Application of the solvent extraction technique to investigation of the anti-inflammatory activity of adlay bran

The current study utilised a bioassay-directed chemical analysis scheme to screen the anti-inflammatory activity of fractions and compounds from adlay bran (AB). Liquid-liquid extraction couple with liquid chromatography-mass spectrometry (LC-MS) was applied to the isolation, analysis and identification of active components in AB samples. Ethanol extracts of AB (ABE) and ethyl acetate extracts AB (ABEa) were obtained and further partitioned with different solvents. The results showed that among all 16 kinds of fractions from ABE and ABEa, ABEa-Ea-B (80% Ea/n-hexane sub-fraction from ABE-Ea) had the most potent inhibitory effects on NO production, iNOS and COX-2 expressions, and proinflammatory IL-6 and TNF-α secretion in lipopolysaccharide-activated RAW264.7 cells system. Mechanistic data from luciferase reporter-gene assay revealed that the anti-inflammatory action of ABEa-Ea-B may be associated with inhibition of NF-kB transcriptional activity. Notably, tangeretin, nobiletin, and p-hydroxybenzoic acid were found to be the main active compounds for the anti-inflammatory properties in ABEa-Ea-B.