Bangladeshi medicinal plants (BMP) have a history of traditional use in treating chronic inflammatory diseases, but a BMP bark’s antioxidant and anti-inflammatory effects remain largely unexplored. This study assessed methanolic extracts’ antioxidant and anti-inflammatory properties from the bark of 15 medicinal plant species native to Bangladesh. The methanol extracts of BMP bark were evaluated for their total antioxidant activity and ability to counteract inflammation induced by lipopolysaccharide (LPS) in RAW 264.7 macrophages. Among the 15 bark extracts from BMP, Albizia odoratissima (A. odoratissima), Engelhardia spicata (E. spicata), and Shorea robusta (S. robusta) showed the highest total phenolic contents and total antioxidant capacity by effectively scavenging free radicals. In particular, these three bark extracts significantly reduced the mRNA expression of LPS-induced inflammatory cytokines and enzymes inducible by inflammation in macrophages. Also, the mRNA expression of NADPH oxidase 2 was significantly suppressed by the three bark extracts in LPS-induced RAW 264.7 macrophages. These results suggest that out of the 15 bark extracts obtained from medicinal plants in Bangladesh, the extracts from A. odoratissima, E. spicata, and S. robusta exhibit substantial total antioxidant capacity by efficiently scavenging free radicals and also inhibit LPS-induced inflammation in macrophages.

Introduction
Materials and Methods
    Chemical reagents
    Sample preparation
    Total phenolic content
    ABTS radical scavenging activity
    DPPH radical scavenging assay
    Ferric reducing antioxidant power assay
    Cell culture
    Cell viability
    Quantitative real time PCR (qRT-PCR)
    Statistical analysis
Results
    Total phenolic content
    Total antioxidant capacity
    Correlation between TPC and total antioxidant capacity
    Comparison of antioxidant capacities by heatmap analysis
Discussion
Conclusions
Acknowledgments
References
Author Information

• Joo Won Lee(Department of Smart Green Technology Engineering, Pukyong National University)
• Mi-Bo Kim(Department of Food Science and Nutrition, Pukyong National University)
• Seungjin Jeong(Department of Smart Green Technology Engineering, Pukyong National University)
• Hyeju Lee(Department of Smart Green Technology Engineering, Pukyong National University)
• Su Hyeon Baek(Department of Smart Green Technology Engineering, Pukyong National University)
• Md. Salah Uddin(Ethnobotanical Database of Bangladesh)
• Sang Woo Lee(International Biological Material Research Center, Korea Research Institute of Bioscience and Biotechnology)
• Sang Gil Lee(Department of Smart Green Technology Engineering, Pukyong National University, Department of Food Science and Nutrition, Pukyong National University) Corresponding author