6 results on '"Leonard Barasa"'
Search Results
2. Tyrosine kinase inhibitor conjugated quantum dots for non-small cell lung cancer (NSCLC) treatment
- Author
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Sabesan Yoganathan, Nishant S. Kulkarni, Jeanette C. Perron, Aaron Muth, Leonard Barasa, Vineela Parvathaneni, Vivek Gupta, and Snehal K. Shukla
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Lung Neoplasms ,Cell Survival ,medicine.drug_class ,Pharmaceutical Science ,non-small cell lung cancer (NSCLC) ,02 engineering and technology ,030226 pharmacology & pharmacy ,Tyrosine-kinase inhibitor ,Cell Line ,03 medical and health sciences ,0302 clinical medicine ,Carcinoma, Non-Small-Cell Lung ,Quantum Dots ,medicine ,Humans ,Viability assay ,Erlotinib Hydrochloride ,Lung cancer ,Protein Kinase Inhibitors ,A549 cell ,Chemistry ,Esterases ,021001 nanoscience & nanotechnology ,medicine.disease ,respiratory tract diseases ,Drug Liberation ,Drug delivery ,Quinazolines ,Cancer research ,Erlotinib ,Lysosomes ,0210 nano-technology ,medicine.drug - Abstract
Non-small cell lung cancer is a major sub-type of lung cancer that is associated with a poor diagnosis resulting in poor therapy for the disorder. In order to achieve a better prognosis, innovative multi-functional systems need to be developed which will aide in diagnosis as well as therapy for the disorder. One such multi-functional delivery system fabricated is Quantum Dots (QDs). QDs are photo-luminescent inorganic nanoparticles utilized for tumor detection, preclinically. Erlotinib hydrochloride, a tyrosine kinase inhibitor, is a first-generation drug developed to treat NSCLC. Its active metabolite, Desmethyl Erlotinib (OSI-420), exhibits similar anticancer activity as erlotinib. OSI-420 was conjugated to QDs to fabricate a delivery system and was then characterized by FT-IR, H NMR, UV-VIS, particle size, zeta potential, fluorescence spectroscopy and TEM. Drug loading was estimated using UV-VIS spectroscopy (52.2 ± 7.5%). A concentration-dependent release of OSI-420 was achieved using esterase enzymes, which was further confirmed using LC-MS. A cellular uptake study revealed the internalization potential of QDs and QD-OSI 420. A cellular recovery study was performed to confirm the internalization potential. Cell viability studies revealed that QD-OSI 420 conjugates had significantly better efficacy than pure drugs in all tested cell lines. QD conjugated OSI-420 demonstrated an IC60 of 2.5 μM in erlotinib-resistant A549 cell lines, where erlotinib or OSI-420 alone could not exhibit 60% inhibition when evaluated up to 20 μM. Similar cytotoxic enhancement of erlotinib was seen with QD-OSI 420 in other NSCLC cell lines as well. These results were strengthened by 3D-SCC model of A549 which revealed that QD-OSI 420 was significantly better in reducing in-vitro 3D tumor volume, as compared to pure drugs. This study, being one of its kind, explores the feasibility of conjugating OSI-420 with QDs as an alternative to traditional anti-cancer therapy, by improving intracellular drug delivery.
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- 2019
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3. An efficient one-pot conversion of carboxylic acids into benzimidazoles via an HBTU-promoted methodology
- Author
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Sabesan Yoganathan and Leonard Barasa
- Subjects
Indole test ,chemistry.chemical_classification ,Benzimidazole ,010405 organic chemistry ,Drug discovery ,General Chemical Engineering ,Synthon ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Combinatorial chemistry ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,chemistry ,Yield (chemistry) ,Pharmacophore ,Alkyl - Abstract
Benzimidazole is a privileged, and routinely used pharmacophore in the drug discovery process. Herein, we report a mild, acid-free and one-pot synthesis of indole, alkyl and alpha-amino benzimidazoles through a novel HBTU-promoted methodology. An extensive library of indole-carboxylic acids, alkyl carboxylic acids and N-protected alpha-amino acids has been converted into the corresponding benzimidazoles in 80–99% yield. Since alpha-aminobenzimidazoles are highly useful synthons as chiral ligands for chemical catalysis, as well as for drug discovery endeavors, our reported method provides direct access to this scaffold in a simple, one-pot operation from commercially available carboxylic acids.
- Published
- 2018
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4. Synthesis and Biological Evaluation of Structurally Diverse Benzimidazole Scaffolds as Potential Chemotherapeutic Agents
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Vikas V. Dukhande, John L. Croft, Alison Yong, Jing Kong, Hari Priya Vemana, Nirupama Surubhotla, Leonard Barasa, Sin S Ha, and Sabesan Yoganathan
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Cancer Research ,Benzimidazole ,Staphylococcus aureus ,Indoles ,Topoisomerase Inhibitors ,Drug Evaluation, Preclinical ,Antineoplastic Agents ,Apoptosis ,Microbial Sensitivity Tests ,01 natural sciences ,HeLa ,03 medical and health sciences ,chemistry.chemical_compound ,Structure-Activity Relationship ,0302 clinical medicine ,Escherichia coli ,Staphylococcus epidermidis ,Humans ,Viability assay ,Amino Acids ,Cytotoxicity ,Pharmacology ,Indole test ,biology ,010405 organic chemistry ,Fatty Acids ,Hep G2 Cells ,Cell cycle ,biology.organism_classification ,0104 chemical sciences ,Anti-Bacterial Agents ,chemistry ,Biochemistry ,A549 Cells ,030220 oncology & carcinogenesis ,Cancer cell ,Molecular Medicine ,Benzimidazoles ,DNA Topoisomerases ,HeLa Cells - Abstract
Background and Objective : Drug resistance and adverse effects are immense healthcare challenges in cancer therapy. Benzimidazole ring-based small molecules have been effective anticancer agents in drug development. In an effort to develop novel chemotherapeutics, we synthesized and assessed the anticancer and antibacterial activities of a small library of structurally unique benzimidazoles. Methods : The benzimidazoles were derived from indole, N-alkyl indole, fatty acid, and alpha-amino acid scaffolds providing a panel of diverse structures. The compounds were tested in three different cancer cell lines for cytotoxicity: HepG2 (human hepatocellular carcinoma), HeLa (human cervical carcinoma), and A549 (human lung carcinoma). Mechanism of cell death induced by benzimidazoles was evaluated using fluorescent dye-based apoptosis-necrosis assay, immunoblotting for active caspases, topoisomerase-II activity assay, and cell cycle assay. Results : Cell viability testing revealed that indole- and fatty acid-based benzimidazoles were most potent followed by the amino acid derivatives. Many compounds induced cytotoxicity in a concentration-dependent manner with cellular cytotoxicity (CC50) Conclusion: The reported benzimidazole derivatives possess promising anticancer and antibacterial properties. Additionally, we discovered apoptosis to be the primary mechanism for cancer cell death induced by the tested benzimidazoles. Our findings suggest that further development of these scaffolds could provide drug leads towards new chemotherapeutics.
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- 2019
5. Benzimidazole scaffolds as potential anticancer agents: Synthesis and Biological evaluation
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Sabesan Yoganathan, Sin Sil Ha, Leonard Barasa, John L. Croft, Christian Palaguachi, Vikas V. Dukhande, Nirupama Surubhotla, Jing Kong, and Hari Priya Vemana
- Subjects
Benzimidazole ,chemistry.chemical_compound ,chemistry ,Genetics ,Molecular Biology ,Biochemistry ,Combinatorial chemistry ,Biotechnology ,Biological evaluation - Published
- 2019
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6. 4′-Prenyloxyderrone from the stem bark of Millettia oblata ssp. teitensis and the antiplasmodial activities of isoflavones from some Millettia species
- Author
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Edwin Kamau, Matthias Heydenreich, Solomon Derese, Leonard Barasa, Abiy Yenesew, Amir O. Yusuf, and Hoseah M. Akala
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chemistry.chemical_classification ,Millettia leucantha ,Traditional medicine ,biology ,Chemistry ,Tephrosin ,Plant Science ,Isoflavones ,biology.organism_classification ,Biochemistry ,Rotenoid ,Millettia ,chemistry.chemical_compound ,Triterpene ,Institut für Chemie ,Chrysin ,Agronomy and Crop Science ,Biotechnology ,Lupeol - Abstract
The CH 2 Cl 2 /MeOH (1:1) extract of the stem bark of Millettia oblata ssp. teitensis showed antiplasmodial activity (IC 50 = 10–12 μg/mL) against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum . Chromatographic separation of the extract led to the isolation of a new isoflavone, 4′-prenyloxyderrone ( 1 ), together with known isoflavones (8- O -methylretusin, durmillone, maximaisoflavone B, maximaisoflavone H and maximaisoflavone J), a rotenoid (tephrosin) and a triterpene (lupeol). Similar investigation of Millettia leucantha resulted in the identification of the isoflavones afrormosin and wistin, and the flavone chrysin. The identification of these compounds was based on their spectroscopic data. Five of the isoflavones isolated from these plants as well as 11 previously reported compounds from Millettia dura were tested and showed good to moderate antiplasmodial activities (IC 50 = 13–53 μM), with the new compound, 4′-prenyloxyderrone, being the most active (IC 50 = 13–15 μM).
- Published
- 2014
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