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Kumar M, Kumar R, Rana N, Prasad AK. Synthesis of 3′-azido/-amino-xylobicyclonucleosides. RSC Adv 2016. [DOI: 10.1039/c5ra25222a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Lipozyme® TL IM mediated the selective deacetylation of one of the two acetoxy groups in 4-C-acetoxymethyl-5-O-acetyl-3-azido-3-deoxy-1,2-O-isopropylidene-α-d-xylofuranose, leading to the first efficient syntheses of 3′-azido/3′-amino-xylobicyclonucleosides T, U, C and A.
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Kumar R, Kumar M, Maity J, Prasad AK. Chemo-enzymatic synthesis of 3′-O,4′-C-methylene-linked α-l-arabinonucleosides. RSC Adv 2016. [DOI: 10.1039/c6ra17218k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Biocatalytic methodology has been developed for the efficient and environment friendly synthesis of 3′-O,4′-C-methylene-linked α-l-arabinonucleosides.
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Kumar M, Sharma VK, Kumar R, Prasad AK. Biocatalytic route to C-3'-azido/-hydroxy-C-4'-spiro-oxetanoribonucleosides. Carbohydr Res 2015; 417:19-26. [PMID: 26386197 DOI: 10.1016/j.carres.2015.08.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 08/25/2015] [Accepted: 08/26/2015] [Indexed: 11/28/2022]
Abstract
The lipase, Novozyme(®)-435, exclusively deacetylates the 5-O-acetyl over 4-C-acetyloxymethyl group of almost identical reactivity in 5-O-acetyl-4-C-acetyloxymethyl-3-azido-3-deoxy-1,2-O-isopropylidene-α-D-ribofuranose that led to the development of first and efficient synthesis of 3'-azido-/3'-amino-C-4'-spiro-oxetanoribonucleosides T, U, C and A in 20-24% overall yields. The X-ray study on the compound obtained by tosylation of lipase-mediated monodeacetylated product unambiguously confirmed the point of diastereoselective monodeacetylation on diacetoxy-azido-ribofuranose derivative. The capability of Novozyme(®)-435 for selective deacylation of 5-O-acetyl group in 5-O-acetyl-4-C-acetyloxymethyl-3-O-benzyl-1,2-O-isopropylidene-α-D-ribofuranose recently discovered by us has been successfully used for the synthesis of C-4'-spiro-oxetanoribonucleosides A and C in good yields. These results clearly indicate that the broader substrate specificity and highly selective capability of Novozyme(®)-435 for carrying out acetylation/deacetylation reactions can be utilized for the development of environment friendly selective methodologies in organic synthesis.
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Khatri V, Kumar A, Singh B, Malhotra S, Prasad AK. Synthesis of β-C-Glycopyranosyl Aldehydes and 2,6-Anhydro-heptitols. J Org Chem 2015; 80:11169-74. [DOI: 10.1021/acs.joc.5b01933] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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80
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Rangarajan T, Devi K, Ayushee, Prasad AK, Pal Singh R. A general, mild and efficient palladium-catalyzed 2,2,2-trifluoroethoxylation of activated aryl bromides and bromo-chalcones: bromo-chalcones a new coupling partner in cross-coupling reaction. Tetrahedron 2015. [DOI: 10.1016/j.tet.2015.08.071] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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81
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Reddy L CS, Sharma VK, Kumar R, Singh A, Parmar VS, Sanghvi YS, Prasad AK. Facile Access to 5'-S-(4,4'-Dimethoxytrityl)-2',5'-Dideoxyribonucleosides via Stable Disulfide Intermediates. CURRENT PROTOCOLS IN NUCLEIC ACID CHEMISTRY 2015; 62:1.34.1-1.34.9. [PMID: 26380902 DOI: 10.1002/0471142700.nc0134s62] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Thionucleosides represent an important class of modified nucleos(t)ides that have found distinct applications in the chemical biology of synthetic oligonucleotides, but the use of these compounds is substantially lessened by the instability or high reactivity of the sulfhydryl group. This unit describes a protocol for the synthesis of 2',5'-dideoxy-5'-thioribonucleoside disulfides by utilizing Mitsunobu reaction conditions on 3'-O-levulinyl-2'-deoxyribonucleosides in the presence of thiobenzoic acid followed by facile hydrolysis and in situ oxidation of the resulting 5'-thiolated nucleosides using methanolic ammonia. The utility of these disulfides has been demonstrated as stable precursors for the synthesis of 5'-thio-modified 2'-deoxynucleosides. To validate the potential of the methodology, 5'-S-(4,4'-dimethoxytrityl)-2',5'-dideoxythymidine phosphoramidite has been synthesized by in situ cleavage of the disulfide linkage of 2',5'-dideoxy-5'-thiothymidine disulfide followed by protection with a dimethoxytriphenyl (DMT) group and 3'-phosphitylation using 2-cyanoethyl N,N-diisopropylchlorophosphoramidite.
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82
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Miri R, Nejati M, Saso L, Khakdan F, Parshad B, Mathur D, Parmar VS, Bracke ME, Prasad AK, Sharma SK, Firuzi O. Structure-activity relationship studies of 4-methylcoumarin derivatives as anticancer agents. PHARMACEUTICAL BIOLOGY 2015; 54:105-10. [PMID: 26017566 DOI: 10.3109/13880209.2015.1016183] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
CONTEXT Cancer is a leading cause of death worldwide and novel chemotherapeutic agents with better efficacy and safety profiles are much needed. Coumarins are natural polyphenolic compounds with important pharmacological activities, which are present in many dietary plants and herbal remedies. OBJECTIVES The objective of this study is to investigate natural and synthetic coumarin derivatives with considerable anticancer capacity against three human cancer cell lines. MATERIALS AND METHODS We synthesized 27 coumarin derivatives (mostly having 4-methyl moiety) and examined their cytotoxic effect on three human cancer cell lines, K562 (chronic myelogenous leukemia), LS180 (colon adenocarcinoma), and MCF-7 (breast adenocarcinoma) by MTT reduction assay. Screened compounds included 7-hydroxy-4-methylcoumarins (7-HMCs), 7-acetoxy-4-methylcoumarins (7-AMCs), and different dihydroxy-4-methylcoumarin (DHMC) and diacetoxy-4-methylcoumarin (DAMC) derivatives. Some compounds with methoxy, amine, and bromine substitutions were also examined. RESULTS 7,8-DHMCs bearing alkyl groups at C3 position were the most effective subgroup, and of which, the most potent is compound 11, with an n-decyl chain at C3, which had IC50 values of 42.4, 25.2, and 25.1 µM against K562, LS180, and MCF-7 cells, respectively. The second most active subgroup was 7,8-DAMCs containing ethoxycarbonylmethyl and ethoxycarbonylethyl moieties at C3 position. Compound 27 (6-bromo-4-bromomethyl-7-hydroxycoumarin), the only derivative containing bromine also showed reasonable cytotoxic activities (IC50 range: 32.7-45.8 µM). DISCUSSION AND CONCLUSION This structure-activity relationship (SAR) study of 4-methylcoumarins shows that further investigation of these derivatives may lead to the discovery of novel anticancer agents.
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Sharma VK, Singh SK, Bohra K, L CSR, Khatri V, Olsen CE, Prasad AK. Design and synthesis of LNA-based mercaptoacetamido-linked nucleoside dimers. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2015; 32:256-72. [PMID: 23581718 DOI: 10.1080/15257770.2013.783218] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Three LNA-based mercaptoacetamido-linked nonionic nucleoside dimers TL-S-T, T-S-TL, and TL-S-TL have been synthesized by HOBT and HBTU catalyzed condensation of silyl-protected 2-S-(thymidin-5 '-yl)mercaptoacetic acid or 2-S-(2 '-O,4 '-C-methylenethymidin-5 '-yl)mercaptoacetic acid with 3 '-amino-3 '-deoxy-5 '-O-DMT-2 '-O,4 '-C-methylenethymidine or with 3 '-amino-3 '-deoxy-5 '-O-DMT-β-thymidine followed by desilylation of the protected dimers. The 3 '-O-phosphoramidite derivative of one of the nucleoside dimers was successfully prepared by condensation with [P(-Cl)(-OCH2CH2CN)-N(iPr)2}] in DCM in the presence of N,N-diisopropylethylamine (DIPEA), which is a building block for the preparation of mercaptoacetamido-linked oligonucleotides of therapeutic applications.
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Rangarajan T, Brahma R, Ayushee, Prasad AK, Verma AK, Singh RP. Mild and efficient palladium/BrettPhos-catalyzed methoxylation and deuteriomethoxylation of activated aryl bromides. Tetrahedron Lett 2015. [DOI: 10.1016/j.tetlet.2015.03.045] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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85
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Sharma VK, Rungta P, Maikhuri VK, Prasad AK. An astute synthesis of locked nucleic acid monomers. ACTA ACUST UNITED AC 2015. [DOI: 10.1186/s40508-015-0028-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Abstract
Novel attributes of Locked Nucleic Acid (LNA) makes it preferable over most of the other classes of modified nucleic acid analogues and therefore, it has been extensively explored in different synthetic oligonucleotide based therapeutics. In addition to five oligonucleotides of this class undergoing clinical trials, a healthy pipeline in pre-clinical studies validates the tenacity of LNA. Due to the increasing demand, an efficient biocatalytic methodology has recently been devised for the convergent synthesis of LNA monomers via selective enzymatic monoacetylation of diastereotopic hydroxymethyl functions of 3-O-benzyl-4-C-hydroxymethyl-1,2-O-isopropylidene-α-D-ribofuranose. This commentary article provides an insight into the different synthetic strategies followed for the synthesis of LNA monomers and their triumphs in clinical biotechnology.
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86
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Kumar G, Dhawan A, Singh BK, Sharma NK, Sharma SK, Prasad AK, Van der Eycken EV, Len C, Watterson AC, Parmar VS. Highly Selective Biocatalytic Transesterification Reactions on Aryl 3-hydroxy-2-(hydroxymethyl)-2-methylpropanoates. Catal Letters 2015. [DOI: 10.1007/s10562-014-1447-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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87
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Verma A, Venkateswaran K, Farooque A, Bhatt AN, Kalra N, Arya A, Dhawan A, Arya MB, Raj HG, Prasad AK, Parmar VS, Dwarakanath BS. Cytotoxic and radio-sensitizing effects of polyphenolic acetates in a human glioma cell line (BMG-1). Curr Pharm Des 2015; 20:1161-9. [PMID: 24552186 DOI: 10.2174/1381612820666140220112720] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2013] [Accepted: 10/07/2013] [Indexed: 11/22/2022]
Abstract
BACKGROUND AND AIMS Polyphenolic acetates (PAs) have antioxidant/ pro-oxidant properties and can also acetylate proteins (enzymes) by a novel acetoxy drug: calreticulin transacetylase acetylation system. While PAs have been investigated as pharmacological agents for the treatment of various diseases, their potential as anti-cancer agents or their efficacy as an adjuvant in anti-cancer therapeutics remains to be explored. In the present study we investigated the cytotoxic and radio-sensitizing effects of 7, 8- diacetoxy-4-methyl coumarin (DAMC) and 7- acetoxy-4-methyl coumarin (7-AMC) in a human glioma cell line (BMG-1). METHODS Cytotoxic and radio-sensitizing effects were investigated by studying reactive oxygen species (ROS) levels, metabolic viability, clonogenic survival, growth inhibition, cell cycle perturbation, DNA repair and cytogenetic damage, besides analyzing the histone (H3) acetylation. RESULTS Exposure of cells to DAMC and 7-AMC for 24 h showed a dose dependent increase in toxicity as indicated by reduced metabolic viability, clonogenic survival and cell proliferation, with DAMC being more toxic than 7-AMC. The degree of radiosensitization by DAMC was also higher as compared to 7-AMC as reflected by a decrease in the clonogenicity, enhanced radiation-induced cell cycle perturbation and apoptosis. DAMC impaired the removal of radiation-induced DNA double stranded breaks (measured by γH2AX immuno- fluorescence) and enhanced the cytogenetic damage (micronuclei formation), leading to an increase in mitotic death. While DAMC alone induced pan nuclear γH2AX fluorescence, both pan nuclear and spatially restricted foci was observed with the combined treatment (DAMC + Radiation) suggesting a complex nature of DNA damage and repair. DAMC- induced cytotoxic and radio-sensitizing effects were independent of its pro-oxidant activity, whereas histone H3 lysine (9/14) hyperacetylation appeared to be a potential target, regulating cellular responses to ionizing radiation (IR). CONCLUSIONS The polyphenolic acetate 7, 8- diacetoxy-4-methyl coumarin (DAMC) demonstrates both anticancer effects and radiosensitizing potential under in vitro conditions.
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Kumari M, Billamboz M, Leonard E, Len C, Böttcher C, Prasad AK, Haag R, Sharma SK. Self-assembly, photoresponsive behavior and transport potential of azobenzene grafted dendronized polymeric amphiphiles. RSC Adv 2015. [DOI: 10.1039/c5ra08047a] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
An azobenzene based light responsive polymeric system was developed to study the transport potential and photo-controlled release of encapsulated guests.
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89
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Joshi R, Rohil V, Arora S, Kumar A, Manral S, Goel S, Priya N, Singh P, Ponnan P, Chatterji S, Dwarakanath BS, Saluja D, Rawat DS, Prasad AK, Saso L, Kohli E, DePass AL, Bracke ME, Parmar VS, Raj HG. The Competence of 7,8-Diacetoxy-4-Methylcoumarin and Other Polyphenolic Acetates in Mitigating the Oxidative Stress and their Role in Angiogenesis. Curr Top Med Chem 2015; 15:179-186. [PMID: 25547104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Revised: 08/13/2014] [Accepted: 10/10/2014] [Indexed: 06/04/2023]
Abstract
The potential role of polyphenolic acetate (PA) in causing diverse biological and pharmacological actions has been well studied in our laboratory. Our investigations, for the first time, established the role of calreticulin transacetylase (CRTAase) in catalyzing the acetylation of nitric oxide synthase (NOS) by Pas leading to robust activation of NOS. 7, 8- Diacetoxy-4-methylcoumarin (DAMC) and other acetoxycoumarins augmented the expression of thioredoxin (TRX) and vascular endothelial growth factor (VEGF) in human peripheral blood mononuclear cells (PBMCs). These findings substantiated our earlier observations that DAMC was a superb inducer of angiogenesis. The enhanced expression of thioredoxin reductase (TRXR) and diminished expression of thioredoxin interacting protein (TRXIP) leading to increased expression and activity of TRX in PBMCs due to the action of DAMC was revealed by real time RT-PCR analysis. The possible activation of TRX due to acetylation was confirmed by the fact that TRX activity of PBMCs was enhanced by various acetoxycoumarins in tune with their affinities to CRTAase as substrates. DAMC caused enhanced production of NO by way of acetylation of NOS as mentioned above and thereby acted as an inducer of VEGF. Real time RT-PCR and VEGF ELISA results also revealed the overexpression of TRX. DAMC and other PAs were found to reduce the oxidative stress in cells as proved by significant reduction of intracellular ROS levels. Thus, the crucial role of TRX in DAMC-induced angiogenesis with the involvement of VEGF was established.
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Prasad AK, Rashid M, Heidari N. The novel use of an external fixator connecting rod and synthetic bone substitute to achieve anatomic reduction of depressed tibial plateau fracture fragments. Ann R Coll Surg Engl 2014; 97:78. [PMID: 25519280 DOI: 10.1308/rcsann.2015.97.1.78] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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91
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Joshi R, Arora S, Kumar A, Manral S, Rohil V, Goel S, Priya N, Singh P, Ponnan P, Chatterji S, Dwarakanath BS, Saluja D, Rawat DS, Prasad AK, Saso L, Kohli E, DePass AL, Bracke ME, Parmar VS, Raj HG. The Competence Of 7,8-Diacetoxy-4-Methylcoumarinand Other Polyphenolic Acetates In Mitigating The Oxidative Stress And Their Role In Angiogenesis. Curr Top Med Chem 2014:CTMC-EPUB-63886. [PMID: 25496273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Revised: 08/13/2014] [Accepted: 10/10/2014] [Indexed: 06/04/2023]
Abstract
The potential role of polyphenolic acetate (PA) in causing diverse biological and pharmacological actions has been well studied in our laboratory. Our investigations, for the first time, established the role of calreticulin transacetylase (CRTAase) in catalyzing the acetylation of nitric oxide synthase (NOS) by Pas leading to robust activation of NOS. 7, 8-Diacetoxy-4-methylcoumarin (DAMC) and other acetoxycoumarins augmented the expression of thioredoxin (TRX) and vascular endothelial growth factor (VEGF) in human peripheral blood mononuclear cells (PBMCs). These findings substantiated our earlier observations that DAMC was a superb inducer of angiogenesis. The enhanced expression of thioredoxin reductase (TRXR) and diminished expression of thioredoxin interacting protein (TRXIP) leading to increased expression and activity of TRX in PBMCs due to the action of DAMC was revealed by real time RT-PCR analysis. The possible activation of TRX due to acetylation was confirmed by the fact that TRX activity of PBMCs was enhanced by variousacetoxycoumarins in tune with their affinities to CRTAase as substrates. DAMC caused enhanced production of NO by way of acetylation of NOS as mentioned above and thereby acted as an inducer of VEGF. Real time RT-PCR and VEGF ELISA results also revealed the overexpression of TRX. DAMC and other PAs were found to reduce the oxidative stress in cells as proved by significant reduction of intracellular ROS levels. Thus, the crucial role of TRX in DAMC-induced angiogenesis with the involvement of VEGF was established.
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92
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Venkateswaran K, Verma A, Bhatt AN, Agrawala PK, Raj HG, Malhotra S, Prasad AK, Wever OD, Bracke ME, Saso L, Parmar VS, Shrivastava A, Dwarakanath BS. Modifications of cell signalling and redox balance by targeting protein acetylation using natural and engineered molecules: implications in cancer therapy. Curr Top Med Chem 2014; 14:2495-507. [PMID: 25478886 DOI: 10.2174/1568026614666141203122005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 09/29/2014] [Accepted: 10/10/2014] [Indexed: 11/22/2022]
Abstract
Acetylation of proteins with the addition of an acetyl group on the lysine residue is one of the vital posttranslational modifications that regulate protein stability, function and intracellular compartmentalization. Like other posttranslational modifications, protein acetylation influences many if not all vital functions of the cell. Protein acetylation has been originally associated with histone acetylation regulated by Histone Acetyl Transferase (HAT) and Histone Deacetylase (HDAC) and was mainly considered to be involved in epigenetic regulation through chromatin remodelling. It is now widely referred to as lysine acetylation orchestrated by lysine acetyl transferase (KAT) and lysine deacetylase (KDAC) and influences many cellular functions. Protein acetylation fine tunes the redox balance and cell signalling in the context of cancer by exerting its control on expression of two very important redox sensors viz. Nrf2 and NF-κB. Accumulating evidences show that inhibitors of deacetylase (KDACi), responsible for cytotoxic effects in cancer cells, mediate their actions by inhibiting the deacetylases, thereby simulating an hyperacetylation state of histone as well as non-histone proteins, similar to the one created by KATs. Emergence of calreticulin (CRT) mediated protein acetylation system using polyphenolic acetates as donors coupled with over expression of CRT has opened new avenues for targeting protein acetylation for improving cancer therapy. Modifiers of protein acetylation are therefore, emerging as a class of anticancer therapeutics and adjuvant as they inhibit growth, induce differentiation and death (apoptosis) differentially in cancer cells and also exhibit chemo-radiation sensitizing potential. Although pre-clinical investigations with many natural and synthetic KDAC inhibitors have been very promising, their clinical utility has so far been limited to certain types of cancers of the hematopoietic system. The future of protein acetylation modifiers appears to depend on the development of newer engineered molecules and their rational combinations that can exploit the differences in the regulation of protein acetylation between tumor and normal cells/tissues.
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Rangarajan TM, Singh R, Brahma R, Devi K, Singh RP, Singh RP, Prasad AK. BrettPhos Ligand Supported Palladium-Catalyzed CO Bond Formation through an Electronic Pathway of Reductive Elimination: Fluoroalkoxylation of Activated Aryl Halides. Chemistry 2014; 20:14218-25. [DOI: 10.1002/chem.201404121] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Indexed: 02/05/2023]
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94
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Sharma VK, Kumar M, Sharma D, Olsen CE, Prasad AK. Chemoenzymatic Synthesis of C-4′-Spiro-oxetanoribonucleosides. J Org Chem 2014; 79:8516-21. [DOI: 10.1021/jo501655j] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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95
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Mathur D, Prasad AK, Cameron TS, Jha A. Novel approach to 3,3-dimethyl-4-morpholino-3,4-dihydrocoumarins via hetero-Diels–Alder reaction. Tetrahedron 2014. [DOI: 10.1016/j.tet.2014.06.083] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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96
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Kumar M, Sharma VK, Olsen CE, Prasad AK. Chemo-enzymatic synthesis of bicyclic 3′-azido- and 3′-amino-nucleosides. RSC Adv 2014. [DOI: 10.1039/c4ra06805j] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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97
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Singh P, Sinha R, Tandon R, Tyagi G, Khatri P, Chandra Shekhar Reddy L, Saini NK, Pathak R, Varma-Basil M, Prasad AK, Bose M. Revisiting a protocol for extraction of mycobacterial lipids. Int J Mycobacteriol 2014; 3:168-72. [PMID: 26786484 DOI: 10.1016/j.ijmyco.2014.07.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 07/17/2014] [Indexed: 11/19/2022] Open
Abstract
Determination of lipid content of any biological sample is essential for various kinds of studies related to pathogenicity and drug development. Thus, reliable methods for the quantitative extraction of lipids are of critical importance. The mycobacterial cell wall is largely composed of lipids. Commonly used methods to extract lipids, such as the Bligh and Dyer method or the Folch method, yield a low amount of lipids when applied to mycobacterial cells. This study presents an efficient modification of Chandramauli's method, a less known method developed at this institute earlier that is able to yield a considerably higher concentration of mycobacterial lipids.
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Arya A, Mathur D, Tyagi A, Kumar R, Kumar V, Olsen CE, Saxena RK, Prasad AK. Chemoenzymatic synthesis of 3'-deoxy-3'-(4-substituted-triazol-1-YL)-5-methyluridine. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2014; 32:646-59. [PMID: 24328562 DOI: 10.1080/15257770.2013.847957] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
An efficient protocol has been developed for the synthesis of a small library of 3'-deoxy-3'-(4-substituted-triazol-1-yl)-5-methyluridine using Cu(I)-catalyzed Huisgen-Sharpless-Meldal 1,3-dipolar cycloaddition reaction of 3'-azido-3'-deoxy-5-methyluridine with different alkynes under optimized condition in an overall yields of 76%-92%. Here, the azido precursor compound, i.e., 3'-azido-3'-deoxy-5-methyluridine was chemoenzymatically synthesized from D-xylose in good yield. Some of the alkynes used in cycloaddition reaction were synthesized by the reaction of hydroxycoumarins or naphthols with propargyl bromide in acetone using K2CO3in excellent yields. All synthesized compounds were unambiguously identified on the basis of their spectral (IR, (1)H-, (13)C NMR spectra, and high-resolution mass spectra) data analysis.
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Sharma VK, Kumar M, Olsen CE, Prasad AK. Chemoenzymatic Convergent Synthesis of 2′-O,4′-C-Methyleneribonucleosides. J Org Chem 2014; 79:6336-41. [DOI: 10.1021/jo5008338] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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100
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Dhawan A, Balwani S, Prasad AK, Ghosh B, Parmar VS. Synthesis and Evaluation of 2,2-Dimethylchroman Derivatives as Inhibitors of ICAM-1 Expression on Human Endothelial Cells. J Heterocycl Chem 2014. [DOI: 10.1002/jhet.1860] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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