Current synthetic inhibitors of human neutrophil elastase

Biocompounds from rapeseed oil industry co-stream as active ingredients for skin care applications

OBJECTIVE

Despite the great number of substances produced by the skincare industry, very few of them seem to truly have an effect on the skin. Therefore, given the social implications surrounding physical appearance, the search for new bioactive compounds to prevent or attenuate skin ageing and enhance self-image is a priority of current research. In this context, being rich in valuable compounds, such as proteins, phenolics, lipids and vitamins, this study is focused on the potential activity of rapeseed press cake hydrolysates to be used as raw materials for skincare applications.

METHODS

In this study, the protein-rich press residue from the rapeseed oil industry was converted enzymatically into short-chain biologically active peptides using four protease products with varying substrate specificity - Alcalase 2.4L FG, Protex 6L, Protamex and Corolase 7089. The antioxidant, anti-wrinkle and anti-inflammatory activities of the obtained hydrolysates were evaluated in vitro while their biocompatibility with human skin fibroblasts was tested.

RESULTS

All hydrolysates were biocompatible with skin fibroblasts after 24 h of exposure, while the non-hydrolysed extract induced cell toxicity. Alcalase 2,4L FG and Protex 6L-obtained hydrolysates were the most promising extracts showing improved bioactivities suitable for skin anti-ageing formulations, namely antioxidant activity, inhibiting approximately 80% cellular reactive oxidative species, anti-inflammatory and anti-wrinkle properties, inhibiting around 36% of myeloperoxidase activity and over 83% of elastase activity.

CONCLUSION

The enzymatic technology applied to the rapeseed oil industry costream results in the release of bioactive compounds suitable for skincare applications.

Synthesis, stability, biochemical and pharmacokinetic properties of a new potent and selective 4-oxo-β-lactam inhibitor of human leukocyte elastase

The 4-oxo-β-lactams (azetidine-2,4-diones) are potent acylating agents of the human leukocyte elastase (HLE), a neutrophil serine protease that plays a key role in several inflammatory diseases. A novel 4-oxo-β-lactam containing a N-(4-(phenylsulphonylmethyl)phenyl) group, 3, was designed as a potential mechanism-based inhibitor capable of undergoing elimination of phenylsulphinate upon Ser-195 acylation. Compound 3 was found to be a potent slow-tight binding inhibitor of HLE, presenting a remarkable second-order rate constant of 1.46 x 10⁶ M⁻¹s⁻¹ and displaying selectivity over the proteinase 3 and cathepsin G. However, liberation of phenylsulphinate was not observed in the hydrolysis of 3 in both pH 7.4 phosphate buffer and human plasma. The C(max) values of 1207 μg/total blood, 179 μg/g spleen and 106 μg/g lung were determined by HPLC, following a single 30 mg/kg dose of 3 given intraperitoneally to NMRI mice, suggesting that the inhibitor distributes well into tissues. Although being a powerful selective inhibitor of HLE, 4-oxo-β-lactam 3 has a limited stability, being susceptible to off-target reactions (plasma and liver enzymes).

Synthesis and in vitro evaluation of pseudosaccharinamine derivatives as potential elastase inhibitors

Pseudosaccharinamine derivatives were evaluated for elastase inhibitory activity. Ester derivatives of pseudosaccharinamine displayed reversible and high inhibition of human leukocyte elastase (HLE) as compared to porcine pancreatic elastase (PPE). Cyanomethyl (2S,3S)-2-(1,1-dioxobenzo[d]isothiazol-3-ylamino)-3-methylpentanoate was found to inhibit HLE at Ki=0.8 microM.

Clarification of mechanism of human sputum elastase inhibition by a new inhibitor, ONO-5046, using electrospray ionization mass spectrometry

Liquid chromatography electrospray ionization mass spectrometry (LC/ESI-MS) to probe the nature of the covalent E-I complex was successfully applied to clarify the mechanism of human sputum elastase (HSE) inhibition by a new inhibitor, ONO-5046. The mass spectrum of the four HSE isozymes displayed their molecular ion peaks at m/z=26,018, 25,929, 25,200, and 25,054, respectively. Immediately after incubation, inactivation of HSE with ONO-5046 increased the four molecular ion peaks by approximately 84 amu, which was assigned to the mass unit of the pivaloyl moiety of ONO-5046. An additional minute of incubation of E-I complex restored the original molecular ion peaks. These observations strongly suggested that ONO-5046 inactivates HSE by a reversible 'acylation-deacylation' mechanism.

Neutrophil elastase inhibitors as treatment for COPD

Chronic obstructive pulmonary disease, characterised by a slowly progressive, irreversible airways limitation, is a major worldwide cause of chronic morbidity and mortality. The imbalance between human neutrophil elastase and endogenous antiproteases may cause excess human neutrophil elastase in pulmonary tissues, which may be considered a major pathogenic factor in chronic obstructive pulmonary disease. Great effort has been devoted to finding a method to restore the balance, resulting in the discovery of potent two-typed small-molecular-weight human neutrophil elastase inhibitors. In the application of chronic obstructive pulmonary disease therapy, the human neutrophil elastase inhibitors mainly focused upon include ONO-5046, MR-889, L-694,458, CE-1037, GW-311616 and TEI-8362 as the acyl-enzyme inhibitors; and ONO-6818, AE-3763, FK-706, ICI-200,880, ZD-0892 and ZD-8321 as the transition-state inhibitors. In this review, various problems that remain to be solved in the clinical use of human neutrophil elastase inhibitors are discussed.