Identification and evaluation of anti-inflammatory compounds from Kaempferia parviflora

The rhizome of Kaempferia parviflora has been used in traditional Thai medicine. In this study, we identified and compared specific compounds from the hexane extract of K. parviflora with those from other Zingiberaceous plants by using gas chromatography-mass spectrometry. We identified 5,7-dimethoxyflavone (DMF), 5-hydroxy-3,7,3',4'-tetramethoxyflavone (TMF), estimated 3,5,7-trimethoxyflavone, 5-hydroxy-7,4'-dimethoxyflavone, 3,5,7,4'-tetramethoxyflavone, and investigated their anti-inflammatory effects in rat basophilic leukemia (RBL-2H3) cells stimulated with an IgE antigen or a calcium ionophore. We found that DMF and TMF more potently inhibited antigen-induced degranulation than did nobiletin, a well-known anti-inflammatory agent. In addition, compared to RBL-2H3 cells stimulated with a calcium ionophore, those treated with DMF and TMF showed more marked inhibition of the degranulation and the production and mRNA expression of inflammatory mediators. These results suggest that DMF and TMF inhibit an early step in the high-affinity IgE receptor signaling cascade rather than intracellular calcium release and protein kinase C activation.