Discovery of M3 Antagonist-PDE4 Inhibitor Dual Pharmacology Molecules for the Treatment of Chronic Obstructive Pulmonary Disease.

In this paper, we report the discovery of dual M3 antagonist-PDE4 inhibitor (MAPI) compounds for the inhaled treatment of pulmonary diseases. The identification of dual compounds was enabled by the intuition that the fusion of a PDE4 scaffold derived from our CHF-6001 series with a muscarinic scaffold through a common linking ring could generate compounds active versus both the transmembrane M3 receptor and the intracellular PDE4 enzyme. Two chemical series characterized by two different muscarinic scaffolds were investigated. SAR optimization was aimed at obtaining M3 nanomolar affinity coupled with nanomolar PDE4 inhibition, which translated into anti-bronchospastic efficacy ex vivo (inhibition of rat trachea contraction) and into anti-inflammatory efficacy in vitro (inhibition of TNFα release). Among the best compounds, compound 92a achieved the goal of demonstrating in vivo efficacy and duration of action in both the bronchoconstriction and inflammation assays in rat after intratracheal administration.

Mapping the structural requirements of inducers and substrates for decarboxylation of weak acid preservatives by the food spoilage mould Aspergillus niger.

Moulds are able to cause spoilage in preserved foods through degradation of the preservatives using the Pad-decarboxylation system. This causes, for example, decarboxylation of the preservative sorbic acid to 1,3-pentadiene, a volatile compound with a kerosene-like odour. Neither the natural role of this system nor the range of potential substrates has yet been reported. The Pad-decarboxylation system, encoded by a gene cluster in germinating spores of the mould Aspergillus niger, involves activity by two decarboxylases, PadA1 and OhbA1, and a regulator, SdrA, acting pleiotropically on sorbic acid and cinnamic acid. The structural features of compounds important for the induction of Pad-decarboxylation at both transcriptional and functionality levels were investigated by rtPCR and GCMS. Sorbic and cinnamic acids served as transcriptional inducers but ferulic, coumaric and hexanoic acids did not. 2,3,4,5,6-Pentafluorocinnamic acid was a substrate for the enzyme but had no inducer function; it was used to distinguish induction and competence for decarboxylation in combination with the analogue chemicals. The structural requirements for the substrates of the Pad-decarboxylation system were probed using a variety of sorbic and cinnamic acid analogues. High decarboxylation activity, ~100% conversion of 1mM substrates, required a mono-carboxylic acid with an alkenyl double bond in the trans (E)-configuration at position C2, further unsaturation at C4, and an overall molecular length between 6.5Å and 9Å. Polar groups on the phenyl ring of cinnamic acid abolished activity (no conversion). Furthermore, several compounds were shown to block Pad-decarboxylation. These compounds, primarily aldehyde analogues of active substrates, may serve to reduce food spoilage by moulds such as A. niger. The possible ecological role of Pad-decarboxylation of spore self-inhibitors is unlikely and the most probable role for Pad-decarboxylation is to remove cinnamic acid-type inhibitors from plant material and allow uninhibited germination and growth of mould spores.

Total synthesis of (-)-ulapualide A, a novel tris-oxazole macrolide from marine nudibranchs, based on some biosynthesis speculation.

A new, second generation, total synthesis of ulapualide A (1), whose stereochemistry was recently determined from X-ray analysis of its complex with the protein actin, is described. The synthesis is designed and based on some speculation of the biosynthetic origin of the contiguous tris-oxazole unit in ulapualide A, alongside that of the related co-metabolites that contain only two oxazole rings, e.g. 6 and 7. The mono-oxazole carboxylic acid 67b and the mono-oxazole secondary 55b alcohol which, together, contain all of the 10 asymmetric centres in the natural metabolite, were first elaborated using a combination of contemporary asymmetric synthesis protocols. Esterification of 67b with 55b under Yamaguchi conditions gave the ester 77 which was then converted into the omega-amino acid 18a following simultaneous deprotection of the t-butyl ester and the N-Boc protecting groups. Macrolactamisation of 18a, using HATU, now gave the key intermediate macrolactam 17, containing two of the three oxazole rings in ulapualide A (1). A number of procedures were used to introduce the third oxazole ring in ulapualide A from 17, including: a) cyclodehydration to the oxazoline 78a followed by oxidation using nickel peroxide leading to 76; b) dehydration to the enamide 79, followed by conversion into the methoxyoxazoline 78b, via 80, and elimination of methanol from 78b using camphorsulfonic acid. The tris-oxazole macrolide 76 was next converted into the aldehyde 82b in four straightforward steps, which was then reacted with N-methylformamide, leading to the E-alkenylformamide 83. Removal of the TBDPS protection at C3 in 83 finally gave (-)-ulapualide A, whose 1H and 13C NMR spectroscopic data were indistinguishable from those obtained for naturally derived material. It is likely that the tris-oxazole unit in ulapualide A (1) is derived in nature from a cascade of cyclodehydrations from an acylated tris-serine precursor, e.g.9, followed by oxidation of the resulting tris-oxazoline intermediate, i.e.10. It is also plausible to speculate that the biosynthesis of metabolites related to ulapualide A, e.g. the bis-oxazole 6 and the imide 7, involve cyclisations of just two of the serine units in 9. These speculations were given some credence by carrying out pertinent interconversions involving the bis-oxazole amide 24, the enamide 25, the imide 26, the oxazoline 27 and the tris-oxazole 30 as model compounds. An alternative strategy to the tris-oxazole macrolide intermediate 76 was also examined, involving preliminary synthesis of the aldehyde 73, containing a shortened (C25-C34) side chain from 67b and 47b. A Wadsworth-Emmons olefination reaction between 73 and the phosphonate ester 74 led smoothly to the E-alkene 75, but we were not able to reduce selectively the conjugated enone group in 75 to 76 without simultaneous reduction of the oxazole alkene bond, using a variety of reagents and reaction conditions.