Photocontrolled endogenous reactive oxygen species (ROS) generation

Discovery of an SphK1 inhibitor: A hybrid approach involving a receptor–ligand-complex-based pharmacophore and docking-based virtual screening

Sphingosine kinase is a lipid kinase that catalyzes the phosphorylation of sphingosine to sphingosine-1-phosphate. Sphingosine-1-phosphate is a bioactive lipid that regulates biological processes. The overexpression of sphingosine kinases is related to a variety of pathophysiological conditions. For example, SphK1 has been shown to be highly expressed in various cancer cells including ovarian, cervical, colon, stomach, lung, and brain cancer. Inhibition of sphingosine kinases is a promising way to treat diseases such as cancer. Through computer-aided drug design, we have discovered a new SphK1 inhibitor named Amb30572637 (SAMS10). In this report, we describe the discovery process and biological characteristics. In biochemical experiments, SAMS10 shows a prominent inhibitory effect on SphK1, with an IC50 value of 9.8 μM. Subsequent MTT experiments show that SAMS10 has anticancer effects toward A549, SKVO3, A375, and LOVO cell lines and has essentially no cytotoxicity against the healthy cell L929. SAMS10 has significant inhibitory activity against the A549 and LOVO cell lines, with IC50 values of 14.64 and 14.48 μM, respectively. It belongs to a moderately active SphK1 inhibitor with lower anticancer activity than the control compound cisplatin, but the effect of SAMS10 toward SphK1 and its anticancer activity indicate that it is a promising lead compound for the development of effective SphK1 anticancer inhibitors.

Metagenomics insights into the selective inhibition of NOB and comammox by phenacetin: Transcriptional activity, nitrogen metabolism and mechanistic understanding

Phenacetin (PNCT), a common antipyretic and analgesic drug, is often used to treat fever and headache. However, the effect of PNCT on nitrifiers in wastewater treatment processes remains unclear. The practicability of attaining partial nitrification (PN) through inhibitor-PNCT was investigated in this study. The optimal treatment conditions of soaking once for 18 h with 2.50 × 10^-3 g PNCT/(g MLSS) were applied to the PN stability experiment. The results showed that ammonia oxidation activity recovered quickly after 3 cycles of operation, while nitrite oxidation activity was suppressed steadily. In addition, average ammonium removal efficiency and nitrite accumulation ratio during 138 cycles could reach 94.94% and 85.38%, respectively. Complimentary DNA high-throughput sequencing and oligotyping analysis showed that the activity of Nitrosomonas would gradually surpass Nitrospira after PNCT treatment only once. The decrease of Nitrospira activity was accompanied by the simplification of oligotypes after PNCT treatment, while Nitrosomonas could adapt to PNCT stress by reducing the differences between oligotypes. Metagenomics revealed that the decrease in the number of NXR in the nitrogen metabolism pathways was the key reason for achieving PN. The potential mechanisms might be that the dominant nitrite-oxidizing bacteria and complete ammonia oxidizers were bio-killed by PNCT.

Targeted and activatable nanosystem for fluorescent and optoacoustic imaging of immune-mediated inflammatory diseases and therapy via inhibiting NF-κB/NLRP3 pathways

Immune-mediated inflammatory diseases (IMIDs) represent a diverse group of diseases and challenges remain for the current medications. Herein, we present an activatable and targeted nanosystem for detecting and imaging IMIDs foci and treating them through blocking NF-κB/NLRP3 pathways. A ROS-activatable prodrug BH-EGCG is synthesized by coupling a near-infrared chromophore with the NF-κB/NLRP3 inhibitor epigallocatechin-3-gallate (EGCG) through boronate bond which serves as both the fluorescence quencher and ROS-responsive moiety. BH-EGCG molecules readily form stable nanoparticles in aqueous medium, which are then coated with macrophage membrane to ensure the actively-targeting capability toward inflammation sites. Additionally, an antioxidant precursor N-acetylcysteine is co-encapsulated into the coated nanoparticles to afford the nanosystem BH-EGCG&NAC@MM to further improve the anti-inflammatory efficacy. Benefiting from the inflammation-homing effect of the macrophage membrane, the nanosystem delivers payloads (diagnostic probe and therapeutic drugs) to inflammatory lesions more efficiently and releases a chromophore and two drugs upon being triggered by the overexpressed in-situ ROS, thus exhibiting better theranostic performance in the autoimmune hepatitis and hind paw edema mouse models, including more salient imaging signals and better therapeutic efficacy via inhibiting NF-κB pathway and suppressing NLRP3 inflammasome activation. This work may provide perceptions for designing other actively-targeting theranostic nanosystems for various inflammatory diseases.

Low-dose Ultraviolet-A irradiation selectively eliminates nitrite oxidizing bacteria for mainstream nitritation

Nitritation is currently known as a bottleneck for mainstream nitrite shunt or partial nitritation/anammox (PN/A). Here we propose a new approach to selectively eliminate nitrite oxidizing bacteria (NOB) for mainstream nitritation by low-dose ultraviolet-A (UVA) irradiation. The results showed that mainstream nitritation was rapidly achieved within 10 days with UVA irradiation at the dose of 0.87 μE L^-1 s^-1, and nitrite accumulation ratio (NO₂^--N/(NO₂^--N + NO₃^--N) ×100%) stabilized over 80%. Microbial community analysis revealed that two typical NOB populations (Nitrospira and Ca. Nitrotoga) detected in the control reactor were suppressed efficiently in UVA irradiation reactor, whereas the Nitrosomonas genus of ammonium oxidizing bacteria (AOB) remained at similar level. Intracellular reactive oxygen species (ROS) analysis indicated that NOB-dominant sludge tends to generate more intracellular ROS compared with AOB-dominant sludge in the presence of UVA, leading to the inactivation and elimination of NOB. Additionally, amounts of microalgae found in UVA irradiation reactor could help to suppress NOB by generating ROS during photosynthesis. Briefly, the UVA irradiation approach proposed in this study was shown to be promising in NOB suppression for reliable mainstream nitritation.

Photochemical reactions between 1,4-benzoquinone and O2•

The superoxide anion radical (O2•-) is one of the most predominant reactive oxygen species (ROS), which is also involved in diverse chemical and biological processes. In this study, O2•- was generated by irradiating riboflavin in an O2-saturated solution using an ultraviolet lamp (λem = 365 nm) as the light source. The photochemical reduction of 1,4-benzoquinone (p-BQ) by O2•- was explored by 355-nm laser flash photolysis (LFP) and 365-nm UV light steady irradiation. The results showed that the photodecomposition efficiency of p-BQ was influenced by the riboflavin concentration, p-BQ initial concentration, and pH values. The superoxide anion radical originating from riboflavin photolysis served as a reductant to react with p-BQ, forming reduced BQ radicals (BQ•-) with a second-order rate constant of 1.1 × 109 L mol-1 s-1. The main product of the photochemical reaction between p-BQ and O2•- was hydroquinone (H2Q). The present work suggests that the reaction with O2•- is a potential transformation pathway of 1, 4-benzoquinone in atmospheric aqueous environments.

Taking advantage of the aromatisation of 7-diethylamino-4-methyl-3,4-dihydrocoumarin in the fluorescence sensing of superoxide anion

The aromatisation of 7-diethylamino-3,4-dihydrocoumarin provides an alternative fluorescent probing technique to selectively detect the concentration of superoxide anion in solution. In addition, we reported the advantage of evaluating O₂˙^- sensing probes in anhydrous DMSO instead of in aqueous buffers when using KO₂ as the surrogate of O₂˙^-.

A Photoactivatable Formaldehyde Donor with Fluorescence Monitoring Reveals Threshold To Arrest Cell Migration

Controlled light-mediated delivery of biological analytes can enable the investigation of highly reactivity molecules within living systems. As many biological effects are concentration dependent, it is critical to determine the location, time, and quantity of analyte donation. In this work, we have developed the first photoactivatable donor for formaldehyde (FA). Our optimized photoactivatable donor, photoFAD-3, is equipped with a fluorescence readout that enables monitoring of FA release with a concomitant 139-fold fluorescence enhancement. Tuning of photostability and cellular retention enabled quantification of intracellular FA release through cell lysate calibration. Application of photoFAD-3 uncovered the concentration range necessary for arresting wound healing in live cells. This marks the first report where a photoactivatable donor for any analyte has been used to quantify intracellular release.

Aggregation-induced emission luminogens for RONS sensing

The development of AIE bioprobes for RONS sensing in living systems is now summarized. We discuss some representative examples of AIEgen based bioprobes in terms of their molecular design, sensing mechanism and sensitive sensing in vitro and in vivo.

Novel natural myricetin with AIE and ESIPT characteristics for selective detection and imaging of superoxide anions in vitro and in vivo

A novel reversible AIE + ESIPT probe, myricetin, easily obtained from vine tea, for detection and imaging of O₂^•−.