Peroxisome Proliferator-Activated Receptor γ Ligands Isolated from Adlay Seed (Coix lacryma-jobi L. var. ma-yuen STAPF.)

Through screening for natural ligands against peroxisome proliferator-activated receptor gamma (PPAR gamma) using the PPAR gamma luciferase reporter assay, 6 hydroxy unsaturated fatty acids were isolated from adlay seed (Coix lacryina-jobi L. var. ma-yuen STAPF.) extracts with acetone and 70% ethanol. The structures of these compounds were determined via spectral analysis as 13-hydroxy-(9E,11E)-octadecadienoic acid (13-E,E-HODE) (1), 9-hydroxy-(10E,12E)-octadecadienoic acid (9-E,E-HODE) (2), 9-hydroxy-(10E)-octadecenoic acid (3), 10-hydroxy-(8E)-octadecenoic acid (4), 8-hydroxy-(9E)-octadecenoic acid (5), 11-hydroxy-(9Z)-octadecenoic acid (6). 9-E,E-HODE (2) exhibited the most potent PPAR gamma agonist activity of the isolated hydroxy unsaturated fatty acids. 9E,E-HODE (2) and 13-E,E-HODE (1) are the respective geometrical isomers of 9-hydroxy-(10E,12Z)-octadecadienoic acid and 13-hydroxy-(9Z,11E)-octadecadienoic acid, both of which are likely to be natural PPAR gamma agonists produced in various mammalian cells, suggesting that 9-E,E-HODE may also act as PPAR gamma agonist.