Anti-inflammatory mechanisms of compounds from Curcuma mangga rhizomes using RAW264.7 macrophage cells

Curcuma mangga extract and its compounds were investigated for their anti-inflammatory mechanisms against nitric oxide (NO) and prostaglandin E2 (PGE2) release using RAW 264.7 cells. From bioassay-guided fractionation, demethoxycurcumin (1) was isolated from the chloroform fraction, whereas 15,16 bisnorlabda-8(17), 11-dien-13-one (2) and (E)-15,15-diethoxylabda-8(17),12-dien-16-al (3) were from the n-hexane fraction. Bisdemethoxycurcumin (4), the structure of which is similar to that of 1, was also tested. Of the tested compounds, 3 exhibited the highest activity against NO release with an IC50 value of 9.4 microM, followed by 1 (IC50 = 12.1 microM), 4 (IC50 = 16.9 microM) and 2 (IC50 = 30.3 microM). For the effect on PGE2 release, 1 possessed the highest activity (IC50 = 4.5 microM, followed by 4 (IC50 = 5.6 microM), 3 (IC50 = 35.3 microM) and 2 (IC50 = 42.5 microM). The mechanism at transcriptional level revealed that 1, 3 and 4 down-regulated the mRNA expressions of iNOS and COX-2 in a dose-dependent manner, whereas 2 had an effect only on iNOS mRNA. These results indicate that C. mangga and its compounds do exert anti-inflammatory activity. Moreover, this is the first report of the isolation of 3 from C. mangga rhizomes.