A Turn-On Fluorescent Probe for Highly Selective Detection and Visualization of Hydrogen Sulfide in Fungi.

Hydrogen sulfide (H2S) is a significant actor in the virulence and pathogenicity of fungi. The analysis of endogenous H2S in fungi benefits the prevention and treatment of pathogenic infections. Herein, a H2S-activated turn-on fluorescent probe named DDX-DNP was developed for the sensitive and selective detection of H2S. Using DDX-DNP, the ability of several oral fungi strains to produce H2S was identified, which was also validated using a typical chromogenic medium. In addition, DDX-DNP was successfully used for the visual sensing of endogenous H2S in fungal cells via microscope, flow cytometry, and colony imaging, along with a specific validation with the co-incubation of H2S production inhibitors in living cells. Above all, DDX-DNP could be used for H2S detection, the fluorescent imaging of fungi, and even the identification of related fungi.

Discovery of Potential Antituberculosis Agents Targeted Methionine Aminopeptidase 1 of Mycobacterium tuberculosis by the Developed Fluorescent Probe.

Tuberculosis (TB) is a chronic systemic infectious disease caused by Mycobacterium tuberculosis (M. tuberculosis). Methionine aminopeptidase 1 (MtMET-AP1) is a hydrolase that mediates the necessary post-translational N-terminal methionine excision (NME) of peptides during protein synthesis, which is necessary for bacterial proliferation and is a potential target for the treatment of tuberculosis. Based on the functional characteristics of MtMET-AP1, we developed an enzymatic activated near-infrared fluorescent probe DDAN-MT for rapid, highly selective, and real-time monitoring of endogenous MtMET-AP1 activity in M. tuberculosis. Using the probe DDAN-MT, a visually high-throughput screening technique was established, which obtained three potential inhibitors (GSK-J4 hydrochchloride, JX06, and lavendustin C) against MtMET-AP1 from a 2560 compounds library. More importantly, these inhibitors could inhibit the growth of M. tuberculosis H37Ra especially (MICs < 5 µM), with low toxicities on intestinal bacteria strains and human cells. Therefore, the visual sensing of MtMET-AP1 was successfully performed by DDAN-MT, and MtMET-AP1 inhibitors were discovered as potential antituberculosis agents.

High-throughput fluorescent screening of ß-lactamase inhibitors to improve antibiotic treatment strategies for tuberculosis.

Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis (Mtb), which is a major threat to global public health. Currently, ß-lactam antibiotics are rarely used in the treatment of TB, since Mtb naturally expresses ß-lactamase (Blac) which renders Mtb resistant to such antibiotics due to ß-lactam cleavage. Fortunately, antibiotic resistance can be overcome when ß-lactam antibiotics are combined with a Blac inhibitor. With the current research, a near-infrared fluorescent probe LXMB was developed for the real-time detection and imaging of endogenous Blac activity in Mtb. Furthermore, a high-throughput screening platform was established using LXMB to screen Blac inhibitors from herbal medicines. Guided by the visual bioassay, Tannic acid was isolated from Galla Chinensis as a potential Blac inhibitor and was further evaluated in combination with several ß-lactam antibiotics which resulted in an enhanced inhibitory effect toward M. tuberculosis H37Ra. Finally, LXMB was used to label live M. tuberculosis H37Ra phagocytosed within macrophages. Consequently, LXMB was a useful fluorescent tool to explore the mechanism of drug resistance based on Blac and can assist in the development of new tuberculosis treatments.

Detecting the combined toxicity of 18 binary and 24 ternary pesticide combinations to carboxylesterase based on fluorescence probe technology.

A rapid test method for the determination of pesticide toxicity was established by using carboxylesterase (CES) and fluorescence probe ACE-NH based on the principle of enzyme inhibition, and this method was applied to detect the combined toxicity of 18 binary and 24 ternary pesticide combinations commonly used for fruits and vegetables to CES. The results show that chlorpyrifos + carbendazim, carbofuran + carbendazim, imidacloprid + carbendazim, imidacloprid + dimethomorph, dimethoate + dimethomorph, prochloraz + carbendazim and imidacloprid + acetamiprid + carbendazim had synergistic effects under three concentration gradients, it indicated that most binary combinations containing carbendazim or imidacloprid had synergistic effects. Based on structure-activity relationship between pesticides and CES, pesticides with phosphate ester bonds had great toxicity to CES, or though they have no toxicity to CES alone, they showed a strong synergistic effect when mixed with other pesticides. Pesticides with amide or ester bond had medium toxicity and little synergistic effect. Pesticides with urea, carbamate or nitrite nitrogen group had little or no toxicity, while there was a strong synergistic effect after mixing with other pesticides. The test method and results in this study can provide scientific basis for risk assessment of cumulative exposure to mixed pesticide residues.