Effect of Adlay (Coix lachryma-jobi L. var. ma-yuen Stapf) Testa and Its Phenolic Components on Cu2+-Treated Low-Density Lipoprotein (LDL) Oxidation and Lipopolysaccharide (LPS)-induced Inflammation in RAW 264.7 Macrophages

The aims of this study were to investigate the effects of adlay testa (AT) on Cu2+-treated low-density lipoprotein (LDL) oxidation, 2,2'-diphenyl-1-picrylhydrazyl (DPPH)-scavenging capacity, and lipopolysaccharide (LPS)-induced inflammation in RAW 264.7 macrophages and determine its active components. The AT ethanolic extract (ATE) was partitioned into four fractions by various solvents as follows: n-hexane (ATE-Hex), ethyl acetate (ATE-Ea), n-butanol (ATE-Bu), and water (ATE-H2O). ATE-Ea and ATE-Bu were further fractionated into ATE-Ea-a-ATE-Ea-h and ATE-Bu-A-ATE-Bu-F, respectively, by column chromatography. Results showed that ATE-Ea, ATE-Bu, ATE-Ea-e, and ATE-Bu-C expressed antiradical, antioxidative, and anti-inflammatory activities with respect to the DPPH-scavenging capacity, LDL protection effect, and nitric oxide (NO) inhibitory activity. Inflammation was further modulated by ATE-Ea, ATE-Bu, ATE-Ea-e, and ATE-Bu-C through downregulating the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) proteins. The following components were found in ATE-Ea-e and ATE-Bu-C after purification and high-performance liquid chromatographic analysis: chlorogenic acid (CGA), vanillic acid (VA), caffeic acid (CA), p-coumaric acid (PCA), ferulic acid (FA), and 2-O-beta-glucopyranosyl-7-methoxy-4(H-2)-benzoxazin-3-one (GMBO). Results showed that CGA, CA, and FA were the major components responsible for the antioxidative and anti-inflammatory activities of ATE-Ea-e and ATE-Bu-C. Subsequently, each gram of ATE-Bu-C had 30.3 mg of CGA, 9.02 mg of CA, and 189 mg of GMBO, while each gram of ATE-Ea-e had 1.31 mg of VA, 3.89 mg of PCA, and 47.6 mu g of FA. In conclusion, ATE has antioxidative and anti-inflammatory activities, and its effects are partially related to its phenolic components. Thus, ATE has the potential to be developed as a functional food targeting chronic diseases.