Department of Chemistry

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Author: search.filters.author.Addy, Partha SarathiSubject: search.filters.subject.Chemistry

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Now showing 1 - 10 of 23
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    Aggregation-induced emission: a curious case of molecular luminescence
    (Springer, 2024-11) Addy, Partha Sarathi
    Aggregation-induced emission (AIE) is an interesting luminescence phenomenon. This process describes how unity in the molecular world can produce bright emissions (luminescence). Chemists have adopted this technique to design various luminescent materials to develop efficient diagnostics and therapeutics. In this article, a concise description of AIE and its development is documented. The application of AIE is significant in the field of materials and biology. In the last part of the article, a brief description of various uses is presented.
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    Aggregation induced emission based luminogenic (aiegenic) probes for the biomarker detection
    (Wiley, 2025-01) Addy, Partha Sarathi
    Various biomarkers such as proteins play key roles in controlling crucial biochemical processes. The critical concentration of the biomarkers is important to maintain a healthy life. In fact, imbalance in concentration or irregular activity of these can lead to various diseases like Cancer, Alzheimer's etc. Therefore, the disease related biomarkers and their timely detection are key to control the illness. In the literature, a few activity-based probes for the detection of such biomarkers are available. As per the requirement an ideal probe should be very specific to recognize the target analyte and that could be achieved by virtue of having a robust structure and stimuli responsive nature. In this regard, several fluorescent probes are of great choice. Although these fluorescent probes face certain challenges such as aggregation caused quenching, which heavily affects the sensitivity and photostability is another major concern for many fluorescent probes. To overcome these challenges aggregation-induced emissive fluorescent probes found to be an excellent alternative. Aggregation induced emissive luminogens (AIEgens) offer higher signal to noise ratios and found to possess better photostability during sensing and imaging. In the present review we have summarized the development of AIEgenic probes for sensing and imaging of disease related biomarkers. We believe this review could be a guide to design efficient AIEgenic probes for the diagnostics development.
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    Labeling Proteins at Site-Specifically Incorporated 5-Hydroxytryptophan Residues Using a Chemoselective Rapid Azo-Coupling Reaction
    (Springer, 2019-07-23) Addy, Partha Sarathi
    Chemoselective protein labeling is a valuable tool in the arsenal of modern chemical biology. The unnatural amino acid mutagenesis technology provides a powerful way to site-specifically introduce nonnatural chemical functionalities into recombinant proteins, which can be subsequently functionalized in a chemoselective manner. Even though several strategies currently exist to selectively label recombinant proteins in this manner, there is considerable interest for the development of additional chemoselective reactions that are fast, catalyst-free, use readily available reagents, and are compatible with existing conjugation chemistries. Here we describe a method to express recombinant proteins in E. coli site-specifically incorporating 5-hydroxytryptophan, followed by the chemoselective labeling of this residue using a chemoselective rapid azo-coupling reaction.
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    Synthesis of bicyclic γ-lactam derivatives by intramolecular carbene insertion and aza-Wittig reaction
    (J-Global, 2013) Addy, Partha Sarathi
    A comparative study of the various methodologies to construct bicyclic γ-lactams is reported. Thus RhII-catalyzed decomposition of 2-pyrrolidone and pyrrolidine derived diazomalonates were attempted to synthesize fused γ-lactams. Spectral evidences revealed the formation of diastereomeric alcohols instead of desired C-H or N-H insertion products, indicating significant conformational bias towards insertion process. On the other hand, the method involving the N-H insertion onto the lactam nitrogen of 2-pyrrolidone ring was successful. Intramolecular aza-Wittig reaction was also successfully explored to construct bicyclic γ-lactam scaffolds. All the bicyclic analogues showed weak antibacterial activity against S. aureus and E. coli.
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    Synthesis of highly efficient pH-sensitive DNA cleaving aminomethyl N-substituted cyclic enediyne and its L-lysine conjugate
    (Elsiever, 2013-02-20) Addy, Partha Sarathi
    Two 10-membered benzo-fused N-substituted cyclic enediynes, one an amino methyl and the other, a C-lysine conjugated derivative 2 and 3, respectively were synthesized (as a 1.2:1 mixture of regioisomers) and their DNA-cleavage efficiency studied. Both the compounds showed much better DNA-cleavage profile than that of the parent unsubstituted enediyne 1. The lysine conjugate 3 showed an efficient pH dependent cleavage to the extent of ∼50% of linear DNA formation under ambient conditions.
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    Garratt-Braverman Cyclization: a Powerful Tool for C-C Bond Format
    (Thieme, 2012-08) Addy, Partha Sarathi
    Development of new strategies for C–C bond formation remains in the forefront of organic synthesis. The base-mediated rearrangement of bis-propargyl sulfones via bis-allenes generated in situ, now known as the Garratt–Braverman cyclization (GBC), leads to the formation of two new C–C bonds. The reaction has recently drawn attention from organic chemists due to the wide scope as well as interesting mechanism. This report aims to give an account of the developments in this area with particular emphasis on synthetic applications.
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    Glucose Directly Promotes Antifungal Resistance in the Fungal Pathogen, Candida spp
    (Elsiever, 2014-09-12) Addy, Partha Sarathi
    Effects of glucose on the susceptibility of antifungal agents were investigated against Candida spp. Increasing the concentration of glucose decreased the activity of antifungal agents; voriconazole was the most affected drugs followed by amphotericin B. No significant change has been observed for anidulafungin. Biophysical interactions between antifungal agents with glucose molecules were investigated using isothermal titration calorimetry, Fourier transform infrared, and 1H NMR. Glucose has a higher affinity to bind with voriconazole by hydrogen bonding and decrease the susceptibility of antifungal agents during chemotherapy. In addition to confirming the results observed in vitro, theoretical docking studies demonstrated that voriconazole presented three important hydrogen bonds and amphotericin B presented two hydrogen bonds that stabilized the glucose. In vivo results also suggest that the physiologically relevant higher glucose level in the bloodstream of diabetes mellitus mice might interact with the available selective agents during antifungal therapy, thus decreasing glucose activity by complex formation. Thus, proper selection of drugs for diabetes mellitus patients is important to control infectious diseases.
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    A facile Garratt–Braverman cyclization route to intercalative DNA-binding bis-quinones
    (Elsiever, 2012-01-04) Addy, Partha Sarathi
    Bispropargyl ethers (both symmetrical and non-symmetrical) equipped with 1,4-dimethoxyaryl groups were synthesized. Under strongly basic conditions (KOBut/toluene/reflux), these ethers underwent Garratt–Braverman type cyclization to the tetramethoxy bi-aryl systems in high yields presumably via the bisallenes. The products could be successfully converted to the bis-quinones via CAN-mediated demethylation cum oxidation. This two-step protocol offers a simple route to bis-quinones, connected by C1–C2′ bonds, in good yields. Fluorescence based EB-displacement assay, CD spectroscopy and viscosity measurements confirmed the DNA-binding ability of the synthesized quinones via intercalation.
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    1,3,5-Trisubstituted benzenes as fluorescent photoaffinity probes for human carbonic anhydrase II capture
    (RSC, 2013) Addy, Partha Sarathi
    The ‘capture’ of proteins by small molecules via irreversible cross-linking mediated by photo-irradiation is of interest in the field of proteomics (for reviews see ref. 1). The technique has the potential for profiling protein-binding by small molecules, an objective of importance both for basic cell biology and in pharmaceutical science. Capture compounds, or photoaffinity probes, are typically endowed with three functions comprising (i) a selectivity function, such as an enzyme inhibitor, (ii) a photo-cross linking group (capture function) and (iii) a sorting group to enable separation of the captured protein from biological mixtures, such as biotin or an alkyne for subsequent modification. The captured protein(s) can be isolated using streptavidin beads and identified by mass spectrometry or Western blotting (for examples see ref. 2)
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