Browsing by Author "Prahalad Singh Bharti"

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New D-π-A-Based Coumarin- Derived Fluorescent Theranostic Probes With Broad-Spectrum Antimicrobial Activity
(John Wiley and Sons Inc, 2025) Himanshu Rai; Atul Kumar Tiwari; Aishwarya Nikhil; Ankit Tiwari; Prahalad Singh Bharti; Suresh Kumar Maury; Munesh Kumar Gupta; Sundaram Singh; Saroj Kumar; Gyan Prakash Modi
Understanding how multidrug-resistant (MDR) bacteria and fungi defy the existing antimicrobial agents requires innovative tools and techniques for real-time, in situ exploration of bacterial responses to antibiotics. Fluorescence-tagged antibiotics or dyes with inherent antimicrobial activity can provide a profound understanding of the molecular biology underlying antibiotic action and resistance mechanisms. Cutting-edge research highlights the pursuit of benzo-α-pyrone (coumarin) derivatives due to their excellent pharmacokinetics, diverse pharmacological activities, and innovative fluorescence molecular probes. In this study, donor-π-acceptor-based coumarin dyes were designed and evaluated for antimicrobial efficacy against fungal strains (Candida albicans), Gram-negative pathogens (Escherichia coli), and Gram-positive bacteria (Staphylococcus aureus). I-6 exhibited notable antimicrobial activity against S. aureus and C. albicans compared with E. coli. Conversely, I-9, a congener of I-6, showed a comparable affinity for S. aureus but found poor activity against the remaining tested strains. Mechanistic investigative studies unveiled that the inhibitory efficacy of I-6 can be attributed to its capacity to generate high reactive oxygen species (ROS) formation. Despite the evident antimicrobial potential of I-6 in the data, our future prospects, including real-time visualization to study physiological processes like uptake, distribution, and mechanism of action through fluorescence-based imaging modalities, could enhance the applicability of these probes. © 2025 Deutsche Pharmazeutische Gesellschaft.
Rhodanine composite fluorescence probes to detect pathological hallmarks in Alzheimer's disease models
(Elsevier B.V., 2024) Himanshu Rai; Rishabh Singh; Prahalad Singh Bharti; Prabhat Kumar; Sanskriti Rai; Tanmaykumar Varma; Brijesh Singh Chauhan; Aishwarya Srikant Nilakhe; Joy Debnath; Renu Dhingra; Vijay N. Mishra; Sarika Gupta; Sairam Krishnamurthy; Jian Yang; Prabha Garg; Saripella Srikrishna; Saroj Kumar; Gyan Modi
Amyloid fibrils and hyperphosphorylated tau tangles are widely acceptable histological and biochemical pathogenic markers in Alzheimer's Disease (AD). Detecting these markers at an early stage could be beneficial for differentiating AD from other neuronal anomalies. Herein, a series of rhodanine (acceptor) based dyes in conjugation with a coumarin or carbostyril (donor) were synthesized and tested their ability to detect these biomarkers. The lead probe 19 displayed staining affinity for Aβ fibrils and tau tangles with little or no interaction with abundant plasma protein (BSA). Minimal cytotoxicity, brain accessibility, biocompatibility, and fluorescence sustainability across physiological pHs rendering it suitable for in-vivo imaging. Dual staining of histological samples validated affinity of probe 19 for Aβ plaques and tau tangles in AD brain tissue specimens via immunofluorescence, ThT (aggregated Aβ specific dye), and Tau-1 (tau filament-specific dye). Moreover, live in-vivo fluorescence imaging in mice and ocular labeling of Aβ in AD Drosophila models extend the preclinical applicability of probe 19 for screening purposes. On behalf of the following data, we assume that probe 19 can successfully detect pathological AD biomarkers in investigational studies. © 2024 Elsevier B.V.