It was found that narciclasine retarded the growth of human cancer cells and plant suspension cells in dose-dependent manner. The inhibitory mechanism of narciclasine was found to be apoptosis for the DNA histogram showed an apoptotic peak in narciclasine-treated A375 cancer cells. The fluorescent signal dUTP fluorescein was found in the narciclasine-treated A735 cancer cell in TUNEL assay. The Annexin-V-FLUOS stained A375 cancer cell at 24-hour treatment with no PI found. These results suggest that narciclasine triggered early apoptosis in A375 cancer cell. Immunoblot analysis of the apoptotic signalling pathway showed that narciclasine induced apoptosis through the intrinsic pathway. Narciclasine induced the cleavage of caspase-9 but not the caspase-8, which was triggered by cytochrome c release from mitochondrial intermembrane space into cytosol. The activated caspase-9 triggered caspase cascade (e.g. cleavage of caspase-3, caspase-6 and caspase-7) which induced the cleavage of PARP. / Narciclasine is an isoquinoline alkaloid extracted from the bulb of Narcissus tazetta. It shows a wide range of biological activities such as antitumour, antiviral and plant growth inhibitory activities. However, little information is available regarding such inhibitory activities. The objective of this study is to elucidate the mechanisms of the cytotoxic effects of narciclasine in different cell models. / On the other hand, narciclasine triggered programmed cell death (PCD) in plant cells as proved by the increased intensity of Evans blue in narciclasine-treated suspension cells. Fluorescent microscopy showed that narciclasine induced PCD in tobacco BY2 cell with the dUTP fluorescein stained in narciclasine-treated cell. The induction of PCD was in dose-dependent and time-dependent manner. / Proteomic studies showed that narciclasine may affect A375 cancer cell and rice meristemic cells in similar manner. Narciclasine may affect the metabolism and defence system of both A375 cancer cell and rice meristemic cells through down-regulating the expression of metabolic enzymes (e.g. triosephosphate isomerase in A375 cancer cell and fructose bisphosphate aldolase in rice root tip) and defensive proteins (e.g. peroxiredoxin in A375 cancer cell and catalase in rice root tip). Narciclasine down-regulated the heat-shock proteins (HSP) which is involved in regulating cellular homeostasis and promoting cell survival. Therefore, narciclasine reduced HSP to lower the cell survival ability and induced the caspase cascade or caspase-like activity in A375 cancer cell and rice respectively. / To summarize, narciclasine induced apoptosis in A375 cancer cell and programmed cell death in tobacco BY2 cell. / Wong, Chi Fai. / "October 2007." / Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4576. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 230-255). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

1. A new route towards the synthesis of drugs and alkaloids by using N-alkylsulfonylacetamide and unsaturated ester as starting materials via stepwise [3+3] annulation. 2. The application of regioselective nucleophilic addition of glutarimide which prepared via stepwise [3+3] annulation. 3. Synthesis of (E)-3-Substituted-N-Alkylacryl-amides and 3,4-Disubstituted Succinimides by using N-alkylsulfonyl-acetamide and alkyl halides as starting materials in the different reaction condition.

The cortistatins are a recently identified class of marine natural products that were found to exhibit potent and selective inhibition of human umbilical vein endothelial cells (HUVECs), making them promising leads for the development of anti-angiogenic drugs. In our synthesis, we envisioned that natural cortistatins and unnatural analogs could be prepared by late-stage introduction of isoquinolines to 17-keto precursors, and that these differentially substituted precursors could all be derived from a common key intermediate 112. We developed a robust synthetic route to prepare gram quantities of key intermediate 112 starting from readily available benzylzinc reagent 116 and enol triflate 117. Key intermediate 112 was next converted to cortistatin precursors 108, 109, 110, and 111 in three to eight steps, representing each of the four natural cortistatin ABC-ring substitution patterns. Subsequently, a generally applicable method was developed to introduce the isoquinoline moiety. After complexation to N,N,N',N'-tetramethylethylenediamine (TMEDA), 7-lithio-isoquinoline added to 17-keto precursors to provide the corresponding 1,2-addition products; the resulting tertiary alcohols underwent radical deoxygenation via their trifluoroacetates to afford the desired (17S)-products. This organolithium-addition-deoxygenation sequence provided cortistatins A (1, on a 20-mg scale), J (9), K (10), and L (11) in good overall yields. We also synthesized cortistatin primary amines (176 and 186) and used them to prepare several cortistatin based affinity reagents. By employing these reagents in pull-down experiments, we identified a 55-kD membrane kinase as a putative protein target of cortistatins. We wanted to prepare cortistatin analogs with isoquinoline modifications due to the importance of this ring for the biological activity of cortistatins. This led us to develop a novel and versatile synthesis of substituted isoquinolines. In our method, lithiated o-tolualdehyde tert-butylimines were condensed with different nitriles to generate eneamido anion intermediates, which were trapped in situ with various electrophiles at the C4-position, affording a wide range of substituted isoquinolines. Further diversification was achieved by modification of the work-up conditions and by subsequent transformations. / Chemistry and Chemical Biology

The decomposition mechanisms of various coal constituents undergoing pyrolysis are of great concern in environmental circles (especially those coal constituents containing nitrogen). Most methods of burning coal that are efficient involve doing so at high temperatures. This invariably results in a large portion of non-combusting coal being heated to high temperatures also causing pyrolysis of the original coal constituents. The end result of such pyrolysis is the production of a number of noxious gaseous products. If we are to design methods of reducing the amount of toxins that are produced from the industrial use of coal, it is necessary to understand the pyrolysis process mechanistically. Due to the great number of coal constituents, a reasonable approach to such a mechanistic study is to use a simpler model. Pyridine makes an excellent starting model upon which to build. Our study focuses on interpretation of proposed reaction channels from experimental work on pyridine, quinoline and isoquinoline shock-tube decomposition in light of new ab initio energy calculations using Gaussian 98. The pathways thus determined support the proposed pyrolysis mechanisms and agree with experimental evidence obtained from independent groups of researchers performing shock tube pyrolysis.

The last decade has been marked by a large increase of demand for green chemistry processes. Consequently, chemists have focused their efforts on the development of more direct routes toward different classes of targets. In that regard catalysis has played a crucial role at enabling key bond formations that were otherwise inaccessible or very energy and resources consuming. The central theme of this body of work concerns the formation of C–N bonds, either through transition metal catalysis or organocatalysis. These structural units being highly recurrent in biologically active molecules, the establishment of more efficient routes for their construction is indispensable. The first part of this thesis describes a new method for the synthesis of isoquinolines from the oxidative coupling/annulation of alkynes with N-tert-butyl benzaldimines via Rh(III) catalysis (Chapter 2). Preliminary mechanistic investigations of this system pointed to the involvement of Rh(III) in the C–H bond cleavage step as well as in the C–N bond reductive elimination that provides the desired heterocycle. Following this oxidative process, a Rh(III)-catalyzed redox-neutral approach to isoquinolones from the reaction of benzhydroxamic acids with alkynes is presented (Chapter 3). The discovery that an N–O bond contained in the substrate can act as an internal oxidant was found to be very enabling. Indeed, it allowed for milder reaction conditions, broader scope (terminal alkyne and alkene compatible) and low catalyst loadings (0.5 mol%). Mechanistic investigations on this system were also conducted to identify the nature of the C–N bond formation/N–O bond cleavage as well as the rate-determining step. The second part of this work presents mechanistic investigations performed on a recently developed intermolecular hydroamination reaction catalyzed through tethering organocatalysis (Chapter 4). This transformation operates via the reversible covalent attachment of two reactants, a hydroxylamine and an allylamine, to an aldehyde catalyst by the formation of a mixed aminal. This allows a difficult intermolecular Cope-type hydroamination to be performed intramolecularly. The main kinetic parameters associated with this reaction were determined and they allowed the generation of a more accurate catalytic cycle for this transformation. Attempts at developing new families of organocatalysts are also discussed.

Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Botany and Ecology Candidate: Daniela Hulcová Consultant: Prof. RNDr. Lubomír Opletal, CSc. Title of Diploma Thesis: Biological aktivity of plants metabolites. XXVII. Alkaloids of Fumaria officinalis L. and their effect on acetylcholinesterase and butyrylcholinesterase The summary ethanolic and diethylether extract were prepared from the herbs of a plant Fumaria officinalis L. We have obtained 201 fractions from this extract by column chromatography on the neutral Al2O3 (aluminium oxide). Joined fraction 68-76 were processed by thin layer chromatography, and 3 substances were obtained in pure state: DH-1, DH-2, DH-3. These 3 compounds were identified as protopine, (+)-fumariline and N- methylcorydaldine by the comparison with the literature and results of MS and NMR. These alkaloids were tested for the inhibitory activity against human erythrocytic acetylcholinesterase and plasmatic butyrylcholinesterase by Ellman`s method. The isolated alkaloids did not show any significant inhibitory activity (IC50, µM) compared with the standard galanthamine (IC50, µM; AChE 1,710 ± 0,065, BuChE 42,30 ± 1,30): protopin: AChE: 345,42 ± 31,12, BuChE: 239,66 ± 20,89, (+)-fumarilin: AChE: 2939,2 ± 309,41, BuChE: 330,62 ±...

No description available.

Transition metal mediated [2 + 2 + 2] cyclizations have been well researched over the past several years. As a well-developed methodology, [2 + 2 + 2] chemistry has been employed as a major pathway to various carbo- and heterocyclic synthetic targets. Numerous transition metals have been applied as catalysts for these cyclizations. Previous work in our group developed cobalt(I) catalyzed inter- and intramolecular [2 + 2 + 2] cyclizations of two alkynes and a nitrile, leading to the preparation of tetrahydro-naphthyridines. Pyridazines could be generated if the cyclization could be accomplished with two nitriles and an alkyne, which would be a novel way to synthesize 1,2-diazines through the formation of the N-N bond. To this end, metal-catalyzed intramolecular [2 + 2 + 2] cyclizations between an alkyne and two nitriles were investigated. The intramolecular nature of the reaction provided the entropic advantage to successfully assist the formation of the critical N-N bond. Optimal conditions were achieved with cobalt(I) catalysts under microwave irradiation in chlorobenzene, producing the desired pyridazines in moderate to good yields. This success led to the preparation of a series of annulated pyridazines. The use of two tethering nitrogens in the preparation of the cyclization precursors incorporated points for further diversification, the next step in the development of this chemistry. This ring closure through N,N-bond formation allowed the construction of annulated pyridazine scaffolds that were utilized further in a small molecule library synthesis. Using this methodology, sixteen new annulated pyridazines were prepared. Inverse electron demand Diels-Alder (IEDDA) reactions of arynes and 1,2,4-triazines were also investigated for the generation of isoquinoline core structures. The results showed that only triazines with electron withdrawing groups participated in the IEDDA reactions with benzyne as a partner after screening of several different arynes, which limited the scope of the reaction. Liebeskind–Srogl reactions of 3-methylthiotriazines and boronic acids were investigated during the diversification of triazines, and microwave irradiation with palladium and copper catalysts were found to be the optimal conditions for the coupling. The chemistry allowed for further triazine diversification.

The last decade has been marked by a large increase of demand for green chemistry processes. Consequently, chemists have focused their efforts on the development of more direct routes toward different classes of targets. In that regard catalysis has played a crucial role at enabling key bond formations that were otherwise inaccessible or very energy and resources consuming. The central theme of this body of work concerns the formation of C–N bonds, either through transition metal catalysis or organocatalysis. These structural units being highly recurrent in biologically active molecules, the establishment of more efficient routes for their construction is indispensable. The first part of this thesis describes a new method for the synthesis of isoquinolines from the oxidative coupling/annulation of alkynes with N-tert-butyl benzaldimines via Rh(III) catalysis (Chapter 2). Preliminary mechanistic investigations of this system pointed to the involvement of Rh(III) in the C–H bond cleavage step as well as in the C–N bond reductive elimination that provides the desired heterocycle. Following this oxidative process, a Rh(III)-catalyzed redox-neutral approach to isoquinolones from the reaction of benzhydroxamic acids with alkynes is presented (Chapter 3). The discovery that an N–O bond contained in the substrate can act as an internal oxidant was found to be very enabling. Indeed, it allowed for milder reaction conditions, broader scope (terminal alkyne and alkene compatible) and low catalyst loadings (0.5 mol%). Mechanistic investigations on this system were also conducted to identify the nature of the C–N bond formation/N–O bond cleavage as well as the rate-determining step. The second part of this work presents mechanistic investigations performed on a recently developed intermolecular hydroamination reaction catalyzed through tethering organocatalysis (Chapter 4). This transformation operates via the reversible covalent attachment of two reactants, a hydroxylamine and an allylamine, to an aldehyde catalyst by the formation of a mixed aminal. This allows a difficult intermolecular Cope-type hydroamination to be performed intramolecularly. The main kinetic parameters associated with this reaction were determined and they allowed the generation of a more accurate catalytic cycle for this transformation. Attempts at developing new families of organocatalysts are also discussed.

Boronic acids play an important role in the design and synthesis of chemosensors for carbohydrates due to their ability to reversibly bind with diol-containing compounds. Along this line, the availability of boronic acids that change fluorescence upon sugar binding is critical to a successful sensor design effort. Here, two boronic acids that show strong fluorescent intensity changes upon sugar binding are reported: isoquinoline-7-boronic acid (7-IQBA) and phenoxathiin-4-boronic acid (4-POBA).