Antibacterial and anti-inflammatory effects of Thunbergia laurifolia Lindl., Moringa oleifera Lam. and Phyllanthus amarus Schumach. & Thonn. extracts

Introduction

There is increasing evidence suggesting that chronic inflammation in the gastrointestinal tract may be caused by pathogenic infections, leading to destructive inflammatory conditions such as periodontal disease. This study aimed to investigate the antimicrobial and anti-inflammatory properties of ethanolic extracts from Thunbergia laurifolia Lindl. (TLE), Phyllanthus amarus Schumach. & Thonn. (PAE), and Moringa oleifera Lam. (MOE).

Methods

The antimicrobial activity of crude ethanol extracts was assessed using disk diffusion and broth dilution methods against Bacillus cereus, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Vibrio cholerae. The anti-inflammatory properties of herbal extracts by measuring the level of interleukin-6 (IL-6), tumour necrosis factor-alpha, and monocyte chemoattractant protein-1 (MCP-1) secretion in THP-1 macrophage cells over 24 hours, both in the absence and presence of lipopolysaccharide.

Results

All herbal extracts exhibited antibacterial activity against B. cereus, S. aureus, and V. cholerae, but were ineffective against E. coli and P. aeruginosa. The inhibitory effects were dose-dependent, with minimum inhibitory concentration (MIC) values ranging from 625 to 5 000 µg/ml and minimum bactericidal concentration values ranging from 625 to 10 000 µg/ml. MOE showed the highest antibacterial activity against V. cholerae (MIC = 625 µg/ml), while PAE exhibited the most inhibitory effects against B. cereus (MIC = 625 µg/ml). Additionally, PAE and TLE as low as 200 µg/ml completely inhibit IL-6 secretion and reduce Tumor Necrosis Factor-alpha (TNF-α) and MCP-1 secretion in a concentration-dependent manner.

Conclusions

All three herbal extracts have the potential to attenuate the secretion of inflammatory cytokines and exhibit antibacterial activity that may prevent foodborne infections.