An Allysine-Conjugatable Probe for Fluorogenically Imaging Fibrosis.

Allysine, a pivotal biomarker in fibrogenesis, has prompted the development of various radioactive imaging probes. However, fluorogenic probes targeting allysine remain largely unexplored. Herein, by leveraging the equilibrium between the nonfluorescent spirocyclic and the fluorescent zwitterionic forms of rhodamine-cyanine hybrid fluorophores, we systematically fine-tuned the environmental sensitivity of this equilibrium toward the development of fluorogenic probes for fibrosis. The trick lies in modulating the nucleophilicity of the ortho-carboxyl group, which is terminated with a hydrazide group for allysine conjugation. Probe B2 was developed with this strategy, which featured an N-sulfonyl amide group and exhibited superior fibrosis-to-control imaging contrast. Initially presenting as nonfluorescent spirocyclic aggregates in aqueous solutions, B2 displayed a notable fluorogenic response upon conjugation with protein allysine through its hydrazide group, inducing deaggregation and switching to the fluorescent zwitterionic form. Probe B2 outperformed the traditional Masson stain in imaging contrast, achieving an about 260-2600-fold ratio for fibrosis-to-control detection depending on fibrosis severity. Furthermore, it demonstrated efficacy in evaluating antifibrosis drugs. Our results emphasize the potential of this fluorogenic probe as an alternative to conventional fibrosis detection methods. It emerges as a valuable tool for antifibrosis drug evaluation.

Identification of N- and C-3-Modified Laudanosoline Derivatives as Novel Influenza PAN Endonuclease Inhibitors.

Influenza PAN inhibitors are of particular importance in current efforts to develop a new generation of antiviral drugs due to the growing emergence of highly pathogenic influenza viruses and the resistance to existing antiviral inhibitors. Herein, we design and synthesize a set of 1,3-cis-N-substituted-1,2,3,4-tetrahydroisoquinoline derivatives to enhance their potency by further exploiting the pockets 3 and 4 in the PAN endonuclease based on the hit d,l-laudanosoline. Particularly, the lead compound 35 exhibited potent and broad anti-influenza virus effects with EC50 values ranging from 0.43 to 1.12 µM in vitro and good inhibitory activity in a mouse model. Mechanistic studies demonstrated that 35 could bind tightly to the PAN endonuclease of RNA-dependent RNA polymerase, thus blocking the viral replication to exert antiviral activity. Overall, our study might establish the importance of 1,2,3,4-tetrahydroisoquinoline-6,7-diol-based derivatives for the development of novel PAN inhibitors of influenza viruses.

Multiscale imaging of peroxynitrite in gliomas with a blood-brain barrier permeable probe reveals its potential as a biomarker and target for glioma treatment.

Cancer development is driven by diverse processes, and metabolic alterations are among the primary characteristics. Multiscale imaging of aberrant metabolites in cancer is critical to understand the pathology and identify new targets for treatment. While peroxynitrite (ONOO-) is reported being enriched in some tumors and plays important tumorigenic roles, whether it is upregulated in gliomas remains unexplored. To determine the levels and roles of ONOO- in gliomas, efficient tools especially those with desirable blood-brain barrier (BBB) permeability and can realize the in situ imaging of ONOO- in multiscale glioma-related samples are indispensable. Herein, we proposed a strategy of physicochemical property-guided probe design, which resulted in the development of a fluorogenic probe NOSTracker for smartly tracking ONOO-. The probe showed sufficient BBB permeability. ONOO- triggered oxidation of its arylboronate group was automatically followed by a self-immolative cleavage of a fluorescence-masking group, liberating its fluorescence signal. The probe was not only highly sensitive and selective towards ONOO-, but its fluorescence favored desirable stability in various complex biological milieus. Guaranteed by these properties, multiscale imaging of ONOO- was realized in vitro in patient-derived primary glioma cells, ex vivo in clinical glioma slices, and in vivo in the glioma of live mice. The results showed the upregulation of ONOO- in gliomas. Furthermore, a specific ONOO- scavenger uric acid (UA) was pharmaceutically used to downregulate ONOO- in glioma cell lines, and an anti-proliferative effect was observed. These results taken together imply the potential of ONOO- as a biomarker and target for glioma treatment, and propose NOSTracker as a reliable tool to further explore the role of ONOO- in glioma development.

Synthesis and SARs of dopamine derivatives as potential inhibitors of influenza virus PAN endonuclease.

Currently, influenza PAN endonuclease has become an attractive target for development of new drugs to treat influenza infections. Herein we report the discovery of new PAN endonuclease inhibitors derived from a chelating agent dopamine moiety. A series of dopamine amide derivatives and their conformationally constrained 1,2,3,4-tetrahydroisoquinoline-6,7-diol-based analogs were elaborated and assayed against influenza virus A/WSN/33 (H1N1). Most compounds exhibited moderate to excellent antiviral activities, generating a preliminary SARs. Among them, compounds 14 and 19 showed stronger anti-IAV activity compared with the reference Peramivir. Moreover, 14 and 19 demonstrated a concentration-dependent inhibition of PAN endonuclease based on both FRET assay and SPR assay. Docking studies were also performed to elucidate the binding mode of 14 and 19 with the PAN protein and to identify amino acids involved in their mechanism of action, which were well consistent with the biological data. This finding was beneficial to laying the foundation for the rational development of more effective PAN endonuclease inhibitors.