A comparative study on hulled adlay and unhulled adlay through evaluation of their LPS-induced anti-inflammatory effects, and isolation of pure compounds

Coicis semen (=the hulled seed of Coix lacryma-jobi L. var. ma-yuen (Rom.Caill.) Stapf; Gramineae), commonly known as adlay and Job's tears, is widely used in traditional medicine and as a nutritious food. Bioassay-guided fractionation of the AcOEt fraction of unhulled adlays, using measurement of nitric oxide (NO) production on lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells, led to the isolation and identification of two new stereoisomers, (+)-(7′S,8′R,7″S,8″R)-guaiacylglycerol β-O-4′-dihydrodisinapyl ether (1) and (+)-(7′S,8′R,7″R,8″R)-guaiacylglycerol β-O-4′-dihydrodisinapyl ether (2), together with six known compounds, 3-8. Compounds 3 and 4 exhibited inhibitory activities on LPS-induced NO production with IC₅₀ values of 1.4 and 3.7 μM, respectively, and suppressed inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein expressions in RAW 264.7 macrophage cells. Simple high-performance liquid chromatography with ultraviolet detection (HPLC/UV) was used to compare the AcOEt fraction of unhulled adlays responsible for the anti-inflammatory activity in RAW 264.7 cells and the inactive AcOEt fraction of hulled adlays.