Anti-Inflammatory Activities of Extracts of Thai Spices and Herbs with Lipopolysaccharide-Activated RAW 264.7 Murine Macrophages

Abstract

Nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha) play important roles in inflammatory processes. This study examined whether 13 spices/herbs commonly used in Thai dishes modulate the production of NO and TNF-alpha by the RAW 264.7 mouse macrophage cell line pretreated with plant extracts (1-100 microg/mL) prior to activation by bacterial lipopolysaccharide (LPS). Tested plant tissues were extracted with ethanol with the exception of roselle, which was extracted with 70% acetone. Eight of the 13 plant extracts inhibited NO and TNF-alpha production in a dose-dependent manner without exerting cytotoxicity. Extract from Limnophila aromatica (Kyeng) was the most robust suppressor of NO production, followed by dill, kaffer lime, chili, Teaw, mint, sweet basil, and pea eggplant, respectively (range of 50% inhibitory concentration [IC(50)] = 11.4-74.6 microg/mL). Kyeng also exhibited the greatest inhibition of TNF-alpha production (IC(50) = 10.5 microg/mL). IC(50) values for NO and TNF-alpha production in LPS-activated RAW 264.7 cells for these extracts were highly correlated (r = 0.772, P = .025). These results suggest that extracts from some spices/herbs in the habitual Thai diet possess anti-inflammatory activity. Moreover, the results support the use of NO production in LPS-activated RAW 264.7 cells as a rapid and cost-effective tool for screening the anti-inflammatory activity of extracts of spices/herbs.