Structure-activity relationships in platelet-activating factor (PAF). 10. From PAF antagonism to inhibition of HIV-1 replication

Insight into antimicrobial activity of substituted phenylcarbamoyloxypiperazinylpropanols

3-[4-(Substituted)phenyl-/4-(diphenylmethyl)phenylpiperazin-1-yl]-2-hydroxypropyl-1-[(substituted)phenyl]carbamates and their salts with hydrochloric acid were synthesized, characterized, and tested in vitro against Staphylococcus aureus ATCC 29213 and Enterococcus faecalis ATCC 29212 as reference and quality control strains, against three methicillin-resistant isolates of S. aureus, and three isolates of vancomycin-resistant E. faecalis. All the compounds were evaluated against Mycobacterium tuberculosis H₃₇R_a/ATCC 25177, M. kansasii DSM 44162, and M. smegmatis ATCC 700084. All of the tested compounds demonstrated very good activity against all the tested strains/isolates comparable with or better than that of clinically used drugs (ampicillin, ciprofloxacin, vancomycin, isoniazid). 1-[{(3-Trifluoromethyl)phenyl}carbamoyloxy-2-hydroxypropyl]-4-(3,4-dichlorophenyl)piperazin-1-ium chloride demonstrated the highest potency against all the tested strains/isolates (MICs ranged from 3.78 to 30.2 µM), and 1-[{(3-trifluoromethyl)phenyl}carbamoyloxy-2-hydroxypropyl]-4-(diphenylmethyl)piperazin-1-ium chloride was the most effective against all the screened mycobacterial strains (MICs ranged from 3.64 to 14.5 µM). All the investigated derivatives had strong antibiofilm activity against S. aureus ATCC 29123 and a synergistic or additive effect with gentamicin against isolates of E. faecalis with both intrinsic and acquired resistance to gentamicin. The screening of the cytotoxicity of the compounds was performed using human monocytic leukemia THP-1 cells. The IC₅₀ values of the most effective compounds ranged from ca. 2.8 to 7.3 µM; thus, it can be stated that the antimicrobial effect is closely connected with their cytotoxicity. These observations disqualify these compounds from further development as antimicrobial agents, but they can be considered potential multi-target drugs with a preferred anticancer effect with good water solubility and additional anti-infectious activity.

PMS1077 sensitizes TNF-α induced apoptosis in human prostate cancer cells by blocking NF-κB signaling pathway

Our previous studies have demonstrated that PMS1077, a platelet-activating factor (PAF) antagonist, could induce apoptosis of Raji cells. However, the mechanism of action has not yet been determined. The nuclear transcription factor-kappa B (NF-κB) signaling pathway plays a critical role in tumor cell survival, proliferation, invasion, metastasis, and angiogenesis, so we determined the effects of PMS1077 and its structural analogs on tumor necrosis factor-α (TNF-α) induced activation of NF-κB signaling. In this study, we found that PMS1077 inhibited TNF-α induced expression of the NF-κB regulated reporter gene in a dose dependent manner. Western blot assay indicated that PMS1077 suppressed the TNF-α induced inhibitor of κB-α (IκB-α) phosphorylation, IκB-α degradation, and p65 phosphorylation. PMS1077 consistently blocked TNF-α induced p65 nuclear translocation as demonstrated in the immunofluorescence assay used. Docking studies by molecular modeling predicted that PMS1077 might interact directly with the IκB kinase-β (IKK-β) subunit. These results suggested that PMS1077 might suppress the activation of NF-κB by targeting IKK-β involved in the NF-κB signaling pathway. Finally, we showed that PMS1077 sensitized cells to TNF-α induced apoptosis by suppressing the expression of NF-κB regulated anti-apoptotic genes. Our results reveal a novel function of PMS1077 on the NF-κB signaling pathway and imply that PMS1077 can be considered as an anti-tumor lead compound.

In Vitro and In Vivo Effects of Statins on Platelet-Activating Factor and Its Metabolism

Platelet activating factor (PAF) is implicated in cardiovascular disease (CVD). Statins are widely used in these situations. Therefore, we assessed their effect on the biological activities and metabolism of PAF. Several statins, including simvastatin, exhibited an inhibitory effect against PAF, comparable with that of PAF-inhibitors. Simvastatin also suppressed in vivo PAF-biosynthesis via the de novo pathway, in leukocytes of 6 simvastatin-treated volunteers. Total cholesterol and low-density lipoprotein cholesterol were also significantly decreased, whereas high-density lipoprotein cholesterol, triacylglycerol, EC50, and lag time were unaffected in these participants. Simvastatin with an intact lactone ring also inhibited PAF-activities, while incubation of human mesangial cells with it also resulted in decreased de novo PAF-biosynthesis. This suggests that these simvastatin-dependent effects are independent of its lactone ring. These new actions of statins should be further studied in PAF-implicated pathological conditions such as CVD, cancer, and renal disease.

Development of a platelet-activating factor antagonist for HIV-1 associated neurocognitive disorders

The neuroregulatory activities of PMS-601, a platelet activating factor antagonist, were investigated in laboratory and animal models of HIV-1 encephalitis (HIVE). For the former, PMS-601 reduced monocyte-derived macrophage pro-inflammatory secretions, multinucleated giant cell (MGC) formation, and neuronal loss independent of antiretroviral responses. PMS-601 treatment of HIVE severe combined immunodeficient mice showed reduced microgliosis, MGCs and neurodegeneration. These observations support the further development of PMS-601 as an adjunctive therapy for HIV-1 associated neurocognitive disorders.

Structure–activity relationships in platelet-activating factor. Part 14: Synthesis and biological evaluation of piperazine derivatives with dual anti-PAF and anti-HIV-1 activity

As HIV-associated dementia prevalence has risen with the lifespan of HIV-infected individuals, there is an important need for antiretroviral and anti-inflammatory drugs targeting the central nervous system. Platelet-activating factor, a mediator of inflammation, is an HIV-induced neurotoxin secreted in the infected brain. In this work, we developed piperazine derivatives bearing a heterocyclic moiety as PAF-antagonists and HIV-1 replication inhibitors with micromolar potency.

Structure-activity relationships in platelet-activating factor. Part 13: synthesis and biological evaluation of piperazine derivatives with dual anti-PAF and anti-HIV-1 or pure antiretroviral activity

HIV-1 infection of the brain and PAF neurotoxicity are implicated in AIDS dementia complex. We previously reported that a trisubstituted piperazine derivative is able to diminish both HIV-1 replication in monocyte-derived macrophages and PAF-induced platelet aggregation. We report in this work new compounds obtained by modifying its piperazine substituents. The structure-activity relationship study shows that a better dual activity or even pure antiretroviral compounds can be obtained in this series.

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Structure-activity relationships in platelet-activating factor. 12. Synthesis and biological evaluation of platelet-activating factor antagonists with anti-HIV-1 activity

The HIV-1 central nervous system infection leads to the onset of neurological impairments called AIDS dementia complex (ADC). PAF plays an important role in this pathology, as it is an HIV-1-induced neurotoxin produced by infected or activated macrophages and microglia, in the brain. We previously reported that PAF-antagonists bearing a trisubstituted piperazine presented in vitro anti-HIV-1 activity in human macrophages. To improve the pharmacological activities of our lead compound, 1a, we modified its carbamate function and evaluated both its antiretroviral and anti-PAF activities. One carbamate derivative (10c) demonstrated a similar antiviral activity but a higher anti-PAF potency, whereas 4a, with an ureide function, presents an increased antiviral activity and can be considered as a pure antiretroviral drug, as it does not present PAF-antagonism. Moreover, we measured the ability of 1a to cross the blood-brain barrier, using the in situ mouse brain perfusion method and its plasmatic concentrations after iv and po administration. The transport parameter measured (K(in)) proves that 1a is able to cross this biological barrier, but a pharmacokinetic study reveals its weak bioavailability in rats.

Aspirin-like molecules that inhibit human immunodeficiency virus 1 replication

Some anti-inflammatory molecules are also known to possess anti-human immunodeficiency virus (HIV) activity. We found that o-(acetoxyphenyl)hept-2-ynyl sulfide (APHS), a recently synthesized non-steroidal anti-inflammatory molecule can inhibit HIV-1 replication. The aim of this study was to clarify the mechanism of action of APHS. When administered during the first steps of the infection, APHS was capable of inhibiting the replication of several HIV-1 strains (macrophage-tropic and/or lymphocytotropic) in a dose-dependent manner in both peripheral blood mononuclear cells (PBMC), monocyte-derived macrophages and peripheral blood lymphocytes with 50% inhibitory concentration values of approximately 10 microM. The 50% toxic concentration of APHS varied between 100 and 200 microM in the different primary cells tested. APHS did not affect HIV-1 replication once the provirus was already inserted into the cellular genome. APHS also did not inhibit HIV-1 entry into the host cells as determined by quantification of gag RNA inside PBMC 2h after infection. However, APHS did inhibit gag DNA synthesis during reverse transcription in primary cells, which indicates that APHS may target the reverse transcription process.

Platelet CD62p expression and microparticle in murine acquired immune deficiency syndrome and chronic ethanol consumption

AIMS

Abnormal platelet counts have been noticed in acquired immune deficiency syndrome (AIDS) patients. However, the actual state of platelets in AIDS is unclear. We hypothesize that platelets are activated and platelet-derived microparticles increase in murine AIDS.

METHODS

To elucidate the ethanol effects on platelets in murine AIDS, we studied four groups: control, murine AIDS, ethanol, and ethanol plus murine AIDS. Platelet CD62p as a platelet activation marker and CD61(+) microparticles as platelet microparticles (PMPs) were measured by flow cytometry.

RESULTS

Platelets were significantly activated in mice with murine AIDS and chronic ethanol consumption. Increased platelet CD62p expression and increased PMPs were most pronounced in advanced stages of murine AIDS. Chronic ethanol consumption persistently enhanced platelet activation and PMP formation.

CONCLUSIONS

Elevated platelet CD62p and PMPs may represent a pro-thrombotic status that have important pathological consequences.

Effect of lignans isolated from Hernandia nymphaeifolia on estrogenic compounds-induced calcium mobilization in human neutrophils

The effect of five lignans isolated from Hernandia nymphaeifolia on estrogenic compounds (17beta-estradiol, tamoxifen and clomiphene)-induced Ca(2+) mobilization in human neutrophils was investigated. The five lignans were epi-yangambin, epi-magnolin, epi-aschantin, deoxypodophyllotoxin and yatein. In Ca(2+)-containing medium, the lignans (50-100 microM) inhibited 10 microM 17beta-estradiol- and 5 microM tamoxifen-induced increases in intracellular free Ca(2+) levels ([Ca(2+)](i)) without changing 25 microM clomiphene-induced [Ca(2+)](i) increase. 17beta-estradiol and tamoxifen increased [Ca(2+)](i) by causing Ca(2+) influx and Ca(2+) release because their responses were partly reduced by removing extracellular Ca(2+). In contrast, clomiphene solely induced Ca(2+) release. The effect of the lignans on these two Ca(2+) movement pathways underlying 17beta-estradiol- and tamoxifen-induced [Ca(2+)](i) increases was explored. All the lignans (50-100 microM) inhibited 10 microM 17beta-estradiol-and 5 microM tamoxifen-induced Ca(2+) release, and 17beta-estradiol-induced Ca(2+) influx. However, only 100 microM epi-aschantin was able to reduce tamoxifen-induced Ca(2+) influx while the other lignans had no effect. Collectively, this study shows that the lignans altered estrogenic compounds-induced Ca(2+) signaling in human neutrophils in a multiple manner.

Cytotoxic activity and QSAR of N,N'-diarylalkanediamides

The one- and two-step syntheses of N,N'-(dinitrophenyl)alkanediamides and N,N'-(diaminophenyl)alkanediamides from 4-nitroaniline were carried out. These compounds were subjected to cytotoxic evaluation against different tumoural cell lines. A QSAR analysis for the aminated series, introducing a QSAR descriptor (D(CL)) designed herein for groove binders, reveals that the activity in the K562 cell line is related to the charge, polarisability, volume and length of the molecules.

PMS-601, a new platelet-activating factor receptor antagonist that inhibits human immunodeficiency virus replication and potentiates zidovudine activity in macrophages

We assessed the anti-human immunodeficiency virus (anti-HIV) activity in vitro of new platelet-activating factor (PAF) receptor antagonists, as PAF and viral replication are thought to be involved in HIV neuropathogenesis. We found that PMS-601 inhibited proinflammatory cytokine synthesis and HIV replication in macrophages and potentiated the antiretroviral activity of zidovudine. These results suggest that PMS-601 is of potential value as an adjuvant treatment for HIV infection.