were evaluated in cell based assays for cytotoxicity and antiviral activity against representative viruses of two of the three genera of the Flaviviridae family, i.e.: Pestivirus (BVDV) and Flavivirus (YFV). These compounds were also tested against a large panel of different pathogenic RNA and DNA viruses. Most of the new 1-3,5-triphenyl-pyrazolines (4a-j, 5a-j, 6a-j) exhibited a specific activity against YFV, showing EC 50 values in the low micromolar range with almost a 10-fold improvement in potency compared to the reference inhibitor 6-azauridine. However, the selectivity indexes of the unsubstituted (4a-j) and the phenoxy (5a-j) analogues were generally modest due to the pronounced cytotoxicity against BHK-21 cells. Otherwise, the benzyloxy derivatives (6a-j) generally coupled high potency and selectivity. On the basis of both anti-YFV activity and selectivity index, pyrazolines 6a and 6b were chosen for time of addition experiments. The selected pyrazolines and the reference inhibitor 6-azauridine displayed maximal inhibition when added in the pretreatment or during the infection., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

Following our studies on structure-activity relationships of anti-rhinovirus chromene and chroman derivatives, we designed and synthesized new series of 3-phenylalkyl-2H-chromenes and -chromans bearing differently sized, aliphatic linker chains between the two cycles. The cytotoxicity and the antiviral activity of the new compounds on human rhinovirus (HRV) serotype 1B and 14 infection were evaluated in HeLa cell cultures. Most of the tested compounds interfered with HRV1B multiplication in the micromolar or submicromolar concentrations while HRV14 was less susceptible. 3-[3-(4-Chlorophenyl)propyl]chroman (9c) was selected for preliminary mechanism of action studies due to its potent activity against both serotypes (IC 50 of 0.48μM and 1.36μM towards HRV1B and 14, respectively) coupled with high selectivity (SI=206.18 and 73.26, respectively). Results of time of addition/removal studies suggest that 9c, similarly to related derivatives, behaves as a capsid binder interfering with some early events of the HRV1B infectious cycle., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

A series of N-((1,3-diphenyl-1H-pyrazol-4-yl)methyl)anilines were synthesized and evaluated in vitro for cytotoxicity and antiviral activity against a large panel of viruses. Most of the tested compounds interfered with RSV replication in the micromolar concentrations (EC50s ranging from 5 μM to 28 μM). SAR studies suggested that the presence of a trifluoromethyl group in R(1) abolished the anti-RSV activity and enhanced the cytotoxicity while the best results in term of both anti-RSV activity and selectivity were obtained by the introduction in R(1) of a chlorine or a bromine atom., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Human rhinoviruses (HRVs) are the most common cause of viral respiratory infections and their complications. So far, no anti-viral agent has been approved for prevention or treatment of HRV infections. Pursuing our researches on small molecules with anti-rhinovirus activity, in this paper we describe the synthesis and in vitro anti-HRV 1B and 14 properties of new [2-(2H-chromen-3-yl)vinyl]pyridines and 3-[2-(pyridinyl)vinyl]-4H-chromen-4-ones. Generally, the synthesized compounds interfered with the replication of both serotypes at the micromolar or submicromolar concentrations. Preliminary results on their mechanism of action, performed on selected (E)-2-[2-(2H-chromen-3-yl)vinyl]pyridine, indicate an interference with the early step(s) of HRV 1B and 14 replication, probably at the uncoating level., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

As part of an effort to generate broad-spectrum inhibitors of rhinovirus replication, novel series of (E)-3-[(E)-3-phenylallylidene]chroman-4-ones 1a-e, (E)-3-(3-phenylprop-2-yn-1-ylidene)chroman-4-ones 2a and 2b, (Z)-3-[(E)-3-phenylallylidene]chromans 3a-e, and (E)-3-(3-phenylprop-1-en-1-yl)-2H-chromenes 4a-d were designed and synthesized. All the compounds were tested in vitro for their efficacy against infection by human rhinovirus (HRV) 1B and 14, two representative serotypes for rhinovirus group B and A, respectively. Most of the analogues were found to be potent and selective inhibitors of both HRVs, although HRV 1B was generally more susceptible than HRV 14. Mechanism of action studies of (E)-6-chloro-3-(3-phenylprop-1-en-1-yl)-2H-chromene 4b, the most potent compound on HRV 1B infection, suggested that 4b behaves as a capsid-binder probably acting at the uncoating level., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

A series of 3-benzyl chromenes and chromans were synthesized and tested in vitro against human rhinovirus (HRV) 1B and 14, two representative serotypes for rhinovirus group B and A, respectively. All the new compounds, with the exception of 3-benzyl-2H-chromene (3a), showed a potent activity against HRV serotype 1B within micro or submicromolar range (IC(50)s from 0.11 to 6.62 microM). The low cytotoxicity of all the derivatives resulted in compounds with high therapeutic index (TI). On the contrary, HRV 14 infection was only weakly inhibited by the majority of these compounds. The 3-benzylidenechromans 2b and 2c showed the highest anti-HRV 1B activity (IC(50) 0.12 and 0.11 microM, respectively) coupled with remarkable TI (625.00 and 340.91, respectively). Mechanism of action studies on (Z)-3-(4-chlorobenzylidene)chroman (2b) suggest that the new compounds behave as capsid binders and interfere with very early stages of HRV 1B replication, similarly to related flavanoids.

The antiviral activity of homoisoflavonoids, a class of flavonoids, was determined in vitro against a large panel of enteroviruses. The inhibition of viral replication was monitored on BGM (Buffalo Green Monkey) cells, and the concentration required for 50% inhibition (IC50), as well as the selectivity index (SI) were determined. None of the substances were effective against Sabin type 1 poliovirus (PV1), but most of them showed a low cytotoxicity and a marked antiviral activity against Coxsackie virus B1, B3, B4, A9 and echovirus 30.

Fluoro-substituted flavones and 2-styrylchromones, related to natural and synthetic flavonoids previously described, were prepared, characterized and tested for anti-rhinovirus activity. Structural elucidation of the new compounds was performed by IR, NMR spectra and X-ray crystal structure analysis for 6-fluoro-3-hydroxy-2-styrylchromone. The antiviral potency was evaluated by a plaque reduction assay in HeLa cell cultures infected with rhinoviruses 1B and 14, selected as representative serotypes for viral groups B and A of human rhinoviruses, respectively. In comparison with results previously obtained, the introduction of the fluorine atom seems to exert a positive influence on the activity against serotype 14 while counteracting the effect against serotype 1B.

Recently, we identified 2-styrylchromones as a new class of antirhinovirus flavonoids with moderate activity against both rhinovirus groups A and B. In order to improve the antiviral effect of the first series of tested 2-styrylchromones, a hydroxy or methoxy group was introduced in position 3 of the chromone ring. Cytotoxicity and antiviral activity of the new synthesized compounds were evaluated in HeLa cell cultures infected with rhinoviruses 1B and 14, selected as representative serotypes for viral groups B and A of human rhinoviruses (HRVs), respectively. These antiviral results compared to those obtained for 3-unsubstituted 2-styrylchromones indicate the greater potency of 3-hydroxy and 3-methoxy derivatives against both serotypes.

Abstract: Substituted (E)-3-styryl-4H-chromen-4-ones 1a–d, 3-[(1E,3E)-4-phenylbuta-1,3-dienyl]-4H-chromen-4-ones 2a–d, (E)-3-styryl-2H-chromenes 3a–d and 3-[(1E,3E)-4-phenylbuta-1,3-dienyl]-2H-chromenes 4a–d were designed and synthesized to improve the anti-picornavirus activity of previously tested analogues. The new compounds were evaluated in vitro against human rhinovirus (HRV) serotypes 1B and 14 and enterovirus (EV) 71. All the compounds interfered with the replication of picornaviruses, although considerable differences were observed in the sensitivity of viruses to each compound. Generally, both HRVs were more susceptible than EV71 and their sensitivity was dependent upon the linker chain length as well as upon the oxidation state of the heterocyclic ring. (E)-3-Styryl-2H-chromene (3a) emerged as the most effective inhibitor of both HRVs showing IC50 values of 0.20μM and 1.38μM towards serotype 1B and 14, respectively. The potent activity was also coupled with low cytotoxicity resulting in high therapeutic indexes (250 and 36, respectively). Mechanism of action studies indicated that 3a, like structurally related compounds, behaves as a capsid binder interfering with the early stages of rhinovirus infection, probably at the adsorption and/or uncoating level. [ABSTRACT FROM AUTHOR]