13-Oxo-9(Z),11(E),15(Z)-octadecatrienoic Acid Activates Peroxisome Proliferator-Activated Receptor γ in Adipocytes

Peroxisome proliferator-activated receptor (PPAR)gamma is expressed in adipose tissue and plays a key role in the regulation of adipogenesis. PPAR gamma activators are known to have potent antihyperglycemic activity and are used to treat insulin resistance associated with diabetes. Therefore, many natural and synthetic agonists of PPAR gamma are used in the treatment of glucose disorders. In the present study, we found that 13-oxo-9(Z),11(E),15(Z)-octadecatrienoic acid (13-oxo-OTA), a linolenic acid derivative, is present in the extract of tomato (Solanum lycopersicum), Mandarin orange (Citrus reticulata), and bitter gourd (Momordica charantia). We also found that 13-oxo-OTA activated PPAR gamma and induced the mRNA expression of PPAR gamma target genes in adipocytes, thereby promoting differentiation. Furthermore, 13-oxo-OTA induced secretion of adiponectin and stimulated glucose uptake in adipocytes. To our knowledge, this is the first study to report that 13-oxo-OTA induces adipogenesis through PPAR gamma activation and to present 13-oxo-OTA as a valuable food-derived compound that may be applied in the management of glucose metabolism disorders.