Department of Chemistry

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Exploring the hidden potential of a benzothiazole-based Schiff-base exhibiting AIE and ESIPT and its activity in pH sensing, intracellular imaging and ultrasensitive & selective detection of aluminium
(RSC, 2018) Roy, Ram Kinkar; Chowdhury, Rajdeep; Laskar, Inamur Rahaman
In this article, we tried to redefine the unexplored potential of a benzothiazole type of Schiff-base (OM), which was identified as an AIE-active molecule that exhibits excited-state intramolecular proton transfer (ESIPT). Interestingly, this compound shows ultra-sensitivity and selectivity in the detection of Al(III) (12 pM; 456 ppt). The OM was capable of pH sensing and was also tested for internalization in cancerous cells for intracellular imaging. Computational modeling was performed and the results were in good agreement with the experimental UV-Vis spectrum and the energy gap obtained in basic and acidic media.
Facile Incorporation of “Aggregation-Induced Emission”-Active Conjugated Polymer into Mesoporous Silica Hollow Nanospheres: Synthesis, Characterization, Photophysical Studies, and Application in Bioimaging
(ACS, 2019-07-26) Laskar, Inamur Rahaman; Chowdhury, Rajdeep
Typical aggregation-induced emission (AIE) luminogens tetraphenylethylene (TPE) and triphenylamine have been used to construct an AIE-active conjugated polymer, namely, poly(N,N-diphenyl-4-(4-(1,2,2-triphenylvinyl)styryl)aniline) (PTPA), which consist of D−π–A architecture by Wittig polymerization. We fabricated mesoporous silica hollow nanospheres (MSHNs) which were encapsulated with the AIE-active polymer for applications in cellular imaging. It exhibits a positive solvatochromism effect by increasing solvent polarity, supported by theoretical calculation using density functional theory. The structure of the monomers and polymer was confirmed by Fourier transform infrared, nuclear magnetic resonance, and high-resolution mass spectrometry techniques. Considering the advantage of high brightness in the fluorescence of PTPA, it was encapsulated into MSHNs by a noncovalent approach, and the surface was functionalized with an anti-EpCAM (antiepithelial cell adhesion molecule) aptamer through conjugation with γ-glycidoxypropyltrimethoxysilane for targeting cancer cells specifically. The aptamer-functionalized Apt-MSHNs exhibited excellent biocompatibility with the liver cancer-Huh-7 cells used for this study and was efficiently internalized by these cells. Because EpCAM are overexpressed in multiple carcinomas, including liver cancer, these aptamer-conjugated AIE MSHNs are therefore good candidates for targeted cellular imaging applications.
Novel Spiro/non-Spiro Pyranopyrazoles: Eco-Friendly Synthesis, In-vitro Anticancer Activity, DNA Binding, and In-silico Docking Studies
(Thieme, 2019) Shukla, Paritosh; Chowdhury, Rajdeep
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 finding
Synthesis and evaluation of bile acid amides of α -cyanostilbenes as anticancer agents
(Springer, 2018-05) Sakhuja, Rajeev; Jha, Prabhat Nath; Chowdhury, Rajdeep
A series of amino-substituted [Formula: see text]-cyanostilbene derivatives and their bile acid (cholic and deoxycholic acid) amides were designed and synthesized. A comparative study on the anticancer and antibacterial activity evaluation on the synthesized analogs was carried against the human osteosarcoma (HOS) cancer cell line, and two gram -ve (E. coli and S. typhi) and two gram [Formula: see text]ve (B. subtilis and S. aureus) bacterial strains. All the cholic acid [Formula: see text]-cyanostilbene amides showed an [Formula: see text] in the range 2-13 [Formula: see text] against human osteosarcoma cells (HOS) with the most active analog (6g) possessing an [Formula: see text] of [Formula: see text]. One of the amino-substituted [Formula: see text]-cyanostilbene, 4e, was found to possess an [Formula: see text] of [Formula: see text]. An increase in the number of cells at the sub-[Formula: see text] phase of the cell was observed in the in vitro cell cycle analysis of two most active compounds in the series (4e, 6g) suggesting a clear indication toward induction of apoptotic cascade. With respect to antibacterial screening, amino-substituted [Formula: see text]-cyanostilbenes were found to be more active than their corresponding bile acid amides. The synthesized compounds were also subjected to in silico study to predict their physiochemical properties and drug-likeness score.