Browsing by Author "Shakuja, Rajeev"

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    Tandem transformation of indazolones to quinazolinones through pd-catalyzed carbene insertion into an n–n bond
    (ACS, 2023-01) Shakuja, Rajeev
    Serendipitous and expedite transformation of 1-aryl- and 2-aryl-1,2-dihydro-3H-indazol-3-ones to 1,2-di(hetero)aryl- and 2,3-di(hetero)aryl-2,3-dihydroquinazolin-4(1H)-ones, respectively, was achieved in high efficiency by reacting them with aldehydic N-tosylhydrazones. The protocol proceeded through a cascade process involving base-mediated Pd-carbenoid generation by the decomposition of N-tosylhydrazones, nucleophilic attack of indazolone on the Pd-carbenoid complex, and intramolecular ring expansion via N–N bond cleavage. The utility of the strategy is demonstrated toward the synthesis of bioactive NPS 53574, a calcium receptor antagonist.
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    Ursolic acid conjugates: a new frontier in anticancer drug development
    (Wiley, 2024-07) Shakuja, Rajeev
    New Ursolic Acid (UA) conjugates were synthesized using optimized synthetic protocols through the molecular hybridization approach at C-3 and C-28. This resulted in the targeted molecules being produced in good yields. Some of the synthesized conjugates showed significantly relevant bioactivity against mammalian cells and in animal models of cancers. Selected UA conjugates were tested against bladder and breast cancer cell lines. The conjugates showed moderate to significantly enhanced antiproliferative activities against Triple Negative Breast Cancer (TNBC; MDA-MB 231), which is an aggressive tumor making up about 10–15 % of all breast cancers and bladder (T24 and 5637) cancer cell lines. These properties were superior to the parent UA. Among all the synthesized compounds, 18 c and 18 d have exhibited promising antiproliferative and cytotoxic properties against all tested cancer cell lines. However, 18 d has proved to be exceptionally selective for cancer cell lines, showing more cytotoxicity towards them than normal epithelial cells (MCF-12A). Compound 18 d has demonstrated cytotoxicity against tumor cells, including those intrinsically resistant to chemotherapy drugs such as 2-difluoro-deoxy cytidine (Gemcitabine). The activity of the UA conjugates on tumor cells was mediated by multiple cytotoxic mechanisms, including drug-induced cytotoxic autophagy and programmed cell death, indicating a novel possibility of combination therapy.