Department of Biological Sciences
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Item Pyridinium-based schiff-base fluorescent chemosensor for sequential detection of al3+ ions and tnp: applications in cell imaging and latent fingerprint visualization(Wiley, 2024-12) Jha, Prabhat Nath; Khungar, BhartiA fluorescent pyridinium-based chemosensor (E)-1-(2-(3-hydroxy-4-((pyridin-2-ylimino) methyl) phenoxy) ethyl) pyridin-1-ium bromide (BzPySB) was synthesized and characterized using various spectroscopic techniques. The chemosensing potential of BzPySB was explored using UV-vis and fluorescence spectroscopy in the aqueous medium. The turn-on fluorescence behavior was observed for BzPySB in the presence of Al3+, while other metal ions were non-responsive. The B−H and Job′s plot confirmed the 1 : 1 stoichiometric ratio of the BzPySB and Al3+. The in situ generated complex BzPySB-Al3+ offered selectivity toward TNP via fluorescence turn-off phenomena with high Ksv and LOD values. The “off-on-off” sensing mechanism was elucidated through 1H NMR, mass spectrometry, and DFT calculations. The probe also detected Al3+ in plant and MCF-7 cells, highlighting its potential in biological systems. Moreover, BzPySB exhibited solid-state luminescent properties credited to weak π-π interaction, leading to its successful application in the visualization of latent fingerprints.Item Novel Spiro/non-Spiro Pyranopyrazoles: Eco-Friendly Synthesis, In-vitro Anticancer Activity, DNA Binding, and In-silico Docking Studies(Bentham Science, 2019) Chowdhury, Rajdeep; Shukla, Paritosh; Sharma, AshokBackground: Cancer being a deadly disease, many reports of new chemical entities are available. Pyranopyrazole (PPZ) compounds have also been disclosed as bioactive molecules but mainly as antimicrobial agents. Based on one previous report and our interest in anticancer drug design, we decided to explore PPZs as anticancer agents. To the best of our knowledge, we found that a comprehensive study, involving synthesis, in-vitro biological activity determination, exploration of the mechanism of inhibition and finally in-silico docking studies, was missing in earlier reports. This is what the present study intends to accomplish. Methods: Ten spiro and eleven non-spiro PPZ molecules were synthesized by environment-friendly multicomponent reaction (MCR) strategy. After subjecting each of the newly synthesized molecules to Hep3b hepatocellular carcinoma cell lines assay, we selectively measured the Optical Density (OD) of the most active ones. Then, the compound exhibiting the best activity was docked against human CHK- 1 protein to get an insight into the binding affinities and a quick structure activity relationship (SAR) of the PPZs. Results: The two series of spiro and non-spiro PPZs were easily synthesized in high yields using microwave assisted synthesis and other methods. Among the synthesized compounds, most compounds showed moderate to good anticancer activity against the MTT assay. After performing the absorbance studies we found that the non-spiro molecules showed better apoptosis results and appeared to bind to DNA causing disruption in their structures. Finally, the docking results of compound 5h (having N,Ndimethylamino substituted moiety) clearly showed good binding affinities as predicted by our experimental findings. Conclusion: The paper describes a comprehensive synthesis, in-vitro and docking studies done on new PPZs. The newly synthesized series of spiro and non-spiro PPZs were found to possess antineoplasmic activity as evinced by the studies on hep3b cells. Also, the UV visible absorbance study gave clues to the possible binding of these molecules to the DNA. Docking studies corroborated well with the experimental results. Thus, these new molecules appear to be potential anticancer agents, but further studies are required to substantiate and elaborate on these findings.Item Evaluation of novel platinum(ii) based AIE compound-encapsulated mesoporous silica nanoparticles for cancer theranostic application(RSC, 2018) Chowdhury, Rajdeep; Laskar, Inamur RahamanAdvanced biomedical research has established that cancer is a multifactorial disorder which is highly heterogeneous in nature and responds differently to different treatment modalities, due to which constant monitoring of therapy response is becoming extremely important. To accomplish this, different theranostic formulations have been evaluated. However, most of them are found to suffer from several limitations extending from poor resolution, radiation damage, to high costs. In order to develop a better theranostic modality, we have designed and synthesized a novel platinum(II)-based ‘aggregation induced emission’ (AIE) molecule (named BMPP-Pt) which showed strong intra-cellular fluorescence and also simultaneously exhibited potent cytotoxic activity. Due to this dual functionality, we wanted to explore the possibility of using this compound as a single molecule based theranostic modality. This compound was characterized using elemental analysis, NMR and IR spectroscopy, mass spectrometry and single crystal X-ray structure determination. BMPP-Pt was found to exhibit a high AIE property with emission maxima at 497 nm. For more efficient cancer cell targeting, BMPP-Pt was encapsulated into mesoporous silica nanoparticles (Pt-MSNPs) and the MSNPs were further surface modified with an anti-EpCAM aptamer (Pt-MSNP-E). Pt-MSNPs exhibited higher intracellular fluorescence compared to free BMPP-Pt, though both of them induced a similar degree of cell death via the apoptosis pathway, possibly via cell cycle arrest in the G1 phase. Anti-EpCAM aptamer modification was found to increase both cytotoxicity and intracellular fluorescence compared to unmodified MSNPs. Our study showed that EpCAM functionalized BMPP-Pt loaded MSNPs can efficiently internalize and induce apoptosis of cancer cells as well as show strong intracellular fluorescence. This study provides clues towards the development of a potential single compound based theranostic modality in future.Item Functional Autophagic Flux Regulates AgNP Uptake And The Internalized Nanoparticles Determine Tumor Cell Fate By Temporally Regulating Flux(Dove Press, 2019) Pande, Surojit; Chowdhury, RajdeepSilver nanoparticles (AgNPs) are known to induce the conserved, cellular, homeostatic process- autophagy in tumor cells. Previous studies primarily focus on the pro-survival role of autophagy post AgNP exposure in tumor cells, but seldom on its role in AgNP uptake, or on the functional significance of autophagy temporal dynamics. Our study sheds more light on the extensive crosstalk that exists between AgNP and autophagy, which can be critical to the improvement of AgNP-induced therapeutic effectsItem A New Aggregation Induced Emission Active Halochromic White Light Emissive Molecule: Combined Experimental and Theoretical Study(RSC, 2020) Chowdhury, Rajdeep; Laskar, Inamur Rahaman; Roy, Ram KinkarRed/near infrared-emissive organic molecules that are aggregation induced emission (AIE) active and having a pH-sensitive core are high in-demand for real-world applications. We have designed and synthesized a far-red to near infrared (NIR) fluorogenic donor–acceptor (D–A) type probe 4-((4-(2-(3,3-dimethyl-3H-indole-2-yl)vinyl)phenyl)(phenyl)amino)benzaldehyde (TPA-SCY), that can undergo protonation with a stronger intramolecular charge transfer. The molecule is pH-sensitive and responds to the acidic behavior of chloroform to produce a unique halochromic white-light emission. Owing to its sensitivity toward pH and its highly emissive nature in the red/NIR region at low pH (approximately 3–5), it accumulates in the intracellular lysosomes and can be used as a live-tracker for lysosomes. Successful application of time-dependent density functional theory with the use of an optimally tuned range-separated hybrid functional reproduces the experimental absorption and emission spectra within the 1–5 nm range (which is not observed when conventional range-separated hybrid functionals are used). Thus, the present work embodies synthesis and photophysical studies (supported by an efficient and highly accurate theoretical tool) of a new AIE active halochromic white light emissive molecule with extensive charge transfer properties and having the ability to behave as a live LysoTracker.Item A multistimuli responsive heteroleptic iridium(iii) complex: role of hydrogen bonding in probing solvent, pH and bovine serum albumin (BSA)(RSC, 2020) Chowdhury, Shibasish; Laskar, Inamur RahamanThis article focuses on the vital role of hydrogen bonding to explain some unusual photophysical behaviors of an ‘Aggregation-induced emission’ (AIE) active Iridium(III) complex. The preponderance of hydrogen bonding leads to the complex's multifunctional character, viz., sensing ability of base and protein (BSA), pH probing, and solvatochromism. Depending on the hydrogen bonding capacity of the solvents, the emission properties of the complex are changed, i.e., green emission in non-polar solvents, yellowish-green emission in a chlorinated solvent, bright yellow emission in a polar aprotic solvent and weak yellow emission in polar protic solvent. A robust green emission was obtained with the addition of BSA into a solution of 1. The sensitivity of the complex to BSA was measured to be 9.3 pM. The mechanisms in all these cases have been explored based on control experiments and computational calculations/studies (DFT, TD-DFT, Docking).Item Engineering a light-driven cyanine based molecular rotor to enhance the sensitivity towards a viscous medium(RSC, 2021) Chowdhury, Rajdeep; Laskar, Inamur Rahaman; Majumder, Syamantak; Mukherjee, SudeshnaThis article describes the enhanced sensitivity to a viscous medium by a molecular rotor based fluorophore (RBF), TPSI I. The TPSI I molecule is designed in such a way that it consists of a rotor and a fluorophore with a π-rich bridge between them. TPSI I is a light-responsive material in solution as well as in the solid state. The structural design of the molecule allows flexible rotation and photo-induced cis–trans isomerization both in the solid state as well as in solution. These combined attributes of TPSI I are responsible for the ultrasensitive viscosity response of the new material, which was verified through the Förster–Hoffmann equation. According to this equation, the derived ‘x’ value is 1.02 (x is related to the sensitivity) which is the highest among the contemporary reports for RBFs. The facts were evidenced both by experimental as well as theoretical data. The ultrasensitivity towards viscosity was further analyzed in in vitro studies by detecting the subtle changes in the alteration of intracellular viscosity in normal and cancerous cells. An alteration of intracellular viscosity in cells treated with viscosity modulators was also confirmed using a previously well-established viscosity measurement technique, dynamic measurement through the piezoelectric patch. Our research offers a detailed mechanism to improve viscosity sensors and an efficient probe for detecting minute changes in intracellular viscosity.Item Hepatotoxicity of Microcystis aeruginosa Strains Growing as Blooms in Certain Eutrophic Ponds(TUD, 2006) Jha, Prabhat N.; Kumar, AnilCritical assessment of five eutrophicated ponds of Varanasi city (India) revealed the presence of heavy blooms of cyanobacteria consisting mainly of Microcystis aeruginosa. Crude aqueous extracts of blooms as well as laboratory grown M. aeruginosa isolated from three ponds, namely Lakshmikund, Durgakund and Adityanagar showed toxicity in mouse bioassay test. Crude aqueous extracts from these samples caused death of test mice within 1h of administration (i.p.) with a LD50 of 60 mg/kg body weight and the treated animals showed clinical signs of hepatotoxicity. However such an effect was not associated with the blooms from Laatbhairov and Surajkund ponds suggesting that not all strains of M. aeruginosa are toxic. Based on spectral properties (?max 230 nm), and comparison with standard microcystin-LR, the toxin is tentatively identified as microcystin-LR. The purified toxin caused death of test mice within 40 min of its administration with a LD50 of 100 µg/ kg body weight and induced gross morphological and functional changes in liver. A 1.55 fold increase in liver weight accompanied by deep red coloration most probably due to hemorrhage and blood pooling suggested the hepatotoxic properties of the toxin. Hepatotoxicity was also evident from the drastic increase (up to 2.5 fold) in activity of serum enzymes such as glutamate pyruvate transaminase/alanine aminotransferase (GPT/ALT), lactate dehydrogenase (LDH) and alkaline phosphatase (APase) following toxin treatment. ^14C-labelling experiments demonstrated maximum accumulation (~15%) of ^14C- toxin after 20 min. of toxin administration. Appreciable level of toxin was also detected in water of four ponds. In conclusion these results clearly demonstrate that microcystin-producing blooms of M. aeruginosa are common in eutrophicated ponds of Varanasi city but not all ponds harbour toxic blooms.Item ChemInform Abstract: Novel Grinding Synthesis of Pyranopyrazole Analogues and Their Evaluation as Antimicrobial Agents.(Wiley, 2016) Jha, Prabhat N.; Shukla, ParitoshCompounds are prepared and screened for their antibacterial and antifungal activitiesItem Biochemistry and genetics of ACC deaminase: a weapon to “stress ethylene” produced in plants(Frontiers, 2015-09) Jha, Prabhat N.; Kumar, Anil1-aminocyclopropane-1-carboxylate deaminase (ACCD), a pyridoxal phosphate-dependent enzyme, is widespread in diverse bacterial and fungal species. Owing to ACCD activity, certain plant associated bacteria help plant to grow under biotic and abiotic stresses by decreasing the level of “stress ethylene” which is inhibitory to plant growth. ACCD breaks down ACC, an immediate precursor of ethylene, to ammonia and α-ketobutyrate, which can be further metabolized by bacteria for their growth. ACC deaminase is an inducible enzyme whose synthesis is induced in the presence of its substrate ACC. This enzyme encoded by gene AcdS is under tight regulation and regulated differentially under different environmental conditions. Regulatory elements of gene AcdS are comprised of the regulatory gene encoding LRP protein and other regulatory elements which are activated differentially under aerobic and anaerobic conditions. The role of some additional regulatory genes such as AcdB or LysR may also be required for expression of AcdS. Phylogenetic analysis of AcdS has revealed that distribution of this gene among different bacteria might have resulted from vertical gene transfer with occasional horizontal gene transfer (HGT). Application of bacterial AcdS gene has been extended by developing transgenic plants with ACCD gene which showed increased tolerance to biotic and abiotic stresses in plants. Moreover, distribution of ACCD gene or its homolog's in a wide range of species belonging to all three domains indicate an alternative role of ACCD in the physiology of an organism. Therefore, this review is an attempt to explore current knowledge of bacterial ACC deaminase mediated physiological effects in plants, mode of enzyme action, genetics, distribution among different species, ecological role of ACCD and, future research avenues to develop transgenic plants expressing foreign AcdS gene to cope with biotic and abiotic stressors. Systemic identification of regulatory circuits would be highly valuable to express the gene under diverse environmental conditions.