A Single-Step Asymmetric Phosphodiester Synthesis from Alcohols with Phosphoenolpyruvate Phosphodiester

Phosphodiesters are important structural motifs observed in a diverse field of molecular science. It is, thus, important to develop a simple and robust way to synthesize them from corresponding alcohols. Here we report a single-step asymmetric phosphodiester synthesis from alcohols with phosphoenolpyruvate phosphodiesters as phosphoryl donors. This transformation allows for the use of various functionalized alcohols as substrates, and would be useful for diverse fields including biology and medicine.

Axially-substituted silicon phthalocyanine payloads for antibody-drug conjugates

IR700, a silicon phthalocyanine (SiPc) photosensitizer, is an antibody-drug conjugate payload used clinically. It is, however, the sole SiPc payload to date, possibly due to the difficulty of its synthesis, resulting from its asymmetric phathalocyanine skeleton. Here we report a new axially-substituted SiPc payload with easier synthesis. Trastuzumab conjugated with the SiPc showed light- and antigen-dependent cytotoxicity in HER2-overexpressed cancer cell lines.

Chemical Catalysis Intervening to Histone Epigenetics

Life emerges from complicated and sophisticated chemical networks comprising numerous biomolecules (e.g., nucleic acids, proteins, sugars, and lipids) and chemical reactions catalyzed by enzymes. Dysregulation of these chemical networks is linked to the emergence of diseases. Our research goal is to develop abiotic chemical catalysts that can intervene into life's chemical networks by complementing, surrogating, or exceeding enzymes in living cells or multicellular organisms such as animals or plants. Mending dysregulated networks in pathological states by the chemical catalysts will lead to a new medicinal strategy, catalysis medicine. This research direction will also advance catalysis science, because highly active and selective chemical catalysts must be developed to promote the intended reactions in a complex mixture of life in aqueous solution at body temperature.Epigenetics exists at the crossroads of chemistry, biology, and medicine and is a suitable field to pursue this idea. Post-translational modifications (PTMs) of histones epigenetically regulate chromatin functions and gene transcription and are intimately related to various diseases. Investigating the functions and cross-talk of histone PTMs is crucial for mechanistic elucidation of diseases and their treatments. We launched a program to develop chemical catalysts enabling endogenous histone modifications in living cells without relying on enzymes. We reported two types of chemical catalyst systems so far for synthetic histone acylation. The first system comprised a DNA-binding oligo-4-dimethylaminopyridine (DMAP) catalyst and a phenyl ester acyl donor, PAc-gly. This system promoted histone hyperacetylation in Xenopus laevis sperm chromatin. Using the thus-synthesized hyperacetylated sperm chromatin, we found a novel relationship between histone acetylation and DNA replication. The second system involved a histone-binding catalyst, LANA-DSH, composed of a catalytic motif (DSH) and a histone-binding peptide ligand (LANA), and thioester acyl donors, including endogenous acyl-CoA. This system regioselectively (i.e., selectively to a lysine residue at a specific position) acylated lysine 120 of histone H2B (H2BK120), a lysine residue proximal to the DSH motif defined by binding of the LANA ligand to a nucleosome substrate. This catalyst system was optimized to achieve H2BK120-selective acetylation in living cells without genetic manipulation. The synthetically introduced H2BK120Ac inhibited enzyme-catalyzed ubiquitination at the same lysine residue, acting as a protecting group. H2BK120Ub is a mark recognized by methyltransferase that plays an essential role in mixed-lineage leukemia (MLL)-rearranged leukemia, suggesting the potential of the catalyst system as an epigenetic tool and a cancer therapy. We also discuss the prospects of chemical catalyst-promoted synthetic epigenetics for future PTM studies and therapeutic uses.

Photo-oxygenation by a biocompatible catalyst reduces amyloid-β levels in Alzheimer's disease mice

Amyloid formation and the deposition of the amyloid-β peptide are hallmarks of Alzheimer's disease pathogenesis. Immunotherapies using anti-amyloid-β antibodies have been highlighted as a promising approach for the prevention and treatment of Alzheimer's disease by enhancing microglial clearance of amyloid-β peptide. However, the efficiency of antibody delivery into the brain is limited, and therefore an alternative strategy to facilitate the clearance of brain amyloid is needed. We previously developed an artificial photo-oxygenation system using a low molecular weight catalytic compound. The photocatalyst specifically attached oxygen atoms to amyloids upon irradiation with light, and successfully reduced the neurotoxicity of aggregated amyloid-β via inhibition of amyloid formation. However, the therapeutic effect and mode of actions of the photo-oxygenation system in vivo remained unclear. In this study, we demonstrate that photo-oxygenation facilitates the clearance of aggregated amyloid-β from the brains of living Alzheimer's disease model mice, and enhances the microglial degradation of amyloid-β peptide. These results suggest that photo-oxygenation may represent a novel anti-amyloid-β strategy in Alzheimer's disease, which is compatible with immunotherapy.

Targeted inhibition of EPAS1-driven IL-31 production by a small-molecule compound

BACKGROUND

IL-31 is a major pruritogen associated with atopic dermatitis (AD). Although a specific antibody for IL-31 receptor has been shown to alleviate pruritus in patients with AD, therapeutic approaches to inhibition of IL-31 production remain unexploited. IL-31 production by T_H cells critically depends on the transcription factor EPAS1, which mediates IL31 promoter activation in collaboration with SP1.

OBJECTIVE

We aimed at developing small-molecule inhibitors that selectively block IL-31 production by T_H cells.

METHODS

We generated the reporter cell line that inducibly expressed EPAS1 in the presence of doxycycline to mediate Il31 promoter activation, and we screened 9600 chemical compounds. The selected compounds were further examined by using T_H cells from a spontaneous mouse model of AD and T_H cells from patients with AD.

RESULTS

We have identified 4-(2-(4-isopropylbenzylidene)hydrazineyl)benzoic acid (IPHBA) as an inhibitor of IL31 induction. Although IPHBA did not affect nonspecific T-cell proliferation, IPHBA inhibited antigen-induced IL-31 production by T_H cells from both an AD mouse model and patients with AD without affecting other cytokine production and hypoxic responses. In line with this, itch responses induced by adoptive transfer of IL-31-producing T_H cells were attenuated when mice were orally treated with IPHBA. Mechanistically, IPHBA inhibited the association between EPAS1 and SP1, resulting in defective recruitment of both transcription factors to the specific sites of the IL31 promoter. We also determined the structure-activity relationship of IPHBA by synthesizing and analyzing 201 analogous compounds.

CONCLUSION

IPHBA could be a potential drug leading to inhibition of EPAS1-driven IL-31 production.

Catalytic photooxygenation degrades brain Aβ in vivo

Protein degradation induced by small molecules by recruiting endogenous protein degradation systems, such as ubiquitin-proteasome systems, to disease-related proteins is an emerging concept to inhibit the function of undruggable proteins. Protein targets without reliable ligands and/or existing outside the cells where ubiquitin-proteasome systems do not exist, however, are beyond the scope of currently available protein degradation strategies. Here, we disclose photooxygenation catalyst 7 that permeates the blood-brain barrier and selectively and directly degrades an extracellular Alzheimer's disease-related undruggable protein, amyloid-β protein (Aβ). Key was the identification of a compact but orange color visible light-activatable chemical catalyst whose activity can be switched on/off according to its molecular mobility, thereby ensuring high selectivity for aggregated Aβ. Chemical catalyst-promoted protein degradation can be applied universally for attenuating extracellular amyloids and various pathogenic proteins and is thus a new entry to induced protein degradation strategies.

Introduction to hybrid catalysis

Motomu Kanai and Matthias Beller introduce the Organic & Biomolecular Chemistry themed issue on hybrid catalysis.

Live-cell epigenome manipulation by synthetic histone acetylation catalyst system

Chemical modifications of histones, such as lysine acetylation and ubiquitination, play pivotal roles in epigenetic regulation of gene expression. Methods to alter the epigenome thus hold promise as tools for elucidating epigenetic mechanisms and as therapeutics. However, an entirely chemical method to introduce histone modifications in living cells without genetic manipulation is unprecedented. Here, we developed a chemical catalyst, PEG-LANA-DSSMe 11, that binds with nucleosome's acidic patch and promotes regioselective, synthetic histone acetylation at H2BK120 in living cells. The size of polyethylene glycol in the catalyst was a critical determinant for its in-cell metabolic stability, binding affinity to histones, and high activity. The synthetic acetylation promoted by 11 without genetic manipulation competed with and suppressed physiological H2B ubiquitination, a mark regulating chromatin functions, such as transcription and DNA damage response. Thus, the chemical catalyst will be a useful tool to manipulate epigenome for unraveling epigenetic mechanisms in living cells.

Integrating abiotic chemical catalysis and enzymatic catalysis in living cells

We review hybrid systems of abiotic catalysis and enzymatic catalysis, which function in living cells. This research direction will stimulate multidisciplinary fields, including complex molecule synthesis, energy production, and life science.

Chromium-Catalyzed Linear-Selective Alkylation of Aldehydes with Alkenes

We developed a chromium-catalyzed, photochemical, and linear-selective alkylation of aldehydes with alkylzirconium species generated in situ from a wide range of alkenes and Schwartz's reagent. Photochemical homolysis of the C-Zr bond afforded alkyl radicals, which were then trapped by a chromium complex catalyst to generate the alkylchromium(III) species for polar addition to aldehydes. The reaction proceeded with high functional group tolerance at ambient temperature under visible-light irradiation.

Time interval from left ventricular stimulation to QRS onset is a predictor of mortality in patients with cardiac resynchronization therapy

Introduction

In our previous report, the time interval from left ventricular (LV) pacing to the earliest onset of QRS (S-QRS interval) has been found to be an independent predictor of mechanical response to cardiac resynchronization therapy (CRT). The S-QRS interval may indicate the conduction disturbance relevant to the localized tissue property such as scar or fibrotic lesion. Therefore, S-QRS interval longer than 37ms was associated with poor response to CRT, and proposed as suboptimal LV lead position. Then, we hypothesized that the longer S-QRS interval at the LV pacing site could be related to long term mortality and heart failure events in patients with CRT.

Methods

This retrospective study included 82 consecutive heart failure patients with sinus rhythm, reduced LV ejection fraction (≤35%), and a wide QRS complex (≥120ms), who undergone CRT implantation between 2012 January and 2017 December. Patients were divided into Short S-QRS group (<37ms, SS-QRS) and Long S-QRS group (≥37ms, LS-QRS) according to the previously reported optimal cut off value. A responder was defined as one with ≥15% reduction in LV end-systolic volume assessed by echocardiography at 6 months after CRT. The primary endpoint was total mortality, which included LV assist device implantation or heart transplantation. The secondary endpoints included the composite endpoint of total mortality or heart failure hospitalization.

Results

The study patients were divided into SS-QRS (N=43, age 65.9±13.2 years, 77% male) and LS-QRS (N=39, age 63.0±13.4, 85% male). In the electrocardiographic measurements, there were no significant differences in baseline QRS duration (162.4±30.3ms in SS-QRS vs. 154.5±31.6ms in LS-QRS, P=0.19) and LV local activation time assessed as Q-LV interval (118.3±34.3ms in SS-QRS vs. 115.3±32.0ms in LS-QRS, P=0.71). S-QRS interval was 25.9±5.3ms in SS-QRS and 51.5±13.7ms in LS-QRS (P<0.01), and the responder rate was significantly higher in SS-QRS compared with LS-QRS (79% vs. 29%, P<0.01). During mean follow up of 47.7±22.4 months, 24 patients (29%) reached to the primary endpoint, while the secondary endpoints were observed in 47 patients (57%). LS-QRS patients had significantly worse event-free survival for both primary and secondary endpoints (Figure). After the multivariate Cox regression analysis, LS-QRS (≥37ms) was an independent predictor of total mortality (HR=2.6, 95% CI: 1.11 to 6.12, P=0.03) and the secondary composite events (HR=2.4, 95% CI: 1.31 to 4.33, P<0.01).

Conclusion

The S-QRS interval longer than 37ms, which may reflect the conduction disturbance relevant to the scar or fibrotic lesion at the LV pacing site, was a significant predictor of the total mortality and heart failure hospitalization. These findings have implications for the optimal LV lead placement in patients with CRT device.

Clinical outcomes according to S-QRS

Funding Acknowledgement

Type of funding source: None

Prognostic impact of free-fat mass index on elderly patients with acute decompensated heart failure: from CURE-HF registry

Background

Free-Fat Mass Index (FFMI) is an indicator of malnutrition and sarcopenia. We hypothesized that low FFMI would be associated with worse prognosis in elderly patients with heart failure.

Methods

In 800 patients who discharged after treatment for HF were prospectively enrolled from 13 medical centers. Free-Fat Mass Index was calculated dividing the square of the patients heights in meters into lean body mass. All-cause mortality (cardiovascular, non-cardiovascular) was followed-up by telephone interview and chart review.

Results

In our study cohort (median age, 78 [range 72–87]), FFMI was 16.7 [15.2, 18.0]. All-cause mortality was observed in 211 patients during 631 [266, 983] days follow-up. In Kaplan-Meier analysis, lower FFMI was associated with all-cause mortality. Furthermore, FFMI was an independent predictor of mortality after adjustment for age, gender, albumin, hemoglobin, creatinine, brain natriuretic peptide, and left ventricular ejection fraction (HR 95% CI: 0.841 (0.745–0.944), p=0.004). In subgroup analysis, low FFMI was associated with both cardiac and non-cardiac mortality in patients with HF with reduced ejection fraction (EF) (Log-rank p=0.002, p=0.013, respectively) (Figure). Furthermore, low FFMI was significantly associated non-cardiac death in patients with preserved EF (Log-rank p=0.033) (Figure).

Conclusions

Free-Fat Mass Index was significantly associated with mortality in elderly patients with HF.

Funding Acknowledgement

Type of funding source: None

Phenotypic difference of sarcopenia in the prediction of mortality for elderly patients with heart failure: from CURE-HF registry

Background

Sarcopenia and malnutrition are associated with mortality in elderly patients with heart failure (HF). However, impact of phenotypic difference of sarcopenia on mortality is not well investigated. We hypothesized that evaluation using both body mass index (BMI) and free-fat mass index (FFMI) enabled distinction of phenotypic difference of sarcopenia and risk stratification for mortality in elderly patients with heart failure.

Methods

In 800 patients who discharged after treatment for HF were prospectively enrolled from 13 medical centers. Body mass index and FFMI was evaluated. Free-fat mass index was calculated dividing the square of the patients' heights in meters into lean body mass. All-cause mortality was followed-up. Patients were divided into 3 subgroups according to BMI and FFMI values, and compared incidence of mortality among them.

Results

In our study cohort (median age, 78 [range 72–87]), BMI was 21.1 [18.9, 23.8] and FFMI was 16.7 [15.2, 18.0]. 211 patients were experienced all-cause mortality during 631 [266, 983] days follow-up. In Kaplan-Meier analysis, lower BMI and lower FFMI was associated with all-cause mortality (Log-rank p<0.001, p<0.001, respectively). Furthermore, FFMI was an independent predictor of adverse events after adjustment for age, gender, albumin, hemoglobin, creatinine, brain natriuretic peptide, and left ventricular ejection fraction (HR 95% CI: 0.841 (0.745–0.944), p=0.004). In subgroup analysis, comparing with low-BMI and low-FFMI subgroup, better prognosis was observed in the other 2 subgroups (Log-rank p<0.001, p=0.022, Figure 1).

Conclusions

Phenotypic difference was evident in elderly patients with HF. A combination of BMI and FFMI would be useful for risk stratification of mortality in those patients.

Figure 1

Funding Acknowledgement

Type of funding source: None

Photocatalytic redox-neutral hydroxyalkylation of N-heteroaromatics with aldehydes

Hydroxyalkylation of N-heteroaromatics with aldehydes was achieved using a binary hybrid catalyst system comprising an acridinium photoredox catalyst and a thiophosphoric acid organocatalyst. The reaction proceeded through the following sequence: (1) photoredox-catalyzed single-electron oxidation of a thiophosphoric acid catalyst to generate a thiyl radical, (2) cleavage of the formyl C-H bond of the aldehyde substrates by a thiyl radical acting as a hydrogen atom transfer catalyst to generate acyl radicals, (3) Minisci-type addition of the resulting acyl radicals to N-heteroaromatics, and (4) a spin-center shift, photoredox-catalyzed single-electron reduction, and protonation to produce secondary alcohol products. This metal-free hybrid catalysis proceeded under mild conditions for a wide range of substrates, including isoquinolines, quinolines, and pyridines as N-heteroaromatics, as well as both aromatic and aliphatic aldehydes, and tolerated various functional groups. The reaction was applicable to late-stage derivatization of drugs and their leads.

Catalytic Allylation of Aldehydes Using Unactivated Alkenes

Simple feedstock organic molecules, especially alkenes, are attractive starting materials in organic synthesis because of their wide availability. Direct utilization of such bulk, inert organic molecules for practical and selective chemical reactions, however, remains limited. Herein, we developed a ternary hybrid catalyst system comprising a photoredox catalyst, a hydrogen-atom-transfer catalyst, and a chromium complex catalyst, enabling catalytic allylation of aldehydes with simple alkenes, including feedstock lower alkenes. The reaction proceeded under visible-light irradiation at room temperature and with high functional group tolerance. The reaction was extended to an asymmetric variant by employing a chiral chromium complex catalyst.

P450The difference in the prognosis among three categories of the post-procedural left ventricular ejection fraction in patients undergoing atrial fibrillation ablation

Funding Acknowledgements

None

Background

Atrial fibrillation (AF) ablation has been known to contribute to a good prognosis in heart failure patients and improve their systolic function. However, the impact of the post-procedural systolic function on the prognosis in them remains unclear. 

Purpose

To investigate the impact of the left ventricular ejection fraction (LVEF) following AF ablation in patients with systolic dysfunction. 

Methods

Out of 1078 consecutive patients who underwent AF ablation including extensive pulmonary vein and superior vena cava isolation, 170 with an impaired pre-procedural LVEF (< 50%) were evaluated. They experienced at least one echocardiographic follow-up within one year after the index procedure. The primary outcome was the composite of all-cause death or heart failure hospitalisations (HFHs). In addition, we categorised the patients into three groups according to the post-procedural LVEF within one year to evaluate the outcome: reduced LVEF (rEF, LVEF < 40%), mid-range EF (mrEF, 40% ≤ LVEF < 50%) and preserved LVEF (pEF, LVEF > 50%). 

Results

After the index procedure, the patients’ LVEF improved with an average increase of 8%, and the post-procedural LVEF consisted of an rEF in 27 (16%), mrEF in 41 (24%), and pEF in 102 (60%) patients. During a median follow-up of 31 months, a total of 22 (13%) patients experienced the composite outcome, including 18 (11%) HFHs and 10 (6%) all-cause deaths (5 with cardiac issues, 2 any malignancies, and 3 other issues). In the Kaplan-Meier analysis using a Bonferroni correction, there was a significant difference in achieving the outcome between the rEF and mrEF, and rEF and pEF, but not between the mrEF and pEF groups (Figure). In a univariate analysis, the hazard ratio of the outcome was shown as follows: an age ≥ 65 years (hazard ratio, HR: 3.4 [95% confidence interval, CI: 1.4–8.5], p = 0.006), history of HFHs for AF (HR: 1.7 [95%CI: 0.7–4.0], p = 0.25), known underlying heart disease (HR: 1.9 [95%CI: 0.8–1.2], p = 0.13), pre-procedural LVEF < 40% (HR: 3.1 [95%CI: 1.3–7.5], p = 0.009), atrial tachyarrhythmia recurrence (HR: 3.0 [95%CI: 1.2–7.8], p = 0.01), and the post-procedural LVEF category (mrEF and rEF, compared with pEF) (HR: 2.0 [95%CI: 0.4–7.7], p = 0.34; and HR: 8.6 [95%CI: 2.7–37.5], p < 0.0001). Furthermore, in a multivariate analysis, patients with a rEF was the sole independent predictor of the composite outcome after adjusting for confounders including an age≥65 years and pre-procedural LVEF < 40% (HR: 12.0 [95%CI: 3.9–40.0], p < 0.0001), whereas those with a mrEF was not (HR: 1.8 [95%CI: 0.4–7.3], p = 0.42), as compared to those with a pEF. 

Conclusions

Patients with a mrEF had a comparable prognosis to those with a pEF in a relatively long follow-up, while those with a rEF had the poorest outcome of the three categories, regardless of the pre-procedural LVEF severity.

Abstract Figure. The difference in the rate of outcome

Synthetic hyperacetylation of nucleosomal histones

We report combinations of a DMAP-based catalyst and phenyl acetate with optimal electron density as a new chemical system for high-yield, selective synthetic acetylation of histone lysine residues. The utility of this chemical system as a unique biologic tool is demonstrated by applying it to Xenopus laevis sperm chromatin.

A chemical catalyst system enabling high-yielding and comprehensive lysine acetylation of nucleosomal histones was developed as an epigenetics tool.

A Bond-Weakening Borinate Catalyst that Improves the Scope of the Photoredox α-C–H Alkylation of Alcohols

The development of catalyst-controlled, site-selective C(sp3)–H functionalization reactions is currently a major challenge in organic synthesis. In this paper, a novel bond-weakening catalyst that recognizes the hydroxy group of alcohols through formation of a borate is described. An electron-deficient borinic acid–ethanolamine complex enhances the chemical yield of the α-C–H alkylation of alcohols when used in conjunction with a photoredox catalyst and a hydrogen atom transfer catalyst under irradiation with visible light. This ternary hybrid catalyst system can, for example, be applied to functional-group-enriched­ peptides.

Sulfanylmethyldimethylaminopyridine as a Useful Thiol Additive for Ligation Chemistry in Peptide/Protein Synthesis

Sulfanylmethyl-installed dimethylaminopyridine, 2-sulfanylmethyl-4-dimethylaminopyridine (2), has an acidic thiol group comparable to that in aryl thiols due to the formation of a zwitterion consisting of a thiolate anion and a pyridinium cation. It can be used as an additive for native chemical ligation. The alkyl thiol in 2 allows it to be used for the one-pot native chemical ligation-desulfurization protocol in peptide synthesis. The utility of 2 in the synthesis of cyclic peptides is demonstrated.

A Stable and Cleavable O-Linked Spacer for Drug Delivery Systems

Anti-cancer chemotherapy with good efficacy and fewer side effects is highly desirable. A drug delivery system comprising a cancer-targeting module and a cytotoxic agent connected with a cleavable linker is promising for reducing side effects. The development of a cleavable linker satisfying the requirements of both stability and cleavability, however, is difficult, especially when a carbonate moiety is used for conjugating the linker to a hydroxy group in a drug of interest. We herein report a new stable linker comprising carbamate and ester spacers, which can be introduced on a hydroxy group of a drug. This linker is more stable in aqueous neutral buffer than a corresponding carbonate-type linker, and releases a payload anti-cancer drug, SN-38, through a two-step sequence upon cathepsin B treatment. This linker may have potential use in other drug delivery systems to lower side effects by selectively transporting cytotoxic drugs to tumor cells.

Synthesis of Tryptophan–Folate Conjugates

A mild protocol for the synthesis of folate–peptide/protein conjugates targeting tryptophan residues is described. This synthetic protocol is advantageous for homogeneous conjugation of chemically sensitive folates to biomolecules, with potential applications in cancer therapy and diagnostics.