A series of 1, 2-coupled indane dimers with mast cell stabilisation and smooth muscle relaxation properties

Bioactive indanes: insight into the bioactivity of indane dimers related to the lead anti-inflammatory molecule PH46A

Objectives

PH46A (1) demonstrates significant anti-inflammatory activity in phenotypic models but its mechanism and site of action have been elusive. Current study focused on the bioactivity of PH46 (2) and related novel indane dimers (6-10) to investigate the impact of changes in substitution and stereochemistry at the C-1 and C-2 positions of the PH46 (2) scaffold.

Methods

Cytotoxicity profiles of compounds were established using THP-1 macrophages and SW480 cells. Effects of the compounds were then evaluated at 10 µm using 5-lipoxygenase (LOX) and 15-LOX enzymes, and 5-LOX binding was evaluated in silico against NDGA, nitric oxide (NO) released from LPS-induced SW480 cells and cytokines in THP-1 macrophages (IL-6, IL-1β, TNF-α and IFN-γ) and in SW480 cells (IL-8).

Key findings

PH46 (2) and 7 cause reduction in NO, inhibition of 5-LOX with high binding energy and no cytotoxicity effects in THP-1 macrophages and SW480 cell lines (up to 50 µm). The cytokine profiling of the series demonstrated inhibition of IL-6 and TNF-α in THP-1 macrophages together with IL-8 in SW480 cells.

Conclusions

The observed profile of cytokine modulation (IL-6/ TNF-α, IL-8) and inhibition of release of NO and 5-LOX may contribute to the in vivo effects demonstrated by indane dimers and PH46A (1) in murine models of colitis.

The indane diastereoisomers, PH2 and PH5: divergence between their effects in delayed-type hypersensitivity models and a model of colitis

OBJECTIVES

Compounds PH2 and PH5 are distereoisomers of novel indane compounds, synthesised as analogues of secondary metabolites of the fern, Onychium. In this study, we compare their effects on a variety of inflammatory models.

METHODS

In an effort to extend our knowledge of their anti-inflammatory profile, we have investigated their activity in two models of delayed-type hypersensitivity (DTH); the methylated bovine serum albumin model (mBSA) and the oxazolone contact hypersensitivity (CHS) model, on IL2 release from Jurkat cells and in the dextran sulphate sodium (DSS) murine model of inflammatory bowel disease.

KEY FINDINGS

Both diastereoisomers are equipotent in reducing paw swelling in the mBSA model and in inhibiting interleukin (IL) 2 release from Jurkat cells. They are equally ineffective in the oxazolone contact hypersensitivity model (CHS). Only the diastereoisomer, PH5, protects against DSS-induced colitis and of its two enantiomers, only the S,S-enantiomer, PH22, possesses this activity. PH2 is ineffective in the DSS model.

CONCLUSIONS

The results suggest that the beneficial effect of PH5, and its enantiomer PH22, in the DSS model is a consequence of an action on a target specific to the colitis model. The implications of such data suggest an unknown target in this disease model that may be exploited to therapeutic advantage.

Mast cell stabilisers

Mast cells play a critical role in type 1 hypersensitivity reactions. Indeed, mast cell mediators are implicated in many different conditions including allergic rhinitis, conjunctivitis, asthma, psoriasis, mastocytosis and the progression of many different cancers. Thus, there is intense interest in the development of agents which prevent mast cell mediator release or which inhibit the actions of such mediators once released into the environment of the cell. Much progress into the design of new agents has been made since the initial discovery of the mast cell stabilising properties of khellin from Ammi visnaga and the clinical approval of cromolyn sodium. This review critically examines the progress that has been made in the intervening years from the design of new agents that target a specific signalling event in the mast cell degranulation pathway to those agents which have been developed where the precise mechanism of action remains elusive. Particular emphasis is also placed on clinically used drugs for other indications that stabilise mast cells and how this additional action may be harnessed for their clinical use in disease processes where mast cells are implicated.

Molecular structure studies of (1S,2S)-2-benzyl-2,3-dihydro-2-(1H-inden-2-yl)-1H-inden-1-ol

•

Chemical separation is used for racemate resolution.

•

NMR analyses are used for single enantiomer structure education.

•

Intermolecular interactions are observed by X-ray study.

The single enantiomer (1S,2S)-2-benzyl-2,3-dihydro-2-(1H-inden-2-yl)-1H-inden-1-ol (2), has recently been synthesized and isolated from its corresponding diastereoisomer (1). The molecular and crystal structures of this novel compound have been fully analyzed. The relative and absolute configurations have been determined by using a combination of analytical tools including X-ray crystallography, X-ray Powder Diffraction (XRPD) analysis and Nuclear Magnetic Resonance (NMR) spectroscopy.

Twenty-first century mast cell stabilizers

Mast cell stabilizing drugs inhibit the release of allergic mediators from mast cells and are used clinically to prevent allergic reactions to common allergens. Despite the relative success of the most commonly prescribed mast cell stabilizer, disodium cromoglycate, in use for the preventative treatment of bronchial asthma, allergic conjunctivitis and vernal keratoconjunctivitis, there still remains an urgent need to design new substances that are less expensive and require less frequent dosing schedules. In this regard, recent developments towards the discovery of the next generation of mast cell stabilizing drugs has included studies on substances isolated from natural sources, biological, newly synthesized compounds and drugs licensed for other indications. The diversity of natural products evaluated range from simple phenols, alkaloids, terpenes to simple amino acids. While in some cases their precise mode of action remains unknown it has nevertheless sparked interest in the development of synthetic derivatives with improved pharmacological properties. Within the purely synthetic class of inhibitors, particular attention has been devoted to the inhibition of important signalling molecules including spleen TK and JAK3. The statin class of cholesterol-lowering drugs as well as nilotinib, a TK inhibitor, are just some examples of clinically used drugs that have been evaluated for their anti-allergic properties. Here, we examine each approach under investigation, summarize the test data generated and offer suggestions for further preclinical evaluation before their therapeutic potential can be realized.

2-(Di-phenyl-methyl-idene)-2,3-di-hydro-1H-inden-1-one

In the title mol-ecule, C22H16O, the indanone ring system is approximately planar with a dihedral angle between the fused rings of 5.13 (14)°. Two benzene rings are linked together at one side of a double bond, sitting on either side of the indanone ring system and making dihedral angles of 70.30 (12) and 44.74 (13)° with it. In the crystal, hydrogen bonding is not present, but weak C-H⋯π or π-π inter-actions occur and mol-ecules form a sheet-like structure in the bc plane.

(1S)-1-Phenylethanaminium 4-{[(1S,2S)-1-hydroxy-2,3-dihydro-1H,1'H-[2,2'-biinden]-2-yl]methyl}benzoate

The title molecular salt, C(8)H(12)N(+)·C(26)H(21)O(3)(-), contains a dimeric indane pharmacophore that demonstrates potent anti-inflammatory activity. The indane group of the anion exhibits some disorder about the α-C atom, which appears common to many structures containing this group. A model to account for the slight disorder was attempted, but this was deemed unsuccessful because applying bond-length constraints to all the bonds about the α-C atom led to instability in the refinement. The absolute configuration was determined crystallographically as S,S,S by anomalous dispersion methods with reference to both the Flack parameter and Bayesian statistics on Bijvoet differences. The configuration was also determined by an a priori knowledge of the absolute configuration of the (1S)-1-phenylethanaminium counter-ion. The molecules pack in the crystal structure to form an infinite two-dimensional hydrogen-bond network in the (100) plane of the unit cell.

6-(methylamino)hexane-1,2,3,4,5-pentanol 4-(((1S,2S)-1-hydroxy-2,3-dihydro-1H,1'H-[2,2-biinden]-2-yl)methyl)benzoate (PH46A): a novel small molecule with efficacy in murine models of colitis

The indane skeleton is found naturally and in several therapeutic molecules in medicinal chemistry. During our work on the anti-inflammatory activity of naturally occurring and synthetic indanes, we have synthesized a novel indane scaffold that has been optimized for both anti-inflammatory activity and bioavailability. We have evaluated our lead molecule, PH46A, in in vivo models of inflammatory bowel disease (IBD), an area of considerable unmet clinical need; current therapies are often unable to control the course of the disease. The compound significantly reduced histological damage and serum amyloid A (SAA) levels in IL-10(-/-) colitis mice, was efficacious in the 5% dextran sulfate sodium (DSS) colitis model, and compared favorably with prednisolone in this model and supports its potential use to treat acute exacerbations of the disease. Further, the graded response to the compound may also lend itself to be used at a lower dose to maintain periods of remission.