Modulation of NF-κB and MAPK signalling pathways by hydrolysable tannin fraction from Terminalia chebula fruits contributes to its anti-inflammatory action in RAW 264.7 cells

Abstract

Objectives: Hydrolysable tannin fraction (HTF) derived from Terminalia chebula fruit pericarps was assessed for its anti-inflammatory potential in LPS-induced RAW 264.7 cells. Its molecular mechanism was also established and compared with individual tannins - chebulagic acid (CH) and corilagin (CO).

Methods: The effect of HTF on LPS-stimulated RAW 264.7 cells was studied by estimating the release of NO, ROS, cytokines and changes in nuclear morphology by DAPI staining. Furthermore, the effect of HTF, CO and CH was compared with the expression of p65, p38 and pERK proteins by immunoblotting and the mRNA transcript level of COX-2, iNOS and TNF-α by quantitative PCR. The in-silico interactions of various hydrolysable tannins present in HTF with molecular targets of inflammation were studied using Maestro software.

Key findings: HTF at the dose levels of 25, 50 and 100 µg/ml was able to decrease the release of NO, ROS and cytokines from LPS-induced RAW 264.7 cells without disturbing the cell nuclear morphology. Investigation of molecular mechanism revealed that inhibition of NF-κB and MAPK signalling pathways was responsible for its anti-inflammatory action. The effect of HTF was higher than the individual tannins CH and CO.

Conclusion: HTF can be developed as an effective anti-inflammatory agent.

Keywords: Terminalia chebula; RAW 264.7 cells; anti-inflammatory; chebulagic acid; corilagin; hydrolysable tannins.