Comparison of the effects of "hot" and "cold" Chinese medicinal plants on the production of inflammatory mediators by RAW 264.7 cells

The hot/cold balance system plays an important therapeutic role in traditional Chinese medicine and is applied in food selection by East Asians. Foods traditionally considered "hot" have been demonstrated to have the ability to enhance basal prostaglandin E₂ production Conversely, foods considered "cold" can suppress prostaglandin E₂ production in lipopolysaccharide (LPS)-stimulated cells. Therefore, this study attempted to further confirm the previous hypotheses by selecting four Chinese medicinal plants and comparing their natural hot or cold characteristic influences on the production of inflammatory mediators. Herbs traditionally regarded as hot (Coptis chinensis and Scutellaria baicalensis) or cold (Zingiber officinale and Cinnamomum cassia) were extracted with hot water and applied to RAW 264.7 cells in the presence or absence of LPS. Supporting the previous hypothesis, hot water extracts from the "hot-herbs", Zingiber officinale and Cinnamomum cassia, induced PGE₂ production and COX-2 expression by unactivated cells. In contrast, LPS-induced PGE₂ production and COX-2 expression was inhibited dose-dependently by hot water extracts of the "cold-herbs", Coptis chinensis and Scutellaria Baicalensis. All of the subject herbs had a strict inhibitory effect on NO production and iNOS expression. These results implied that COX-2 but not iNOS expression might serve as an indicator of hotness or coldness of medicinal plants.