Sally Freeman

Fenamate NSAIDs inhibit the NLRP3 inflammasome and protect against Alzheimer’s disease in rodent models

Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenase-1 (COX-1) and COX-2 enzymes. The NLRP3 inflammasome is a multi-protein complex responsible for the processing of the proinflammatory cytokine interleukin-1β and is implicated in many inflammatory diseases. Here we show that several clinically approved and widely used NSAIDs of the fenamate class are effective and selective inhibitors of the NLRP3 inflammasome via inhibition of the volume-regulated anion channel in macrophages, independently of COX enzymes. Flufenamic acid and mefenamic acid are efficacious in NLRP3-dependent rodent models of inflammation in air pouch and peritoneum. We also show therapeutic effects of fenamates using a model of amyloid beta induced memory loss and a transgenic mouse model of Alzheimers disease. These data suggest that fenamate NSAIDs could be repurposed as NLRP3 inflammasome inhibitors and Alzheimers disease therapeutics.

Acyclic nucleosides as antiviral compounds

Acyclovir is an effective drug for the treatment of HSV and VZV infections, which after phosphorylation to the triphosphate, inhibits viral DNA polymerase. Acyclovir has low oral bioavailability, therefore prodrugs have been developed, and the L-valyl ester, valaciclovir, recently has been licensed for the treatment of shingles. Ganciclovir is used against CMV, and famciclovir, a lipophilic prodrug of penciclovir, is marketed for shingles. The acyclic nucleoside phosphonates are active against thymidine kinase-resistant viral strains. Promising analogs are PMEA (in clinical trial for the treatment of AIDS) and (S)- HPMPC (good in vivo activity against HSV, VZV, CMV, and EBV). Oligonucleotides incorporating acyclic nucleosides at the 3’t and 5’t-ends, or constituted of amino acyclic nucleosides, are resistant to cleavage by nucleases and may be useful in antisense and/or antigene therapy. HEPT is active against HIV-1: It binds in a hydrophobic pocket on reverse transcriptase, rather than in the polymerase active site. Some acyclic nucleosides are potent inhibitors of purine and pyrimidine nucleoside phosphorylase. These compounds may have a therapeutic niche in combination therapy with antiviral and anticancer nucleosides, and in the treatment of diseases involving the T-cell.

Regulation of Ca2+-dependent Cl- conductance in a human colonic epithelial cell line (T84): cross-talk between Ins(3,4,5,6)P4 and protein phosphatases.

1 We have studied the regulation of whole‐cell chloride current in T84 colonic epithelial cells by inositol 3,4,5,6‐tetrakisphosphate (Ins(3,4,5,6)P4). New information was obtained using (a) microcystin and okadaic acid to inhibit serine/threonine protein phosphatases, and (b) a novel functional tetrakisphosphate analogue, 1,2‐bisdeoxy‐1,2‐bisfluoro‐Ins(3,4,5,6)P4 (i.e. F2‐Ins(3,4,5,6)P4). 2 Calmodulin‐dependent protein kinase II (CaMKII) increased chloride current 20‐fold. This current (ICl,CaMK) continued for 7 ± 1.2 min before its deactivation, or running down, by approximately 60 %. This run‐down was prevented by okadaic acid, whereupon ICl,CaMK remained near its maximum value for ≥ 14.3 ± 0.6 min. 3 F2‐Ins(3,4,5,6)P4 inhibited ICl,CaMK (IC50= 100 μM) stereo‐specifically, since its enantiomer, F2‐Ins(1,4,5,6)P4 had no effect at <= 500 μM. Dose‐response data (Hill coefficient = 1.3) showed that F2‐Ins(3,4,5,6)P4 imitated only the non‐co‐operative phase of inhibition by Ins(3,4,5,6)P4, and not the co‐operative phase. 4 Ins(3,4,5,6)P4 was prevented from blocking ICl,CaMK by okadaic acid (IC50= 1.5 nM) and microcystin (IC50= 0.15 nM); these data lead to the novel conclusion that, in situ, protein phosphatase activity is essential for Ins(3,4,5,6)P4 to function. The IC50 values indicate that more than one species of phosphatase was required. One of these may be PP1, since F2‐Ins(3,4,5,6)P4‐dependent current blocking was inhibited by okadaic acid and microcystin with IC50 values of 70 nM and 0.15 nM, respectively.

Arylethylamine psychotropic recreational drugs: a chemical perspective.

The arylethylamines substituted in the aryl ring, side-chain carbons and on the terminal amine, comprise a large number of human mood and behaviour altering chemicals. Some of these psychotropic drugs have been used since pre-history, but in many states are proscribed and are consequently subject to clandestine synthesis and illegal traffic world-wide in the forms particularly of amphetamines and to a lesser extent tryptamines. The chemistry employed in the synthesis of these compounds is dictated often by the available precursors and relies usually on relatively simple, unsophisticated conversion reactions to a suitable product. The internet web sites and documentation of the recreational drug culture have been studied alongside the professional scientific and regulatory literature. The review demonstrates the great complexity of the chemistry and neuro-pharmacology of these chemicals and the challenge faced by legislative bodies to control their traffic and use for the sake of social welfare.

Inhibiting the Inflammasome: A Chemical Perspective

Inflammasomes are high molecular weight complexes that sense and react to injury and infection. Their activation induces caspase-1 activation and release of interleukin-1β, a pro-inflammatory cytokine involved in both acute and chronic inflammatory responses. There is increasing evidence that inflammasomes, particularly the NLRP3 inflammasome, act as guardians against noninfectious material. Inappropriate activation of the NLRP3 inflammasome contributes to the progression of many noncommunicable diseases such as gout, type II diabetes, and Alzheimers disease. Inhibiting the inflammasome may significantly reduce damaging inflammation and is therefore regarded as a therapeutic target. Currently approved inhibitors of interleukin-1β are rilonacept, canakinumab, and anakinra. However, these proteins do not possess ideal pharmacokinetic properties and are unlikely to easily cross the blood-brain barrier. Because inflammation can contribute to neurological disorders, this review focuses on the development of small-molecule inhibitors of the NLRP3 inflammasome.

AMT (3-(2-aminopropyl)indole) and 5-IT (5-(2-aminopropyl)indole): an analytical challenge and implications for forensic analysis

5-(2-Aminopropyl)indole (5-IT) and 3-(2-aminopropyl)indole (α-methyltryptamine, AMT) are isomeric substances and their differentiation can be a challenge under routine analytical conditions, especially when reference material is unavailable. 5-IT represents a very recent addition to the battery of new psychoactive substances that are commercially available from online retailers. This report illustrates how subtle differences observed under mass spectral and UV conditions can help to facilitate the differentiation between the two isomers. Analyses included (1)  H and (13) C NMR, GC-EI/CI ion trap MS, applications of several U/HPLC-DAD and HPLC-MS methods. Investigations currently underway also highlight the confirmation that AMT was detected in a number of fatal intoxications. These findings also demonstrate that there is a potential risk of misidentification when dealing with both substances.

Synthesis and iron binding studies of myo-inositol 1,2,3-trisphosphate and (±)-myo-inositol 1,2-bisphosphate, and iron binding studies of all myo-inositol tetrakisphosphates☆

The first syntheses of the natural products myo-inositol 1,2,3-trisphosphate and (+/-)-myo-inositol 1,2-bisphosphate are described. The protected key intermediates 4,5,6-tri-O-benzoyl-myo-inositol and (+/-)-3,4,5,6-tetra-O-benzyl-myo-inositol were phosphorylated with dibenzyl N,N-di-isopropylphosphoramidite in the presence of 1H-tetrazole and subsequent oxidation of the phosphite. The crystal structures of the synthetic intermediates (+/-)-1-O-(tert-butyldiphenylsilyl)-2,3,O-cyclohexylidene-myo-inos itol and (+/-)-4,5,6-tri-O-benzoyl-1-O-(tert-butyldiphenylsilyl)-2,3-O-cycl ohexylidene- myo-inositol are reported. myo-Inositol 1,2,3-trisphosphate, (+/-)-myo-inositol 1,2-bisphosphate, and all isomeric myo-inositol tetrakisphosphates were evaluated for their ability to alter HO. production in the iron-catalysed Haber-Weiss reaction. The results demonstrated that a 1,2,3-grouping of phosphates in myo-inositol was necessary for inhibition, also that (+/-)-myo-inositol 1,2-bisphosphate potentiated HO. production. myo-Inositol 1,2,3-trisphosphate resembled myo-inositol hexakisphosphate (phytic acid) in its ability to act as a siderophore by promoting iron-uptake into Pseudomonas aeruginosa.

Bioreversible protection for the phospho group: chemical stability and bioactivation of di(4-acetoxybenzyl) methylphosphonate with carboxyesterase

In contrast to high chemical stability (t1/2 55.4 h at 36.4 °C), with porcine liver Carboxyesterase the title compound 1 spontaneously decomposes first to the monoester 2 then to methylphosphonate, both reactions proceeding via the 4-hydroxybenzyl intermediates 3 and 4.

Inhibitors of Inositol Monophosphatase

Inositol monophosphatase (IMPase) catalyses the hydrolysis of myo-inositol monophosphates to myo-inositol, which is required in the phosphatidyl inositol cell signalling pathway. Here the enzyme structure, mechanism and inhibition of IMPase are reviewed. Lithium, an effective therapy for manic depression, is an uncompetitive inhibitor. In the search for alternative inhibitors to lithium, substrate-based inhibitors, bisphosphonates, terpenoid and tropolone analogues are described.

3 Prodrug Design for Phosphates and Phosphonates

Publisher Summary This chapter discusses prodrug design for phosphates and phosphonates. The phosphate group has an important role in virtually all of the major metabolic pathways in nature. There is little therapeutic scope for underivatized phosphate and phosphonate analogues because they are doubly ionized at physiological pH and are unable to cross cell membranes by passive diffusion. Only a few compounds can utilize active transporter pathways. These include the antiviral phosphonoformate (1), which shows some affinity for inorganic phosphate transporters [1, 2], the herbicide bialaphos (2) , which is transported by a peptide carrier, and the antibiotic fosfomycin (3) , which utilizes the 3-phosphoglycerate transport pathway. Phosphate monoesters are also prone to rapid hydrolysis by phosphatases, another property, which makes them unsuitable drugs. This instability coupled with their high aqueous solubility makes phosphate monoesters ideal prodrug modifications of drugs, which have low aqueous solubility. A wide range of prodrug modifications have been utilized in the design of lipophilic triesters of phosphates or diesters of phosphonates. Cleavage to the parent drug can occur by chemical hydrolysis or be catalyzed by a range of enzymes, including carboxyesterases and phosphodiesterases.