Synthesis of IB-01212 by multiple N-methylations of peptide bonds.

There are many natural peptides with multiple N-methylamino acids that exhibit potent attractive biological activities. N-methylation of a peptide bond(s) is also one of the standard approaches in medicinal chemistry of bioactive peptides, to improve the potency and physicochemical properties, especially membrane permeability. In this study, we investigated a facile synthesis process of N-methylated peptides via simultaneous N-methylation of several peptide bonds in the presence of peptide bonds that were not to be methylated. As a model study, we investigated the synthesis of the antiproliferative depsipeptide, IB-01212. We used a pseudoproline to protect the non-methylated peptide bond during a simultaneous N-methylation with MeI-Ag[2]O. Using further manipulations including a dimerization/cyclization process, IB-01212 and its derivatives were successfully synthesized. A preliminary structure-activity relationship study demonstrated that the symmetric structure contributed to the potent cytotoxic activity of IB-01212

Synthesis and biological evaluation of the [d-MeAla(11)]-epimer of coibamide A.

Coibamide A is a highly potent antiproliferative cyclic depsipeptide, which was originally isolated from a Panamanian marine cyanobacterium. In this study, the synthesis of coibamide A has been investigated using Fmoc-based solid-phase peptide synthesis followed by the cleavage of the resulting linear peptide from the resin and its subsequent macrolactonization. The peptide sequence of the linear coibamide A precursor was constructed on a solid-support following the optimization of the coupling conditions, where numerous coupling agents were evaluated. The macrocyclization of the resulting linear peptide provided the [d-MeAla(11)]-epimer of coibamide A, which exhibited nanomolar cytotoxic activity towards a number of human cancer cell lines

A Novel Peptide Derived from the Fusion Protein Heptad Repeat Inhibits Replication of Subacute Sclerosing Panencephalitis Virus In Vitro and In Vivo.

Subacute sclerosing panencephalitis (SSPE) is a persistent, progressive, and fatal degenerative disease resulting from persistent measles virus (MV) infection of the central nervous system. Most drugs used to treat SSPE have been reported to have limited effects. Therefore, novel therapeutic strategies are urgently required. The SSPE virus, a variant MV strain, differs virologically from wild-type MV strain. One characteristic of the SSPE virus is its defective production of cell-free virus, which leaves cell-to-cell infection as the major mechanism of viral dissemination. The fusion protein plays an essential role in this cell-to-cell spread. It contains two critical heptad repeat regions that form a six-helix bundle in the trimer similar to most viral fusion proteins. In the case of human immunodeficiency virus type-1 (HIV-1), a synthetic peptide derived from the heptad repeat region of the fusion protein enfuvirtide inhibits viral replication and is clinically approved as an anti-HIV-1 agent. The heptad repeat regions of HIV-1 are structurally and functionally similar to those of the MV fusion protein. We therefore designed novel peptides derived from the fusion protein heptad repeat region of the MV and examined their effects on the measles and SSPE virus replication in vitro and in vivo. Some of these synthetic novel peptides demonstrated high antiviral activity against both the measles (Edmonston strain) and SSPE (Yamagata-1 strain) viruses at nanomolar concentrations with no cytotoxicity in vitro. In particular, intracranial administration of one of the synthetic peptides increased the survival rate from 0% to 67% in an SSPE virus-infected nude mouse model

Neither Trimethylamine-N-Oxide nor Trimethyllysine Is Associated with Atherosclerosis: A Cross-Sectional Study in Older Japanese Adults

Recent evidence suggests that trimethylamine-N-oxide (TMAO), a metabolite of L-carnitine and choline, is linked to atherosclerosis and cardiovascular diseases. As TMAO content is very high in fish, we raised the following question: why do Japanese people, who consume lots of fish, show a low risk of atherosclerosis? To address this question, we investigated the effects of TMAO and other L-carnitine-related metabolites on carotid intima–media thickness (IMT). Participants were recruited from a small island and a mountainous region. Plasma L-carnitine, γ-butyrobetaine (γBB), TMAO, trimethyllysine (TML), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) levels were measured using liquid or gas chromatography–mass spectrometry. Plasma L-carnitine concentration was higher in men than in women. TMAO and TML were significantly higher in the residents of the island than in the mountainous people. In multiple linear regression analyses in all participants, TML showed a significant inverse association with max-IMT and plaque score (PS), whereas TMAO did not show any associations. In women, L-carnitine was positively associated with max-IMT and PS. TMAO was correlated with both EPA and DHA levels, implying that fish is a major dietary source of TMAO in Japanese people. Our study found that plasma TMAO was not an apparent risk factor for atherosclerosis in elderly Japanese people, whereas a low level of TML might be a potential risk. L-carnitine may be a marker for atherosclerosis in women

Effects of synthesized peptides on the SSPE virus in nude mice.

<p>(A) 24 nude mice (n = 6 for per group) were intracranially infected with the SSPE Yamagata-1 strain and administered M1, M2EK, or enfuvirtide. Control mice were administered minimal essential medium alone. The difference in the survival rate of mice receiving M2EK was statistically significant compared with that of control mice, whereas there was no statistically significant difference in survival rate between other pairwise groups (<i>P</i> < 0.05, log rank test for survival curves; post-hoc comparisons with Tukey’s test). (B) 15 nude mice (n = 5 per group) were intracranially infected with the SSPE Yamagata-1 strain and administered M1, M2EK, or enfuvirtide. Viral RNA copies in each entire brain were quantified on day 14 post-infection. Error bars indicate the standard error of the mean. *<i>P</i> < 0.05; Kruskal–Wallis test, Steel–Dwass post-hoc test.</p

Effects of the novel peptide on PFU at different stages of virus infection.

<p>The synthetic peptides M1 and M2EK were added at three distinct time points: prior to infection (pretreatment), at the same time as virus infection, or post-infection (post-entry). (A) Effects of each peptide administration prior to or at the same time as virus infection: There was no statistically significant difference in viral plaque numbers between groups or peptides. The experiments were performed in duplicate, three times independently and error bars represent the standard deviation of the means. (B) Effect of each peptide administration post-infection: The starting point when cells were incubated at 0°C for 30 min was defined as t0. The vertical axis represents the percentage of plaque forming units (PFUs) for the control group in both figure panels. Both peptide inhibited viral replication during the viral fusion stage but not during the adsorption stage. The error bars indicate the standard deviation of three independent experiments, each performed in duplicate.</p

Effects of synthesized peptides on the measles and SSPE viruses.

<p>Effects of synthesized peptides on the measles and SSPE viruses.</p

Fusion protein of the measles virus and HIV-1 and amino acid sequences of measles virus heptad repeat (HR) regions.

<p>(A) A schematic of the HIV-1 transmembrane protein and measles virus fusion protein showing the locations of structurally significant domains, including the HR region. There are structural and functional similarities between the measles virus and HIV-1 virus. Amino acid sequence data for the measles virus HR1 region (positions 145–184) (B) and the HR2 region (positions 445–493) (C). Amino acid sequence data on measles virus strains were selected based on Measles Surveillance Data of World Health Organization that were currently active measles virus clades worldwide. (<a href="http://www.who.int/immunization/monitoring_surveillance/burden/vpd/surveillance_type/active/measles_monthlydata/en/" target="_blank">http://www.who.int/immunization/monitoring_surveillance/burden/vpd/surveillance_type/active/measles_monthlydata/en/</a>) The letters in red show the amino acid substitution points compared with the Edmonston strain. The amino acid sequences in the lower column represent those of the HR regions of the Edmonston and SSPE Yamagata-1 strains used in our experiments. The amino acid position numbers shown here relate to the MV Edmonston strain sequence, which is available in the UniProtKB/Swiss-Prot database under accession number P69353. The amino acid sequences of other viruses were derived from the GenBank and DDBJ databases under the following accession numbers: New Jersey.USA/45.05, JN635408; Treviso.ITA/03.10/1, KC164757; Virginia.USA/15.09, JN635404.1; Venice.ITA/06.11/1, KC164758; Pennsylvania.USA/20.09, JN635411; Kobe-1, AB254456; OSA-1, AF179433; OSA-2, AF179436; Kitaken, AB453046; and Yamagata-1, D10548.</p

Time course of SSPE virus-infected nude mouse model.

<p>(A) The brains of nude mice were harvested 3 h after 30 μl intracranial hematoxylin or normal saline administration. Hematoxylin was found to have spread beneath the subarachnoid space. (B) Nude mice exhibited weight loss 2–3 days before death and died 16–31 days after virus inoculation. Neurological symptoms were observed shortly before or at the same time as weight loss began; typical neurological symptoms in nude mice were sudden jumps, convulsions, hypersensibility, and gait disorder, but the degree of these symptoms was different for each mouse.</p