Identification of phenolics and nucleoside derivatives in Gastrodia elata by HPLC-UV-MS

An HPLC-UV-MS method for simultaneous identification of predominant phenolics and minor nucleoside derivatives in Gastrodia elata was developed, which was based on their UV and MS characteristics summarized through a series of homemade reference standard experiments. Phenolics showed characteristic UV lambda(max) at 267 nm, [M + NH4](+) base peak in positive mode and [M - H](-) base peak in negative mode while nucleosides exhibited UV lambda(max) at 255 nm, [M + H](+), [M - H + 2H(2)O](-) or [M - H + CH3COOH](-). Phenolics conjugates mainly underwent the consecutive loss of gastrodin residue (- 268 U) and the combined loss of H2O and CO2 from the citric acid unit under negative MS/MS conditions whereas nucleosides simply lost the ribose (- 132 U) under positive MS/MS conditions. According to these characteristics, a special pattern under MS/MS conditions and reported compound data for G. elata in the literature, not only 15 phenolics were identified but also 6 nucleoside derivatives were identified. Among these compounds, seven phenolics and three nucleoside derivatives have not been reported yet from G. elata.

Determination of alcohols by high-performance liquid chromatography with fluorimetric detection after pre-column derivatisation with carbazole-9-N-acetic acid and chromatographic behaviour of alcoholic derivatives

Alcohols were derivatised to their carbazole-9-N-acetic acid (CRA) esters with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC . HCl) as the dehydrating agent. Studies on derivatisation conditions indicated that the coupling reaction proceeded rapidly and smoothly in the presence of a base catalyst in acetonitrile to give the corresponding sensitively fluorescent derivatives. The retention behaviour of alcohol derivatives was investigated by varying mobile phase compositions (ACN-water and MeOH-water). The parameters from the equation log k'=A-BX were evaluated by retention data of derivatives using an isocratic elution with different mobile phases. The results indicated that the parameters derived allowed computation of retention factors in good agreement with experiments. At the same time, a general equation was derived that makes possible predictions of partition coefficient in binary mobile phases with different proportions of organic solvent to water based on some simple regression analysis. The LC separation for the derivatised alcohols containing higher carbon alcohols showed good reproducibility on a reversed-phase C-18 column with gradient elution. The detection limits (excitation at 335 nm, emission at 360 nm) for derivatised alcohols (signal-to-noise ratio=3:1) were in the range of 0.1-0.4 pg per injection. (C) 2001 Elsevier Science B.V. All rights reserved.

Synthesis and luminescence properties of lanthanide(III) chelates with polyacid derivatives of thienyl-substituted terpyridine analogues

Two new polyacid derivative ligands of thienyl-substituted terpyridine analogues, N,N,N-1,N-1-[4'-(2"'-thienyl)-2,2':6',2"-terpyridine-6,6"-diyl]bis(methylenenitrilo) tetrakis(acetic acid) (TTTA) and N,N,N-1,N-1-[2,6-bis(3'-amino-methyl-1'-pyrazolyl)-4-(2"-thienyl)pyridine] tetrakis(acetic acid) (BTTA), were synthesized, and the luminescence properties of their Eu3+ and Tb3+ chelates were investigated. The Eu3+ chelates of the two ligands are strongly luminescent having luminescence quantum yields of 0.150 (TTTA-Eu3+) and 0.114 (BTTA-Eu3+), and lifetimes of 1.284 ms (TTTA-Eu3+) and 1.352 ms (BTTA-Eu3+), whereas their Tb3+ chelates are weakly luminescent. The TTTA-Eu3+ chelate was used for streptavidin (SA) labeling, and the labeled SA was used for time-resolved fluoroirnmunoassay of insulin in human sera. The method gives the detection limits of 33 pg ml(-1). (C) 2003 Elsevier B.V. All rights reserved.

Complete hydrodechlorination of chlorobenzene and its derivatives over supported nickel catalysts under liquid phase conditions

Liquid phase hydrodechlorination of chlorobenzene was studied over Ni/active carbon (Ni/AC), Ni/gamma-Al2O3, Ni/SiO2 and Raney Ni. The complete hydrodechlorination of chlorobenzene was realized at 333-343 K on Ni/AC under hydrogen atmosphere of 1.0 MPa in the presence of alkaline hydroxide. Aryl halides, three chlorotoluenes (o-, m- and p-), three chloroanilines, three chlorobenzotrifluorides, three dichlorobenzenes and two trichlorobenzenes (1,2,3- and 1,2,4-) were also completely hydrodechlorinated under the similar conditions. Chlorobenzene derivatives having either an electron-donating group or an electron-withdrawing group decreased their reactivities with respect to the unsubstituted chlorobenzene.

Anticancer and antiangiogenic activity of surfactant-free nanoparticles based on self-assembled polymeric derivatives of vitamin e: Structure-activity relationship

α-Tocopheryl succinate (α-TOS) is a well-known mitochondrially targeted anticancer compound, however, it is highly hydrophobic and toxic. In order to improve its activity and reduce its toxicity, new surfactant-free biologically active nanoparticles (NP) were synthesized. A methacrylic derivative of α-TOS (MTOS) was prepared and incorporated in amphiphilic pseudoblock copolymers when copolymerized with N-vinylpyrrolidone (VP) by free radical polymerization (poly(VP-co-MTOS)). The selected poly(VP-co-MTOS) copolymers formed surfactant-free NP by nanoprecipitation with sizes between 96 and 220 nm and narrow size distribution, and the in vitro biological activity was tested. In order to understand the structure-activity relationship three other methacrylic monomers were synthesized and characterized: MVE did not have the succinate group, SPHY did not have the chromanol ring, and MPHY did not have both the succinate group and the chromanol ring.

Design, synthesis and development of novel indolocarbazole derivatives as potential anti-cancer agents

This thesis describes work carried out on the design of new routes to a range of bisindolylmaleimide and indolo[2,3-a]carbazole analogs, and investigation of their potential as successful anti-cancer agents. Following initial investigation of classical routes to indolo[2,3-a]pyrrolo[3,4-c]carbazole aglycons, a new strategy employing base-mediated condensation of thiourea and guanidine with a bisindolyl β-ketoester intermediate afforded novel 5,6-bisindolylpyrimidin-4(3H)-ones in moderate yields. Chemical diversity within this H-bonding scaffold was then studied by substitution with a panel of biologically relevant electrophiles, and by reductive desulfurisation. Optimisation of difficult heterogeneous literature conditions for oxidative desulfurisation of thiouracils was also accomplished, enabling a mild route to a novel 5,6-bisindolyluracil pharmacophore to be developed within this work. The oxidative cyclisation of selected acyclic bisindolyl systems to form a new planar class of indolo[2,3-a]pyrimido[5,4-c]carbazoles was also investigated. Successful conditions for this transformation, as well as the limitations currently prevailing for this approach are discussed. Synthesis of 3,4-bisindolyl-5-aminopyrazole as a potential isostere of bisindolylmaleimide agents was encountered, along with a comprehensive derivatisation study, in order to probe the chemical space for potential protein backbone H-bonding interactions. Synthesis of a related 3,4-arylindolyl-5-aminopyrazole series was also undertaken, based on identification of potent kinase inhibition within a closely related heterocyclic template. Following synthesis of approximately 50 novel compounds with a diversity of H-bonding enzyme-interacting potential within these classes, biological studies confirmed that significant topo II inhibition was present for 9 lead compounds, in previously unseen pyrazolo[1,5-a]pyrimidine, indolo[2,3-c]carbazole and branched S,N-disubstituted thiouracil derivative series. NCI-60 cancer cell line growth inhibition data for 6 representative compounds also revealed interesting selectivity differences between each compound class, while a new pyrimido[5,4-c]carbazole agent strongly inhibited cancer cell division at 10 µM, with appreciable cytotoxic activity observed across several tumour types.

Synthesis and reactivity of α-diazosulfoxide and α-diazosulfone derivatives

The research described in this thesis involves the synthesis of α-diazo-β-oxo sulfoxides, and exploration of their reactivity. The first chapter includes an introduction to diazocarbonyl chemistry, specifically focusing on the synthesis of diazo compounds, and diazosulfoxide derivatives. The chemistry of sulfines, in particular the generation of α-oxo sulfines and their subsequent trapping as cycloadducts and dimerisation is discussed. The results of this research are discussed in the second and third chapters. The design, synthesis and reactivity of α-diazo-β-oxo sulfoxides is described in chapter 2 where diazo transfer adjacent to sulfoxides to form stable α-diazo-β-oxo sulfoxides has been achieved in cyclic systems. Decomposition of theses α-diazosulfoxides using rhodium carboxylate or carboxamide catalysts is also described. These processes proceed via a Wolff type rearrangement to form α-oxo sulfine intermediates, which were trapped as cycloadducts with dienes. In the absence of a diene trap, dimerisation of the sulfine intermediate was observed. Intramolecular C-H insertion reasctios of α-diazo-α-sulfonyl esters to form substituted sulfolane esters is described in chapter 3. The reactivity of these sulfolane esters is briefly explored. The fourth chapter contains the experimental details and the spectral and analytical data for all new compounds reported.

Studies of rhodium, platinum and palladium derivatives of some arsena-, carba- and telluraboranes

The research described in this thesis involved the synthesis and characterisation of rhodium, platinum and palladium derivatives of arsena-, carba- and telluraboranes.

Synthesis and evaluation of novel azaindolocarbazole derivatives as cancer chemotherapeutics

This thesis details the design and implementation of novel chemical routes towards a series of highly propitious 7-azaindolyl derivatives of the indolocarbazole (ICZ) and bisindolylmaleimide (BIM) families, with subsequent evaluation for use as cancer chemotherapeutic agents. A robust synthetic strategy was devised to allow the introduction of a 7-azaindolyl moiety into our molecular template. This approach allowed access to a wide range of β-keto ester and β-keto nitrile intermediates. Critical analysis identified F-ring modulation as a major theme towards the advancement of ICZ and BIM derivatives in drug therapy. Thus, the employment of cyclocondensation methodology furnished a number of novel aminopyrazole, isoxazolone, pyrazolone and pyrimidinone analogues, considerably widening the scope of the prevalent maleimide functionality. Photochemical cyclisation provided for the first reported aza ICZ containing a six-membered F-ring. Another method towards achieving the aza ICZ core involved use of a Perkin-type condensation approach, with chemical elaboration of the headgroup instigated post-aromatisation. Subsequent use of a modified Lossen rearrangement allowed access to further analogues containing a six-membered F-ring. Extensive screening of the novel aza ICZ and BIM derivatives was carried out against the NCI-60 cancer cell array, with nine prospective candidates selected for continued biological evaluation. From these assays, a number of compounds were shown to inhibit cancer cell growth at concentrations of below 10 nM. Indeed, the most active aza ICZ tested is currently under assessment by the Biological Evaluation Committee of the NCI due to excellent antiproliferative activity demonstrated across the panel of cell lines, with a mean GI50 of 34 nM, a mean total growth inhibition (TGI) of 4.6 μM and a mean cytotoxicity (LC50) of 63.1 μM. Correlation to known topoisomerase I (topo I) inhibitors was revealed by COMPARE analysis, and subsequent topo I-mediated DNA cleavage assays showed inhibitory activity below 1 μM for several derivatives.

Crystallisation and crystal forms of carbohydrate derivatives

This thesis is focused on the synthesis and solid state analysis of carbohydrate derivatives, including many novel compounds. Although the synthetic chemistry surrounding carbohydrates is well established in the literature, the crystal chemistry of carbohydrates is less well studied. Therefore this research aims to improve understanding of the solid state properties of carbohydrate derivatives through gaining more information on their supramolecular bonding. Chapter One focuses on an introduction to the solid state of organic compounds, with a background to crystallisation, including issues that can arise during crystal growth. Chapter Two is based on glucopyranuronate derivatives which are understudied in terms of their solid state forms. This chapter reports on the formation of novel glucuronamides and utilising the functionality of the amide bond for crystallisation. TEMPO oxidation was completed to form glucopyranuronates by oxidation of the primary alcohol groups of glucosides to the carboxylic acid derivatives, to increase functionality for enhanced crystal growth. Chapter Three reports on the synthesis of glucopyranoside derivatives by O-glycosylation reactions and displays crystal structures, including a number of previously unsolved acetate protected and deprotected crystal structures. More complex glycoside derivatives were also researched in an aim to study the resultant supramolecular motifs. Chapter Four contains the synthesis of aryl cellobioside derivatives including the novel crystal structures that were solved for the acetate protected and deprotected compounds. Research was carried out to determine if 1-deoxycellodextrins could act as putative isostructures for cellulose. Our research displays the presence of isostructural references with 1-deoxycellotriose shown to be similar to cellulose III11, 1-deoxycellotetraose correlates with cellulose IV11 and 1-deoxycellopentose shows isostructurality similar to that of cellulose II. Chapter Five contains the full experimental details and spectral characterisation of all novel compounds synthesised in this project and relevant crystallographic information.

Anti-AIDS agents 81. Design, synthesis, and structure-activity relationship study of betulinic acid and moronic acid derivatives as potent HIV maturation inhibitors.

In our continuing study of triterpene derivatives as potent anti-HIV agents, different C-3 conformationally restricted betulinic acid (BA, 1) derivatives were designed and synthesized in order to explore the conformational space of the C-3 pharmacophore. 3-O-Monomethylsuccinyl-betulinic acid (MSB) analogues were also designed to better understand the contribution of the C-3' dimethyl group of bevirimat (2), the first-in-class HIV maturation inhibitor, which is currently in phase IIb clinical trials. In addition, another triterpene skeleton, moronic acid (MA, 3), was also employed to study the influence of the backbone and the C-3 modification toward the anti-HIV activity of this compound class. This study enabled us to better understand the structure-activity relationships (SAR) of triterpene-derived anti-HIV agents and led to the design and synthesis of compound 12 (EC(50): 0.0006 microM), which displayed slightly better activity than 2 as a HIV-1 maturation inhibitor.