Akhilesh Verma | NORTH EASTERN HILL UNIVERSITY,SHILLONG (original) (raw)
Papers by Akhilesh Verma
Medicinal Chemistry Research, 2012
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Microscopy and Microanalysis, 2013
Cantharidin, a type of terpenoid, is the blistering agent of blister beetles frequently used in t... more Cantharidin, a type of terpenoid, is the blistering agent of blister beetles frequently used in traditional medicine. The isolation and anticancer activity of cantharidin from blister beetles, Mylabris cichorii has been recently reported by us. This study deals with changes in mitochondrial structure and function and understanding their significance in the underlying mechanism(s) in cantharidin-mediated antitumor effects in Dalton's lymphoma (DL) bearing mice. Cantharidin treatment caused the appearance of abnormal mitochondrial features which included roundish mitochondria with thickened membranes, irregularity in cristae, and appearance of small and large size vacuoles in mitochondria of DL cells. Cantharidin treatment resulted in a decrease in mitochondrial reduced glutathione, succinate dehydrogenase activity, mitochondrial membrane potential, and induced apoptosis and necrosis in DL cells. The decrease/release of mitochondrial cytochrome c were also observed after cantharid...
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Journal of Ethnopharmacology, 2013
The blister beetles Epicauta hirticornis and Mylabris cichorii are used as a folk medicine by the... more The blister beetles Epicauta hirticornis and Mylabris cichorii are used as a folk medicine by the Karbi tribe in Karbi Anglong district of Assam, India for the treatment of different human ailments, including cancer cases. It includes field survey related to zoo-therapeutic aspects of two blister beetles in Karbi community, isolation of bio-active compound and evaluation of its antitumor potential with possible mode of action against murine Ehrlich ascites carcinoma (EAC). The main bio-active compound of blister beetles was isolated from ethyl acetate extract and the structure was confirmed as cantharidin using NMR, IR, Mass and X-ray diffractometer. The effect of cantharidin on apoptosis, necrosis, autophagy and the apoptosis related signaling pathways were determined using different bioassays, including cell cycle analysis, mitochondrial membrane potential, western blot analysis of cytochrome c, caspases 9, 3/7 assays, and lactate dehydrogenase (LDH) assay. Cantharidin induced apoptosis, necrosis and autophagy cell death in EAC cells. The decrease in mitochondrial membrane potential was observed, which may help to release cytochrome c from mitochondria to cytosol. Cantharidin treatment caused up-regulation of caspases 9 and -3/7 and a decrease in LDH activity in EAC cells. The major bioactive compound of these blister beetles is cantharidin which induces severe apoptosis in EAC cells involving mitochondrial intrinsic pathway. Cantharidin-mediated inhibition of LDH activity may lead to short supply of NAD(+) and cut off energy and anabolic supply to cancer cells.
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The Journal of organic chemistry, Jan 5, 2016
A highly efficient metal and protection-free approach for the regioselective synthesis of C-3-fun... more A highly efficient metal and protection-free approach for the regioselective synthesis of C-3-functionalized quinolines from azadienes (in situ generated from 2-aminobenzyl alcohol) and terminal alkynes through [4 + 2] cycloaddition has been developed. An unprecedented reaction of 2-aminobenzyl alcohol with 1,3- and 1,4-diethynylbenzene provided the C-3 tolylquinolines via [4 + 2] HDA and oxidative decarboxylation. The -NH2 group directed mechanistic approach was well supported by the control experiments and deuterium-labeling studies and by isolating the azadiene intermediate. The reactivity and selectivity of unprotected azadiene in metal-free base-assisted hetero-Diels-Alder reaction is exploited to quickly assemble an important class of C-3-functionalized quinolines, which are difficult to access.
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The Journal of Organic Chemistry, 2016
An atom-economical Pd-catalyzed approach for the synthesis of benzophenazine derivatives using su... more An atom-economical Pd-catalyzed approach for the synthesis of benzophenazine derivatives using substituted 2-aryl-3-(aryl/alkylethynyl) quinoxaline in the presence of trifluoroacetic acid at 65 °C has been described. The chemistry involves in situ generation of cationic Pd(II) species, which functionalized the aromatic C-H bonds via electrophilic metalation followed by concomitant intramolecular trans-insertion of C-C triple bond to aryl-Pd complex. The results were supported by various control experiments including with electron-deficient arenes and deuterium labeling studies. The deuterium labeling studies supports electrophilic palladation of aromatic C-H over activation of C-C triple bond of alkyne. The structure of synthesized compounds was further confirmed by X-ray crystallography studies. This catalytic protocol has been efficiently applied for novel synthesis of highly functionalized benzo fused phenazines.
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The Journal of Organic Chemistry, 2016
An environmentally benign Au(III)-catalyzed regio- and stereoselective domino synthesis of oxazol... more An environmentally benign Au(III)-catalyzed regio- and stereoselective domino synthesis of oxazolo fused pyridoindoles 7a-v and benzofurooxazolo pyridines 8a-n by the reaction of o-alkynylaldehydes 4a-t and 5a-k with (S)-phenylglycinol 6a and (R)-phenylglycinol 6b under mild reaction conditions using water as reaction medium is reported. The reaction proceeded via selective C-N bond formation on the more electrophilic alkynyl carbon through 6-endo-dig cyclization. The reaction tolerates a wide variety of functional groups. The developed chemistry has been successfully extended for the synthesis of a diverse class of γ-carbolines and benzofuro[3,2-c]pyridines using corresponding ester hydrochlorides of serine, threonine, and cystine as a nitrogen source.
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J Biol Inorg Chem, 2011
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The Journal of Organic Chemistry, Oct 1, 2010
Chemoselective behavior of iodine in different solvents in the electrophilic iodocyclization of o... more Chemoselective behavior of iodine in different solvents in the electrophilic iodocyclization of o-alkynyl aldehydes is described. o-Alkynyl aldehydes 3a-t on reaction with I2 in CH2Cl2 with appropriate nucleophiles provides pyrano[4,3-b]quinolines 4a-f, via formation of cyclic iodonium intermediate Q; however, using alcohols as a solvent as well as nucleophile, o-alkynyl esters 5a-y were obtained selectively in good to excellent yields via formation of hypoiodide intermediate R. Subsequently, o-alkynyl esters were converted in to pyranoquinolinones 6a-i and isocoumarin 6j by electrophilic iodocyclization. This developed oxidative esterification provides a novel access for the chemoselective synthesis of esters 5q-u from aldehydes 3n-p without oxidizing primary alcohol present in the substrate.
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Journal of Organic Chemistry, 2011
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International Journal of Contemporary Dental and Medical Reviews, Jan 4, 2015
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European Journal of Medicinal Chemistry, Oct 31, 2008
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Cheminform, Feb 26, 2013
AbstractUnsymmetrical internal alkynes such as (X) or (XII) generate selectively a single isomers... more AbstractUnsymmetrical internal alkynes such as (X) or (XII) generate selectively a single isomers [cf.(XI) or (XIII)].
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The 3rd European Wireless Technology Conference, 2010
A constant-gain ultra-wideband semi-circular disc monopole with a quasi-planar surface-mounted sh... more A constant-gain ultra-wideband semi-circular disc monopole with a quasi-planar surface-mounted short TEM horn and a semi-circular reflector is proposed. The total length of the antenna is only 70 mm i.e. nearly 0. 67 λ at 2.86 GHz. The gain of the antenna is nearly constant: 6.5 ± 1.1 dBi from 2.86 GHz to 15 GHz, and 6.5 ± 0.7 dBi from 3.1 GHz to 10.6 GHz,. It has broad azimuth pattern and its compact integrated configuration is suitable for several ultra-wideband (UWB) wireless and radar applications.
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Organic letters, Jan 6, 2016
A base promoted, protection-free, and regioselective synthesis of highly functionalized quinoline... more A base promoted, protection-free, and regioselective synthesis of highly functionalized quinolines via [4 + 2] cycloaddition of azadienes (generated in situ from o-aminobenzyl alcohol) with internal alkynes has been discovered. The reaction tolerates a wide variety of functional groups which has been successfully extended with diynes, (2-aminopyridin-3-yl)methanol, and 1,4-bis(phenylethynyl)benzene to afford (Z)-phenyl-2-styrylquinolines, phenylnaphthyridine, and alkyne-substituted quinolines, respectively. The proposed mechanism and significant role of the solvent were well supported by isolating the azadiene intermediate and deuterium-labeling studies.
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2010 Asia Pacific Microwave Conference, Dec 1, 2010
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2014 Fourth International Conference of Emerging Applications of Information Technology, Dec 19, 2014
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Journal of Pharmacy and Nutrition Sciences, Apr 30, 2013
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Journal of Food Science and Technology, 2009
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Int J Electron, 2011
This article addresses a CAD-oriented closed-form expressions for dispersive and conductor thickn... more This article addresses a CAD-oriented closed-form expressions for dispersive and conductor thickness-based line parameters for symmetrical coplanar strip lines (CPS) on a finite-thickness dielectric substrate. The conductor and dielectric losses are also computed. The models are extended to non-planar CPS – elliptical coplanar strip line (ECPS) and cylindrical coplanar strip lines (CCPS). Finally, accurate circuit model for these structures is
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Journal of Earth System Science, Mar 19, 2015
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Medicinal Chemistry Research, 2012
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Microscopy and Microanalysis, 2013
Cantharidin, a type of terpenoid, is the blistering agent of blister beetles frequently used in t... more Cantharidin, a type of terpenoid, is the blistering agent of blister beetles frequently used in traditional medicine. The isolation and anticancer activity of cantharidin from blister beetles, Mylabris cichorii has been recently reported by us. This study deals with changes in mitochondrial structure and function and understanding their significance in the underlying mechanism(s) in cantharidin-mediated antitumor effects in Dalton's lymphoma (DL) bearing mice. Cantharidin treatment caused the appearance of abnormal mitochondrial features which included roundish mitochondria with thickened membranes, irregularity in cristae, and appearance of small and large size vacuoles in mitochondria of DL cells. Cantharidin treatment resulted in a decrease in mitochondrial reduced glutathione, succinate dehydrogenase activity, mitochondrial membrane potential, and induced apoptosis and necrosis in DL cells. The decrease/release of mitochondrial cytochrome c were also observed after cantharid...
Bookmarks Related papers MentionsView impact
Journal of Ethnopharmacology, 2013
The blister beetles Epicauta hirticornis and Mylabris cichorii are used as a folk medicine by the... more The blister beetles Epicauta hirticornis and Mylabris cichorii are used as a folk medicine by the Karbi tribe in Karbi Anglong district of Assam, India for the treatment of different human ailments, including cancer cases. It includes field survey related to zoo-therapeutic aspects of two blister beetles in Karbi community, isolation of bio-active compound and evaluation of its antitumor potential with possible mode of action against murine Ehrlich ascites carcinoma (EAC). The main bio-active compound of blister beetles was isolated from ethyl acetate extract and the structure was confirmed as cantharidin using NMR, IR, Mass and X-ray diffractometer. The effect of cantharidin on apoptosis, necrosis, autophagy and the apoptosis related signaling pathways were determined using different bioassays, including cell cycle analysis, mitochondrial membrane potential, western blot analysis of cytochrome c, caspases 9, 3/7 assays, and lactate dehydrogenase (LDH) assay. Cantharidin induced apoptosis, necrosis and autophagy cell death in EAC cells. The decrease in mitochondrial membrane potential was observed, which may help to release cytochrome c from mitochondria to cytosol. Cantharidin treatment caused up-regulation of caspases 9 and -3/7 and a decrease in LDH activity in EAC cells. The major bioactive compound of these blister beetles is cantharidin which induces severe apoptosis in EAC cells involving mitochondrial intrinsic pathway. Cantharidin-mediated inhibition of LDH activity may lead to short supply of NAD(+) and cut off energy and anabolic supply to cancer cells.
Bookmarks Related papers MentionsView impact
The Journal of organic chemistry, Jan 5, 2016
A highly efficient metal and protection-free approach for the regioselective synthesis of C-3-fun... more A highly efficient metal and protection-free approach for the regioselective synthesis of C-3-functionalized quinolines from azadienes (in situ generated from 2-aminobenzyl alcohol) and terminal alkynes through [4 + 2] cycloaddition has been developed. An unprecedented reaction of 2-aminobenzyl alcohol with 1,3- and 1,4-diethynylbenzene provided the C-3 tolylquinolines via [4 + 2] HDA and oxidative decarboxylation. The -NH2 group directed mechanistic approach was well supported by the control experiments and deuterium-labeling studies and by isolating the azadiene intermediate. The reactivity and selectivity of unprotected azadiene in metal-free base-assisted hetero-Diels-Alder reaction is exploited to quickly assemble an important class of C-3-functionalized quinolines, which are difficult to access.
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The Journal of Organic Chemistry, 2016
An atom-economical Pd-catalyzed approach for the synthesis of benzophenazine derivatives using su... more An atom-economical Pd-catalyzed approach for the synthesis of benzophenazine derivatives using substituted 2-aryl-3-(aryl/alkylethynyl) quinoxaline in the presence of trifluoroacetic acid at 65 °C has been described. The chemistry involves in situ generation of cationic Pd(II) species, which functionalized the aromatic C-H bonds via electrophilic metalation followed by concomitant intramolecular trans-insertion of C-C triple bond to aryl-Pd complex. The results were supported by various control experiments including with electron-deficient arenes and deuterium labeling studies. The deuterium labeling studies supports electrophilic palladation of aromatic C-H over activation of C-C triple bond of alkyne. The structure of synthesized compounds was further confirmed by X-ray crystallography studies. This catalytic protocol has been efficiently applied for novel synthesis of highly functionalized benzo fused phenazines.
Bookmarks Related papers MentionsView impact
The Journal of Organic Chemistry, 2016
An environmentally benign Au(III)-catalyzed regio- and stereoselective domino synthesis of oxazol... more An environmentally benign Au(III)-catalyzed regio- and stereoselective domino synthesis of oxazolo fused pyridoindoles 7a-v and benzofurooxazolo pyridines 8a-n by the reaction of o-alkynylaldehydes 4a-t and 5a-k with (S)-phenylglycinol 6a and (R)-phenylglycinol 6b under mild reaction conditions using water as reaction medium is reported. The reaction proceeded via selective C-N bond formation on the more electrophilic alkynyl carbon through 6-endo-dig cyclization. The reaction tolerates a wide variety of functional groups. The developed chemistry has been successfully extended for the synthesis of a diverse class of γ-carbolines and benzofuro[3,2-c]pyridines using corresponding ester hydrochlorides of serine, threonine, and cystine as a nitrogen source.
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J Biol Inorg Chem, 2011
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The Journal of Organic Chemistry, Oct 1, 2010
Chemoselective behavior of iodine in different solvents in the electrophilic iodocyclization of o... more Chemoselective behavior of iodine in different solvents in the electrophilic iodocyclization of o-alkynyl aldehydes is described. o-Alkynyl aldehydes 3a-t on reaction with I2 in CH2Cl2 with appropriate nucleophiles provides pyrano[4,3-b]quinolines 4a-f, via formation of cyclic iodonium intermediate Q; however, using alcohols as a solvent as well as nucleophile, o-alkynyl esters 5a-y were obtained selectively in good to excellent yields via formation of hypoiodide intermediate R. Subsequently, o-alkynyl esters were converted in to pyranoquinolinones 6a-i and isocoumarin 6j by electrophilic iodocyclization. This developed oxidative esterification provides a novel access for the chemoselective synthesis of esters 5q-u from aldehydes 3n-p without oxidizing primary alcohol present in the substrate.
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Journal of Organic Chemistry, 2011
RefDoc Bienvenue - Welcome. Refdoc est un service / is powered by. ...
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International Journal of Contemporary Dental and Medical Reviews, Jan 4, 2015
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European Journal of Medicinal Chemistry, Oct 31, 2008
Bookmarks Related papers MentionsView impact
Cheminform, Feb 26, 2013
AbstractUnsymmetrical internal alkynes such as (X) or (XII) generate selectively a single isomers... more AbstractUnsymmetrical internal alkynes such as (X) or (XII) generate selectively a single isomers [cf.(XI) or (XIII)].
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The 3rd European Wireless Technology Conference, 2010
A constant-gain ultra-wideband semi-circular disc monopole with a quasi-planar surface-mounted sh... more A constant-gain ultra-wideband semi-circular disc monopole with a quasi-planar surface-mounted short TEM horn and a semi-circular reflector is proposed. The total length of the antenna is only 70 mm i.e. nearly 0. 67 λ at 2.86 GHz. The gain of the antenna is nearly constant: 6.5 ± 1.1 dBi from 2.86 GHz to 15 GHz, and 6.5 ± 0.7 dBi from 3.1 GHz to 10.6 GHz,. It has broad azimuth pattern and its compact integrated configuration is suitable for several ultra-wideband (UWB) wireless and radar applications.
Bookmarks Related papers MentionsView impact
Organic letters, Jan 6, 2016
A base promoted, protection-free, and regioselective synthesis of highly functionalized quinoline... more A base promoted, protection-free, and regioselective synthesis of highly functionalized quinolines via [4 + 2] cycloaddition of azadienes (generated in situ from o-aminobenzyl alcohol) with internal alkynes has been discovered. The reaction tolerates a wide variety of functional groups which has been successfully extended with diynes, (2-aminopyridin-3-yl)methanol, and 1,4-bis(phenylethynyl)benzene to afford (Z)-phenyl-2-styrylquinolines, phenylnaphthyridine, and alkyne-substituted quinolines, respectively. The proposed mechanism and significant role of the solvent were well supported by isolating the azadiene intermediate and deuterium-labeling studies.
Bookmarks Related papers MentionsView impact
2010 Asia Pacific Microwave Conference, Dec 1, 2010
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2014 Fourth International Conference of Emerging Applications of Information Technology, Dec 19, 2014
Bookmarks Related papers MentionsView impact
Journal of Pharmacy and Nutrition Sciences, Apr 30, 2013
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Journal of Food Science and Technology, 2009
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Int J Electron, 2011
This article addresses a CAD-oriented closed-form expressions for dispersive and conductor thickn... more This article addresses a CAD-oriented closed-form expressions for dispersive and conductor thickness-based line parameters for symmetrical coplanar strip lines (CPS) on a finite-thickness dielectric substrate. The conductor and dielectric losses are also computed. The models are extended to non-planar CPS – elliptical coplanar strip line (ECPS) and cylindrical coplanar strip lines (CCPS). Finally, accurate circuit model for these structures is
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Journal of Earth System Science, Mar 19, 2015
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