Design, Synthesis, Antiviral Evaluation, and SAR Studies of New 1-(Phenylsulfonyl)-1H-Pyrazol-4-yl-Methylaniline Derivatives.

A series of N-((3-phenyl-1-(phenylsulfonyl)-1H-pyrazol-4-yl)methyl)anilines 7a-p and 8a-l, structurally related to previously synthesized and tested (N-(1,3-diphenyl-1H-pyrazol-4-yl)methyl)anilines (1a-v), were designed and synthesized. The new derivatives were evaluated in cell-based assays for their cytotoxicity and antiviral activity against a large panel of RNA and DNA viruses of public health significance. Generally, the tested compounds did not display cytotoxicity toward the cell lines used. The majority of derivatives 7a-p were able to interfered with YFV and RSV replication in the micromolar range showing a marked improvement in potency and selectivity with respect to the reference inhibitors 6-azauridine and ribavirin, respectively. The introduction of a p-methoxy substituent on the phenylsulfonyl group (compounds 8a-l) completely abolished the anti-RSV activity and reduced or eliminated the potency against YFV. On the contrary, several p-methoxy analogs were able to interfere with BVDV replication with a comparable (8b, 8c, 8g, and 8k) or better (8a and 8f) potency than the reference inhibitor, ribavirin. Compound 7e, selected for time of addition experiments on BHK-21 cell cultures infected with YFV, achieved the highest reduction of virus titer when added 2 h post infection and maintained up to 4 h post infection.

3-Phenylalkyl-2H-chromenes and -chromans as novel rhinovirus infection inhibitors.

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 (IC50 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.

(E)-3-Heteroarylidenechroman-4-ones as potent and selective monoamine oxidase-B inhibitors.

A series of (E)-3-heteroarylidenechroman-4-ones (1a-r) was designed, synthesized and investigated in vitro for their ability to inhibit the enzymatic activity of both human monoamine oxidase (hMAO) isoforms, hMAO-A and hMAO-B. All the compounds were found to be selective hMAO-B inhibitors showing IC50 values in the nanomolar or micromolar range. (E)-5,7-Dichloro-3-{[(2-(dimethylamino)pyrimidin-5-yl]methylene}chroman-4-one (1c) was the most interesting compound identified in this study, endowed with higher hMAO-B potency (IC50 = 10.58 nM) and selectivity (SI > 9452) with respect to the reference selective inhibitor selegiline (IC50 = 19.60 nM, IC50 > 3431). Molecular modelling studies were performed for rationalizing at molecular level the target selective inhibition of our compounds, revealing a remarkable contribution of hydrogen bond network and water solvent.

Synthesis and anti-rhinovirus activity of novel 3-[2-(pyridinyl)vinyl]substituted -2H-chromenes and -4H-chromen-4-ones.

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.

Design, synthesis, and in vitro hMAO-B inhibitory evaluation of some 1-methyl-3,5-diphenyl-4,5-dihydro-1H-pyrazoles.

A series of 1-methyl-3,5-diphenyl-4,5-dihydro-1H-pyrazoles (3a-k and 4a-u) were designed, synthesized, and evaluated for their inhibitory efficacy towards the two hMAO isoforms. Most of the derivatives were found to be potent and selective hMAO-B inhibitors. In particular, derivative 3g showed greater hMAO-B affinity than selective inhibitor selegiline coupled with high selectivity index (SI=145). The most selective hMAO-B inhibitor was the 3-methyl analogue 3f with an SI higher than 909.

1,5-Diphenylpenta-2,4-dien-1-ones as potent and selective monoamine oxidase-B inhibitors.

A series of (2E,4E)-1-(2-hydroxyphenyl)-5-phenylpenta-2,4-dien-1-ones (3a-r) and (2Z,4E)-3-hydroxy-1-(2-hydroxyphenyl)-5-phenylpenta-2,4-dien-1-ones (6a-l) were synthesized and evaluated in vitro as inhibitors of the two human Monoamine oxidase (hMAO) isoforms, MAO-A and MAO-B. Most of the compounds showed a selective MAO-B inhibitory activity in the nanomolar or low micromolar range. (2E,4E)-5-(4-Chlorophenyl)-1-(2-hydroxy-4-methoxyphenyl)penta-2,4-dien-1-one (3g) and (2E,4E)-5-(4-chlorophenyl)-1-(2,4-dihydroxyphenyl)penta-2,4-dien-1-one (3h) were the most potent hMAO-B inhibitors exhibiting IC(50) of 4.51 nM and 11.35 nM, respectively, coupled with high selectivity. Moreover, partial recovery of MAO-B activity was observed after repeated washing in the presence of isatin (reversible inhibitor) and compounds 3g and 3h suggesting a reversible inhibition of the enzyme. Molecular mechanics and quantum chemistry methods were used to elucidate the MAO recognition of the most active inhibitors 3g and 3h.

Design, synthesis and in vitro evaluation of novel chroman-4-one, chroman, and 2H-chromene derivatives as human rhinovirus capsid-binding inhibitors.

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.