Inhibitory Effects of Methanol Extract of Seeds of Job's Tears (Coix Lachryma-Jobi L Var. Ma-Yuen) On Nitric Oxide and Superoxide Production in Raw 264.7 Macrophages

Abstract

Overproduction of nitric oxide (NO) or superoxide (O₂) by activated macrophages is known to be involved in acute or chronic inflammation. The seeds of Job's Tears (Coix lachryma-jobi L. var. ma-yuen) have been used as anti-inflammatory medicine and health food. However, it is still unclear how the seeds show anti-inflammatory properties. Using murine macrophage-like RAW 264.7 cells, we tried to know whether the overproduction of NO and O₂ by activated macrophages could be prevented by the methanol (MeOH) extract of the seeds of Job's Tears. RAW 264.7 cells were activated with interferon-γ plus lipopolysaccharide to produce NO and with pholbol ester to produce O₂. The MeOH extract showed marked inhibition of NO production by activated RAW 264.7 cells in a dose-dependent manner via suppression of inducible NO synthase mRNA expression. The MeOH extract also showed inhibition of O₂ production by activated RAW 264.7 cells in dose- and time-dependent manners, possibly by interfering with NADPH oxidase machinery of macrophages. Collectively, these results demonstrate that the MeOH extract of the seeds of Job's Tears shows anti-inflammatory properties which may, in part, involve an inhibition of NO and O₂ production by activated macrophages.