The Cytokine IL-1β and Piperine Complex Surveyed by Experimental and Computational Molecular Biophysics.

Marinônio Lopes Cornélio,Gabriel Zazeri,Marcelo De Freitas Lima,Ana Paula Ribeiro Povinelli

doi:10.3390/biom10091337

Marinônio Lopes Cornélio, Gabriel Zazeri + Show 2 more

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https://doi.org/10.3390/biom10091337

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Abstract

The bioactive piperine, a compound found in some pepper species, has been widely studied because of its therapeutic properties that include the inhibition of an important inflammation pathway triggered by interleukin-1 beta (IL-1β). However, investigation into the molecular interactions between IL-1β and piperine is not reported in the literature. Here, we present for the first time the characterisation of the complex formed by IL-1β and piperine through experimental and computational molecular biophysical analyses. Fluorescence spectroscopy unveiled the presence of one binding site for piperine with an affinity constant of 14.3 × 104 M−1 at 298 K. The thermodynamic analysis indicated that the interaction with IL-1β was spontaneous (∆G = −25 kJ/mol) and, when split into enthalpic and entropic contributions, the latter was more significant. Circular dichroism spectroscopy showed that piperine did not affect IL-1β secondary structure (~2%) and therefore its stability. The set of experimental data parameterized the computational biophysical approach. Through molecular docking, the binding site micro-environment was revealed to be composed mostly by non-polar amino acids. Furthermore, molecular dynamics, along with umbrella sampling, are in agreement with the thermodynamic parameters obtained by fluorescence assays and showed that large protein movements are not present in IL-1β, corroborating the circular dichroism data.

Highlights

Interleukin-1β (IL-1β) is a protein that belongs to the cytokine family of cell mediators produced mainly by mononuclear phagocytes, activated in response to infection and injury [1]
Fluorescence spectroscopy analysis revealed that IL-1β has one binding site for piperine, with the binding constant being (14.3 ± 0.1) × 104 M−1, while the thermodynamic parameters indicated that the complexation was a spontaneous process (∆G = −25.09 kJ/mol) with high entropic contribution, indicating that non-specific interactions played an important role in both the complex formation and stabilization
Circular Dichroism results showed that the interactions of piperine with the IL-1β did not cause significant secondary structure changes

Summary

Introduction

Interleukin-1β (IL-1β) is a protein that belongs to the cytokine family of cell mediators produced mainly by mononuclear phagocytes, activated in response to infection and injury [1]. With 17 kDa of molecular weight and 153 amino acids, this protein is the main soluble mediator of inflammation that triggers the activation pathway of the NF-κB responsible for the transcription of cytokine genes and other pro-inflammatory proteins [2]. Ying et al [2] reported that piperine inhibited the IL-1β-mediated activation of NF-κB and as consequence, the production of PGE2 and NO is downregulated as well as the IL-1β-stimulated gene expression and production of MMP-3, MMP-13, iNOS and COX-2 in human osteoarthritis chondrocyte. Bang et al [3] showed that piperine acts through the inhibition of IL-1β and NF-κB inflammation pathway, leading to the downregulation of pro-inflammatory proteins, which reinforces the anti-inflammatory activity of this molecule. Piperine has been widely studied by the scientific community because of its anti-inflammatory, anti-carcinogenic, immunomodulatory and hepatoprotective activities [6]

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