Facile and Stereoselective Synthesis of (Z)-15-Octadecenoic Acid and (Z)-16-Nonadecenoic Acid: Monounsaturated Omega-3 Fatty Acids

Expanding the π-system of Fatty Acid-Anion Transporter Conjugates Modulates Their Mechanism of Proton Transport and Mitochondrial Uncoupling Activity

Mitochondrial uncoupling by small molecule protonophores is a promising strategy for developing novel anticancer agents. Recently, aryl urea substituted fatty acids (aryl ureas) were identified as a new class of protonophoric anticancer agents. To mediate proton transport these molecules self-assemble into membrane-permeable anionic dimers in which intermolecular hydrogen bonds between the carboxylate and aryl-urea anion receptor delocalise the negative charge across the aromatic π-system. In this work, we extend the aromatic π-system by introducing a second phenyl substituent to the aryl urea scaffold and compare the proton transport mechanisms and mitochondrial uncoupling actions of these compounds to their monoaryl analogues. It was found that incorporation of meta-linked phenyl substituents into the aryl urea scaffold enhanced proton transport in vesicles and demonstrated superior capacity to depolarise mitochondria, inhibit ATP production and reduce the viability of MDA-MB-231 breast cancer cells. In contrast, diphenyl ureas linked through a 1,4-distribution across the phenyl ring displayed diminished proton transport activity, despite both diphenyl urea isomers possessing similar binding affinities for carboxylates. Mechanistic studies suggest that inclusion of a second aryl ring changes the proton transport mechanism, presumably due to steric factors that impose higher energy penalties for dimer formation.

Expansion of the structure-activity relationship of branched chain fatty acids: Effect of unsaturation and branching group size on anticancer activity

Branched chain fatty acids (BCFAs) are a class of fatty acid with promising anticancer activity. The BCFA 13-methyltetradecanoic acid (13-MTD) inhibits tumour growth in vivo without toxicity but efficacy is limited by moderate potency, a property shared by all known BCFAs. The mechanism of action of BCFAs has not been fully elucidated, and in the absence of a clearly defined target optimisation of BCFA potency must rely on structure-activity relationships. Our current understanding of the structural features that promote BCFA anticancer activity is limited by the low structural diversity of reported BCFAs.The aim of this study was to examine the effects of two new structural modifications- unsaturation and branching group size- on BCFA activity. Thus, homologous series of saturated and cis-Δ11 unsaturated BCFAs were synthesised bearing methyl, ethyl, propyl and butyl branching groups, and were screened in vitro for activity against three human cancer cell lines. Potencies of the new BCFAs were compared to 13-MTD and an unbranched monounstaurated fatty acid (MUFA) bearing a cis-Δ11 double bond. The principal findings to emerge were that the anticancer activity of BCFAs was adversly affected by larger branching groups but significantly improved by incorporation of a cis-Δ11 double bond into the BCFA alkyl chain. This study provides new structure-activity relationship insights that may be used to develop BCFAs with improved potency and therapeutic potential.

Synthesis and Characterization of Novel Acyl-Glycine Inhibitors of GlyT2

It has been demonstrated previously that the endogenous compound N-arachidonyl-glycine inhibits the glycine transporter GlyT2, stimulates glycinergic neurotransmission, and provides analgesia in animal models of neuropathic and inflammatory pain. However, it is a relatively weak inhibitor with an IC₅₀ of 9 μM and is subject to oxidation via cyclooxygenase, limiting its therapeutic value. In this paper we describe the synthesis and testing of a novel series of monounsaturated C18 and C16 acyl-glycine molecules as inhibitors of the glycine transporter GlyT2. We demonstrate that they are up to 28 fold more potent that N-arachidonyl-glycine with no activity at the closely related GlyT1 transporter at concentrations up to 30 μM. This novel class of compounds show considerable promise as a first generation of GlyT2 transport inhibitors.