Alan F. Gasiecki

Scaffold oriented synthesis. Part 4: Design, synthesis and biological evaluation of novel 5-substituted indazoles as potent and selective kinase inhibitors employing heterocycle forming and multicomponent reactions

We report the synthesis and biological evaluation of 5-substituted indazoles as kinase inhibitors. The compounds were synthesized in a parallel synthesis fashion from readily available starting materials employing heterocycle forming and multicomponent reactions and were evaluated against a panel of kinase assays. Potent inhibitors were identified for Gsk3β, Rock2, and Egfr.

Scaffold oriented synthesis. Part 3: Design, synthesis and biological evaluation of novel 5-substituted indazoles as potent and selective kinase inhibitors employing [2+3] cycloadditions

We report the synthesis and biological evaluation of 5-substituted indazoles and amino indazoles as kinase inhibitors. The compounds were synthesized in a parallel synthesis fashion from readily available starting materials employing [2+3] cycloaddition reactions and were evaluated against a panel of kinase assays. Potent inhibitors were identified for numerous kinases such as Rock2, Gsk3β, Aurora2 and Jak2.

Characterization of prostaglandin E receptors in canine small intestine using [3H] prostaglandin E1 binding

Prostaglandin E (PGE) receptors in canine small intestinal mucosal and muscle membrane preparations were labeled with [3H] PGE1. Saturable, high affinity binding of [3H] PGE1 was observed in both preparations. The density of binding sites (fmol/mg protein) was 39 for mucosal membranes and 60 for muscle membranes, with corresponding dissociation constants of 10.6 nM and 5.8 nM, respectively. [3H] PGE1 binding sites in both preparations showed stereospecificity and high affinity for natural PGE1 and PGE2, but not for I or F-type PGs. Synthetic PGEs such as misoprostol and enisoprost had lower affinity than PGE1 or PGE2. Several analogs of enisoprost bound weakly to the binding sites. A highly significant correlation (C.C. = 0.9) was demonstrated between mucosal and muscle binding potency for a series of enisoprost analogs. There was also a significant positive correlation between the receptor binding potency and rat diarrheagenic activity for these analogs. These results indicate that PGE receptors in canine intestinal mucosa and muscle can be directly studied with [3H] PGE1 binding. The mucosal and muscle PGE receptors may have similar ligand binding specificity. We speculate that these receptors are likely to be associated with the diarrheagenic activity of PGEs.

Stabilization of a prostaglandin tertiary allylic alcohol system by fluorine: synthesis, acid stability studies and pharmacology of a 16-fluoromethyl analog of SC-46275.

Abstract The synthesis of a 16-fluoromethyl analog of SC-46275, a potent, long-acting and selective analog of enisoprost, is described. Introduction of a fluorine atom to the C-16 methyl group of SC-46275 conveys a remarkable increase in stability toward acid induced epimerization, dehydration and allylic rearrangement while having minimal influence on the pharmacological profile. The synthesis of a 16-fluoromethyl analog of SC-46275, a potent, long-acting and selective analog of enisoprost, is described. Introduction of a fluorine atom to the C-16 methyl group of SC-46275 conveys a remarkable increase in stability toward acid induced epimerization, dehydration and allylic rearrangement while having minimal influence on the pharmacological profile.

Alpha chain unsaturated derivatives of misoprostol

Misoprostol, a 15-deoxy-16-hydroxy-16-methyl analog of PGE1, is an effective agent for the treatment of peptic ulcer disease. Efforts to impede metabolic degradation of the alpha chain of misoprostol led to the discovery of a second clinical candidate in this series. Enisoprost, a delta 4Z derivative of misoprostol, is more potent as a gastric antisecretory agent and longer acting than misoprostol. These findings prompted further work to determine the effects that two double bonds in the alpha chain might have on the activity profile of misoprostol. The most promising structure in this series was a 1:1 mixture of 3E,5Z and 3Z,5Z dienes which was about three times more potent than misoprostol in inhibiting gastric secretion in dogs, while the separation of the diarrheogenic effect was significantly improved. Chromatographic separation of the mixture was very difficult, but small amounts of each isomer were obtained by HPLC, and preliminary antisecretory studies indicated that most of the activity resided in the 3E,5Z isomer. A stereospecific synthesis of the 3E,5Z isomer was carried out to provide sufficient quantities for complete pharmacological assessment. The 3E,5Z diene was about three times more potent than misoprostol in inhibiting gastric acid secretion in dogs and also in producing diarrhea in rats.

Evaluation of Misoprostol and Analogs as Inhibitors of T-Cell Activation.

Prostaglandin E2 (PGE2) is known to inhibit in vitro T-cell responses to mitogenic and antigenic stimuli. Interaction of PGE2 with a G protein-coupled receptor activates adenylyl cyclase, leading to cAMP formation and inhibition of interleukin-2 (IL-2) production and T-cell proliferation. Despite these effects, the application of PGE2 as an anti-inflammatory agent has been compromised by its unfavorable pharmacodynamic and side-effect profile. Because of the potential utility of synthetic analogs as prostaglandin-based therapeutics, we evaluated the effect of misoprostol and over 100 structural analogs on cAMP formation and T-cell activation. Our results indicate that micromolar concentrations of misoprostol and particular analogs elicited a rapid and substantial rise in cAMP levels in human peripheral blood mononuclear cells. Analogs which increased cAMP also suppressed IL-2 production and T-cell growth in vitro, whereas those devoid of suppressive activity weakly induced nucleotide synthesis. Despite extensive chemical alteration of the prostanoid structure, no single analog was superior to misoprostol in inducing cAMP or modulating T-cell activity. Misoprostol and suppressive analogs were also evaluated in vivo in a murine model of antigen-induced T-cell proliferation. Prostaglandins, administered at maximum tolerable doses, were ineffective in blocking a T-cell response to alloantigenic stimulation, whereas cyclosporine and prednisolone were potent inhibitors of this response. Overall, our results indicate that misoprostol and related analogs suppress T-cell activation in vitro but require concentrations 1000-fold greater than the low nanomolar plasma levels achieved with clinical doses of misoprostol. Whether misoprostol analogs of sufficient potency can be developed for pharmacologic attentuation of T-cell activation in vivo remains to be determined.