Ulf Wellmar

Design and synthesis of galectin inhibitors.

Galectins, a lectin family, have shown binding affinities towards b-galactosides. Galectins have been proposed to be involved in a wide range of functions like for example, cell growth, adhesion, migration, chemo taxis and apoptosis. They have also been associated with various cancer types. However, the detailed functions of galectins are still very much unknown. High affinity inhibitors towards the galectins would thus be of value as research tools, as well as possible future pharmaceutical agents. Existing inhibitors have undesirable properties, for example high molecular weight and instability. This thesis concerns the synthesis of small high affinity galectin inhibitors. A previously published X-ray structure of galectin-3 together with LacNAc revealed an extended binding pocket close to 3´-C of the galactoside residue. Filling this pocket with additional chemical entities was hypothesized to allow for further interactions and hence creating higher affinity ligands as compared to the naturally occurring ligand. The hypothesis was probed by substituting the 3´-hydroxyl group on the galactose unit of LacNAc with an amine, which enables the introduction of functional groups under mild reaction conditions. We synthesised a collection of more than 60 LacNAc derivatives with various functional groups at 3´-C of the galactose unit. The measurements of inhibitor potencies towards galectins were made in a novel fluorescence polarisation (FP) assay, which is a solution phase method, as well as a general technique that do not need major re-optimisation to enable the study of other galectins. Hence, it enabled us to study the panel of synthetic inhibitors towards galectin-1, -3 and –4. Selective and high affinity inhibitors were discovered, which is of value as often more than one galectin is present in one and the same system. We found that aromatic amides in particular showed high affinity towards galectin-3. In addition, the X-ray structure of one of the best inhibitors (Kd 0.9 mM) revealed that Arg-144 on galectin-3 had moved 3.5 A to enable a face-to-face stacking interaction with a 4-methoxy-2,3,5,6-tetrafluorobenzamido substituent. The best inhibitor synthesised as of yet, carried a 2-naphthamido functionality at 3´of the galactose residue. This inhibitor had a Kd of 0.3 mM, which the strongest binding affinity achieved as compared to any monovalent inhibitor. It shows over 200 times higher affinity towards galectin-3 than the unfunctionalised LacNAc. (Less)

Inhibition of Human DHODH by 4‐Hydroxycoumarins, Fenamic Acids, and N‐(Alkylcarbonyl)anthranilic Acids Identified by Structure‐Guided Fragment Selection

A strategy that combines virtual screening and structure‐guided selection of fragments was used to identify three unexplored classes of human DHODH inhibitor compounds: 4‐hydroxycoumarins, fenamic acids, and N‐(alkylcarbonyl)anthranilic acids. Structure‐guided selection of fragments targeting the inner subsite of the DHODH ubiquinone binding site made these findings possible with screening of fewer than 300 fragments in a DHODH assay. Fragments from the three inhibitor classes identified were subsequently chemically expanded to target an additional subsite of hydrophobic character. All three classes were found to exhibit distinct structure–activity relationships upon expansion. The novel N‐(alkylcarbonyl)anthranilic acid class shows the most promising potency against human DHODH, with IC50 values in the low nanomolar range. The structure of human DHODH in complex with an inhibitor of this class is presented.

Synthesis of Mimics to Thymidine and 5-(2″-Thienyl)-2′-Deoxyuridine Triphosphates

Abstract Dicarboxylic acid 5′-monoesters of thymidine and 5-(2-thienyl)-2′′-deoxyuridine have been synthesised and evaluated as triphosphate mimics. Glutaric (25, 29), adipic (26, 30), pimelic (27, 31) and trans-1,4-cyclohexane dicarboxylic acids (28, 32) were employed to vary the distance between two carboxylate functions and were structurally compared to the triphosphate moiety by molecular modelling. The glutarate and adipate derivatives can assume conformations fitting the triphosphate, and the thienyl compounds 29 and 30 were the ones having overall best inhibitory activities against DNA pol α and HIV-1 RT.

No inhibitory effect on receptor neurone activity by sulphur analogues of the sex pheromone component (Z)-5-decenyl acetate in the turnip moth, Agrotis segetum (Lepidoptera: Noctuidae)

Abstract. Olfactory responses from the entire antenna and from single antennal sensilla of the male turnip moth, Agrotis segetum (Lepidoptea: Noctuidae Schiff.), were recorded after stimulation of the antenna with the sex pheromone component, (Z)‐5‐decenyl acetate (Z5‐10:OAc), and three sulphur analogues of this compound. Adaptation of olfactory receptor neurones tuned to Z5‐10:OAc was investigated after pre‐exposure of these receptor neurones to the key stimulus and to the three sulphur analogues. Both electro‐antennographic and single sensillum recordings revealed that the sulphur analogues had a significantly decreased effect compared to the natural stimulus. The pre‐exposure experiments demonstrated that no further inhibition of neural activity was observed than could be expected from receptor neurone adaptation. Earlier reports, describing sulphur analogues as possible hyperagonists acting on moth pheromone receptor neurones, are not supported by the present study.

Synthesis of various 5-(3-substituted phenyl)-2′-deoxyuridines

A series pf 5-aryl-2′-deoxyuridines has been prepared and evaluated as antiviral agents. The following substituents have been used in position 3 of the phenyl ring: chloro, iodo, amino, azido, methylthio, and vinyl. None of the new compounds showed any significant activity when tested against human immunodeficiency virus 1 (HI V-I), herpes simplex virus 1 (HSV-I), or human cytomegalovirus (HCMV).