[1,2,4]Triazolo[1,5-a]pyrimidine derivatives: Structure-activity relationship study leading to highly selective ENPP1 inhibitors.

The STING (stimulator of interferon genes) pathway is one of the pathways that regulate innate immunity, and the extracellular hydrolytic enzyme ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) has been identified as its dominant negative regulator. Since activation of the innate immune system is a promising strategy for the treatment of various infectious diseases and cancers, ENPP1 inhibitors have attracted great attention as candidate drugs. We have previously identified small-molecule ENPP1 inhibitors having a [1,2,4]triazolo[1,5-a]pyrimidine scaffold by means of chemical screening using a fluorescence probe, TG-mAMP.

The Effects of a Red-Light Controllable Nitric Oxide Donor, NORD-1, on Erectile Dysfunction in Rats with Streptozotocin Induced Diabetes Mellitus.

Purpose: Patients with diabetes mellitus (DM) often exhibit refractory erectile dysfunction (ED). Red-light-controllable nitric oxide donor (NORD-1) and red-light irradiation have successfully enhanced erectile function in intact rats. In this study, we investigated whether the combination of NORD-1 and red-light irradiation effectively treated ED in streptozotocin (STZ)-treated rats with DM.

Theoretical Design and Synthesis of Caged Compounds Using X-Ray-Triggered Azo Bond Cleavage.

Caged compounds are frequently used in life science research. However, the light used to activate them is commonly absorbed and scattered by biological materials, limiting their use to basic research in cells or small animals. In contrast, hard X-rays exhibit high bio-permeability due to the difficulty of interacting with biological molecules.

A BODIPY-picolinium-cation conjugate as a blue-light-responsive caged group.

Caged compounds protected with photolabile protecting groups (PPGs) are useful for controlling various biological events with high spatiotemporal resolution. Most of the commonly used PPGs are controlled by ultraviolet light irradiation, but it is desirable to have PPGs controlled by visible light irradiation in order to minimize tissue damage. Here, we describe a boron-dipyrromethene (BODIPY)-picolinium conjugate (BPc group) that functions as a blue-light-controllable PPG.

Substituent Effects at the N-Nitrosoaminophenol Moiety of a Photoinduced-Electron-Transfer-Driven Nitric Oxide Releaser.

Nitric oxide (NO) has multiple physiological activities, including roles in vasorelaxation, neurotransmission, and immune response. Indeed, NO-releasing compounds are utilized as therapeutic agents for cardiovascular diseases based on the potent and rapid vasorelaxation induced by NO. We have developed a series of photoinduced-electron-transfer-driven (PeT-driven) NO releasers composed of a light-harvesting antenna moiety and an NO-releasing N-nitrosoaminophenol moiety, which efficiently release NO upon irradiation with blue (500 nm), green (560 nm), or red (650 nm) light.

Photoinduced NO-release from polymer dots doped with an Ir(III) complex and -methyl--nitroso-4-aminophenol.

Nitric oxide (NO) is a signaling molecule that plays a variety of functions in the human body, but it is difficult to use it in biological experiments or for therapeutic purposes because of its high reactivity and instability in the biological milieu. Consequently, photocontrollable NO releasers, which enable spatiotemporal control of NO release, have an important role in elucidating the functions of NO. Our group has developed visible-light-controllable NO-releasing molecules that contain a fluorescent dye structure as a light-harvesting antenna moiety and an -nitrosoaminophenol structure as an NO-releasing moiety.

An Optochemical Oxygen Scavenger Enabling Spatiotemporal Control of Hypoxia.

We present an optochemical O scavenging system that enables precise spatiotemporal control of the level of hypoxia in living cells simply by adjusting the light intensity in the illuminated region. The system employs rhodamine containing a selenium or tellurium atom as an optochemical oxygen scavenger that rapidly consumes O by photochemical reaction with glutathione as a coreductant upon visible light irradiation (560-590 nm) and has a rapid response time, within a few minutes. The glutathione-consuming quantum yields of the system were calculated as about 5 %.

Efficacy of a Red-Light Controllable Nitric Oxide Releaser for Neurogenic Erectile Dysfunction: A Study Using a Rat Model of Cavernous Nerve Injury.

Purpose: Neurogenic erectile dysfunction (ED) is a common side effect of radical prostatectomy (RP) because of cavernous nerve damage. In these patients, the production of nitric oxide (NO), which is important for erection, is decreased in the corpus cavernosum. Therefore, NO donors are useful for post-RP ED.

Development of Nucleoside Diphosphate-Bearing Fragile Histidine Triad-Imaging Fluorescence Probes with Well-Tuned Hydrophobicity for Intracellular Delivery.

Fluorescence-guided cancer surgery can dramatically improve recurrence rates and postoperative quality of life of patients by accurately distinguishing the boundary between normal and cancer tissues during surgery, thereby minimizing excision of normal tissue. One promising target in early stage cancer is fragile histidine triad (FHIT), a cancer suppressor protein with dinucleoside triphosphate hydrolase activity. In this study, we have developed fluorescence probes containing a nucleoside diphosphate moiety, which dramatically improves the reactivity and specificity for FHIT, and a moderately lipophilic ester moiety to increase the membrane permeability.

Ascorbate-assisted nitric oxide release from photocontrollable nitrosonium ion releasers for potent photovasodilation.

We found that -nitrosoaminoanisole derivatives tethered to dyes work as photocontrollable nitrosonium cation releasers and are converted to potent nitric oxide releasers in the presence of sodium ascorbate. The -nitrosoaminoanisole derivative 2 worked as a more potent photovasodilating reagent than previously reported nitric oxide releasers.

Synthesis of Fluorescent Probes Targeting Tumor-Suppressor Protein FHIT and Identification of Apoptosis-Inducing FHIT Inhibitors.

For the early diagnosis of cancer, leading to a better chance of full recovery, marker genes whose expression is already altered in precancerous lesions are desirable, and the tumor-suppressor gene is one candidate. The gene product, FHIT protein, has a unique dinucleoside triphosphate hydrolase (APAase) activity, and in this study, we designed and synthesized a series of FHIT fluorescent probes utilizing this activity. We optimized the probe structure for high and specific reactivity with FHIT and applied the optimized probe in a screening assay for FHIT inhibitors.

Control of rat bladder neck relaxation with NORD-1, a red light-reactive nitric oxide releaser: In vitro study.

We aimed to control the relaxation of rat bladder neck specimens by using NORD-1, a red light-reactive nitric oxide (NO) releaser. Female and male 10-11-week-old Wistar/ST rats were divided into three groups: NORD-1, vehicle, and NORD-1+[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; a soluble guanylyl cyclase inhibitor). We infused 10 M NORD-1 into the bladders of NORD-1 and NORD-1+ODQ group rats and the vehicle into those of vehicle group rats.

A Set of Highly Sensitive Sirtuin Fluorescence Probes for Screening Small-Molecular Sirtuin Defatty-Acylase Inhibitors.

Human sirtuins (SIRT1-7) regulate not only deacetylation but also deacylation of fatty acid-derived acyl moieties (defatty-acylation) at the ε-amino group of lysine residues. SIRT-subtype-specific defatty-acylase activity modulators are needed for detailed investigation of the biological roles of these enzymes, and to find suitable small molecules, we require appropriate screening systems. Here, we designed and synthesized a set of SIRT defatty-acylase activity probes with various quencher moieties and peptide sequences based on our previously developed one-step FRET-based SIRT probe SFP3, using improved methodology.

Development of a Red-Light-Controllable Nitric Oxide Releaser to Control Smooth Muscle Relaxation .

We designed and synthesized a novel Si-rhodamine derivative, NORD-1, as a red-light-controllable nitric oxide (NO) releaser, on the basis of photoredox parameter analysis. Red-light-responsive NO release from NORD-1 was confirmed by ESR spin trapping and quantified with an NO electrode and by means of Griess assay. The NO release cross section (ε·Φ) of NORD-1 was calculated to be 3.

Synthesis of artificial substrate based on inhibitor for detecting LSD1 activity.

Lysine methylation is one of the most important modification, which is regulated by histone lysine methyltransferases and histone lysine demethylases. Lysine-specific demethylase 1 (LSD1) specifically demethylates mono- and dimethyl-lysine on histone H3 (H3K4Me/Me, H3K9Me/Me) to control chromatin structure, resulting in transcriptional repression or activation of target genes. Furthermore, LSD1 is overexpressed in various cancers.

Synthesis, evaluation, and biological applications of visible-light-controllable nitric oxide releasers.

Nitric oxide (NO) is biologically synthesized in human body and mediates various signal pathway. Because NO is too unstable to handle for biological assay, NO releasers had been developed for NO research. Among them, light-controllable NO releasers are quite useful tool because their NO release can be spatiotemporally controlled by light irradiation.

Ratiometric assay of CARM1 activity using a FRET-based fluorescent probe.

One of the regulatory mechanisms of epigenetic gene expression is the post-translational methylation of arginine residues, which is catalyzed by protein arginine methyltransferases (PRMTs). Abnormal expression of PRMT4/CARM1, one of the PRMTs, is associated with various diseases, including cancers. Here, we designed and synthesized a Förster resonance energy transfer (FRET)-based probe, FRC, which contains coumarin and fluorescein fluorophores at the N-terminus and C-terminus of a peptide containing an arginine residue within an appropriate amino acid sequence to serve as a substrate of CARM1; the two fluorophores act as a FRET donor and a FRET acceptor, respectively.

Development of an ENPP1 Fluorescence Probe for Inhibitor Screening, Cellular Imaging, and Prognostic Assessment of Malignant Breast Cancer.

Ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) is a type II transmembrane glycoprotein that is involved in bone metabolism and insulin resistance, hydrolyzes 2',3'-cGAMP (a STING ligand that promotes innate immunity), and is associated with cancer stemness in breast cancers and glioblastoma. Therefore, ENPP1 is considered a candidate therapeutic target and/or biomarker for early diagnosis of malignant tumors. In this study, we designed and synthesized a sensitive ENPP1 fluorescence probe, Tokyo Green (TG) mAMP.

In Cellullo and ex Vivo Availability of a Yellowish-Green-Light-Controllable NO Releaser.

Spatiotemporally controllable nitric oxide (NO) releasers are very attractive chemical tools for investigating the biological activities of NO, which is involved in the regulation of vasodilation, neurotransmission, and immune responses. We previously developed an easily synthesized, yellowish-green-light-controllable NO releaser, NO-Rosa5, and characterized its photoredox reaction mechanism. Here, we aimed to establish the biological applicability of NO-Rosa5 for in cellullo and ex vivo experiments.

Cationic axial ligands on sulfur substituted silicon(iv) phthalocyanines: improved hydrophilicity and exceptionally red-shifted absorption into the NIR region.

Herein, we report the exceptionally red-shifted absorption of sulfur-substituted silicon(iv) phthalocyanines upon introduction of cationic axial ligands. The Q band was red-shifted to approximately 900 nm with improved hydrophilicity by the combination of peripheral sulfur substituents and axial ammonium ligands. One such phthalocyanine exhibited remarkable photocytotoxicity upon irradiation with NIR light (∼810 nm) in live cells.

Development of Peptide-Based Sirtuin Defatty-Acylase Inhibitors Identified by the Fluorescence Probe, SFP3, That Can Efficiently Measure Defatty-Acylase Activity of Sirtuin.

Sirtuins (SIRTs) are a family of nicotinamide adenine dinucleotide-dependent histone deacetylases that serve as epigenetic regulators of many physiological processes. Recent studies have shown that in addition to their well-known deacetylase activity, sirtuins also exhibit deacylase activity, such as demyristoylase activity. Here, we show that our previously reported sirtuin fluorescence probe, SFP3, can measure the defatty-acylase activity of SIRT1-3, enabling selective assay of the deacylase activity.

Improving the Fluorescent Probe Acridonylalanine Through a Combination of Theory and Experiment.

Acridonylalanine (Acd) is a useful fluorophore for studying proteins by fluorescence spectroscopy, but it can potentially be improved by being made longer wavelength or brighter. Here, we report the synthesis of Acd core derivatives and their photophysical characterization. We also performed calculations of the absorption and emission spectra of Acd derivatives, which agree well with experimental measurements.

Development of a highly sensitive fluorescence probe for peptidyl arginine deiminase (PAD) activity.

Peptidyl arginine deiminases (PADs) catalyze the post-translational deimination of arginine residues to citrulline residues. Aberrant levels of PAD activity are associated with various diseases, such as rheumatoid arthritis, Alzheimer's disease, and multiple sclerosis, so there is a need for simple and convenient high-throughput screening systems to discover PAD inhibitors as candidate therapeutic agents. Here, we report a highly sensitive off/on-type fluorescence probe for PAD activity based on the donor-excited photoinduced electron transfer (d-PeT) mechanism, utilizing the specific cycloaddition reaction between the benzil group of the probe and the ureido group of the PAD product, citrulline, under acidic conditions.

Structure-efficiency relationship of photoinduced electron transfer-triggered nitric oxide releasers.

Spatiotemporally controllable nitric oxide (NO) releasers are required for biological studies and as candidate therapeutic agents. Here, we investigate the structure-efficiency relationship of a series of photoinduced electron transfer-triggered NO releasers based on our reported yellowish-green light-controllable NO releaser, NO-Rosa. The distance between the NO-releasing N-nitrosoaminophenol moiety and the rosamine antenna moiety was critical for efficient NO release.