The G-protein-coupled receptor CXCR4 acts as a coreceptor for human immunodeficiency virus type 1 (HIV-1) infection, as well as being involved in signaling cell migration and proliferation. Compounds that block CXCR4 interactions have potential uses as HIV entry inhibitors to complement drugs such as maraviroc that block the alternate coreceptor CCR5 or in cancer therapy. The peptide T140, which contains five arginine residues, is the most potent antagonist of CXCR4 developed to date. In a search for nonpeptide CXCR4 ligands that could inhibit HIV entry, three series of compounds were synthesized from 12 linear and branched polyamines with 2, 3, 4, 6, or 8 amino groups, which were substituted to produce the corresponding guanidines, biguanides, or phenylguanides. The resulting compounds were tested for their ability to compete with T140 for binding to the human CXCR4 receptor expressed on mammalian cells. The most effective compounds bound CXCR4 with a 50% inhibitory concentration of 200 nM, and all of the compounds had very low cytotoxicity. Two series of compounds were then tested for their ability to inhibit the infection of TZM-bl cells with X4 and R5 strains of HIV-1. Spermine phenylguanide and spermidine phenylguanide inhibited infection by X4 strains, but not by R5 strains, at low micromolar concentrations. These results support further investigation and development of these compounds as HIV entry inhibitors.

bAPOBEC3 proteins are restriction factors that induce G¡A hypermutation in retroviruses during replication as a result of cytidine deamination of minus-strand DNA transcripts. However, the mechanism of APOBEC inhibition of murine leukemia viruses (MuLVs) does not appear to be G¡A hypermutation and is unclear. In this report, the incorporation of mA3 in virions resulted in a loss in virion reverse transcriptase (RT) activity and RT fidelity that correlated with the loss of virion-specific infectivity.A POBEC3G (hA3G) in humans and APOBEC3 (mA3) in mice are cytidine deaminases that act on single-stranded DNA during reverse transcription, resulting in G¡A hypermutation of newly synthesized proviral DNA (1, 2). Although exogenous murine leukemia viruses (MuLVs) are relatively insensitive to the actions of mA3 (2-7), several studies have reported partial inhibition of exogenous MuLVs after incorporation of mA3 (2,3,6,(8)(9)(10)(11). Furthermore, the finding that Rfv3, a resistance gene for Friend erythroleukemia, encodes mA3 and is responsible for a decreased infectious titer of the Friend MuLV (Fr-MuLV) (11-13) strongly suggests that mA3 inhibits the replication of exogenous MuLVs in vivo. Exogenous ecotropic MuLVs, such as the FrMuLV and Moloney MuLV (Mo-MuLV), are inhibited through mechanisms that do not appear to involve cytidine deamination (2, 9, 10). In this study, the effects of mA3 on the infectivity, reverse transcriptase (RT) activity, and frequency of mutations of the ecotropic MuLV CasFr KP were examined. Virion-associated mA3 suppresses CasFr KP MuLV infectivity. In order to examine the effects of mA3 incorporated into MuLV virions, we derived clonal cell lines infected with CasFr KP (14). The 3T3mA3 cells were derived by transfection of a plasmid encoding the full-length mA3 derived from the BALB/c mouse strain and was tagged at the C termini with hemagglutinin (HA) (5). Infected clonal cell lines were obtained from 3T3 cells as well as from 3T3 cells expressing mA3 (3T3mA3) and were designated 3T3/CasFr KP and 3T3mA3/CasFr KP , respectively. In agreement with earlier reports (2, 7, 9, 13, 15), the clonal cell line expressing mA3 (3T3mA3/CasFr KP ) released virions that had incorporated an easily detectable level of mA3 (Fig. 1).The infectivity of CasFr KP containing mA3 was compared to that of CasFr KP devoid of mA3 by a focal immunofluorescence assay (FIA) (16) and normalized for virion number using the level of p30 CA protein (Fig. 2A). The specific infectivity of virions released from cells expressing mA3 exhibited over a 90% reduction in infectivity (Fig. 2B), corroborating earlier studies of inhibition by mA3 (2,3,6,(8)(9)(10)(11).Decrease in RT activity in virions containing mA3. A recent study examined the efficiency of virion reverse transcription by monitoring the appearance of strong-stop DNA during the course of the RT reaction using virions isolated from C57BL/6 and BALB/c mice as well as those from mA3 knockout (KO) mice (17). Both mouse strains exhibited a similar decrease in RT activity...

This study investigated the potential antibacterial activity of three series of compounds synthesized from 12 linear and branched polyamines with 2–8 amino groups, which were substituted to produce the corresponding guanides, biguanides, or phenylguanides, against Acinetobacter baumannii, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. Antibacterial activity was measured for each compound by determining the minimum inhibitory concentration against the bacteria, and the toxicity towards mammalian cells was determined. The most effective compound, THAM trisphenylguanide, was studied in time-to-kill and cytoplasmic leakage assays against methicillin-resistant Staphylococcus aureus (MRSA, USA300) in comparison to chlorhexidine. Preliminary toxicity and MRSA challenge studies in mice were also conducted on this compound. THAM trisphenylguanide showed significant antibacterial activity (MIC ∼1 mg/L) and selectivity against MRSA relative to all the other bacteria examined. In time-to-kill assays it showed increased antimicrobial activity against MRSA versus chlorhexidine. It induced leakage of cytoplasmic content at concentrations that did not reduce cell viability, suggesting the mechanism of action may involve membrane disruption. Using an intraperitoneal mouse model of invasive MRSA disease, THAM trisphenylguanide reduced bacterial burden locally and in deeper tissues. This study has identified a novel guanide compound with selective microbicidal activity against Staphylococcus aureus, including a methicillin-resistant (MRSA) strain.

The G-protein coupled receptor CXCR4 is a co-receptor for HIV-1 infection and is involved in signaling cell migration and proliferation. In a previous study of non-peptide, guanide-based CXCR4-binding compounds, spermine and spermidine phenylguanides inhibited HIV-1 entry at low micromolar concentrations. Subsequently, crystal structures of CXCR4 were used to dock a series of naphthylguanide derivatives of the polyamines spermidine and spermine. Synthesis and evaluation of the naphthylguanide compounds identified our best compound, spermine tris-1-naphthylguanide, which bound CXCR4 with an IC50 of 40nM and inhibited the infection of TZM-bl cells with X4, but not R5, strains of HIV-1 with an IC50 of 50–100nM.

Synthesis of new PDT triads that incorporate a tumor-killing porphyrin with large two-photon cross-section for 150 fs laser pulses (2000 GM) in the Near-infrared (NIR) at 840 nm, a NIR imaging agent, and a small peptide that targets over-expressed EGF receptors on the tumor surface. This triad formulation has been optimized over the past year to treat FADU Head and Neck SCC xenograft tumors in SCID mice. Effective PDT triad dose (1-10 mg/Kg) and laser operating parameters (840 nm, 15-45 min, 900 mW) have been established. Light, dark and PDT treatment toxicities were determined, showing no adverse effects. Previous experiments in phantom and mouse models indicate that tumors can be treated directly through the skin to effective depths between 2 and 5 cm. Treated mice demonstrated rapid tumor regression with some complete cures in as little as 15-20 days. No adverse effects were observed in any healthy tissue through which the focused laser beam passed before reaching the tumor site, and excellent healing occurred post treatment including rapid hair re-growth. Not all irradiation protocols lead to complete cures. Since two-photon PDT is carried out by rastering focused irradiation throughout the tumor, there is the possibility that as the treatment depth increases, some parts of the tumor may escape irradiation due to increased scattering, thus raising the possibility that tumor re-growth could be triggered by small islands of untreated cells, especially at the rapidly growing tumor margins, a problem we hope to alleviate by using image-guided two-photon PDT.