N-Acetyldopamine dimers from Oxya chinensis sinuosa attenuates lipopolysaccharides induced inflammation and inhibits cathepsin C activity

Abstract

Oxya chinensis sinuosa (rice field grasshopper) is an edible insect with numerous health beneficial properties, traditionally being used to treat many ailments in Korea and other countries. O. chinensis sinuosa has been used from centuries, however, a little is known about the chemical functionality of its bioactive compounds. Therefore, this study examined the anti-inflammatory and cathepsin C inhibitory activities of N-acetyldopamine dimer (2R, 3S)-2-(3',4'-dihydroxyphenyl)-3-acetylamino-7-(N-acetyl-2 "-aminoe thyl)-1,4-benzodioxane (DAB1) isolated from O. chinensis sinuosa. Results showed that DAB1 reduced the expression of pro-inflammatory mediator (iNOS, COX-2) and cytokines (TNF-alpha, IL-1 beta, and IL-6), and curtailed the nuclear translocation of NF-kappa B by inhibiting the phosphorylation of IKB alpha in lipopolysaccharide stimulated macrophages. Additionally, DAB1 inhibited cathepsin C activity at the cellular level, supported by in vitro assay (Ki, 71.56 +/- 10.21 mM and Kis, 133.55 +/- 18.2 mu M). Moreover, combinatorial molecular simulation and binding free energy analysis suggested a significant stability and binding affinity of cathepsin C-DAB1 complex via formation of hydrogen bond and hydrophobic interactions with the catalytic residues (Gln228, Thr379, Asn380, and Hie381). Also, essential dynamics analysis showed DAB1 induced non-functional motions in cathepsin C structure. Collectively, DAB1 was concluded as antiinflammatory and cathepsin C inhibiting agent and could be used in the drug development against respective diseases. (c) 2022 The Authors. Published by Elsevier B.V. on behalf of Research Network of Computational and Structural Biotechnology. This is an open access article under the CC BY license (http://creativecommons. org/licenses/by/4.0/).