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A self-standing micro-cogeneration system was developed by coupling a microcombustor, thermoelectric (TE) modules, and an air supply device. The microcombustor has a porous monolithic Pt catalyst layer, and a combustion efficiency of 90% was achieved. A microblower is used to supply air to the combustor, and it is driven by electricity from the Bi–Te TE modules through a dc–dc converter. We investigated the optimal point where the output became maximal and the system was self-standing. At the optimal point, the input fuel enthalpy was 13.2 W, and 440 mW of electricity was generated from the TE modules. The microblower consumed 280 mW, and the net generated electricity was 160 mW. Therefore, the final thermal efficiency was 1.21%. The net thermal efficiency of the developed system was the same magnitude as that of TeeDee01 (COX Co. Ltd.), the world’s smallest model plane engine (0.163 cc), even though the magnitude of the output power was less than 1/20 in comparison. [ABSTRACT FROM AUTHOR]

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., Materials and Methods: Seven-week-old male Sprague-Dawley rats were used in this study. Rats in the DM and sham groups received intravenous STZ (50 mg/kg) and saline, respectively. One week after treatment, the blood glucose level of rats in the DM group was >250 mg/dL. Five weeks after the treatment, we performed a functional study by measuring intracavernous pressure (ICP) under cavernous nerve stimulation before and after NORD-1 treatment with and without light irradiation. Additionally, we performed an isometric tension study using the corpus cavernosum of rats treated with NORD-1 or the control compound, SiR650., Results: The ICP/mean arterial pressure (MAP) ratio was significantly lower in the DM group than in the sham group before and after NORD-1 treatment without light irradiation (both p<0.05). After NORD-1 treatment with light irradiation, the ICP/MAP ratio in the sham and DM groups was significantly enhanced than before and after NORD-1 treatment without light irradiation (all p<0.05). The ICP/MAP ratio in the DM group after NORD-1 with light irradiation was similar to that in the sham group under normal conditions before NORD-1 treatment. Moreover, the systemic blood pressure was not affected by NORD-1 or light irradiation. In the tension study, the corpus cavernosum of rats treated with SiR650 was not changed by red light in the sham or DM groups. However, the rats treated with NORD-1 were strongly relaxed by red light in both groups., Conclusions: NORD-1 and red-light irradiation could improve ED in the presence of DM without lowering blood pressure., Competing Interests: The authors have nothing to disclose., (Copyright © 2025 Korean Society for Sexual Medicine and Andrology.)

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. In this study, we evaluated the structure-activity relationships of the hit and lead compounds in detail, and succeeded in developing compounds that strongly and selectively inhibit ENPP1 not only in vitro, but also in cellular systems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Fluorescence lymph imaging with indocyanine green (ICG) is widely utilized as diagnostic tool for lymphatic diseases. While this technique offers numerous advantages, the kinetics of ICG at the injection site can pose challenges for a detailed diagnosis. In this study, we synthesized various ICG derivatives possessing cationic, anionic, or uncharged substituents and examined their photochemical properties, binding affinity to human serum albumin, as well as their correlation to pharmacokinetics in mice. The introduction of different substituents not only affected certain physiochemical properties, but also impacted the pharmacokinetics within the lymph nodes. Immunofluorescence imaging suggested that the extent of uptake of the ICG derivatives by phagocytic cells may affect the retention of the contrast ratios in the lymph nodes. These findings can provide new insights in the pharmacokinetics in lymphatic tissues, which could be useful for the development of novel fluorescent agents for lymph imaging., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

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. With the main goal of developing X-ray activatable caged compounds, azo compounds are designed and synthesized with a positive charge and long π-conjugated system to increase the reaction efficiency with hydrated electrons. The azo bonds in the designed compounds are selectively cleaved by X-ray, and the fluorescent substance Diethyl Rhodamine is released. Based on the results of experiments and quantum chemical calculations, azo bond cleavage is assumed to occur via a two-step process: a two-electron reduction of the azo bond followed by N─N bond cleavage. Cellular experiments also demonstrate that the azo bonds can be cleaved intracellularly. Thus, caged compounds that can be activated by an azo bond cleavage reaction promoted by X-ray are successfully generated., (© 2024 The Authors. Advanced Science published by Wiley‐VCH GmbH.)

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. However, short half-life and systemic side effects are problems of NO application in ED therapy. To avert these problems, we developed a red-light controllable NO releaser, NORD-1. This study aimed to investigate the effect of NORD-1 and red-light irradiation on neurogenic ED using a rat model of bilateral cavernous nerve injury (BCNI)., Materials and Methods: BCNI and sham operations were conducted on 8-week-old rats. After 4 weeks, erectile function was evaluated using changes in intracavernous pressure (ICP) during electrostimulation of the cavernous nerve. ICP was measured under three conditions; without NORD-1 and red-light irradiation, with NORD-1 and without red-light irradiation, and with NORD-1 and red-light irradiation. SiR650 which absorbs red-light but does not release NO was used for the negative control. After the experiment, localization of NORD-1 was observed using a microscope., Results: Erectile function in a BCNI rat model was significantly decreased compared to sham-operated rats (p<0.05). After injecting NORD-1 into the penis, erectile function did not change without red-light irradiation. However, the combination of NORD-1 and red-light irradiation significantly improved erectile function (p<0.05) without affecting systemic arterial pressure. In contrast, when SiR650 was used, erectile function did not change in all three conditions. NORD-1 was detected only in the corpus cavernosum and not in the urethra and dorsal vein., Conclusions: NORD-1 combined with red-light irradiation is effective for ED induced by cavernous nerve injury. This treatment may have low risks of hypotension and urinary incontinence, and it can replace the current treatment for post-RP ED., Competing Interests: The authors have nothing to disclose., (Copyright © 2023 Korean Society for Sexual Medicine and Andrology.)

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. ESR experiments indicate that the photolysis mechanism is based on intramolecular photoinduced electron transfer. We illustrate the applicability of the BPc group to biologically active compounds by employing it firstly to photocontrol release of histamine, and secondly to photocontrol release of a soluble guanylyl cyclase (sGC) activator, GSK2181236A, which induces photovasodilation. The BPc group is expected to be a useful PPG for controlling various biological events with blue light irradiation., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

We present an optochemical O 2 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 2 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 %. The spatiotemporal O 2 consuming in cultured cells was visualized with a hypoxia-responsive fluorescence probe, MAR. Phosphorescence lifetime imaging was applied to confirmed that different light intensities could generate different levels of hypoxia. To illustrate the potential utility of this system for hypoxia research, we show that it can spatiotemporally control calcium ion (Ca 2+ ) influx into HEK293T cells expressing the hypoxia-responsive Ca 2+ channel TRPA1., (© 2023 Wiley-VCH GmbH.)

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 N -nitrosoaminophenol structure as an NO-releasing moiety. Here, we aimed to construct an NO-generating system employing an intermolecular photoredox reaction between the two separate components, since this would simplify chemical synthesis and make it easier to examine various dyes as antennae. For this purpose, we constructed polymer nanoparticles doped with both N -methyl- N -nitroso-4-aminophenol (NAP, 1) and an Ir(III) antenna complex (2, 3 or 4) in order to dissolve in aqueous solution without a co-solvent. These polymer nanoparticles released NO upon photoirradiation in vitro in the purple (400-430 nm) or blue (400-460 nm) wavelength region to activate the doped Ir(III) complex.

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. In this paper, we investigated substituent effects at the 2-position of the N-nitrosoaminophenol moiety by means of spectroscopic, fluorescence, and NO-release measurements. Interestingly, a methyl substituent at this position had no significant effect on the NO-releasing ability, while a nitro group or a methoxy group reduced it. The nitro group may suppress electron transfer to the antenna moiety, while the methoxy group may accelerate electron transfer but suppress deprotonation to afford the phenoxyl radical, which is the key reaction for release of NO. These structure-activity relationships should be helpful for further functionalizing PeT-driven NO releasers.

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. The ester moiety is cleaved by ubiquitous intracellular esterases, and then, FHIT in the cells specifically cleaves nucleoside monophosphate. The remaining phosphate moiety is rapidly cleaved by ubiquitous intracellular phosphatases to release the fluorescent dye. We confirmed that this probe can detect FHIT activity in living cells. A comprehensive evaluation of the effects of various ester moieties revealed that probes with CLogP = 5-7 showed good membrane permeability and were good substrates of the target enzyme; these findings may be helpful in the rational design of other multiple phosphate-containing probes targeting intracellular enzymes.

We found that N -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 N -nitrosoaminoanisole derivative 2 worked as a more potent photovasodilating reagent ex vivo than previously reported nitric oxide releasers.

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 -4  M NORD-1 into the bladders of NORD-1 and NORD-1+ODQ group rats and the vehicle into those of vehicle group rats. Isometric tension was analyzed using circular bladder neck specimens with 10 -5  M N G -nitro-l-arginine methyl ester, an NO synthase inhibitor. Moreover, 10 -5  M ODQ was added into the NORD-1+ODQ group bath. After precontraction with 10 -5  M carbachol, the specimens were irradiated with red light and their relaxation responses were measured. We evaluated NORD-1 tissue permeability by observing the sliced bladder neck specimens. The NORD-1 group specimens relaxed during red light irradiation; the relaxation response increased with the increase in light intensity. The vehicle and NORD-1+ODQ group specimens did not respond to irradiation. Sex-related differences in responsiveness were not noted. NORD-1 permeated into the urothelium of NORD-1 group specimens. Rat bladder neck relaxation was controlled by NORD-1 and light irradiation in vitro. NORD-1 might be a novel therapeutic agent for voiding dysfunction., Competing Interests: Declaration of competing interest There are no conflicts of interest to declare., (Copyright © 2021 The Authors. Production and hosting by Elsevier B.V. All rights reserved.)

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 FHIT is one candidate. The gene product, FHIT protein, has a unique dinucleoside triphosphate hydrolase (AP 3 Aase) 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. Screening of a compound library with this assay identified several hits. Structural development of a hit compound afforded potent FHIT inhibitors. These inhibitors induce apoptosis in FHIT-expressing cancers via caspase activation. Our results support the idea that FHIT binders, no matter whether inhibitors or agonists of AP 3 Aase activity, might be promising anticancer agents.

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. Scanning of this set of probes with SIRT isozymes revealed that certain probe/isozyme combinations showed especially high responses. To illustrate the utility of the combinations thus identified, we applied compound 18 /SIRT2 for inhibitor screening of a large chemical library. This enabled us to discover a new small molecule SIRT2-specific defatty-acylase inhibitor., Competing Interests: The authors declare no competing financial interest., (© 2021 American Chemical Society.)

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 656 nm ·Φ NO ) of NORD-1 was calculated to be 3.65 × 10 2 , which is larger than that of a previously reported yellowish-green-light-controllable NO releaser, NO-Rosa5. The photoresponsiveness of NO release from NORD-1 was precise and efficient enough to induce vasodilation ex vivo under Magnus test conditions. Finally, we showed that intracavernous pressure (ICP) could be controlled in rats in vivo with the combination of NORD-1 and a red-light source without increasing systemic blood pressure, which is a serious side effect of usual NO releasers, such as nitroglycerin and isopentyl nitrite. NORD-1 is expected to be a useful chemical tool for NO research, as well as a candidate agent to control the circulatory system.

Pulsatile gonadotropin-releasing hormone (GnRH) secretion is essential for regulating reproductive functions in mammals. GnRH pulses are governed by a neural mechanism that is termed the GnRH pulse generator. In the present study, we investigated the role of central calcitonin receptor (CTR) signaling in the regulation of the GnRH pulse generator activity in ovariectomized goats by administering amylin, an endogenous ligand for CTR, into the lateral ventricle. GnRH pulse generator activity was measured using multiple unit activity (MUA) recordings in the mediobasal hypothalamus. We analyzed changes in the interval of characteristic increases in MUA (MUA volleys). The MUA volley interval shortened immediately after amylin administration, followed by prolonged intervals. Double in situ hybridization for KISS1 (kisspeptin gene) and CALCR (CTR gene) revealed that low expression levels of CALCR were found in the arcuate kisspeptin neurons, which is suggested as the main population of neurons, involved in GnRH pulse generator activity. These results suggest that central amylin-CTR signaling has a biphasic role in the regulation of GnRH pulse generator activity by acting on cells other than the arcuate kisspeptin neurons in goats., (Copyright © 2020 Elsevier B.V. All rights reserved.)

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 2 , H3K9Me/Me 2 ) to control chromatin structure, resulting in transcriptional repression or activation of target genes. Furthermore, LSD1 is overexpressed in various cancers. Therefore, LSD1 inhibitors would be not only potential therapeutic agents for cancers but also chemical tools to research biological significance of LSD1 in physiological and pathological events. However, known assay methods to date have some inherent drawbacks. The development of simple method in detecting LSD1 activity has been indispensable to identify useful inhibitors. In this study, we designed and synthesized artificial substrates based on inhibitors of LSD1 to examine LSD1 activity by an absorption increment., Competing Interests: No potential conflicts of interest were disclosed., (Copyright © 2020 JCBN.)

Accumulating evidence suggests that kisspeptin neurons in the arcuate nucleus (ARC), which coexpress neurokinin B and dynorphin, are involved in gonadotropin-releasing hormone (GnRH)/luteinizing hormone (LH) pulse generation, while the anteroventral periventricular nucleus (AVPV) kisspeptin neurons are responsible for GnRH/LH surge generation. The present study aims to examine whether GnRH(1-5), a GnRH metabolite, regulates LH release via kisspeptin neurons. GnRH(1-5) was intracerebroventricularly injected to ovariectomized and estrogen-treated Wistar-Imamichi female rats. Immediately after the central GnRH(1-5) administration at 2 nmol, plasma LH concentration increased, resulting in significantly higher levels of the area under the curve and baseline of plasma LH concentrations compared to vehicle-injected controls. On the other hand, in Kiss1 knockout rats, GnRH(1-5) administration failed to affect LH secretion, suggesting that the facilitatory effect of GnRH(1-5) on LH release is mediated by kisspeptin neurons. Double in situ hybridization (ISH) for Kiss1 and Gpr101, a GnRH(1-5) receptor gene, revealed that few Kiss1-expressing cells coexpress Gpr101 in both ARC and AVPV. On the other hand, double ISH for Gpr101 and Slc17a6, a glutamatergic marker gene, revealed that 29.2% of ARC Gpr101-expressing cells coexpress Slc17a6. Further, most of the AVPV and ARC Kiss1-expressing cells coexpress Grin1, a gene encoding a subunit of NMDA receptor. Taken together, these results suggest that the GnRH(1-5)-GPR101 signaling facilitates LH release via indirect activation of kisspeptin neurons and that glutamatergic neurons may mediate the signaling. This provides a new aspect of kisspeptin- and GnRH-neuronal communication with the presence of stimulation from GnRH to kisspeptin neurons in female rats.

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. This article shows how to synthesize visible-light controllable NO releasers based on N-nitrosoaminophenol structure, evaluate NO releasing efficiency in various methods, and apply them for biological experiments., (© 2020 Elsevier Inc. All rights reserved.)

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. Since trypsin specifically hydrolyzes the arginine residue, but not a monomethylarginine or dimethylarginine residue, CARM1 activity can be evaluated from the change of the coumarin/fluorescein fluorescence ratio of FRC in the presence of trypsin., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

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. We used it to screen a chemical library for non-phosphate ENPP1 inhibitors. Structural optimization of a selected hit afforded a potent and specific ENPP1 inhibitor. We further found that ENPP1 mRNA expression in tissue samples from patients with triple-negative breast cancer was significantly inversely related to recurrence-free survival (RFS) and overall survival (OS), and TG-mAMP assay revealed a significant difference in ENPP1 activity between ENPP1 high-expressing and ENPP1 low-expressing samples. Our results suggest that TG-mAMP assay might be a rapid and inexpensive tool for predicting the prognosis of patients with malignant breast cancers.

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.

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. We further utilized this finding to develop the first inhibitors of SIRT2 defatty-acylase activity. Notably, most previously reported sirtuin inhibitors, including compound TM, AGK2, and SirReal2, showed almost no SIRT2 defatty-acylase-inhibitory activity, but are essentially specific deacetylase inhibitors. These results suggest that the active sites catalyzing the deacetylase and defatty-acylase activities of sirtuins may be independent.

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. We synthesized and functionally evaluated a series of probes bearing substituents on the benzil phenyl group, and found that 4MEBz-FluME could successfully detect citrulline with higher sensitivity and broader dynamic range than our previously reported fluorescence probe, FGME. Moreover, we succeeded in establishing multiple assay systems for PAD subtypes activities, including PAD2 and PAD4, with 4MeBz-FluME thanks to its high sensitivity. We expect that our fluorescence probes will become a powerful tool for discovering PAD inhibitors of several subtypes. Thus, it should be suitable for high-throughput screening of chemical libraries for inhibitors of PADs., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

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. Notably, substitution at the phenolic hydroxyl group blocked NO release. We synthesized NO-Rosa-Gal bearing D-galactose (Gal) at this location, and showed that hydrolysis by β-galactosidase restored the photoresponse. This represents proof-of-concept of a strategy for highly specific control of NO release by using a double-lock system involving both enzymatic reactivation and photo-control.